“Log Petrophysics of the Lower Permian Chase Group southwestern Kansas”

“Log Petrophysics of the
Lower Permian Chase Group
in the Hugoton Gas Field of
southwestern Kansas”
John H. Doveton
Kansas Geological Survey
Spectral
Gamma-ray
log of a
Chase Group
section
Examples of spatial variation of
uranium in Chase Group units
From Luczaj (1998)
Permeability versus porosity and uranium
0.1
m
d
6
5
d
1m
3
d
2
1
10
m
Uranium (ppm)
4
0
0
5
10
Porosity (%)
15
20
Lithodensity
neutron logs
of a Chase
Group section
Chase Group RHOmaa – Umaa crossplot
Compositional profile
computed from
gamma-ray, density,
neutron porosity, and
photoelectric factor
logs
Council Grove core porosity
calibration data set
facies
1
2
3
4
5
6
7
8
NM Silt & Sand
NM ShlySilt
Mar Shale & Silt
Mdst/Mdst-Wkst
Wkst/Wkst-Pkst
Sucrosic (Dol)
Pkst/Pkst-Grnst
Grnst/PA Baff
whole
plugs core total outliers final
156
106
262
9
253
167
31
198
2
196
70
33
103
0
103
67
22
89
0
89
147
59
206
2
204
35
19
54
1
53
116
64
180
11
169
34
28
62
2
60
792
362 1154
27
1127
Log/Core porosity comparison
corephi
15
Dphi
NDphi
Porosity%
13
11
9
7
5
1
2
3
4
5
Facies
6
7
8
25
Facies 1
Facies 2
Facies 3
20
Facies 4
Core porosity
Non-marine
(facies 1 & 2)
and marine
(facies 3 and
4) siltstones
15
10
5
0
0
5
10
15
Density porosity (ls equiv)
20
25
Gas effects:
Invasion and
depth of
investigation
of density
and neutron
tools
Example of gas effect in the
Towanda Limestone
Gamma Ray
API units
0
Neutron/Density porosity limestone equiv.
30
20
10
150
density
2850
neutron
caliper
2900
CGR
PeF
SGR
0
Photoelectric factor
barns/electron
10
0
1.9
45
2.0
S
2.1
e
m
Li
40
ne
to
s
e
30
Do
lo
mi
te
2.2
ρb, bulk density (gm/cc)
35
2.3
25
20
2.4
15
2.5
10
2.6
5
2.7
0
-5
2.8
-10
2.9
-15
3.0
0
10
20
30
NPHI neutron porosity (p.u.) apparent limestone porosity)
40
Φd, denity porosity (p.u.) apparent limestone porosity
Towanda
Limestone
gas effect
on neutron
– density
crossplot
an
n
to
ds
1.9
45
2.0
30
2.1
ne
m
Li
25
40
ne
to
s
e
30
mi
te
2.2
2.3
Φ
15
2.4
Do
lo
20
ρb, bulk density (gm/cc)
35
20
30
t
10
25
15
2.5
25
5
10
20
2.6
5
15
2.7
0
10
-5
2.8
5
2.9
0
Φt =
(PHIN +PHID)
-10
2
-15
3.0
0
10
20
30
NPHI neutron porosity (p.u.) apparent limestone porosity)
40
PHID, denity porosity (p.u.) apparent limestone porosity
Relationship
between
Xplot
porosity,
averaged
neutrondensity
porosity, and
gas effect
Sa
sto
nd
Common porosity estimations
with gas correction:
(1) Approximation of the
Gaymard-Poupon equation
2
Φ=
2
(Φn + Φd)
2
(2) Empirical
Φ = 0.33∗Φn + 0.67∗Φd
Chase Group/ Council Grove
statistical analysis of neutron density
porosities calibrated to core porosity
(accommodating gas effect)
Limestones (n = 786 ):
Φ = 0.399∗Φn + 0.610∗Φd
Dolomites (n = 513 ):
Φ = 4.63+0.259∗Φn + 0.523∗Φd
Acknowledgements
We thank our industry partners for their support
of the Hugoton Asset Management Project and their
permission to share the results of the study.
ABP America Production Company
Cimarex Energy Co.
ConocoPhillips Company
E.O.G. Resources Inc.
Medicine Bow Energy Corporation
Osborn Heirs Company
OXY USA, Inc.
Pioneer Natural Resources USA, Inc.