Determining Effective Residual Oil Saturation for Mixed Wettability Reservoirs: Endicott Field, Alaska

Wood, A.R.O.; Wilcox, T.C.; MacDonald, D.G.; Flynn, J.; Angert, P.F.

doi:10.2118/22903-ms

Cited by 14 publications

(13 citation statements)

References 7 publications

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“…Comparison with analogous measurements on undyed n-decane indicates that the addition of ORO reduces towards values more representative of NAPL contaminants (Tuck et al 2003;Powers and Tamblin 1995;Powers et al 1996;Dwarakanath et al 2002) and crude oil under field conditions (Schowalter 1979;Connor 2000;Wood et al 1991;Sutanto et al 1990;Øren et al 1998;Jerauld and Rathmell 1997). A contact angle of s = 76…”

Section: Fluidsmentioning

confidence: 86%

Oil/water displacement in microfluidic packed beds under weakly water-wetting conditions: competition between precursor film flow and piston-like displacement

2018

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Optical microscopy was used to measure depth-averaged oil distribution in a quasi-monolayer of crushed marble packed in a microfluidic channel as it was displaced by water. By calibrating the transmitted light intensity to oil thickness, we account for depth variation in the fluid distribution. Experiments reveal that oil saturation at water breakthrough decreases with increasing Darcy velocity, U w , between capillary numbers Ca = w U w ∕ = 9 × 10 −7 and 9 × 10 −6 , where w is the dynamic viscosity of water and is the oil/water interfacial tension, under the conditions considered presently. In contrast, end-point (long-time) remaining oil saturation depends only weakly on U w . This transient dependence on velocity is attributed to the competition between precursor film flow, which controls early time invasion dynamics but is inefficient at displacing oil, and piston-like displacement, which controls ultimate oil recovery. These results demonstrate that microfluidic experiments using translucent grains and fluids are a convenient tool for quantitative investigation of sub-resolution liquid/liquid displacement in porous media.

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Section: Fluidsmentioning

confidence: 86%

Oil/water displacement in microfluidic packed beds under weakly water-wetting conditions: competition between precursor film flow and piston-like displacement

2018

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“…It has been shown that waterflood residual oil saturation in mixed wettability reservoirs is often a strong function of pore volumes injected 38,83 . The effect of the number of pore volumes injected has been shown for different oil fields with mixed-wet reservoirs, for example, the East Texas Woodbine reservoir 38 and the Endicott Field Alaska 83 .…”

Section: Mixed-wet Systemsmentioning

confidence: 99%

“…The effect of the number of pore volumes injected has been shown for different oil fields with mixed-wet reservoirs, for example, the East Texas Woodbine reservoir 38 and the Endicott Field Alaska 83 . Further decrease in the waterflood residual oil saturation is possible in a mixed-wet reservoir where there is surface film drainage.…”

Section: Mixed-wet Systemsmentioning

confidence: 99%

“…The Endicott Field in Alaska is an example of a mixed-wet reservoir with surface drainage effects 83 . In a preserved reservoir-condition coreflood experiment, it was observed that the waterflood residual oil saturation, S orw , was 40% after 1 PV injection, 22% after 500 PVs, and 12% at infinite PVs.…”

Section: Mixed-wet Systemsmentioning

confidence: 99%

“…al. 83 ). He further reported higher flowable oil saturation in two-phase flow for the mixed-wet cores compared to the water-wet cores.…”

Section: Mixed-wet Systemsmentioning

confidence: 99%

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Characterization and Alteration of Wettability States of Alaskan Reserviors to Improve Oil Recovery Efficiency (including the within-scope expansion based on Cyclic Water Injection - a pulsed waterflood for Enhanced Oil Recovery)

Dandekar¹,

Patil²,

Khataniar³

2008

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Numerous early reports on experimental works relating to the role of wettability in various aspects of oil recovery have been published. Early examples of laboratory waterfloods show oil recovery increasing with increasing water-wetness. This result is consistent with the intuitive notion that strong wetting preference of the rock for water and associated strong capillaryimbibition forces gives the most efficient oil displacement. This report examines the effect of wettability on waterflooding and gasflooding processes respectively. Waterflood oil recoveries were examined for the dual cases of uniform and non-uniform wetting conditions. Based on the results of the literature review on effect of wettability and oil recovery, coreflooding experiments were designed to examine the effect of changing water chemistry (salinity) on residual oil saturation. Numerous corefloods were conducted on reservoir rock material from representative formations on the Alaska North Slope (ANS). The corefloods consisted of injecting water (reservoir water and ultra low-salinity ANS lake water) of different salinities in secondary as well as tertiary mode. Additionally, complete reservoir condition corefloods were also conducted using live oil. In all the tests, wettability indices, residual oil saturation, and oil recovery were measured. All results consistently lead to one conclusion; that is, a decrease in injection water salinity causes a reduction in residual oil saturation and a slight increase in water-wetness, both of which are comparable with literature observations. These observations have an intuitive appeal in that water easily imbibes into the core and displaces oil. Therefore, low-salinity waterfloods have the potential for improved oil recovery in the secondary recovery process, and ultra low-salinity ANS lake water is an attractive source of injection water or a source for diluting the high-salinity reservoir water.As part of the within-scope expansion of this project, cyclic water injection tests using high as well as low salinity were also conducted on several representative ANS core samples. These results indicate that less pore volume of water is required to recover the same amount of oil as compared with continuous water injection. Additionally, in cyclic water injection, oil is produced even during the idle time of water injection. It is understood that the injected brine front spreads/smears through the pores and displaces oil out uniformly rather than viscous fingering.iii The overall benefits of this project include increased oil production from existing Alaskan reservoirs. This conclusion is based on the performed experiments and results obtained on lowsalinity water injection (including ANS lake water), vis-à-vis slightly altering the wetting conditions. Similarly, encouraging cyclic water-injection test results indicate that this method can help achieve residual oil saturation earlier than continuous water injection. If proved in field, this would be of great use, as more oil can be recovered through...

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Laboratory investigation of capillary trapping under mixed‐wet conditions

Tanino

Blunt

2013

Water Resources Research

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[1] Remaining oil saturation established by waterflooding was measured in Indiana limestone in its original, water-wet state and under mixed-wet conditions established by adding organic acid to the oil phase. The porous plate technique was used to establish initial oil saturations ranging from S nwi ¼ 0.23 to 0.93 under capillary-dominated conditions. For water-wet conditions, the residual oil saturation increased linearly with its initial saturation. In contrast, the remaining oil saturation under mixed-wet conditions, S nw , displayed three distinct regimes. First, S nw increased with its initial saturation up to S nwi ¼ 0.58. Next, S nw decreased from S nwi ¼ 0.58 to 0.76. Finally, S nw increased again as S nwi approached one. The nonmonotonic dependence of S nw on S nwi at S nwi > 0.5 is well described by a concaveup quadratic function, and may be a salient feature of mixed-wet rocks.

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Determining Effective Residual Oil Saturation for Mixed Wettability Reservoirs: Endicott Field, Alaska

Cited by 14 publications

References 7 publications

Oil/water displacement in microfluidic packed beds under weakly water-wetting conditions: competition between precursor film flow and piston-like displacement

Oil/water displacement in microfluidic packed beds under weakly water-wetting conditions: competition between precursor film flow and piston-like displacement

Characterization and Alteration of Wettability States of Alaskan Reserviors to Improve Oil Recovery Efficiency (including the within-scope expansion based on Cyclic Water Injection - a pulsed waterflood for Enhanced Oil Recovery)

Laboratory investigation of capillary trapping under mixed‐wet conditions

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