Understanding Injectivity in Heterogeneous Reservoirs

Pizarro, Jorge O. S.; Lake, Larry W.

doi:10.2118/39697-ms

Cited by 7 publications

(4 citation statements)

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“…Brine pH/composition: the salinity of connate and invading brines can have a major influence on wettability and oil recovery at reservoir temperatures; additionally, waterwetness and oil recovery by waterflooding increase with decrease in salinity. 101 4. Crude oil composition: changes in wettability induced by crude oil are related to changes in solvency of the crude oil with respect to its heavy components.…”

Section: Factors Affecting Injectivitymentioning

confidence: 99%

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A Literature Analysis of the WAG Injectivity Abnormalities in the CO2 Process

Grigg

2000

All Days

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TX 75083-3836, U.S.A., fax 01-972-952-9435. 3. 3 nitrogen-miscible projects 4. 1 hydrocarbon-immiscible 5. 1 nitrogen-and hydrocarbon-immiscible 6. 6 nitrogen-immiscible CO 2 projects continue to grow in numbers. Immiscible CO 2 projects have dropped to zero while ten new miscible CO 2 projects were planned as of January 1998. Brock and Bryan 2 presented a summary of CO 2 EOR projects and reviewed the performance of 30 full-scale field projects and field pilots up to 1987. In 1992 there were 45 active CO 2 projects in the U.S. 3 Initially the industry outlook was pessimistic; however, by 1992 most projects had been shown to be technically and economically successful. In a number of projects, the production performance has been better than was anticipated. 3 At the beginning of 1998 and based on 1997 production figures, the U.S. production from gas injected EOR was estimated at 307,544 b/d or approximately 4.7% of the total oil production in the US. Oil production from CO 2 activity alone contributed nearly 179,000 b/d, which is an increase of 4.9% over 1996 production attributable to CO 2 production and represents 2.8% of the 1997 US oil production of 6.4 MM bopd. 1 The Permian Basin of west Texas and southeastern New Mexico remains a very active area for CO 2 projects. Eight of the ten planned projects are in the Permian Basin. 1 However, new CO 2 EOR projects are possible for areas of California,

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Section: Factors Affecting Injectivitymentioning

confidence: 99%

“…In a three-dimensional, homogenous five-spot pattern, the dimensionless injectivity can be written as 101 The effective aspect ratio R L H k k L z x = has a strong influence on injectivity estimates. Injectivity increases with R L until vertical equilibrium is achieved.…”

Section: Reservoir Heterogeneity 4 Capillary Forces 5 Dynamics Of Wmentioning

confidence: 99%

A Literature Analysis of the WAG Injectivity Abnormalities in the CO2 Process

Grigg

2000

All Days

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“…Injectivity and sweep patterns are strongly influenced by stratification and reservoir heterogeneities (7) . Heterogeneity delays breakthrough in vertical gravity stable floods because of physical dispersion and reduced gas channelling through high permeability layer.…”

Section: Effect Of Porosity Heterogeneitymentioning

confidence: 99%

Numerical Simulation and Sensitivity Analysis of Gas-Oil Gravity Drainage Process of Enhanced Oil Recovery

Jadhawar

Sarma

2010

Journal of Canadian Petroleum Technology

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The oil recovery process is controlled by the rates of gas injection and oil production, relative permeabilities, reservoir heterogeneities and the balance among viscous, capillary and gravity forces. Crestal gas injection in horizontal, vertical or reef type oil reservoirs recovers significant volumes of the residual oil due to the gas-oil gravity drainage mechanism, indicating the significance of gravity forces. This study investigates the effects of the parameters that control the process (e.g., rate of the gas injection and oil production) and reservoir heterogeneities on the overall performance of immiscible gravity drainage enhanced oil recovery (EOR). Reservoir simulation studies are conducted to map effective combinations of these parameters with respect to the oil recovery performance. Introduction Gravity forces play an important role at nearly every stage of the producing life of the reservoir, whether it is primary depletion, secondary water or gas injection schemes or tertiary enhanced or improved oil recovery methods(1). They can be advantageously used to maximize oil recovery from the oil bearing zone under investigation through gravity drainage mechanism. Several cases reported in the literature suggest that it could deliver as high as 87 to 95% incremental oil recoveries in contrast to other gas injection EOR methods. Gas-Oil Gravity Drainage Process Gravity drainage is a process in which gravity acts as a main driving force and where gas replaces voidage volume(2). It is commonly implemented in either of the dipping or pinnacle reef type reservoirs. CO2-assisted gravity drainage EOR process is a top-down process in which gas is injected in the gas cap through vertical wells at a rate lower than the critical rate (Figure 1). Critical rate is the rate at which injection gas fingers through oil zone (viscous instabilities) leading to its premature breakthrough at the production wells. Injected gas segregates and creates a gas-oil interface. Controlled oil production is started through horizontal wells placed at the bottom of the oil zone such that the voidage created by oil withdrawal (in addition to minor dissolved volumes) is replaced by the equivalent CO2 injection volume. When this happens, pressure differential across the gas cap and oil zone [that is gas-oil contact (GOC)] stay at or close to zero implying that the pressure in the gas zone behind the CO2 floodfront would be constant(3). This helps to maintain the reservoir pressure nearly constant.

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“…Several researchers have studied the injection capacity of different reservoirs and found that the injection volume, injection velocity, formation temperature, formation pressure segment size, and proportion have an impact on the final oil displacement efficiency and recovery factor [24][25][26][27][28][29]. Pizarro and Lake considered the influence of heterogeneity and autocorrelation of reservoir permeability distribution on the injectivity [30]. This model gives insight into why injectivity calculated from a core permeability average is frequently different from the injectivity manifested by the well in question.…”

Section: Introductionmentioning

confidence: 99%

A Simplified Capillary Bundle Model for CO2-Alternating-Water Injection Using an Equivalent Resistance Method

Wang

Meng

et al. 2020

Geofluids

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CO2-alternating-water injection is an effective way of enhancing recovery for low-permeability oil reservoirs. The injection process is one of the essential issues that are facing severe challenges because of the low permeability and poor pore space connectivity. Previous researchers mentioned that water injection ability could be decreased by around 20% after the CO2-flooding; hence, it is necessary to quantify the water injectivity variation during an alternated injection process. In this paper, a CO2 convection-diffusion model is established based on the seepage law of CO2 and dissipation effect. The relationship between the width of miscible flooding and injection time is defined. Besides, an equivalent resistance method is introduced for developing a capillary bundle model for featuring an unequal diameter for CO2 water vapor alternate flooding. CO2-oil and CO2-water interactions are analyzed using the new model. The effects of oil viscosity, pore throat ratio, CO2 slug size, and equivalent permeability of the capillary bundle on water injection are analyzed. The result indicates that water injection ability increases with the rise of CO2 slug size and equivalent permeability of the capillary bundle and decreases with the increase of viscosity and pore throat ratio.

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Understanding Injectivity in Heterogeneous Reservoirs

Cited by 7 publications

References 0 publications

A Literature Analysis of the WAG Injectivity Abnormalities in the CO2 Process

A Literature Analysis of the WAG Injectivity Abnormalities in the CO2 Process

Numerical Simulation and Sensitivity Analysis of Gas-Oil Gravity Drainage Process of Enhanced Oil Recovery

A Simplified Capillary Bundle Model for CO2-Alternating-Water Injection Using an Equivalent Resistance Method

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