Waterflooding Petroleum Reservoirs in the Newcastle/Muddy Formation, Powder River Basin, Wyoming Marron Bingle-Davis Sunshine Valley Petroleum Corporation Casper, WY What is a Waterflood? Primary Production = extracting oil from a reservoir without any additives Production usually declines over time, sometimes rapidly Loss of reservoir pressure 20-30% recovery Secondary Production = treating the reservoir to increase production Injecting water or gas to push oil Increases reservoir pressure 50% total recovery, or an extra 20-30% Water injection = injecting water at higher pressure to push the lighter oil towards a producing well History of Waterfloods 1860s: Oil fields in Pennsylvania had seeping groundwater Ruin a well, but production jumped just prior 1880: John Carll announced that if water was deliberately introduced it would increase production Not regulated, potentially hazardous to water supply 1921: Waterflooding legalized and regulated 1950s: Waterflooding became common practice in most oil fields Patterns Waterflood Problems Reservoir already naturally flooded by formation water so nothing left to sweep High cost depending on type of reservoir Heterogeneous reservoir Rock is mixed lithologies* Intervals of very high and very low permeability* High clay content* * Powder River Basin sandstone intervals Newcastle/Muddy Formation In Wyoming (PRB), Montana (PRB, WB), North (WB) and South Dakota (BH) Transitional marine Series of fluvial and marine sandstone and shale intervals – very heterogeneous Each sandstone separated by a shale bed Oil producer Different sandstone intervals have produced oil Sandstone intervals are described separately North Skull Creek Study Area Why wasn’t the waterflood successful? High permeability streaks allowed injected water to continue to sweep these zones leaving the rest untouched – Problem in Newcastle Fm How to Fix it… Mix polymers with water to plug up high permeability layers Forces the injected water into untouched zones = more oil Shrink/Swell Clays Injected water makes clays swell Plugs up formation so no more water can be injected Add potassium hydroxide (KOH) before injection Changes clay chemistry Clays become stable Common in the Newcastle Fm Need to add KOH prior to injection – not in North Skull Creek Conclusions Extensive geological evaluation before starting a waterflood Heterogeneity in lithology Porosity, permeability for connectivity Calculate pore volume to know how much to inject Add KOH treatment prior to any injection to stabilize clays Inject polymers to fix permeability Increase production from 20-30% recovery to 50% recovery

1. M A R R O N B I N G L E - D A V I S
S U N S H I N E V A L L E Y P E T R O L E U M C O R P O R A T I O N
C A S P E R , W Y
Waterflooding Petroleum Reservoirs
in the Newcastle/Muddy Formation,
Powder River Basin, Wyoming

2. What is a Waterflood?
 Primary Production = extracting oil from a reservoir
without any additives
 Production usually declines over time, sometimes rapidly
 Loss of reservoir pressure
 20-30% recovery
 Secondary Production = treating the reservoir to increase
production
 Injecting water or gas to push oil
 Increases reservoir pressure
 50% total recovery, or an extra 20-30%
 Water injection = injecting water at higher pressure to
push the lighter oil towards a producing well

3. How a
Waterflood
Works…

4. History of Waterfloods
 1860s: Oil fields in Pennsylvania had seeping
groundwater
 Ruin a well, but production jumped just prior
 1880: John Carll announced that if water was
deliberately introduced it would increase production
 Not regulated, potentially hazardous to water supply
 1921: Waterflooding legalized and regulated
 1950s: Waterflooding became common practice in
most oil fields

5. Patterns
Injection Well
Producing Well
Water Flow
Direction
Line Drive
(original)
5-spot
(most common)
5-spot
Inverse
9-spot
Inverse
9-spot

6. Waterflood Problems
 Reservoir already naturally flooded by formation
water so nothing left to sweep
 High cost depending on type of reservoir
 Heterogeneous reservoir
 Rock is mixed lithologies*
 Intervals of very high and very low permeability*
 High clay content*
* Powder River Basin sandstone intervals

7. Newcastle/Muddy Formation
 In Wyoming (PRB), Montana
(PRB, WB), North (WB) and
South Dakota (BH)
 Transitional marine
 Series of fluvial and marine
sandstone and shale intervals –
very heterogeneous
 Each sandstone separated by a
shale bed
 Oil producer
 Different sandstone intervals
have produced oil
 Sandstone intervals are described
separately
100 Ma
Lower
Cretaceous
Upper
Cretaceous

8. North Skull Creek Parameters
• Discovery: 1946
– Discovery well: Engle 1 (1948) 1
• Area: 3,900 acres
• Producing formation: Newcastle (Muddy)
– Divided into E, D, C, and A/B sands
– Depth to Newcastle: 2875 – 3205 ft
• Producing wells: 18
• Injection wells: 1 active, 7 inactive, 1 plugged
• Average pay thickness: 24 ft
• Average porosity: 15.2 %
• Average water saturation: 48.5 %
• Average permeability: 99 mD
• Oil gravity: 26-28 °API
• Oil viscosity: 81 sec @ 100 °F 1
1 from Wyoming Geological Association, Wyoming Oil and Gas Fields Symposium, Powder River Basin, 2000

9. T45N R62W
North Skull Creek Study Area
- Injection
Well

11. E Sand
D Sand
C Sand
A/B Sand
E Sand
D Sand
C Sand
A/B Sand
Yellow = Oil
Blue = Injected Water
Typical Producing Well Typical Injection Well

12. Production doubled
after response
This production increase is
not attributed to injection
Injection and production
almost doubled
Initial waterflood began in 1972 – 9 injection wells –
1 still active – 7 mmbbls injected

13. Post Injection
Two years after
injection these
wells were
producing
mostly water
About fifteen years
after injection these
wells were
producing mostly
water
Good example of how a water
flood should have worked
1960 1970
1975 1990
%
Oil
%
Water

14. Why wasn’t the waterflood successful?
High permeability streaks allowed injected water to
continue to sweep these zones leaving the rest
untouched – Problem in Newcastle Fm
Yellow = Oil
Blue/Green =
Injected Water

15. Top Depth
(ft)
Bottom
Depth (ft)
Height, h (ft)
Porosity, f
(%)
Horizontal
Permeability, k
(mD)
Vertical
Permeability, k
(mD)
Residual Oil
Saturation,
Sor (%)
Water
Saturation,
Sw (%)
Total
Saturation,
St (%)
Pay
Newcastle E Sand
2,860.5 2,861.5 1.0 9.3% 0.30 86.3% 0.0
2,861.5 2,862.5 1.0 16.5% 52.80 20.5% 49.8% 70.3% 1.0
2,862.5 2,863.5 1.0 15.9% 52.80 19.00 37.3% 55.1% 92.4% 1.0
2,863.5 2,864.5 1.0 21.1% 13.70 2.08 70.0% 1.0
2,864.5 2,865.5 1.0 22.9% 316.00 93.00 25.0% 42.0% 67.0% 1.0
2,865.5 2,866.5 1.0 21.7% 175.00 29.7% 49.9% 79.6% 1.0
Weighted Average 19.6% 53.4% 5.0
Newcastle D Sand
2,866.5 2,867.5 1.0 22.7% 316.00 26.0% 54.2% 80.2% 1.0
2,867.5 2,868.5 1.0 20.5% 139.00 30.3% 49.8% 80.1% 1.0
2,868.5 2,869.5 1.0 23.1% 50.00 22.8% 46.7% 69.5% 1.0
2,869.5 2,870.5 1.0 3.6% 21.60 11.4% 85.2% 96.6% 0.0
2,870.5 2,871.5 1.0 15.3% 26.40 53.7% 1.0
2,875.5 2,876.5 1.0 4.6% 0.10 51.4% 0.0
2,876.5 2,877.5 1.0 15.7% 54.80 31.6% 38.9% 70.5% 1.0
2,877.5 2,878.5 1.0 19.2% 380.00 22.3% 32.2% 54.5% 1.0
2,878.5 2,879.5 1.0 23.8% 526.00 19.0% 39.0% 58.0% 1.0
2,879.5 2,880.5 1.0 20.2% 113.00 22.60 3.5% 70.5% 74.0% 1.0
2,880.5 2,881.5 1.0 20.1% 10.10 11.60 71.2% 1.0
2,881.5 2,882.5 1.0 15.2% 0.79 77.5% 1.0
Weighted Average 19.6% 53.4% 10.0
Newcastle C Sand
2,885.5 2,886.5 1.0 12.6% 1.46 50.7% 50.7% 1.0
2,886.5 2,887.5 1.0 12.8% 0.14 45.9% 45.9% 1.0
2,891.5 2,892.5 1.0 11.7% 9.90 15.2% 40.8% 56.0% 1.0
2,894.5 2,895.5 1.0 16.3% 52.80 14.4% 44.0% 58.4% 1.0
2,895.5 2,896.5 1.0 19.0% 9.14 15.2% 55.2% 70.4% 1.0
2,896.5 2,897.5 1.0 18.7% 80.60 27.0% 30.0% 57.0% 1.0
2,897.5 2,898.5 1.0 18.0% 30.40 20.3% 44.0% 64.3% 1.0
Weighted Average 15.6% 44.4% 7.0
Newcastle A/B Sand
2,898.5 2,899.5 1.0 9.6% 0.20 36.0% 36.0% 0.0
2,899.5 2,900.5 1.0 20.0% 8.58 6.8% 61.0% 67.8% 1.0
2,900.5 2,901.5 1.0 22.4% 91.40 17.0% 43.5% 60.5% 1.0
2,901.5 2,902.5 1.0 17.0% 14.40 9.8% 50.0% 59.8% 1.0
2,902.5 2,903.5 1.0 21.3% 258.00 17.0% 42.8% 59.8% 1.0
2,903.5 2,904.5 1.0 21.0% 135.00 19.7% 36.6% 56.3% 1.0
2,904.5 2,905.5 1.0 18.5% 146.00 20.0% 31.0% 51.0% 1.0
2,905.5 2,906.5 1.0 19.6% 7.22 4.8% 20.0% 24.8% 1.0
2,906.5 2,907.5 1.0 11.8% 0.14 14.8% 66.0% 80.8% 1.0
2,907.5 2,908.5 1.0 16.2% 0.30 13.6% 37.6% 51.2% 1.0
2,908.5 2,909.5 1.0 22.6% 34.20 23.0% 1.0
2,909.5 2,910.5 1.0 18.5% 3.92 45.0% 1.0
2,910.5 2,911.5 1.0 19.7% 130.80 8.3% 47.6% 55.9% 1.0
2,911.5 2,912.5 1.0 17.3% 1.86 5.5% 57.0% 62.5% 1.0
2,912.5 2,913.5 1.0 19.6% 119.20 8.4% 45.2% 53.6% 1.0
2,913.5 2,914.5 1.0 21.2% 296.00 9.8% 43.0% 52.8% 1.0
2,914.5 2,915.5 1.0 21.6% 258.00 6.4% 53.0% 59.4% 1.0
2,915.5 2,916.5 1.0 19.6% 63.20 8.2% 47.5% 55.7% 1.0
2,916.5 2,917.5 1.0 18.5% 6.00 66.5% 1.0
2,917.5 2,918.5 1.0 10.3% 0.15 49.8% 1.0
2,918.5 2,919.5 1.0 10.0% 51.0% 51.0% 1.0
2,919.5 2,920.5 1.0 15.0% 0.32 61.2% 1.0
2,920.5 2,921.5 1.0 20.0% 36.00 6.5% 55.5% 62.0% 1.0
2,921.5 2,922.5 1.0 23.0% 45.80 56.0% 56.0% 1.0
2,922.5 2,923.5 1.0 17.3% 92.20 75.7% 75.7% 1.0
2,923.5 2,924.5 1.0 20.0% 18.20 55.8% 55.8% 1.0
2,924.5 2,925.5 1.0 19.8% 8.58 71.0% 71.0% 1.0
2,925.5 2,926.5 1.0 20.1% 161.20 2.3% 50.5% 52.8% 1.0
2,926.5 2,927.5 1.0 19.3% 42.80 7.3% 73.5% 80.8% 1.0
Weighted Average 18.6% 50.6% 28.0
14: Horton 2, 4520131, SWNE-27-45-62
Permeability streaks where
the water swept –
Removed these layers and
recalculated how much oil
remaining
Revised
Total: 28 ft
Original
Total: 56 ft
Revised Field
OOIP:
20 mmbbls
Original
Field OOIP:
60 mmbbls
Pore volume that can
be touched by injected
water = 65 mmbbls

16. How to Fix it…
 Mix polymers with
water to plug up high
permeability layers
 Forces the injected
water into untouched
zones = more oil
x x x x x x x x x x x
x x x x x x x x x x x
x x x x x x x x x x
x x x x x x x x x x x x x x x x
x x x x x x x x x x
x x x x x x x x x x x x x x x x

17. Shrink/Swell Clays
 Injected water makes clays
swell
 Plugs up formation so
no more water can be
injected
 Add potassium hydroxide
(KOH) before injection
 Changes clay chemistry
 Clays become stable
 Common in the
Newcastle Fm
 Need to add KOH prior to
injection – not in North
Skull Creek
Injectability decline
in a good injector
Injectability
decline in an
injector with high
clay content

18. Conclusions
 Extensive geological evaluation before starting a
waterflood
 Heterogeneity in lithology
 Porosity, permeability for connectivity
 Calculate pore volume to know how much to inject
 Add KOH treatment prior to any injection to
stabilize clays
 Inject polymers to fix permeability
 Increase production from 20-30% recovery to 50%
recovery

19. Any Questions?