Tensleep TZ/ROZ Study, Bighorn Basin
A Revolutionary Concept on Oil Recovery
Peigui Yin Shaochang Wo
Sharon Verdun-Reyes Matthew Johnson
Glen Murrell David Mohrbacher
July 14, 2011
ARI, 2006
Main Pay Zone (MPZ), Transition Zone (TZ) & Residual Oil Zone (ROZ)
Jennings, 1987
0 20 40 60 80 100
So (%)
0
40
80
120
160
200
Thic
kne
ss (
ft)
MP
Z TZ
Pe
rfo
rati
on
RO
Z (1
00
% w
ater
Pro
du
ction
)
Bighorn Basin Tensleep
Tensleep Sandstone
Bighorn Basin
Structural Contour Map of Tensleep Sandstone
Zapp, 1953
Tensleep Sandstone Potentiometric Map
Bredehoeft et al., 1992
Topics
• Tensleep TZ/ROZ in Bighorn Basin.
• Mechanisms for Thick TZ/ROZ.
• Active ROZ CO2-EOR Production in Permian Basin.
• Comments and Future Study.
Tensleep TZ/ROZ in Bighorn Basin
• Below main pay zone within existing reservoirs.
• Around existing reservoirs.
• Non-productive structures (green fields).
• Oil Properties are similar in TZ/ROZ and MPZ
0 0.05 0.1 0.15 0.2 0.25
Porosity0 0.05 0.1 0.15 0.2 0.25
Porosity
0 20 40 60 80 100
1217
1196
1175
1154
1133
1112
1091
1070
So
(%)
Ele
va
tio
n (
ft)
0 20 40 60 80 100
-194
-219
-244
-272
-297
-322
-347
-372.5
So (%)
Ele
va
tio
n (
ft)
0 20 40 60 80 100
1223
1204
1185
1166
1147
1128
1109
1090
So (%)
Ele
vati
on
(ft
)
Below Main Pay Zone within Existing Reservoirs.
0 0.05 0.1 0.15 0.2 0.25
Porosity
A B C
Thick permeable intervals with high So not produced during primary and secondary production
Total Tensleep thickness: 180 ft Average perforation thickness: 47 ft
Perforation Interval in a Tensleep Reservoir
0 20 40 60 80 100
-194
-219
-244
-272
-297
-322
-347
-372.5
So (%)
Ele
va
tio
n (
ft)
0 0.05 0.1 0.15 0.2 0.25
Porosity
0 20 40 60 80 100
55.5
40
24.5
9
-6.5
-22
-37.5
-53
So (%)
Ele
vati
on
(ft
)
0 0.05 0.1 0.15 0.2 0.25
Porosity
0 20 40 60 80 100
787.5
769.5
751.5
733.5
715.5
697.5
679.5
661.5
So (%)
Ele
vati
on
(ft
)
0 20 40 60 80 100
879.5
852
824.5
797
769.5
742
714.5
687
So (%)
Ele
vati
on
(ft
)
0 0.05 0.1 0.15 0.2 0.25
Porosity
Non-commercial Wells around Existing Reservoirs
Wells with high So, but not economically viable by primary and secondary recovery techniques
320410 C L Zwemer 1 57N-97W-21 Bighorn Basin
Core Photos, Non-productive Well
0 20 40 60 80 100
44
32
21
-10
-21
-31
-41
-51
320410
So
Ele
va
tio
n (
ft)
306499
320139
306465
320410
2921388
2920992
0 20 40 60 80 100
40
29
15
-11
-21
-30
-39
-48
320410
So (%)
Ele
vati
on
(ft
)
2920043
0 20 40 60 80 100
-430.5
-433.5
-436.5
-439.5
-442.5
-446.5
-452.5
-458.5
2920043
So (%)
Ele
va
tio
n (
ft)
0 20 40 60 80 100
-16
-32
-44
-51
-70.8
-77
-84
-95
320139
So (%)
Ele
vati
on
(ft
)
0 20 40 60 80 100
837
834
831
828
825
822
819
816
813
306499
So (%)
Ele
vati
on
(ft
)
0 20 40 60 80 100
1448
1444
1440
1436
1432
1428
1419
1415
2921388
So (%)
Ele
vati
on
(ft
)
0 20 40 60 80 100
1127
1105
1083
1061
1039
1016
994
972
2920992
So (%)
Ele
vati
on
(ft
)
0 20 40 60 80 100
-490
-500
-510
-520
-530
-540
-566
-576
306465
So (%)
Ele
vati
on
(ft
)
Oil Saturation Obtained from Core Analysis
Traps with Oil Saturation not High Enough for Primary and Secondary Recovery (Green Fields)
0 20 40 60 80 100
1125
1113
1102
1089
1078
1065
1054
1042
320762
So
(%)
Ele
vati
on
(ft
)
Well Located in Non-commercial Structure (Green Field)
56
N
96W
1 2 3
10 11 12
0 0.05 0.1 0.15 0.2 0.25
320762
PorosityTectonic information from Ploeg, 1985)
Total thickness of Tensleep Sandstone: 142 ft.
3706-3750 ft, sandstone, even light brown heavy oil stain, free oil droplets in samples and within pore spaces, even dark yellow fluorescence, strong petroleum odor. 10-12% log porosity. Perf: 3718-3728 ft (10 ft thick). No production, plug & abandon.
Another Green Field Example
Tectonic information from Ploeg, 1985)
3734
3754
3774
3794
3814
3834
3854
3874
3894
3914
0 20 40 60 80 100
Produce 75 bbls/day with 70% water cut constant over one year
So (%)
De
pth
(ft
)
Perforatio
n
Data from Aufricht, 1965
Example Showing So, Perforation, and Water Cut
Tensleep Reservoirs Aufricht, 1965
• Oil-water transition zone of several hundred feet in thickness.
• Transition zone with So of 80% still produce with extremely high water cuts.
• OOIP approaching 1000 barrels per acre foot may produce at water cuts greater than 95%.
• Intervals with Sw of 15 to 30% are commercially interest for primary and secondary recovery techniques.
ROZ CO2-EOR Potential
• ARI estimated TZ/ROZ OIP in 13 Bighorn Basin Tensleep Productive reservoirs: 4.4 BBbls – These 13 Tensleep reservoirs with cumulative production: from 345.4 to 6.2 MMBbls
13 Bighorn Basin Tensleep Reservoirs
MPZ
OOIP
(BBbls)
MPZ
Remaining OIP
(BBbls)
TZ/ROZ
OIP
(BBbls)
Total Reserve
for CO2-EOR
(BBbls)
1. CO2-miscible fields: 8
2. CO2-immiscible fields: 5
4.5 3.1 4.4 7.5
CO2-EOR recovery: 11% 0.34 0.48 0.82
CO2-EOR recovery: 30% 0.93 1.32 2.25
<
< <
GC Analysis
Reservoir Oil From Non-productive Wells
Oil Properties are similar in TZ/ROZ and MPZ
MPZ
TZ/ROZ
TZ/ROZ
TZ/ROZ
Brown Field
Green Field
Green Field
A Revolutionary Development for Production and Exploration
Primary & secondary
CO2-EOR
CO2-EOR
CO2-EOR
0 20 40 60 80 100
So (%)
0
40
80
120
160
200
Thic
kne
ss (
ft)
MPZ
TZ
Original
CO
2 -EOR
Po
ten
tial CO2-EOR Potential
0 20 40 60 80 100
So (%)
0
40
80
120
160
200
Thic
kne
ss (
ft)
MPZ
TZ
Current
Pe
rfo
rati
on
Pe
rfo
rati
on
ROZ (100% water Production)
ROZ (100% water Production)
?
Mechanisms for Thick TZ/ROZ
• Tertiary oil migration from stratigraphic to structural traps creates rich TZ/ROZ.
• Heavy oil reservoirs favor to generate thick TZ/ROZ.
• Reservoir heterogeneity retards gravity separation of oil from water, resulting a thick TZ with uneven oil saturation.
• Strong hydrodynamic flow aids to generate rich TZ/ROZ.
Late Permian Paleogeographic Map (Phosphoria Period)
Wyoming
Idaho
Southeast Idaho
Central Wyoming
Miller et al., 1991
HC source rock region
Oil Migrated into Tensleep Through Unconformity
Modified from Stone, 1967
Oil Accumulated in Stratigraphic Traps before Laramide Orogeny
Folds and Thrust Faults Generated during Laramide Orogeny
A
B
Zapp, 1953
9500’ thick
Post-Tensleep Strata
Re-Migration of Oil Creating Rich TZ/ROZ
Bighorn Mountain
Bighorn Basin
Oil
Oil
Oil
TOZ/ROZ
TOZ/ROZ
TOZ/ROZ
A B
Meteoric water Flushing
Oil flushed downdip or escaped updip
Tensleep outcropped
After Laramide (Paleocene-Eocene)
Oil migrated and accumulated in structure top
Trapper Canyon Tar Sands
East Flank of Bighorn Basin An Example of Present Hydrocarbon Distribution
Map form Ver Ploeg, 1985
Madison
Big Horn
Gallatin
& Tensleep
Phosphoria
Reservoir with Tilted OWC
320767
Perforation Bottom Deepening from NE to SW
After Lawson and Smith (1966)
Reservoir with Horizontal OWC
Oil-Water-Contact
Oil
TZ/ROZ
Tensleep
Madison
Big Horn
Gallatin
& Tensleep
Phosphoria
Amsden
Stratigraphic Trap
Oil
TZ/ROZ
Mechanism of Secondary Hydrocarbon Migration and Entrapment
• Driving force: buoyancy caused by difference of density between hydrocarbon and water.
• Resistant force: capillary pressure. – Radius of pore throats.
– Hydrocarbon-water interfacial tension.
– Wettability of reservoir rocks.
θ
R
R: Radius of pore throat. θ: contact angle of oil and water against the solid.
From Schowalter, 1979
HC
Water
16
% S
w
80
% S
w
Water Saturation Percent Pore Space
He
igh
t (f
t)
Reservoir A
Reservoir B
Reservoir C
Pc = h(rwg – rog)
Thickness Difference Due to Oil Density
16% Sw 80% Sw
Res
erv
oir
A
(1
4 A
PI)
Res
erv
oir
B
(2
3 A
PI)
Res
ervo
ir C
(34
AP
I)
From Aufricht, 1965
16
% S
w 16
% S
w 80
% S
w
80
% S
w
50
0 f
t
10
0 f
t
50
ft
Heavy Oil Reservoirs with Thick TZ/ROZ
TZ
Water Saturation, Percent Pore Space
Wat
er
Cu
t, P
erc
en
t
Reservoir A
Reservoir B
Reservoir C
Water Cut as Functions of Relative Permeability and Oil Viscosity
Reservoir A 14 API
500 cp
Reservoir B 23 API
10 cp
Reservoir C 34 API
1 cp
From Aufricht, 1965
𝑾𝒂𝒕𝒆𝒓 𝒄𝒖𝒕, % = 𝟏𝟎𝟎 × 𝒇𝒘 =𝟏𝟎𝟎
𝟏 +𝝁𝒘𝝁𝒐
𝒌𝒐𝒌𝒘
70% Water Cut
6% water Cut 1% Water Cut
Hydrodynamic Traps Contributed by Bed Thinning, Faulting, or Bending
Levorson, 1966
Pedry, 1975
ACTIVE ROZ CO2-EOR PROJECTS IN PERMIAN
BASIN
GOLDSMITH FIELD (1)
-920
-1300
Sub
sea Elevatio
n (ft)
Goldsmith San Andres Unit Seminole San Andrews Unit
ROZ Oil Saturation
2010 CO2 Flooding Conference
API: 30-50o
Thurmond. 2010
Goldsmith San Andres Unit
Goldsmith San Andres Unit Seminole San Andres Unit
Oil Production Increase by Including ROZ CO2-EOR
Thurmond, 2010 2010 CO2 Flooding Conference
Oil
Oil Cut
ROZ Phase II
ROZ & MPZ Have Consistent Properties in Permian Basin
• Core oil saturation is consistent.
• Reservoir quality is consistent.
• Bulk oil composition is consistent.
• Chemical process behavior is consistent.
Concluded by Thurmond for Goldsmith San Andres Unit, 2010
Ideas and Future Study
• Recognition of thick Tensleep TZ/ROZ in Bighorn Basin. – TZ/ROZ below main pay zone.
– TZ/ROZ around current reservoirs.
– TZ/ROZ in non-commercial structures.
• New discovery of CO2-EOR resources in Bighorn basin. • EOR resources not counted by traditional main pay zones.
• There will be high potential for CO2-EOR, and even a new wave of exploration for EOR targets.
• Further integrate the TZ/ROZ concept in Tensleep reservoirs.
• Evaluation of all non-productive structures (green fields).
• Search for rich TZ/ROZ fairways.
• Estimation of CO2-EOR potential in TZ/ROZ.
• Communication and cooperative with oil companies.
Thanks
?