IMPROVING DUAL POROSITY SIMULATION OF WATERFLOOD PERFORMANCE IN THE NATURALLY FRACTURED SPRABERRY TEND AREA

1
IMPROVING DUAL POROSITY SIMULATION OF WATERFLOOD
PERFORMANCE IN THE NATURALLY FRACTURED SPRABERRY
TEND AREA
2
Spraberry Trend Area

• It is a very large field in aerial extent
  (400,000 acres)
• A NFR with complex fracture sets
• Poor ultimate recovery

3
Problem
Low productivity of the Spraberry Field
Incorrect well pattern alignment Fracture
mineralization High water injection
rate Stress-sensitive reservoir Complex
fracture network
4
Presentation Outline
Simulation of an old waterflood pilot (Humble
Pilot)
5
Humble Waterflood Pilot Simulation
6
Assumptions for Simulation

• Only two wells were included in the basic model,
  one is injector (SHB-10) and the other is
  producer (SHB-8) as shown in Humble Pilot map.
• The production well was located in the same line
  with injection well (in the on-trend direction,
  along the primary fracture orientation).
• The response of oil production rate in the SHB-8
  well was only affected by water injection from
  the SHB-10 well.

1
MAGNOLIA A
N
3
HUMBLE B
10
2
3
HUMBLE B
4
9
SHACKELFORD
5
UNION
8
13
11
15
2
15
4
SHACKELFORD
16
HUTT
9
12
HUMBLE B
8
16
4
4
10
2
6
7
1
17
2
3
1
3
8
SHACKELFORD
1
HUMBLE B
1
2
4
22
3
SHACKELFORD
1
2
3
4
HUMBLE
21
1
2
TIPPET
2
TIPPET
20
6
TIPPET
3
TIPPET
7
(No Transcript)
8
Reservoir Properties
9
(No Transcript)
10
Effect of Number of Grid Blocks
1
MAGNOLIA A
N
3
HUMBLE B
10
3
2
4
9
SHACKELFORD
5
UNION
8
13
11
15
2
15
4
SHACKELFORD
16
HUTT
9
12
HUMBLE B
8
16
4
4
10
2
6
7
1
17
2
3
1
3
8
SHACKELFORD
1
HUMBLE B
2
1
4
22
3
SHACKELFORD
1
2
3
4
HUMBLE
21
1
TIPPET
2
2
TIPPET
20
6
TIPPET
3
TIPPET
11
Comparison between Observed and Simulated Results
Kx/Ky 100/15000 mD Orientation N500E
Water cut vs. time
BHP vs. time
Water injection rate vs. time
Oil rate vs. time
12
Effect of Reservoir Size on Well Performance
Water cut vs. time
BHP vs. time
Water injection rate vs. time
Oil rate vs. time
13
Effect of Fracture Permeability on Well
Performance
Water cut vs. time
BHP vs. time
Water injection rate vs. time
Oil rate vs. time
14
Effect of Fracture Orientation on Oil Recovery
During Water Injection
Fracture orientation
Qinj1000 STBW/D Produced at Constant Pwf2000
psia
90
72
54
36
18
0
18o
72o
15
Analysis of Tracer Response
16
C-1
1
G-1
D-1
C-2
C-1
E-1
2
30
3
Boone A-1
24
13
D-1
F-1
Boone
A-1
19
32
D-1
6
Brunson
1
31
26
N
12
34
36
B-1
O'Daniel
8W
A-5
47
C-1
1
O'Daniel
46
40
33
42
Boone E-1
28
50
A-6
25
44
49
39
45
41
OBrian
29
38
43
A-7
37
A-3
14
48
35
O'Daniel
A-1
13
10
63
9
5
O'Daniel
9
7
12
8
B-1
OBrian
7
D-1
12
Powell
Floyd
C-1
17
N
C-1
1
G-1
D-1
C-2
C-1
2
E-1
30
3
Boone A-1
24
13
D-1
F-1
Boone
A-1
19
32
D-1
6
Brunson
1
26
31
12
34
36
B-1
O'Daniel
8W
A-5
C-1
47
1
O'Daniel
46
40
33
42
Boone E-1
28
A-6
50
25
44
49
39
45
41
OBrian
29
38
43
A-7
37
A-3
14
48
35
O'Daniel
A-1
13
10
63
9
5
O'Daniel
9
7
12
8
B-1
OBrian
7
D-1
12
Powell
Floyd
C-1
18
N
C-1
1
G-1
D-1
C-2
C-1
E-1
2
30
3
Boone A-1
24
13
D-1
F-1
Boone
A-1
19
32
D-1
Brunson
6
1
26
31
12
34
36
B-1
O'Daniel
8W
A-5
C-1
47
1
O'Daniel
46
40
33
Boone E-1
42
28
A-6
50
25
44
49
39
45
41
OBrian
29
38
43
A-7
37
A-3
14
48
35
O'Daniel
A-1
13
10
63
9
5
O'Daniel
9
7
12
8
B-1
OBrian
7
D-1
12
Powell
Floyd
C-1
19
Concentration
Time
a) Typical Response
20
Effect of grid size in 35 Deg. Orientation With
Kx/Ky 100/15000 for WIW47 to D-1
21
(No Transcript)
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History Match Result (W47-Br.D-1)
Kx/Ky 84/15000 Orientation 43 Deg.
23
(No Transcript)
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History Match Result (W48 To A-1)
Kx/Ky 84/15000 Orientation 43 Deg.
25
Effect of On-trend Permeability (Ky) on Tracer
Response For a Well Located in The On-trend
Direction
26
Effect of On-trend Permeability (Ky) on Tracer
Response For a Well Located in the On-trend
Direction
27
Fracture Orientation Obtained From The Tracer
Test
28
Simulation of ODaniel Unit and Surrounding Wells
29
ODaniel Unit Simulation
Model
30
Building The Model
Structural Map For The ODaniel Unit Simulation
Model
31
The Simulation Model
32
(No Transcript)
33
The Reservoir Model With Fractures
34
N
35
(No Transcript)
36
(No Transcript)
37
(No Transcript)
38
Fracture Water Saturation
39
Conclusions (Humble Pilot)
The fracture permeability values in the on-trend
and off-trend directions of 15000 and 100 md,
respectively, indicate that reservoir
permeability is highly anisotropic. Because of
high permeability in the on-trend direction, the
size of simulation area must be large enough to
avoid a pressure buildup in the confined
area. To achieve fast and sustained response
during water injection, it is recommended to
locate production wells between 0-36 degrees
along the primary fracture orientation.
40
Conclusions (Tracer Test)
The results obtained from this study support
the previous analysis as follows The
permeability on-trend and off-trend close to the
one obtained from the Humble Pilot simulation.
The fracture trend shows similar directions as
obtained from interference tests and horizontal
core analysis.
41
Conclusions (ODaniel Field Simulation)
For the field simulation matching, it is
necessary to introduce existing fractures in
places where there is not enough water
encroachment from the injectors It is
possible to match most of the wells by using the
permeability anisotropy (Kx/Ky) and fracture
orientation obtained from the tracer simulation
in the ODaniel field model Implementation of
the results from this study may result in
rejuvenation of this reservoir considered a poor
waterflood candidate. Each 1 in recovery results
in 100 MMbbls of oil.
42
SUMMARY
Approximately 50,000 barrels of incremental
waterflood oil have been recovered during the
current pilot. Implementation of the results
from this study may result in rejuvenation of
this reservoir considered a poor waterflood
candidate. Each 1 in recovery results in 100
MMbbls of oil. The reasons for poor performance
of waterflooding in Spraberry Trend Area have
been identified. We have developed a simulation
tool capable of predicting waterflood response in
order to re-develop and optimize field-wide water
injection
43
Results from DOE Pilot

• Injection in six ring fence wells begins October
  1999
• Rapid production response noted in several wells
  along fracture orientation
• Responding wells located up one mile away
  whereas small increases in fluid production noted
  in off-trend wells
• Some better wells have demonstrated six to seven
  fold production increases
• 50,000 bbls cumulative oil produced as result of
  water injection

44
Summary of Spraberry Reservoir Study
45
(No Transcript)
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• N42E orientation.
• Average spacing of 3.2 ft
• Smooth mineralized surfaces.

• N32E orientation.
• Average spacing of 1.62 ft.
• Fractures have stepped surfaces.
• No mineralization

Overlay of 1U and 5U Fractures

• N70E orientation.
• Spacing skewed normal distribution with an
  average of 3.79 ft.
• Fractures have smooth surfaces
• No obvious mineralization.

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5U ENE NNE Fractures
48
Horizontal Core Well - ODaniel 28
49
Horizontal Core Well - ODaniel 28
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Vertical, Mineralized Fracture 1U Payzone
Shackelford 1-38A