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Thermal Conductivity, Radiogenic Heat Production and Heat Flow of Some... Cretaceous Rock Units, North Western Desert, Egypt.
Journal of Applied Sciences Research, 6(5): 483-510, 2010
© 2010, INSInet Publication
Thermal Conductivity, Radiogenic Heat Production and Heat Flow of Some Upper
Cretaceous Rock Units, North Western Desert, Egypt.
Abubakr F. Maky and Mohamad A.M. Ramadan
Egyptian petroleum research institute (EPRI) Nasr City-Cairo, Egypt
Abstract: The estimation of thermal conductivity is of great importance for all studies on thermal
evolution of sedimentary basins. Due to the paucity of core samples, the approach proposed here is the
reconstruction of mineralogical model for the studied rock units by interpreting the well, logs data. Then,
the determination of the response equations of the minerals present in each mineralogical model for
extracting the frequency of existing minerals and total porosity of some Upper Cretaceous rock units, such
as the Bahariya Formation and Abu Roash “D,E,F and G” Members at the north western part of Abu ElGharadig Basin, W estern Desert, Egypt. To estimate the thermal conductivity, from a mixing formula, the
geometric average of the individual conductivities weighted by the volumetric proportion of each
component; the radiogenic heat production and heat flow can be defined. The mineralogic model of
Bahariya Formation indicated that, clay minerals as illite, kaolinite, smectite and quartz are the main
minerals present in the studied wells, in combination with some calcite and dolomite. W hereas in A/R“G”
M ember, it reflects that, clay minerals as illite, kaolinite and smectite are the main minerals in association
with some quartz, calcite and dolomite, sometimes with glauconite. Calcite and quartz are the main
minerals present in A/R“F” Member with some clay minerals as illite and kaolinite associated with
dolomite and k-feldspars. The same mineral constituents are present in A/R“E” Member, but with higher
content of clay minerals. At A/R“D” Member, the quartz and calcite are the main minerals with some
clays as illite, kaolinite and smectite, in combination with some dolomite and k-feldspars. The calculated
porosity is varied between low and high values, and filled with variable quantities of water and
hydrocarbons. The average thermal conductivities (ThC) of the different lithologic intervals of Bahariya
Formation; which is considered as a reservoir rock; are ranges between 1.57W /m/K in shaley and
2.78W /m/K in sandstone intervals. W hereas, these of A/R“G” Member are varies from1.37W /m/K in
shaley to 3.32W /m/K in limestone intervales, A/R“F” (sandy limestone) Member ranges from 2.48W /m/K
to 2.7 W /m/K. In A/R “E” Member (ThC), varies between 1.54W /m/K and 3.18W /m/K. Eventually, the
A/R “D” Member has higher (ThC) ranges from 1.74W /m/K to 2.91W /m/K. The radiogenic heat
production (Rhp) of Bahariya Formation varies between low values of 3.96µw/m 3 and reached maximum
values attain from 7.48 to 9.09µw/m3 . In A/R “D” M ember, it ranged between 8.074 and 9.152µw/m 3 ,
eventually the (Rhp) of A/ R“F”, which mainly composed of limestone, is low (3.284µw/m 3 and
4.01µw/m3 ), whereas in A/R “E” Member, the lower part shows lower values, then increase again in some
wells across the study area. The apparent heat flow (HF) of Bahariya Formation is ranged between 67.6
(shale) and 95.2mW /m2 and reached 102.4mW /m2 in limestone intervals; whereas in sandstone, the (HF)
reached 134.7mW /m2 . The A/R“G” Member has (HF) ranged between 70.1 and 82.5, whereas reached
116.9mW /m2 and 158.4mW /m2 in some intervals. In A/R“F” Member, it ranged from 114.75 to
121.02mW /m2 . Eventually in A/R “E and D” Members, they possess higher values of (HF) 135.2 and
145.4mW /m2 in A/R “E” Member, and 124 and 125.8mW /m 2 in A/R “D” Member.
Key wards: W estern Desert, Egypt, thermal conductivity, heat flow and radiogenic heat production.
INTRODUCTION
For understanding the thermal structure of
sedimentary basin, it is important to determine thermal
properties of the sediments, that constitute the basin.
Thermal conductivity is perhaps the most important
factor, that control the configuration of the isotherms
and the flow of heat within the basin [1 6 ] . Radiogenic
heat production in the sediments is known to vary over
several orders of magnitude, with the lowest values in
evaporates and carbonates and the highest values in
black shales. [64 ] . The geothermal gradient in the lowconductivity shale section is elevated (which is the
source rock) relative to the geothermal gradient in the
high conductivity sections[21]. In this paper, we
describe a procedure for calculating the thermal
Corresponding Author: Abubakr F. Maky, Egyptian petroleum research institute (EPRI) Nasr City-Cairo, Egypt
Email [email protected]
483
J. Appl. Sci. Res., 6(5): 483-510, 2010
conductivity, heat flow and radiogenic heat production
of some Upper Cretaceous rock units, as Bahariya
Formation and Abu Roash “D,E,F and G” Members in
Raml-1, Raml-3, El-Faras-1 and El-Faras-3 wells in the
north western part of Abu El-Gharadig basin, which is
the main petroliferous resource in the north W estern
Desert, Egypt.
The major tectonic events of Abu El-Gharadig
basin extended from Paleozoic to Tertiary periods, as
follow: A phase of strong uplift and erosion of the
Paleozoic clastic basin took place in the pre-Jurassic
times. At the end of the Carboniferous age, the first
uplift was active resulting in the major Hercynian
unconformity and the non-deposition of the Permian
and Triassic sediments. This movement was followed
by the major Jurassic transgression. At the end of the
Jurassic, the area was elevated again and another major
u n c o n f o r m i t y d e v e lo p e d . T h e r e a fte r , d u r i n g
Jurassic/Early Cretaceous times, the regional subsidence
resumed with very little tectonic activity, resulting in
a progressive tilting of the Sitra platform towards the
north accompanied by minor faulting. The most
effective tectonic cycles controlling the shape and
development of the area began with the Early
Cretaceous. In the Aptian–Albian times, the Qattara
Ridge became uplifted and subjected to erosion or nondeposition, prior to the onlap of the Late
Albian–Cenomanian clastics. The major fault zone, that
separates the Qattara Ridge from Abu El-Gharadig
basin, was actually already active during the Late
Jurassic times, as well, as during the Aptian times.
During Late Cretaceous times, the tectonics were very
effective with a higher rate of displacement along the
already existing faults, sometimes associated with
lateral displacement. During this time, the tectonic was
resulting in huge and contemporaneous faults, as well
as large amount of Upper Cretaceous sediments and
activity increased drastically.
Extensional tectonic activity was terminated in the
Late Cretaceous by the Syrian arc inversion phase [1 2 ,4 7 ].
The Tertiary was essentially a very quite period and
the tectonic activity was limited to reactivation of the
main faults and to a lesser extent further uplifting of
the oblique ridges [6 9 ].
The Cenomanian Bahariya Formation consists
mainly of fine- to medium- grained quartzitic
sandstone, colorless to pink, occasionally medium to
coarse grained with thin streaks of shales interbeds and
carbonate inclusions [6 3 ] . Bahariya Formation (Early
Cenomanian) is consisted of sandstone with shale
intercalations and limestone interbeds of more maritime
affinity (shallow marine environment), as shown by
Abu El-Ata, [2 ] . This formation is considered as one of
the most important reservoir rocks in the W estern
Desert [6 1 ] . The Bahariya sandstones are the main gas
and / or condensate pay in the Abu El-Gharadig basin.
It represents a gradational phase of fining upwards to
the overlying marine carbonates and shales of the
Turonian -Coniacian Abu Roash Formation. Bahariya
Formation conformably overlies the Burg El-Arab
Formation and subdivided into six units, based on
lithological and electrical logs, of which the unit I is
Geologic Setting: The W estern Desert can be
subdivided, from south to north, into five tectonic
units; Craton, Stable Shelf, Unstable Shelf, Hinge Zone
and Miogeosyncline [6 1 ].
The sedimentary basins of the northern W estern
Desert occupy two provinces separated by the E-W to
ENE-W SW trending Ras Qattara-North Sinai uplift
zone. The northern province includes Shushan, Matruh
and Alamein basins of Late Jurassic– Early Cretaceous
age. The southern province, south of the uplift,
includes mainly Abu El-Gharadig basin of Late
Cretaceous and younger age. Abu El-Gharadig basin is
an E –W oriented intracratonic graben with 300 km
long and 60 km wide. It is bounded by the Sitra
platform to the south and by the Qattara Ridge to the
north. The basin is subdivided into several structural
units, separated by NE-SW trending "oblique ridges" of
varying importance named from E to W : the Mubarak
High, Abu El-Gharadig Anticline and the Mid Basin
Arch [1 2 ].
The most durable phase of tectonism in the
W estern Desert was the Late Cretaceous (Laramian)
event. At some places in the northern W estern Desert,
the Late Cretaceous rocks nonconformably rest directly
on the Jurassic or Paleozoic or even the Basement.
Moreover, at many places, the upper Cretaceous rocks
rest conformably on the lower Cretaceous rocks. The
faulting stage during the late Early and Late Cretaceous
resulted block faults in en-echelon pattern and bordered
by dip-slip faults is an important feature of Abu ElGharadig field, which is a faulted basin located at the
northern central part of the W estern Desert and trended
E-W , [4] . Two main tectonic forces affected the region:
the first is a sinistral shear, which resulted in a
regional NW -SE tectonic feature affected both
provinces in the Jurassic – Early Cretaceous age. The
second is a dextral shear, which resulted in a regional
ENE-W SW tectonics affected the southern provinces
[5 1 ]
. Six major geotectonic cycles or phases can be
recognized in the W estern Desert; these are: the
Caledonian cycle (Cambrian – Devonian), VariscanHercynian (Late Paleozoic), Cimmerian / Tethyian
(Triassic – Early Cretaceous), Sub Hercynian – Early
Syrian Arc (Turonian – Santonian), Syrian Arc main
phase (Paleogene) and the Red Sea phase (OligoceneMiocene) [5 0 ] . These cycles are illustrated in Figure (1).
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J. Appl. Sci. Res., 6(5): 483-510, 2010
the upper pay and the unit IV is the lower pay [4 2 ] . In
the study area, the crude oil is produced from different
intervals of argillaceous sandstone and sands. Also,
Abu Roash Formation is a very significant reservoir
and source rocks in the W estern Desert (Late
Cenomanian – Turonian – Senonian) and is divided
into informal seven members (A,B,C,D,E,F and G), as
shown by Schlumberger (1984). Abu Roash Formation
is formed of arenaceous-argillaceous limestone section
of shallow to open marine environments [2 ].
Generally, it is appeared that, clay minerals as
smectite and kaolinite are the main clays, in association
with some calcite and sandstone of lower API values.
In case of Abu Roash “D” Member, the prevailing
minerals (Fig. 4B), are calcite and quartz, in
association with clays (smectite, kaolinite and illite),
specially in El-Faras-1 well,. There is a valuable
quantity of clay minerals, such as smectite and
kaolinite with some illite in Raml-1& 3 and El-Faras-3
wells, as indicated from the higher API values
associated with sands and cemented by calcite, and
with some secondary dolomite. In case of Abu Roash
“F” Member, which represents carbonate rock unit of
low gamma-ray intensity with little clay content, it is
composed mainly of calcite and sometimes dolomite,
and clay mineral represented by illite, as shown in Fig.
(5A). W hile in Abu Roash “E” Member, the quantities
of clay minerals increase in the form of smectite and
kaolinite with some illite of higher API values, in
combination with quartz and calcite. Eventually, In
case of Abu Roash “D” Member, the clay minerals are
present in valuable fraction around the area of Raml-1
well, as shown in Fig (5B), but there is an increase of
quartz content on the account of clay minerals and
carbonates, specially in Raml -3 well (Fig 5C).
M ineralogic Identification M odels: This study aims to
determine the mineralogic models of the studied rock
units; such as Bahariya Formation and Abu Roash “D,
E, F and G” Members in El-Faras-1, El-Faras-3, Raml1 and Raml-3 wells, that distributed in the northwestern
part of Abu El-Gharadig basin, W estern Desert, Egypt,
as shown in Fig. (3). The study of mineralogic models
and the determination of their volumetric distribution
were done by many authors, as: [3,5,6,7,8,9,10,49,58].
The reconstruction of the mineralogic models and fluid
contents of these rock units from the available well log
data, such as ñ b, ÄT and Ö N is the main target of
this study. Crossplots assist in the selection of the
interpretation parameters and the identification of the
trends and problems of mineralogic models. These
crossplots are sometimes two-dimensional and in other
times are three-dimensional. The formerly mentioned
crossplots are based on knowing and plotting the
matrix coefficient of any mineral, which helps in
driving the mineral constituents of the studied rock
intervals. The minerals present in these rock units are
identified through different crossplots such as:
M Lith- N Lith (M -n) Plot: this type of plots depends
essentially on the fluid and log parameters, which are
incorporated together in three porosity logs (ñ b, ÄT
and Ö N). From these values, two functions (M and N)
are calculated, which are independent of the primary
porosity [18 ] . By using the M-N plot for matrix
identification, the lithologic content for each zone can
be defined, with respect to the standard M and N
values of the common minerals and rocks, as shown by
Abu El-Ata and Ismail [3 ]. In this study, we
concentrated the logging analysis on the mineralogical
identification present in the studied rock units, which
helps in the volumetric detection of each mineral
present in each interval. The studied Bahariya
Formation is characterized by the presence of kaolinite
and illite as the main clay minerals with smectite in all
of the studied wells, in combination with quartz and kfeldspars, while calcite is the main carbonate mineral
with few dolomite, as shown in Fig (6A). The clay
minerals (illite and kaolinite) trend is the main trend in
case of Abu Roash “G” Member with increasing the
calcite content and sometimes the increase of feldspars,
as shown in Fig (6B). Abu Roash “F” Member has
carbonate trend, where the present clay mineral is
directed toward smectite than other clays, as shown in
Fig (7A), which reflects that, this formation is mainly
composed of argillaceous limestone. W hereas the “E
and D” Members are characterized by the increase of
shale content, as kaolinite and illite trend with the
appearance of some dolomite, as shown in Fig (7
B&C).
ñb, vs Ö N with GR Z-plot: This type of plots has
three lines, sandstone line, limestone line and dolomite
line, with points of clay minerals such as illite,
smectite and kaolinite, with gamma ray values in API
units to differentiate between the shaley parts, which
have higher API units of more than 40 API and
characterized by the presence of clay M inerals, such as
illite, smectite and kaolinite; from carbonates, such as
limestone (calcite) and dolomite of lower API units.
Crossplots study and analysis of Bahariya Formation
(Fig 4 A) revealed that, this formation in Raml 1&3
wells is composed of clay minerals as smectite,
kaolinite and illite, in combination with calcite,
dolomite and sandstone, which is represented by quartz.
The presence of higher carbonates reflects maritime
conditions during the deposition of Bahariya Formation.
W hereas in the area around El-Faras-1 and 3 wells, the
quartz content increases, in association with clay
minerals, such as smectite, kaolinite and illite on the
account of carbonate minerals as calcite and dolomite,
so the limy shale, sandy shale and calcareous shale are
prevalent.
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J. Appl. Sci. Res., 6(5): 483-510, 2010
Fig. 1: Regional tectonic highlighting the major geotectonic phases or cycles (after Meshref, 1990)
Fig. 2: Generalized stratigraphic column of Abu El-Gharadig Basin, north W estern Desert, Egypt. (after shell, 2001)
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J. Appl. Sci. Res., 6(5): 483-510, 2010
Fig. 3: Location map of the study area northwest of Abu El-Gharadig Basin.
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J. Appl. Sci. Res., 6(5): 483-510, 2010
Fig. 4: Density versus phi neutron with GR Z plot for Bahariya Formation and Abu Roash "G" Member in the
studied wells, W estern Desert.
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J. Appl. Sci. Res., 6(5): 483-510, 2010
Fig. 5: Density versus phi neutron with GR Z plot for Abu Roash "D,E and F" M embers in the studied wells,
W estern Desert.
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J. Appl. Sci. Res., 6(5): 483-510, 2010
Fig. 6: M Lith N Lith crossplot for Bahariya Formation and Abu Roash "G" Member in the studied wells.
Fig. 7: M Lith N Lith crossplot for Abu Roash "F,E and D" Members in the studied wells.
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J. Appl. Sci. Res., 6(5): 483-510, 2010
Fig. 8: MID plot for Bahariya Formation and Abu Roash "G" Member in the studied wells.
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J. Appl. Sci. Res., 6(5): 483-510, 2010
c-ñ (m a )a vs ÄT (m a )a M ID plot: Such a plot is considered
as complementary way for identifying the lithology, gas
and secondary porosity. It depends on the apparent
matrix parameters as ñ (m a)a and ÄT (m a)a for clean and
shaley zones. They are used in the MID plot to define
the association of essential and accessory minerals, that
form the background of matrix in the analyzed rocks of
the considered zones, as shown by Abu El-Ata and
Ismail[3] .
Ñb= 2.65 VQ + 2.52 VI + 2.41 VK + 2.12 VSem
+ 2.71 VCa + 2.88 VDol + 1.1
ÖN = -0.02 VQ + 0.3 VI + 0.37 VK + 0.44
VSem - 0.01 VCa + 0.01 VDol + 185
ÄT = 55.5 VQ + 110.0 VI + 95 VK + 120VSem
+ 48 VCa + 43.2 VDol + 100
1= VQ + VI + VK + VSem + VCa + VDol + V
where.
VQ
is the volume of quartz fraction.
VI
is the volume of illite fraction.
VK
is the volume of kaolinite fraction.
Vsem
is the volume of smectite fraction.
VCa
is the volume of calcite fraction.
VDol
is the volume of dolomite fraction.
V
is the total porosity.
The resulted frequency distribution of the volumes
of rocks forming minerals and the volumes of fluids
present in the pores of these rock units are used for
calculating the thermal conductivities of these rock
intervals and also the heat flow.
Bahariya Formation: Based on the mineralogic
models of Bahariya Formation in the four studied
wells, the mathematical response equations are shown
as follow:
In Raml-1 well, the mineralogic model includes
quartz, illite, kaolinite, smectite and calcite. The
response equations for this model are as follow:
Ñb= 2.65 VQ + 2.52 VI + 2.41 VK + 2.12 VSem
+ 2.71 VCa + 1.1
ÖN = -0.02 VQ + 0.3 VI + 0.37 VK + 0.44
VSem - 0.01 VCa + 185
ÄT = 55.5 VQ + 110.0 VI + 95 VK + 120VSem
+ 48 VCa + 100
1= VQ + VI + VK + VSem + VCa + V
b- In Raml-3 and El-Faras-1 &3 wells, the
mineralogic model includes quartz, illite, kaolinite,
smectite, calcite and dolomite. The response
equations for this model are as follow:
Ñb= 2.65 VQ + 2.52 VI + 2.41 VK + 2.12 VSem
+ 2.71 VCa + 2.88 VDol + 1.1
ÖN = -0.02 VQ + 0.3 VI + 0.37 VK + 0.44
VSem - 0.01 VCa + 0.01 VDol + 185
ÄT = 55.5 VQ + 110.0 VI + 95 VK + 120VSem
+ 48 VCa + 43.2 VDol + 100
1= VQ + VI + VK + VSem + VCa + VDol + V
Thermal Conductivity: The thermal structure of a
sedimentary basin is controlled by its thermal
conductivity, its boundary conditions, water flow, rate
of sedimentation and erosion, and radiogenic heat
sources. The radiogenic heat production in the
sediments is known to vary over several orders of
magnitudes, with the lowest values in evaporites and
carbonates and the highest values in black shales [6 4 ].
Studying the heat flow and its influences is one of the
prerequisites for modeling the thermal structure of
sedimentary basins and allows the determination of the
geodynamic state, and the composition and structure of
the underlying basement [3 4 ] . As an important aspect of
basin analysis, thermal parameters such as thermal
gradient, radiogenic heat production and heat flow are
crucial to modeling of the thermal maturation of oilsource rocks and the dynamic evolution of a basin [6 6 ].
The hydrocarbon maturation and diagenesis of
sedimentary organic matter are functions of the thermal
history of the host sediments or sedimentary rocks [5 1 ].
The presence of organic matter in the rock matrix can
reduce the rock heat conductivity and so increase the
formation temperature [2 9 ] . Thermal conductivity is
dependent on the composition and geometry of the rock
matrix, on porosity, and on pore medium water or
hydrocarbons. Additional influences in the situation of
a deeply buried rock are pressure and temperature [6 2 ].
Replacement of pore water by gaseous hydrocarbons
results in reduction of heat conductivity and increase of
sediments temperature [3 3 ,3 0] . The geothermal gradient in
the low conductivity shale sections is elevated relative
to the geothermal gradient in the high conductivity
“washing granite” [4 5 ] . The formation of significant
amount of free gas, gas condensate and condensate
Abu Roash Formation: Based on the mineralogic
models of Abu Roash Formation in the four studied
wells, the mathematical response equations are as
follow:
In Raml-1 well, the mineralogic model includes
quartz, illite, kaolinite, smectite and calcite. The
response equations for this model are as follow:
Ñb= 2.65 VQ + 2.52 VI + 2.41 VK + 2.12 VSem
+ 2.71 VCa + 1.1
ÖN = -0.02 VQ + 0.3 VI + 0.37 VK + 0.44
VSem - 0.01 VCa + 185
ÄT = 55.5 VQ + 110.0 VI + 95 VK + 120VSem
+ 48 VCa + 100
1= VQ + VI + VK + VSem + VCa + V
In Raml-3 and El-Faras-1&3 wells, the mineralogic
model includes quartz, illite, kaolinite, smectite, calcite
and dolomite. The response equations for this model
are as follow:
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J. Appl. Sci. Res., 6(5): 483-510, 2010
from organic matter lead to a substantial increase in
temperature up to 5-15ºC. This results from the
reduction of thermal conductivity of the rock as a
result of the lower thermal conductivity of these
hydrocarbon products and the change in heat
conductivity of rocks with dispersed organic matter can
increase the temperature of sedimentary rocks by 3-5ºC
and the rock maturity by not more than 0.02% Ro [3 7 ].
The variability in thermal conductivity of the
sedimentary rocks has to be attributed to the change in
mineral composition (grains and cement) and the rocks,
in which clay cements prevail show distinctively lower
values than rock with silica cement[5 3 ].
Measurements of thermal conductivity cover a
wide spectrum of techniques, that can be subdivided
into direct (laboratory) and indirect (well logging)
approaches. In the past, the most used direct method
was the steady-state divided-bar technique, where either
saturated or non-saturated rock was investigated. Other
techniques use transient heat sources. For example, line
sources are deployed in the pulsed line-source approach
[4 6 ]
, in the needle-probe technique and in the half-space
line-source methods. The two latter two techniques are
described and referenced in more detail by Blackwell,
and Steele [13 ] and Pribnow and Sass, [5 7 ] . A varying
type of direct method recently introduced is termed
‘‘optical scanning’’ [5 4 ] . This method is based on
scanning a sample surface with a focused and movable
heat source, in combination with a temperature sensor.
The thermal conductivity distribution enables a detailed
study of the heterogeneity of the sample. Therefore, the
technique is also of special interest for studying the
physical properties of porous sedimentary rocks under
dry and fluid-saturated conditions [5 5,3 8 ] . Some studies
focused on determining the thermal conductivity from
well logs. [1 6 ] , based on the detailed lithologic
description together with sonic and neutron logs, were
digitized and used for estimating the thermal
conductivity.
This study also makes extensive use of the
previously published thermal conductivity measurements
of rocks from Utah [1 4 ,2 0 ,4 3 ,27 ,5 2,5 6 ] . For formations, where
there are no measured or published conductivity data,
values were used from the measurements of
lithologically similar formations. These are referred to
as assumed thermal conductivity values. Matrix thermal
conductivities in Table (1) are converted to in-situ
conductivities by accounting for porosity and
temperature effects.
In this study, the in-situ thermal conductivity is
based on the volumetric distribution of the mineral
constituents, total porosity and fluid content of the
studied rock units obtained from well log data and,
then geometric mean method for estimating thermal
conductivity of different zones. The conductivity of the
pore water was calculated using the polynomial,
relating temperature to conductivity, given by Deming
and Chapman, [27 ] based on the data of Touloukian et
al, [6 5 ] . No adjustments were made for the salinity of
the pore water. The thermal conductivities of some
rocks forming minerals are shown in Table (1).
Geometric M ean M ethod for Estimating Thermal
Conductivity: The wide variety of thermal conductivity
values for the rock-forming minerals found in Table 1
and the results obtained in this study revealed that: the
knowledge of the complete mineralogy of the rock is
necessary for the accurate assessment of the rock’s
thermal conductivity. Based on the mineralogic
composition, the values of corrected thermal
conductivity ë in (W /m/k) for the different zones in the
studied
rock units can be computed from the
generalized geometric mean method, as expressed by
eq. (1), a method that was successfully used by
W oodside and Messmer, (1961) and Sass et al, (1971):
n
ë m = Ð ëiV i
(1)
i=1
where: Ð represents the product of the thermal
conductivities of the minerals ë raised to the power of
their volumetric proportion v, in which the sum of the
volumetric proportions of the minerals is equal to 1.
The subscript i refers to the i th mineral, there being
z minerals altogether. Equation (1) gives the best
results when the thermal conductivity of each mineral
does not contrast by more than one order of magnitude.
Thermal conductivity (ë) of a porous medium can
be expressed as:
ë= ës
(1 - f)
ëw f ,
(2)
where: ë is the in-situ thermal conductivities, f is
the total porosity, ës is the conductivity of the solid
matrix, and ëw is the conductivity of the pore-filling
fluid, in this case water.
The resulted thermal conductivity for each horizon
obtained from the geometric mean method is corrected
to the formation temperature, since the measured
thermal conductivity is determined at 20ºC. Adjustment
of the matrix conductivity (ë m 2 0 ) values for
temperature was accomplished by using the relation
given by Chapman and Furlong [2 2] .
ë = ë
m 20
[1/ (1 + 0.0005 (T-20))]
(3)
where: ë m 2 0 is the matrix conductivity at 20°C and
T is the formation temperature in degrees Celsius and
the coefficient 0.0005 corresponds to a silty mudstone
lithology [3 6 ] .
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J. Appl. Sci. Res., 6(5): 483-510, 2010
In this discussion of the thermal conductivity, it
has been assumed that, the conductivity is isotropic.
The thermal properties of the studied rock units, such
as Bahariya Formation and Abu Roash “D,E, F, and G’
Members are as follow:
Abu Roash “F” M ember: The thermal conductivity of
Abu Roash “F” M ember, which is composed of
limestone, is ranged between 2.48W /m/K and
2.7W /m/K in Raml-3 well, as shown in Table (9).
These high values of (ThC) in Raml-3 well are mainly
related to the presence of higher content of quartz,
calcite and dolomite minerals, which have higher
thermal conductivities on the expense of the lower
thermal conductivity of clay minerals.
B a ha riya F o rm a tio n: T he corrected therm al
conductivity (ThC) of this formation is shown in Fig
(9) and Table (2). It is clear that, most of the thermal
conductivity in Raml-1 well, is ranged between 1.99
and 2.22W /m/K, except at the upper part, where the
(ThC) is reduced to 1.59W /m/K in the silt and shale
horizons. In Raml -3 well, the (ThC) shows higher
values of 2.62 to 2.68W /m/K. At the lower part of this
formation, it decreases dramatically to 1.85 W /m/K,
then increases at the middle part again where quartz
(sand) content increases, the upper part of this
formation shows reduction in the (ThC) again to a
value of 1.62 W /m/K, as shown in Table (3). In case
of El-Faras-1 well, most of this formation has (ThC) in
the range between 2.2 and 2.73W /m/K, except in two
beds, where it is reduced to 1.7 and 1.78 W /m/K, as
reflected from Table (4). Eventually, the corrected
thermal conductivity of Bahariya Formation at area
surrounding El-Faras-3 well shows uniformity in the
(ThC) lower than that in El-Faras-1 well, which is
ranged from 2.11 to 2.36 W /m/K, as shown in
Table (5).
Abu Roash “E” M ember: This rock unit in Raml-1
well is composed of alternations of shale, limestone
and sandy shale, and has varied thermal conductivities
depending on the difference in percentage of the
present minerals, total porosities and fluid contents. So,
the (ThC) is ranged between 1.68 and 2.04 W /m/K in
the shale horizons and from 1.92 to 3.18W /m/K in the
limestone beds, with an average corrected thermal
conductivity of 2.16W /m/K, as shown in Table (10).
W hereas, the thermal conductivity of this rock unit in
the area around Raml -3 well has a lower thermal
conductivity than in the former well, and is ranged
between 1.54 and 2.03 W /m/K in the calcareous and
sandy shale, to be 2.98 in the limestone beds with an
average corrected thermal conductivity of 2.09W /m/K,
as shown in Table (11). It is mainly related to the
increase of both shale and porosity contents, as well as
the presence of dolomite in this well.
Radiogenic Heat Production: Rocks exhibit a natural
radioactivity caused by the decay of natural
radionuclides [6 2 ] . The three types of isotope decay
series abundant in the different types of rocks are the
uranium series (decay of 238U and 235U), the thorium
series (decay of 232Th), and the decay of potassium
isotope 40K, which is much more abundant in the
shaley rock, especially that contain smectite clay
mineral. The radioactive heat generation (A) in mW /m 3 ,
as a result of isotope decay, is expressed after Rybach
(1976) as follows:
Abu Roash “G” M ember: Abu Roash “G” Member
in Raml-1 well, which is mainly composed of
calcareous shale and limestone, and has
thermal
conductivities ranged between 1.65 and 1.92 W /m/K in
most of the calcareous shale horizons, had reached to
2.75 W /m/K in the horizons of higher calcite content,
as detected in Table(6). In Raml-3 well, due to the
increase of shale content, sometimes the increase of
porosity and the increase of fluid content of lower
thermal conductivity, the (ThC) of this rock unit is
lower than that in case of Raml-1 well, and reduced
down to 1.35W /m/K, and shows higher values up to
3.11W /m/K in the limestone horizons, as shown in
Table (7). The results of the calculated thermal
conductivities of Abu Roash “G” Member in El-Faras-1
well reflected a higher average (ThC) than that
occurred in Raml-1 well, and are ranged between 1.47
and 3.122W /m/K. The shaley parts have thermal
conductivity ranged between 1.48 and 1.76W /m/K,
whereas the limestone horizons reached to 3.12W /m/K.
In El-Faras -3 well, the (ThC) of most of the studied
thick shaley horizons have lower values ranged
between 1.67 and 1.86W /m/K, while the other parts
that are composed of limestone have higher (ThC) and
reached up to 3.32W /m/K.
A = ñ (9:52 U + 2:56 Th + 3:48 K) 10 -5
(4)
W here: ñ is the density of rock (in kg/m 3 ), U and
Th are the contents of uranium and thorium (in ppm)
and K is the content of potassium (in wt.%). The
whole rock abundances of U, Th and K, in principle,
can be determined by chemical analysis, by gammaspectroscopic measurements and from gamma-ray (GR)
borehole logs.
In this study, the radiogenic heat production is
based on the latter approach developed by Bücker and
Rybach [1 7 ] , that uses a linear relationship between the
natural total gamma-ray logs from industrial exploration
(in API units; see Anonymous, [1 1 ] ) and the laboratorymeasured heat production (A, µW /m 3 ), as shown:
494
J. Appl. Sci. Res., 6(5): 483-510, 2010
Fig. 9: MID plot for Bahariya Formation and Abu Roash "F,E and D" Members in the studied wells.
Table 1: Therm al conductivities of som e sedim entary rocks form ing m inerals and som e fluids.
Type
M inerals
Therm al conductivity W /m /K
N on clay
Q uartz
7.80*
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------M inerals
Calcite
3.40*
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------D olom ite
5.10*
------------------------------------------------------------------------------------------------------------Anhydrite
6.40*
------------------------------------------------------------------------------------------------------------Sedrite
3.00*
------------------------------------------------------------------------------------------------------------O rthoclase
2.30*
------------------------------------------------------------------------------------------------------------k-feldspares
2.30*
------------------------------------------------------------------------------------------------------------Albite
2.30*
------------------------------------------------------------------------------------------------------------M ica
2.30*
------------------------------------------------------------------------------------------------------------H alite
6.50*
------------------------------------------------------------------------------------------------------------Gypsum
3.10*
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------Clay
Kaolinite
2.80*
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------M inerals
Chlorite
5.10*
------------------------------------------------------------------------------------------------------------Illite
1.80*
------------------------------------------------------------------------------------------------------------M ixed layer illite/sm ectite
1.90*
------------------------------------------------------------------------------------------------------------Air
0.03**
------------------------------------------------------------------------------------------------------------W ater (20ºC)
0.60**
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------Fluid
O il
0.21***
------------------------------------------------------------------------------------------------------------Gas
0.079***
495
J. Appl. Sci. Res., 6(5): 483-510, 2010
Table 2: Therm al conductivity and heat flow of Bahariya Form ation at Ram l -1 well.
D epth m .
D epth m .
Thickness. m .
Lithology
A. Therm al Conductivity
H eat Flow
1211.59
1205.79
5.79
Shale
1.59
67.58
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------1205.79
1208.23
2.44
silt
1.66
70.55
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------1208.23
1212.50
4.27
S. Shale
1.66
70.55
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------1212.50
1234.76
22.26
Shale
1.61
68.43
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------1234.76
1236.28
1.52
S.s.
2.06
87.55
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------1236.28
1254.88
18.60
S. Shale
1.90
80.75
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------1254.88
1265.85
10.98
Shale
1.71
72.68
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------1265.85
1268.60
2.74
L.S
2.41
102.4
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------1268.60
1281.40
12.80
S. Shale
1.99
84.58
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------1281.40
1283.23
1.83
S.S.
2.24
95.20
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------1283.23
1288.41
5.18
S. Shale
2.15
91.38
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------1288.41
1292.68
4.27
S.S.
2.22
94.35
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------1292.68
1315.24
22.56
S. Shale
1.95
82.88
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------1315.24
1316.16
0.91
S.S
2.27
96.48
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------1316.16
1321.65
5.49
S. Shale
2.02
85.85
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------1321.65
1323.78
2.13
S.S
2.17
92.23
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------1323.78
1329.27
5.49
S. Shale
2.05
87.13
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------1329.27
1334.76
5.49
S.S
2.22
94.35
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------1334.76
1348.78
14.02
S. Shale
2.04
86.70
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------1348.78
1353.35
4.57
S.S
2.24
95.20
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------1353.35
1372.56
19.21
S. Shale
2.13
90.53
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------1372.56
1374.39
1.83
S.S
2.19
93.08
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------1374.39
1376.22
1.83
S. Shale
2.14
90.95
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------1376.22
1379.57
3.35
S.S
2.10
89.25
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------1379.57
1382.62
3.05
S. Shale
2.04
86.70
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------1382.62
1401.52
18.90
S.S.
2.15
91.38
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------1401.52
1408.84
7.32
S. Shale
1.99
84.58
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------Total thickness
197.3
Average
2.033
A = 0.0158 (GR [API] – 0.8)
(5)
Geiger–Müller counters calibrated using Co-60 emitters.
The logs were corrected for the borehole conditions
(borehole diameter and density of the drilling mud) and
for the size and position of the recording unit used.
Logs of a generally abnormal character were discarded.
Abnormal logs could be either a result of abnormal
drill-mud composition (bentonite or KCl mud) or
because of gas entry into the well.
The equation is validated for API values less than
350º and is estimated to give an error of less than
10%.
Total-count gamma-ray (GR) logs were available
for this study. These logs, routinely obtained during
hydrocarbon exploratio n, were m easured with
496
J. Appl. Sci. Res., 6(5): 483-510, 2010
Fig. 10: Minerals distribution, radiogenic heat production and thermal conductivity of Bahariya Formation at Raml
-1 well,
Radiogenic heat production is higher in the finegrained sediments, such as shale, has high radioactive
heat production than sandstone or limestone. So high
heat production group corresponds to the shale horizons
at different ages and may have produced enough heat
for hydrocarbon generation [3 2 ].
The GR logs covering the range of 10–156º API
comprise Bahariya Formation and Abu Roash “D, E, F
and G” Members of Late Cretaceous age were used.
Furthermore, care was taken that only logs were related
to wells with similar drill-mud composition.
Based on equations (5), the radiogenic heat
production (RHP) generated in the studied rock units
are shown as follows in Table (16)
surrounding this well is ranged from 0.15 to 3.96
µW /m 3 , with an average of 1.97µW /m 3 , as shown in
Table (16). This greater variation in (Rh) between these
two wells is due to the higher percentage of clay
minerals in Raml-1 well than in case of Raml-3 well,
especially illite and Kaolinite, which are characterized
by higher percentage of K 4 0 and Thorium .In the area
around El-Faras-1 well, the generated (Rh) is ranged
between 1.02 and 5.399 µW /m 3 , with an average of
3.41 µW /m 3 . W hereas that produced in El-Faras-3 well
is higher than that produced in Raml-3 and El-Faras-1
wells and is ranged from 0.443µW /m 3 to 7.48µW /m 3 ,
with an average of 3.87µW /m 3 . It is clear also that, the
oil producing zones are characterized by higher
radiogenic heat production, that may also related to the
presence of uranium captured by organic matter, from
which the oil produced.
Bahariya Formation: The generated radiogenic heat
(Rh) present in this formation shows a greater effect
from one well to another and is mainly based on the
shale content. In case of Raml-1 well, the generated
radiogenic heat is varied from 0.722 to 9.086 µW /m 3 ,
with an average value of 4.53 µW /m 3 . But in Raml-3
well, the generated radiogenic heat in the area
Abu Roash “G” M ember: The radiogenic heat
production in Abu Roash “G” Member in the studied
well does not show distinctive variation than that
calculated in the Bahariya Formation, except the lower
497
J. Appl. Sci. Res., 6(5): 483-510, 2010
Fig. 11: Minerals distribution, radiogenic heat production and thermal conductivity of Abu Roash "D, E, and F"
Members at Raml -3 well, W estern Desert Egypt.
values in Raml-3 and El-Faras-3 wells, which have
higher values than these of Bahariya Formation. The
opposite is right in case of Raml-1 and El-Faras-1
wells, where the minimum values are higher in case of
Bahariya Formation than that of Abu Roash “G”
M ember, as shown in Table (16). Generally, the
radiogenic heat production (RH) of the area around
Raml-3 well, has lower values than in the area around
the other wells.
production of this rock unit in Raml-1 well, is higher
than that generated in El Raml-3 well. This is mainly
related to the higher content of illite clay mineral in El
Ramal-1 well, which contains, higher K 4 0 .
Abu Roash “E” M ember: The radiogenic heat
production of this rock unit at the area around Raml-1
well, is higher than that around Raml-3well and also
than the underlying Abu Roash “F” Member, as shown
in Table (16). These high values are mainly related to
the presence of excess amounts of clay minerals as
illite, kaolinite and smectite, and also to the presence
of glauconite.
Abu Roash “F” M ember: The radiogenic heat
generated in this rock unit, which is composed mainly
of calcite (limestone), is abruptly reduced for the
maximum value of Raml-1 well, but suddenly increases
for the minimum values, as shown in Table (16). In
Raml-3 well, there is no greater variation in the
maximum or minimum values of these of Abu Roash
“G” Member.
Generally, the radiogenic heat
Abu Roash “D” M ember: In this rock unit, the
produced radiogenic heat reflects higher values in
Raml-1 well than those occurred in Raml-3 well, but
lower than the underlying Abu Roash “E” Member.
498
J. Appl. Sci. Res., 6(5): 483-510, 2010
Table 3: Therm al conductivity and heat flow of Bahariya Form ation at Ram l -3 well.
D epth m .
D epth m .
thickness m .
Lithology,
A. Therm al Conductivity
H eat Flow
1204.88
1207.01
2.13
Shale
1.78
86.86
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------1207.01
1214.02
7.01
S. Shale
2.18
106.38
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------1214.02
1215.24
1.22
Shale
1.63
79.54
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------1215.24
1220.73
5.49
S. Shale
1.83
89.30
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------1220.73
1225.30
4.57
Shale
1.72
83.94
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------1225.30
1230.18
4.88
S. Shale
1.76
85.89
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------1230.18
1231.71
1.52
Shale
1.61
78.57
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------1231.71
1233.54
1.83
S.S.
2.20
107.36
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------1233.54
1257.93
24.39
S. Shale
1.95
95.16
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------1257.93
1269.21
11.28
Shale
1.63
79.54
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------1269.21
1271.95
2.74
L.S
2.25
109.80
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------1271.95
1274.09
2.13
Shale
1.70
82.96
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------1274.09
1276.22
2.13
S. Shale
1.91
93.21
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------1276.22
1278.05
1.83
Shale
1.80
87.84
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------1278.05
1284.45
6.40
S.S
2.01
98.09
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------1284.45
1292.38
7.93
S. Shale
2.37
115.66
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------1292.38
1294.51
2.13
S.S
2.76
134.69
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------1294.51
1318.60
24.09
S. Shale
2.35
114.68
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------1318.60
1320.12
1.52
S.S
2.33
113.70
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------1320.12
1322.87
2.74
Shale
1.85
90.28
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------1322.87
1327.44
4.57
S. Shale
1.84
89.79
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------1327.44
1328.96
1.52
S.S
2.63
128.34
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------1328.96
1335.37
6.40
S. Shale
2.63
128.34
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------1335.37
1339.33
3.96
S.S
2.68
130.78
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------1339.33
1352.44
13.11
S. Shale
2.01
98.09
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------1352.44
1369.82
17.38
S.S
2.62
127.86
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------1369.82
1372.56
2.74
S. Shale
2.48
121.02
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------1372.56
1373.78
1.22
S.S
2.60
126.88
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------1373.78
1402.44
28.66
S. Shale
2.63
128.34
Total thickness
168.9
average
2.13
103.89
Table 4: Therm al conductivity and heat flow of Bahariya Form ation at El-Faras -1 well.
D epth m .
D epth m .
thickness m .
Lithology,
A therm al Conductivity
H eat
765.55
793.29
27.74
Shale
1.98
71.44
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------793.29
798.17
4.88
S.S
2.78
100.39
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------798.17
805.49
7.32
Shale
2.05
74.01
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------805.49
807.32
1.83
S.S
2.46
88.66
----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
499
J. Appl. Sci. Res., 6(5): 483-510, 2010
Table 4: Continue
807.32
814.33
7.01
Shale
2.02
72.97
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------814.33
816.16
1.83
S.S
2.52
91.03
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------816.16
818.29
2.13
Shale
1.78
64.26
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------818.29
820.73
2.44
S.S
2.74
98.90
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------820.73
838.41
17.68
Shale
2.13
76.75
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------838.41
842.68
4.27
Shale
2.26
81.73
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------842.68
845.73
3.05
S.S.
2.53
91.35
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------845.73
860.98
15.24
Shale
2.23
80.46
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------860.98
861.89
0.91
S.S
2.61
94.09
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------861.89
884.15
22.26
Shale
2.19
79.08
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------884.15
914.63
30.49
S. Shale
2.17
78.16
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------914.63
929.27
14.63
S.S
2.68
96.56
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------929.27
930.18
0.91
Shale
2.73
98.57
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------930.18
947.26
17.07
S.S
2.52
90.81
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------947.26
956.10
8.84
S. Shale
2.05
74.08
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------956.10
967.07
10.98
S.S
2.58
93.13
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------967.07
973.17
6.10
S. Shale
1.70
61.29
Total thickness
207.62
average
2.32
83.70
Table 5: Therm al conductivity and heat flow of Bahariya Form ation at El-Faras -3 well.
D epth m .
D epth m .
thickness m .
Lithology,
A. therm al Conductivity
H eat Flow
795.43
822.56
27.13
Shale
1.94
92.73
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------822.56
831.10
8.54
S. Shale
2.23
106.59
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------831.10
833.54
2.44
S.S
2.35
112.33
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------833.54
840.24
6.71
Shale
2.10
100.38
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------840.24
844.51
4.27
S.S
2.39
114.24
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------844.51
862.50
17.99
Shale
1.96
93.69
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------862.50
864.02
1.52
S. Shale
2.57
122.85
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------864.02
867.99
3.96
Shale
2.11
100.86
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------867.99
869.51
1.52
L.S
2.22
106.12
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------869.51
914.63
45.12
Sh. Sand
2.21
105.64
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------914.63
925.61
10.98
S.S
2.33
111.37
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------925.61
927.13
1.52
S. Shale
2.11
100.86
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------927.13
939.02
11.89
S.S
2.33
111.37
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------939.02
946.04
7.01
S. Shale
2.28
108.98
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------946.04
958.54
12.50
S.S
2.36
112.81
500
J. Appl. Sci. Res., 6(5): 483-510, 2010
Table 5: Continue
958.54
959.45
0.91
S. Shale
2.14
102.29
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------959.45
971.95
12.50
S.S
2.36
112.81
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------971.95
973.17
1.22
S. Shale
2.24
107.07
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------973.17
985.37
12.20
S.S
2.39
114.24
Total thickness
189.94
Average
2.26
107.22
Table 6: Therm al conductivity and heat flow of Abu Roash" M em ber at Ram l -1 well.
D epth m .
D epth m .
thickness m .
Lithology
A. therm al Conductivity
H eat Flow
1079.9
1083.8
3.96
Cal Shale
1.93
82.03
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------1083.8
1087.5
3.66
Shale
2.12
90.10
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------1087.5
1091.5
3.96
S. Shale
1.92
81.60
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------1091.4
1138.7
47.26
Shale
1.65
70.13
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------1138.7
1141.5
2.74
L.S
2.25
95.63
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------1141.5
1142.7
1.22
Shale
1.65
70.13
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------1142.7
1144.8
2.13
L.S
1.88
79.90
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------1144.8
1148.5
3.66
Shale
1.94
82.45
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------1148.5
1154.3
5.79
L.S
2.75
116.88
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------1154.3
1156.7
2.44
Shale
1.77
75.23
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------1156.7
1157.9
1.22
L.S
2.15
91.38
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------1162.2
1174.7
12.50
Shale
1.67
70.98
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------1174.7
1176.5
1.83
L.S
1.74
73.95
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------1176.5
1199.4
22.87
S. Shale
1.79
76.08
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------1199.4
1211.6
12.20
L.S
1.79
76.08
Total thickness
Average
1.93
82.13
Table 7: Therm al conductivity and heat flow of Abu Roash "G" M em ber at Ram l -3 well.
D epth m .
D epth m .
thickness m .
Lithology
A. therm al Conductivity
H eat Flow
1083.6
1090.6
7.01
Cal Shale
1.8
87.84
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------1090.6
1094.2
3.66
S.Shale
1.76
85.89
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------1094.2
1143.3
49.09
Shale
1.42
69.30
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------11433
1146.3
3.05
L.S
1.97
96.14
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------1146.3
1147. 6
1.22
Shale
1.67
81.50
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------1147. 6
1149.1
1.52
L.S
2.28
111.26
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------1149.1
1151.8
2.74
Shale
1.37
66.86
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------1151.8
1157.9
6.10
L.S
3.11
151.77
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------1157.9
1159.8
1.83
Shale
1.49
72.71
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------1159.8
1161.3
1.52
L.S
1.97
96.14
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------1161.3
1164.9
3.66
S.Shale
1.82
88.82
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------1164.9
1177.4
12.50
Shale
1.39
67.83
----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
501
J. Appl. Sci. Res., 6(5): 483-510, 2010
Table 7: Continue
1177.4
1178.9
1.52
L.s
1.98
96.62
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------1178.9
1182.9
3.96
Shale
1.53
74.66
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------1182.9
1186. 9
3.96
S.Shale
1.69
82.47
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------1186.9
1190.2
3.35
L.S
1.96
95.65
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------1190.2
1192.7
2.44
Shale
1.35
65.88
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------1192.7
1195.1
2.44
S.Shale
1.72
83.94
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------1195.1
1204.9
9.76
Cal Shale
2.03
99.06
Total thickness
average
1.81
88.12
Table 8: Therm al conductivity and heat flow of Abu Roash "G" M em ber at El-Faras -1 well.
D epth m .
D epth m .
thickness m .
Lithology
A. therm al Conductivity
H eat Flow
649.39
700.61
51.22
Shale
1.58
56.93
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------700.61
710.37
9.76
L.S
2.19
79.20
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------710.37
712.50
2.13
Shale
2.24
80.79
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------712.50
718.90
6.40
L.S
3.12
112.7
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------718.90
731.71
12.80
Shale
1.68
60.68
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------731.71
737.20
5.49
L.S
2.80
101.2
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------737.20
742.99
5.79
Shale
1.74
62.76
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------742.99
749.09
6.10
L.S
2.34
84.31
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------749.09
756.10
7.01
Shale
1.76
63.58
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------756.10
757.62
1.52
S.S
1.48
53.36
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------757.62
762.20
4.57
S. Shale
1.60
57.84
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------762.20
765.55
3.35
L.S
2.13
77.04
Total thickness
116.16
average
2.06
74.20
Table 9: Therm al conductivity and heat flow of Abu Roash "G" M em ber at El-Faras -3 well.
D epth m .
D epth m .
thickness m .
Lithology
A. therm al Conductivity
H eat Flow
677.1
734.15
57.01
Shale
1.67
80.02
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------734.2
736.89
2.74
L.S
2.27
108.48
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------736.9
742.38
5.49
Sh + L.S
2.15
102.64
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------742.4
749.70
7.32
L.S
3.32
158.49
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------749.7
767.68
17.99
Shale
1.86
88.70
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------767.7
771.95
4.27
Sh + L.S
2.26
108.14
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------771.9
776.52
4.57
Shale
1.81
86.52
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------776.5
778.05
1.52
L.S
2.29
109.59
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------778.0
780.49
2.44
Shale
1.81
86.31
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------780.5
795.43
14.94
Sh+ L.S
2.17
103.84
Total thickness
118.29
average
2.26
502
J. Appl. Sci. Res., 6(5): 483-510, 2010
Table 10: Therm al conductivity and heat flow of Abu Roash "D " M em ber at Ram l -1 well.
D epth m .
D epth m .
thickness m .
Lithology
A therm al Conductivity
H eat Flow
934.76
938.11
3.35
S. Shale
2.69
114.33
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------938.11
940.85
2.74
L.S
2.91
123.68
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------940.85
944.51
3.66
Shale
2.34
99.45
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------944.51
951.52
7.01
L.S
2.87
121.98
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------951.52
953.96
2.44
Shale
2.2
93.50
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------953.96
956.10
2.13
L.S
2.39
101.58
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------956.10
962.20
6.10
S. Shale
2.00
85.00
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------962.20
969.51
7.32
L.S
2.64
112.20
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------969.51
974.70
5.18
S. Shale
2.96
125.80
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------974.70
978.35
3.66
L.S
2.61
110.93
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------978.35
988.41
10.06
Cal Shale
2.88
122.40
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------988.41
991.46
3.05
L.S
2.16
91.80
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------10.00
L.S
2.67
113.48
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------Average
2.56
108.93
Table 11: Therm al conductivity and heat flow of Abu Roash "D " M em ber at Ram l -3 well.
D epth m .
D epth m .
thickness m .
Lithology
A therm al Conductivity
H eat Flow
939.63
941.16
1.52
Shale
2.39
116.63
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------941.16
943.90
2.74
L.S
2.31
112.73
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------943.90
947.87
3.96
Shale
2.06
100.53
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------947.87
955.18
7.32
L.S
2.54
123.95
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------955.18
956.40
1.22
Shale
2.46
120.05
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------956.40
957.32
0.91
L.S
1.74
84.91
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------957.32
958.23
0.91
Shale
2.00
97.60
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------958.23
960.67
2.44
L.S
2.24
109.31
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------960.67
966.77
6.10
Cal Shale
2.16
105.41
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------966.77
972.56
5.79
L.S
2.57
125.42
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------972.56
978.66
6.10
S. Shale
2.37
115.66
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------978.66
981.71
3.05
L.S
2.38
116.14
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------981.71
988.72
7.01
Cal Shale
1.82
88.82
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------988.72
994.51
5.79
L.S
2.29
111.75
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------54.88
average
2.24
109.21
503
J. Appl. Sci. Res., 6(5): 483-510, 2010
Table 12: Therm al conductivity and heat flow of Abu Roash "E" M em ber at Ram l -1 well.
D epth m .
D epth m .
thickness m .
Lithology
A therm al Conductivity
H eat Flow
991.46
995.43
3.96
L.S
2.53
107.53
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------995.43
999.09
3.66
Shale
2.04
86.70
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------999.09
1000.6
1.52
L.S
1.92
81.60
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------1000.6
1014.9
14.33
Shale
1.87
79.48
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------1014.9
1017.7
2.74
L.S
2.44
103.70
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------1017.7
1019.5
1.83
Shale
1.68
71.40
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------1019.5
1023.5
3.96
S. Shale
1.88
79.90
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------1023.5
1025.3
1.83
Cal Shale
1.93
82.03
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------1025.3
1031.1
5.79
L.S
3.18
135.15
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------Average
2.16
91.94
Table 13: Therm al conductivity and heat flow of Abu Roash "E" M em ber at Ram l -3 well.
D epth m .
D epth m .
thickness m .
Lithology
A therm al Conductivity
H eat Flow
994.51
997.87
3.35
L.S
2.35
114.68
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------997.87
1002.4
4.57
S.Shale
2.03
99.06
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------1002.4
1004.6
2.13
L.S
2.23
108.82
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------1004.6
1006.7
2.13
Shale
1.54
75.15
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------1006.7
1010.7
3.96
S. Shale
1.79
87.35
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------1010.7
1019.2
8.54
Cal Shale
1.75
85.40
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------1019.2
1025.0
5.79
L.S
2.04
99.55
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------1025.0
1030.5
5.49
S.Shale
2.07
101.02
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------1030.5
1036.6
6.10
L.S
2.98
145.42
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------average
2.09
101.83
Table 14: Therm al conductivity and heat flow of Abu Roash "F" M em ber at Ram l -1 well.
D epth m .
D epth m .
thickness m .
Lithology
1031.1
1079.9
48.78
L.S
Table 15: Therm al conductivity and heat flow of Abu Roash "F" M em ber at Ram l -3 well.
D epth m .
D epth m .
thickness m .
Lithology
1036.6
1083.5
46.95
L.S
A therm al Conductivity
2.7
A therm al Conductivity
2.48
H eat Flow
114.75
H eat Flow
121.02
Table 16: Radiogenic heat production in the studied rock units of the study area
W ell, nam e
Form ation
m ax heat Production
m in heat Production
Average heat Production
Ram l-1
A/R "D "
4.493
0.292
1.458
-----------------------------------------------------------------------------------------------------------------------------------------------------------A/R "E"
5.795
0.071
2.678
-----------------------------------------------------------------------------------------------------------------------------------------------------------A/R "F"
4.011
1.143
2.449
-----------------------------------------------------------------------------------------------------------------------------------------------------------A/R "G"
9.152
0.162
4.202
-----------------------------------------------------------------------------------------------------------------------------------------------------------Bahariya
9.086
0.722
4.529
----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
504
J. Appl. Sci. Res., 6(5): 483-510, 2010
Table 16: Continue
Ram l-3
A/R "D "
3.403
1.741
2.637
-----------------------------------------------------------------------------------------------------------------------------------------------------------A/R "E"
4.275
1.411
2.755
-----------------------------------------------------------------------------------------------------------------------------------------------------------A/R "F"
3.284
1.326
2.329
-----------------------------------------------------------------------------------------------------------------------------------------------------------A/R "G"
3.345
1.029
2.001
-----------------------------------------------------------------------------------------------------------------------------------------------------------Bahariya
3.959
0.147
1.968
--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------El-Faras -1
A/R "G"
6.402
0.386
2.774
-----------------------------------------------------------------------------------------------------------------------------------------------------------Bahariya
5.399
1.018
3.41
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------El-Faras -3
A/R "G"
8.074
0.225
3.363
-----------------------------------------------------------------------------------------------------------------------------------------------------------Bahariya
7.481
0.013
3.871
predetermined is the heat flow, so by iterating through
various surface heat flow magnitudes, alteration of the
calculated geothermal gradient is possible. An optimum
surface heat flow value is found, that minimizes the
differences between a calculated temperature for the
approximate depth and the corrected BHT. The resulted
geothermal gradients of the studied wells and their
averages are shown in Table (17)
Heat-flow Data:
Temperature Data: A transient bottom hole
temperature (BHT) is recorded by a maximum
temperature thermometer through an oil or gas well
logging tool. Temperatures are least perturbed by
drilling at the bottom of the well. As these
temperatures are recorded, the length of the shut- in
time (ts) is also recorded as either clock time or the
length of time elapsed, since the circulation of drilling
mud ceased. If multiple transient BHTs are recorded at
the same depth in a well, then the thermal relaxation
of the well and, in particular, the steady-state BHT can
be calculated [19,4 4] . However, in this study, we used the
chart made by Shell (1982).
Bahariya Formation: Vertical heat flow within Raml-1
well ranges from about 67mW /m 2 to over 100mW /m 2
for the limestone interval, averaging over 86mW /m 2 .
Heat flow drops- off significantly towards the upper
part of this rock unit due to the increase of shale
content and in combination with the increase of
porosity, which filled with water and sometimes oil
with their lower thermal conductivities. In the area
around Raml-3 well, the vertical heat flow can be
divided into two parts, the lower part is characterized
by higher vertical heat flow ranges from 113.7mW /m 2
to 134.7mW /m2 , while the upper part of this formation
has lower heat flow ranges between 78.6mW /m 2 and
98.1mW /m 2 . This area is higher in the heat flow than
the area around Raml-1 well. In El-Faras-1 well, the
vertical heat flow ranges between 61.3mW /m 2 and
100.4mW /m 2 for the sandy part, while the thickest part
of this formation is composed of shale and sandy shale
of low vertical heat flow ranges from 61.3mW /m 2 to
79.04mW /m 2 . Eventually in El-Faras-3 well, most of
the studied horizons have vertical heat flow ranges
from 109mW /m2 to 112.8mW /m 2 , except a horizon of
1.52 m thickness has high vertical heat flow value of
122.9mW /m2 , in which the lowest values are present in
thick shale beds of 27.1 and 18m thicknesses of
vertical heat flow of 92.7mW /m 2 and 93.7mW /m 2 ,
respectively.
Heat Flow Determination: Heat- flow q was
determined using the interval method. It is given by the
Fourier`s law of heat conduction, as follows:
q 0 = ë dt/dz
(6)
where: q 0 is the surface heat flow, ë is the average
of the corrected thermal conductivity of the interval
and dt/dz is the geothermal gradient.
In this study, equation (6) was used for the
primary heat flow calculations. Steady-state BHT data
are combined with ground surface temperatures and
thermal conductivity data as input to equation (6). This
is accomplished using a spreadsheet, which creates a
temperature-depth profile for each heat flow site using
equation (6), based on the heat production, porosity,
temperature effects, steady-state BHT and thermal
conductivity data. In the equation, once the layer
thicknesses, heat production and thermal conductivity
profile have been determined, a temperature at any
given depth can be calculated by assuming a surface
heat flow. In this calculation, the only value that is not
505
J. Appl. Sci. Res., 6(5): 483-510, 2010
Abu Roash “G” M ember: The vertical heat flow in
A/R “G” Member of the area around Raml-1 well
ranges from70.1mW /m2 to 82.5mW /m 2 , except four thin
horizons range from 90.1mW /m 2 to 116.88mW /m 2 and
are composed of shaley sand and limestone, in which
the average value of this rock unit reached
82.13mW /m 2 . W hile the heat flow at the area around
Raml-3 well has higher values in most of the studied
horizons and varies from 81.5mW /m 2 to 88.8mW /m 2 ,
in accommodation with thick shaley horizons of lower
heat flow ranges from 67.8mW /m 2 to 74.66mW /m 2 , the
limestone zones are characterized by higher vertical
heat flow ranges from 96.14mW /m 2 to 151.77mW /m 2 ,
with average value of vertical heat flow in the area
around Raml-3 well of 88.12mW /m 2 . The vertical heat
flow values at the area around El-Faras-1 well range
from 53.36mW /m 2 to 63.6mW /m 2 in most horizons of
this rock unit and from 79.2mW /m 2 to 112.7mW /m 2 in
the sandy and limestone horizons with an average
value of 74.2mW /m 2 , which represents the lowest
vertical heat flow in this rock unit. In the area around
El-Faras-3 well, the heat flow in most of the studied
horizons, which are composed of limestone range from
102.64mW /m2 to 158.5mW /m2 , while the other shaley
and sandy horizons have heat flow values vary from
80.02mW /m2 to 88.7mW /m2 , with an average heat flow
of 103.84mW /m 2 .
This variation of vertical heat flow can be
attributed to the combination of variable thickness of
heat-generating materials in the basement, variation in
percentage of minerals present in the matrix and fluid
content present in pore spaces such as oil, water or
gases. Also, the heat refraction through areas of
relatively shallow basement and varied tectonic events,
which led to the subsidence and development of fault
blocks during the Syrian arc system of Late
Cretaceous.
Summary and C onclusions: T he mineralogic
composition of the rock units studied in the area
around Raml-1 and 3, and El-Faras-1 and 3 wells is
determined from their well log data by the aid of
various types of crossplots and mathematical equations.
These models clear that, most of the analyzed rock
units are mainly composed of variable quantities of
clay minerals such as illite, smectite and kaolinite,
added to quartz, calcite and dolomite. K-feldspare is
present in the Bahariya Formation and in the Abu
Roash “D, E, F and G” Members at Raml-3 well.
From the frequency distribution of the rock forming
–minerals, it is clear that, there are sea level
fluctuations starting with the deposition of Bahariya
Formation of shallow marine environment. This
Formation is characterized by intermediate thermal
conductivities in most of the lower parts which is
characterized by higher quartz content, reduced
upwardly with the increase of shale and also porosity
i,e, increase of fluid contents. The radiogenic heat
production is in ascending order with the increase of
shale content, except in case of El Faras-1 well, where
the thermal conductivity is high, but with lower heat
flow, this is mainly related to the lower geothermal
gradient in this well. This lower geothermal gradient is
related to that the measured bottom hole temperature is
recorded at shale interval, since shale has low thermal
conductivity, so it has low heat loss and good
preservation of the conserved heat energy in this
interval.
In case of Abu Roash “G” Member, with the
increase of transgression of sea, the shale and
carbonate contents increase on the expense of quartz
content, so the thermal conductivity of this rock unit is
reduced in the shaley intervals. W hile the limestone
horizons have higher thermal conductivities than the
underlying Bahariya Formation, the increase of shale
content is also accompanied with the increase of
radiogenic heat production except, in the area around
Raml-3 well. In case of Abu Roash “F” Member, the
carbonate content is more than the underlying Abu
Roash “G” Member, this change of lithology to more
carbonate minerals as calcite and dolomite and the
Abu Roash “F” M ember: The vertical heat flow of
A/R “F” Member, which is composed of thick
limestone bed, in the two studied wells of El-Faras -1
& 3 are 11 4 .7 5 m W /m 2 and 121.024m W /m 2 ,
respectively.
Abu Roash “E” M ember: In this rock unit, the
vertical heat flow is graded from shaley horizons of
low values range from 71.4 to 79.9mW /m 2 to, 81.6 and
135.15mW /m 2 in the limestone horizons, with an
average of 91.94mW /m 2 in El-Faras-1 well. W hile in
El-Faras-3 well, the vertical heat flow of A/R “E”
Member in the area around El-Faras-3 well shows
higher values than in case of El-Faras-1 well, which
range from 108.8mW /m 2 to 145.42mW /m 2 in the
limestone horizons and decrease to values range
between 87.4mW /m2 and 101.02mW /m 2 in the sandy
shale to the lowest value in the shale of 75.2mW /m 2 ,
with an average vertical heat of 101.83mW /m 2 .
Abu Roash “D” M ember: This rock unit in the area
around Raml-1 and 3 wells is characterized by high
vertical heat flow in the range between 99.5 up to
125.8mW /m2 , except few horizons of less than
100mW /m2 . The average values are 108.93mW /m 2
and109.21mW /m2 in Raml-1 and 3 wells, respectively.
506
J. Appl. Sci. Res., 6(5): 483-510, 2010
comparable decrease of clay minerals content and
quartz led to the increase in thermal conductivity than
the shaley beds and also the reduction of radiogenic
heat production. The high heat flow in case of Raml-3
well than in Raml-1 well, is mainly related to the
increase of the geothermal gradient in this well, to
4.87. The uniformity of the lithology of Abu Roash
“F” (limestone) reflects the stability of the sea level
during the deposition of this rock unit. Grading upward
to Abu Roash “E” Member, the sea level started to
oscillate, so this rock unit is variegated in lithology
leading to variation in thermal conductivity and heat
flow between higher values in the limestone horizons
to lower values in the shaley beds. Also, the variation
in radiogenic heat production with higher values in
shaley beds, which are considered the source rocks for
hydrocarbons, so the increase of Rhp helps in the
maturation of the present organic matter. These
variations in lithology and thermal conductivity appear
clearly with the overlying Abu Roash “D” Member, but
with higher values in the thermal conductivity and heat
flow than the lower unit. This is due to the increase of
quartz and limestone, which are supported by the
reduction of radiogenic heat production.
Generally, the radiogenic heat production, thermal
conductivity and heat flow in the sedimentary rock
units are highly affected by lithologic composition,
which is mainly based on the depositional environment.
This means that, at the transgressive stage which is
characterized by the increase of shale content and
reduction of sand (quartz) content, the result is the
decrease of thermal conductivity and heat flow, but the
radiogenic heat production increases, so the loss in heat
is low, leading to the preservation of heat energy. This
causes the measured bottom hole temperature to be
lower than the case of high stand system tract or
regressive stage, which is characterized by the increase
of sands of higher thermal conductivity and higher heat
flow. Radiogenic heat production will be low,
especially in clean sands which are characterized by
low quantity or absence of clay minerals or Kfeldspars, so the measured bottom hole temperature will
be higher than that, measured in the shaley beds, which
are considered as source rock for cooking the organic
matter of generating hydrocarbons.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
13.
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14.
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