Document 2506964

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Example from the Panoma (Council Grove) Field, Hugoton Embayment, Southwest Kansas
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Martin K. Dubois , Alan P. Byrnes , Geoffrey C. Bohling , Shane C. Seals , and John H. Doveton
(1) Kansas Geological Survey, University of Kansas,(2) Pioneer Natural Resources USA, Inc.
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Idealized
Depositional
Model
(AAPG 2003, Salt Lake City, Utah)
Http://www.kgs.ku.edu/PRS/publication/2003/ofr2003-30/index.html
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Statistically-based Lithofacies Predictions for 3-D Reservoir Modeling:
Lithofacies, Sequences,
Depositional Environments
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(Modified after Reservoirs, Inc.)
Flooding Surface
400
0
300
0
100 M
100 K
200
100
0
1930
1940
1950
1960
1970
1980
1990
2000
Cumulative Gas Per Well
(Council Grove)
PANOMA FIELD GAS PRODUCTION
"Lumped" Lithofacies
Council Grove A1- B5
Nonmarine
45%
O
Lithofacies Distribution
Council Grove, Panoma Field
-50
0
NM Shly Silt
536 “LAS” Wells
8000 Wells
120
2,500
100
2,000
80
1,500
60
1,000
40
500
20
536 “LAS” Wells
Maps of the A1SH (top Council Grove) through the B5LM (base Cottonwood)
Hugoton
A1 LM
Panoma
Seven Sequences
The Council Grove Group is comprised of
seven fourth-order marine-nonmarine
sequences bounded by unconformities on
exposed carbonate surfaces. A typical vertical
succession, beginning at the exposed
carbonate surface, are primarily wind blown
silts, very fine sands and clay rich silts with
paleosols. Above a flooding surface are
System Series
generally thin, shallow water carbonates with
grain-supported textures deposited during the
initial, shallow water portion of the flooding
event. These are overlain by deeper water
dark marine siltstones and silty carbonate
mud- and wackestones which are, in turn,
overlain by “cleaner” mud- and wackestones
deposited in shallower water. With progressive
shallowing these are overlain by either
packstones and grainstones, interpreted to
indicate increased wave or tidal agitation; quiet
water, lagoonal, mudstones and wackestones;
or silty dolomites and dolomites, where there
was little or no wave agitation. Fenestral and
laminated tidal flat carbonates are also
common near the top of the carbonate interval.
Exposure is evidenced by well-developed
calcretes, root molds, and other indicators.
Higher frequency cycles are evident in the
Funston and Neva, in particular.
Stratigraphy
Wackestone
NM Shly Silt
Dolomite
Mar Shale & Silt
Packestone
Mudstone
Grnst & PA Baf
Council Grove Group
Formation
Group
Field
Council Grove
Stratigraphy
NM Silt & Sd
Member
Updip Limit
1995
Funston
Modified after Pippin (1985)
Panoma Field
1985
0
2005
600 Meters
1975
Wackestone
Packestone
Strat X-Sections
B1 LM
B2 LM
B3 LM
B4 L
M
Newby 2-28R
Field
Zone
B5
Speiser
Shale
LM
A1
Sumner
Chase
Byerly
Bradshaw
Blue Rapids
Shale
Panoma
Greenwood
Shawnee
Hooser
Shale
Eiss LS
B3
Morrill Ls
Florence Sh
B4
Cottonwood B5
Limestone
Eskridge
Shale
Wabaunsee
Grenola
Limestone
Mdst, Wkst & Shale
Middleburg B2
Limestone
Stearns Shale
Beattie
Limestone
Admire
Pkst, Grnst & Dol.
Easly Creek Sh
Bader
Limestone
Council
Grove
Non Marine
B1
Crouse
Limestone
Neva
Limestone
Salem Point Sh
Burr Ls
Legion Sh
Sallyards Ls
C
Middleburg
Eis
Morr
ill
Cot
ton
wo
od
Funston
Limestone
Hugoton
Crouse
Stratigraphic Cross Section
Datum: Top of Council Grove
Panoma
CL
M
Ne
Not to Scale
va
NM Silt & Sd
NM Shly Silt
Lithofacies are those predicted by neural net models (see Panel
3) in wells without triangles around the well symbols. Lithofacies
by core description are shown in wells with triangles which are
two of the eight ‘keystone wells.”
Maps and cross sections in this panel were created
In geoPLUS Petra with an academic license.
Mar Shale & Silt
Mudstone
Wackestone
Dolomite
Packestone
Grnst & PA Baf
Northwest to southeast
cross sections illustrate the
large-scale lithofacies and
depositional relationships
in the Panoma Field. The
updip limit to the Panoma
coincides with thinned
marine carbonate intervals
and their reciprocally
thicker nonmarine silts and
shaly silts. The smaller
scale cross section of the
same wells shows the 8
lithofacies using Petrel's
interpretive colorfill. It
illustrates some major
lateral and vertical facies
relationships but is not to
be considered a true
representation of the finer
geometries.
4%
Core Photos
Bader Ls
Flooding Surface
Hooser Sh
Sequence Boundary
Stuart
Eiss Ls
Newby
Kimzey
(Key wells are named)
Cores Available
NM Silt & Sd
Mar Shale & Silt
Wackestone
Packestone
NM Shly Silt
Mudstone
Dolomite
Grnst & PA Baf
A1-B5 Pay Facies (L6,7,8)
(Sum of Net / Sum of Gross)
23%
Mar Shale & Silt
Dolomite
200 Feet
0
1965
Generalized Field X-Section
Cumulative Prod. (BCF)
3,000
Alexander
Sequence Boundary
26%
NM Silt & Sd
3,500
140
Beaty
During Council Grove deposition, the Panoma Field
area was situated on a broad shallow shelf or ramp that
dipped gently southward into the Anadarko basin in
Oklahoma. The geometry of the shelf was conducive
for broad, parallel depositional environments and
associated lithofacies belts. In response to cyclical sea
level fluctuations, lithofacies belts migrated across the
shelf resulting in a predictable vertical succession of the
eight major lithofacies.
(SL
)
Mud
Support
30%
Mudstone
160
Shrimplin
12%
4%
16%
7%
8%
Grnst & PA Baf
(For A1 - B5)
Core from Middleburg (B2 LM)
468 “LAS” Wells
Statement of Problem:
1. No comprehensive geologic model for the Council Grove available.
2. Accurate reservoir model is critical for most efficient management of
remaining resources in this large asset.
3. Lithofacies controlled petrophysical properties dictate gas saturations.
4. Accurate discrimination of lithofacies reduces error in predicted
permeability and gas volume.
5. The Council Grove is a large, complex heterogeneous reservoir.
6. Field-wide upscaling of lithofacies distribution for reservoir characterize
-ation and analysis of large heterogeneous reservoirs like the
Panoma Field is impractical by traditional methods.
Capillary Pressure Curves by Facies
1000
1000
100
1-NM Silt & Sand
2-NM Shaly Silt
3-Marine Sh & Silt
4-Mdst/Mdst-Wkst
6-Sucrosic Dol
1
0.1
1-NM Silt & Sand
2-NM Shaly Silt
0.01
3-Marine Sh & Silt
4-Mdst/Mdst-Wkst
0.001
5-Wkst/Wkst-Pkst
6-Sucrosic Dol
7-Pkst/Pkst-Grnst
0.0001
0.00001
0
0
10
20
30
2
4
6
8
10
12
14
16
18
20
22
40
50
60
70
80
90
100
Water Saturation (%)
Capillary Pressure Curves by Facies
(Porosity = 10%)
Council Grove facies identification is important to
reservoir characterization because petrophysical properties
vary between facies. At porosities > 6% permeability in
grainstone/bafflestones can be 30X greater than mudstones
and >100X greater than marine siltstones of similar porosity.
Differences in permeabilities between nonmarine silt/sandstones and shaly siltstones range from 3.3X at 12% porosity
to 7X at 18%.
Capillary pressures and corresponding water
100
1-NM Silt&Sand
2-NM Shaly Silt
3-Marine Sh & Silt
4-Mdst/Mdst-Wkst
5-Wkst/Wkst-Pkst
6-Sucrosic Dol
7-Pkst/Pkst-Grnst
8-Grnst/Grnst-PhAlg Baff
10
0
10
20
30
24
In situ Porosity (%)
10
1000
1. Identify and characterize key lithofacies and tie to core petrophysical
properties.
2. Predict lithofacies for wells without cores using a neural net and electric
log curves and marine-nonmarine indicator curve as predictor
variables. Generate predicted lithofacies and probability curves.
3. Fill 3-D cellular volume with lithofacies and porosity using Petrel.
4. Add lithofacies-constrained permeability and gas saturations to cell
properties with transform formulas and height above free water.
5. Export cellular model with porosity, permeability, and initial gas
saturations to a reservoir simulator.
10
8-Grnst/PhAlg Baff
8-Grnst/PhAlg Baff
wells and fill a 3D volume with lithofacies constrained porosity,
permeability and gas saturations.
100
5-Wkst/Wkst-Pkst
7-Pkst/Pkst-Grnst
Solution: Use artificial intelligence to predict lithofacies in 500
Permeability vs Porosity by Facies
(Porosity = 7%)
In situ Klinkenberg Permeability (md)
Keyes
Dome
500
+50
0
Cherokee
Basin
600
Middleburg LS
Gas-Brine Height Above Free Water (ft)
700
Hug
oto
n
Hugoton
Embayment
Non-Hugoton Gas
In the Panoma Field of southwest Kansas the Council Grove Group comprises seven
fourth-order marine-nonmarine sequences. Through the detailed study of ten widely
distributed and lengthy cores eight major lithofacies were identified and characterized
(see Panel 2).
Grain
Support &
Dolomite
20%
haw
Sedgwick
Basin
Hugoton Area-Panoma
800
Council Grove Structure
CI = 100 feet
Pan
oma
Panoma
900
Shankle
Brads
Forest City
Basin
1,000
Gross Nonmarine
Thickness
Gross Marine
Thickness
A1-B5 Thickness
Greenwo
od
Kansas Annual Gas Production
Lithofacies and Depositional Environments
Luke
Nemaha
Anticline
Salina
Basin
The most striking large-scale geometry feature of the Panoma reservoir is the
reciprocal relationship between nonmarine and marine interval thickness. Though
the total thickness of the Council Grove (A1-B5) in most of the study area varies
less than 50 feet (from 200-250 feet), the summed nonmarine and marine intervals
each vary 120 feet (from 50-170 feet) and their respective summed thicknesses
are reciprocal. Thick nonmarine shale and silt dominates the northwest side of the
study area while marine carbonates dominate to the southeast.
Easly Creek Sh
Gas-Brine Height Above Free Water (ft)
We wish to acknowledge members of the Hugoton Consortium that
contributed data including Pioneer Natural Resources USA, Inc., BP, OXY
USA, Inc., and Anadarko Petroleum Corp. We are grateful to those who
served as technical advisors including Kevin Schepel, Louis Goldstein, and
Randy Offenberger, Pioneer, and those that provided technical support
including Bob Perry, Bill Tulp Jenna Anaya and Susan Leigh, Pioneer, Tim
McGinnley, McGinnley and Associates, David Hamilton and Jeff Kiester,
SCM, Inc., and Ken Dean and Mike Maroney, Kansas Geological Survey.
Central
Kansas
Uplift
Leonardian
The Hugoton Project (http://www.kgs.ku.edu/Hugoton/index.html) is an
Industry, University and Governmental funded consortium whose purpose is
to develop technology and information to better understand the oil and gas
resources of the Hugoton Embayment in Southwest Kansas. This paper is
one of the outcomes of the five year project.
1968
67 BCF
2.88 TCF gas
2600
1.1 BCF to date
1.7 million acres
(1 well per sect)
2500-3200 feet
(+800 to 100)
~60#
~480#
KANSAS
Wolfcampian
Kansas Hugoton Project
Current SIP
OriginaSIPl
Virgilian
Both a neural network and Kipling.xla were “trained” on data from
eight wells including half-foot digital wireline log data and
descriptions of two thousand feet of core utilizing a digital rock
classification scheme. Both models were then used to predict
lithofacies in non-cored wells based on their log attributes.
Techniques employed in this study could be applied to other large
and complex reservoirs where accurate representations of
lithofacies heterogeneity in the 3D volume are key to realistic
reservoir analysis.
Top of pay
Permian
Panoma produces gas from the upper seven fourth-order
sequences of the Permian Council Grove Group containing 50%
nonmarine siliciclastics and 50% marine carbonates and
siliciclastics. Lithofacies controlled petrophysical properties dictate
gas saturations and discrimination of lithofacies reduces standard
error in permeability prediction in marine carbonate facies by a
factor of twelve. Nonmarine siliciclastic facies error was reduced by
a factor of three. At low gas column heights, lithofacies
discrimination can result in predicted saturation differences of 2040% while differences at high gas column heights, near
“irreducible”, are less than 10%.
IInitial Prod
2002 Prod
Cum. Prod
Well count
Per well avg.
Area
0
+100
The Panoma (Council Grove) Field in southwest Kansas lies
stratigraphically subjacent to the more prolific Hugoton (Chase)
Field, and has recovered 2.8 TCF of gas from approximately 2,600
wells across 1.7 million acres since its discovery in the early 1960's.
Field-wide upscaling of lithofacies distribution for reservoir
characterization has proven problematic in large heterogeneous
reservoirs like the Panoma Field, but prediction tools, neural
networks and the Excel add-in Kipling.xla, a non-parametric
discriminant analysis tool, provide solutions to the facies prediction
dilemma.
General Geology
Panoma Field
Statistics
Pennsylvanian
Abstract
The Panoma Field (2.9 TCF gas) produces from
Permian Council Grove Group marine
carbonates and nonmarine silicilastics in the
Hugoton embayment of the Anadarko Basin. It
and the Hugoton Field, which has produced
from the Chase Group since 1928, the top of
which is 300 feet shallower have combined to
produce 27 TCF gas, making it the largest gas
producing area in North America. Both fields
are stratigraphic traps with their updip west and
northwest limits nearly coincident. Maximum
recoveries in the Panoma are attained west of
center of the field. Deeper production includes
oil and gas from Pennsylvanian Lansing-Kansas
City, Marmaton, and Morrow and the
Mississippian.
Annual Production (BCF)
To construct a geologic and petrophysical model of the
Panoma Field in sufficient detail to accurately represent
the fine-scale vertical and lateral heterogeneities for
accurate reservoir modeling of the entire field.
Setting and History
Annual Prod. (BCF/Y)
Purpose
40
50
60
Water Saturation (%)
70
80
90
100
saturations also vary between facies. For example, at 7%
porosity (which represents >50% of all Mstn/Wkstn) at
200 ft above free water Mudstones are 100% water
saturated while grainstones exhibit water saturations of
~40%. Differences in water saturations between facies
increase with decreasing porosity and decreasing height
above free water.