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k Reservoir.types
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Transcript of k Reservoir.types
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Classification of Fractured
Reservoirs
Delineates the reservoir parameters most
important in quantifying the reservoir
(highgrades data acquisition)
Potential production & evaluation problems
can be anticipated
The style of reservoir simulation necessary
can be constrained
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Type I: Fractures provide the essential storage capacity and
permeability in a reservoir. The matrix has little porosity or
permeability.
Type II: Rock matrix provides the essential storage capacity and
fractures provide the essential permeability in a reservoir. The
rock matrix has low permeability, but may have low, moderate, or
even high porosity.
Type III: Fractures provide a permeability assist in an already
economically producible reservoir that has good matrix porosity and
permeability.
Type IV: Fractures do not provide significant additional storage
capacity or permeability in an already producible reservoir, but
instead create anisotropy. (Barriers to Flow)
Nelson (1999)
Fractured Reservoir Classification
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I II
III
IV
All
Fractures
All
Matrix
% of Total Porosity
% o
f To
tal
Perm
eab
ilit
y
100 % k f
100% k m
100% f m 100% f f
Increasing Effect of Fractures
Decreasing Effect of Matrix
Schematic Distribution of
Fractured Reservoir Types
Nelson (1999)
M
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Evaluation Characteristics by
Fractured Reservoir Type
Type 1 (Fractures provide essential por. & perm.)
Fracture characteristics define reserves
Static description is critical
Production highly variable in 4-D
Few wells required to deplete
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Evaluation Characteristics by
Fractured Reservoir Type
Type 2 (Fractures provide essential perm.)
Cross flow and rate control are critical
Fractures define rate
Water influx must be monitored & intervention
planned
If overpressured, fracture closure must be
controlled
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Evaluation Characteristics by
Fractured Reservoir Type
Type 3 (Fractures provide a perm. assist)
Fractures define anisotropy
Highly customized flood patterns needed
Rates & drainage areas better than predicted
from matrix alone
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Evaluation Characteristics by
Fractured Reservoir Type
Type 4 (Fractures create perm. reduction)
Fractures create baffles, barriers and
compartments (flow & saturation)
Fracture descriptions made generally by core
only
Inefficient drainage & sweep
Rates & reserves lower than predicted from
matrix alone
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Examples Of Fields In Which
Fractures Provide The Essential Porosity
And Permeability To The Reservoir
Reservoir Type 1
_____________________________________________________
Field Location Reserves
I . Amal Libya 1700 mmbbl
2. (5)Ellenburger Fields Texas 107.8 (1957)
3. Edison California 42
4. Wolf Springs Montana 5.4
5. (8) PC Fields Kansas 3.8
6. Big Sandy Kent./W.V 3 Tcf
Reservoir Type 1 Fields
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Examples of Contrasting History
__________________________________________________
Reservoir Type 1:
Fractures Provide the Essential Porosity
and Permeability
Edison (California) Poor HistoryTectonic Fractures
Big Sandy (Kentucky/W. Virginia) Good HistoryRegional Fractures
The Difference is Primarily One of Drainage
Area and Fracture Type.
Contrasting History
-
Examples Of Fields In Which
Fractures Provide The Essential
Permeability To The Reservoir
Reservoir Type 2
Field Location Reserves
1 . Agha Jari Iran 9500 mmbbI
2. Haft Kel Iran 2660
3. Rangely Colorado 600
4. Spraberry Texas 447
5. Altamont- Utah 250
Bluebell
6. Sooner Trend Oklahoma 70
7. La Paz/Mara Venezuela 800
Reservoir Type 2 Examples
-
Examples of Contrasting History
Reservoir Type 2:
Fractures Provide the Essential Permeability
Spraberry (Texas) Poor HistoryUnderpressured
Altamont-Blue Bell (Utah) Good HistoryOverpressured
The Difference is One of Reservoir Energy.
Contrasting History
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Fractures Provide A Permeability
Assist To The Reservoir
Reservoir Type 3:
Field Location Reserves
1 . Kirkuk Iraq 15000 mmbbi
2. Gachsaran Iran 8000
3. Hassi Messaoud Algeria 6000
4. Dukhan Qatar 4570
5. Cottonwood Creek Wyoming 182
6. Lacq France 8.8 TCF
Reservoir Type 3 Examples
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Reservoir Type 3:
Fractures Provide a Permeability Assist
Cottonwood Creek (Wyoming) Poor HistoryLate Recognition of Fractures
Kirkuk (Iraq) Good HistoryEarly Recognition of Fractures
One Difference is When the Fracture Systems
Were Recognized in Production Procedures.
Contrasting History
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Reservoir Type 3
Fractures Provide a Permeability Assist
1. Reserves dominated by matrix properties
2. Reserve distribution fairly homogeneous
3. High sustained well rates
4. Great reservoir continuity
Reservoir Type 1.
Fractures Provide Essential Porosity and Permeability
1. Drainage areas per well are large.
2. Few wells needed in development
(in-fill for rate acceleration only)
3. Good correlation between well rates and well
4. Best wells are often early
5. Generally high IPs 6. Can produce from non-standard and non-reservoir
Reservoir Type 2.
Fractures Provide Essential Permeability
1. Can develop low permeability rocks
2. Often higher than anticipated well rates
3. Hydrocarbon charge often fostered by fractures
Attributes of
Reservoir Types
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100% 0%
0%
100%
%Porosity in Fractures
%P
erm
eab
ilit
y i
n F
ract
ure
s
Matrix
All
All Fractures
Valhall
Hod
Blackburn
West Rozel
Pineview
Ryckman Creek
Lost Soldier
Tensleep
Lost Soldier
Madison
Opon
Hugoton
Anschutz Ranch East,High
Anschutz Ranch East, Low
Beaver River/
Pointed Mountain
Beaver Creek
Sabria/
El Franig
Middle Ground Shoals/
Granite Point
Pearsall Sajaa/
Kahaif
Pressure, Wellbore Stability & Rate control
Reserve
Calculation &
Rate Decline
Inappropriate
Floods & Non-Recognition
Development Patterns
& Well Paths
Whitney Canyon
Liuhua
Wamsutter
Critical Exploration & Development Issues by Fractured Reservoir Type
Darius
Rijn Cedar Rim
R.A.Nelson, 1999