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Abstract
The injection of modified salinity water (MSW) within hydrocarbon reservoirs generally improves oil production by inducing a shift in the relative mobility of the aqueous and oleic phases. In chalk, translating the success of MSW from core flooding experiments to field scale simulations is challenging and determined by the coupled multiphysical processes as described in the introductory Chapter 1. This thesis comprises four main chapters illustrating challenges for simulations of the coupled processes and provides further insights and solutions.
Chapter 2 reviews the importance of measuring the secondary drainage and imbibition saturation curves in the field scale simulation of modified salinity waterflooding of water-flooded reservoirs with highly non-uniform saturation history. Since oil-bearing chalk exhibits a long capillary transition zone, we address the challenge of wettability alteration modeling by preserving the saturation history (hysteresis) through relative permeability functions. To that end, three models are proposed for characterizing the interplay among wettability alteration, hysteresis effect, and fluid flow transport in porous media. The models capture the wettability alteration impact that causes a change in the saturation curves for imbibition and secondary drainage versus salinity. It is found that including hysteresis with the wettability alteration process can better quantify the re-trapping of the oil that is mobilized due to the wettability alteration of the reservoir.
Chapter 3 investigates the impact of dynamic wettability alternation (moving from non-water-wet to water-wet condition) on the saturation front stability. It is shown that the wettability alteration during an immiscible two-phase flow can cause the growth of fingers due to not only the viscosity ratio but also the new shape of relative permeability curves and their end-point values. This is an important observation since this may result in delayed oil mobilization in hydrocarbon reservoirs.
Chapter 4 provides the state-of-the-art modeling and simulation of coupled Thermo-Hydro-Mechanical-Chemical (THMC) processes during water injection in chalk reservoirs. First, we quantify the experimental observations of hydrostatic pore collapse strength and bulk modulus of water-saturated chalk specimens as a function of temperature and sulfate concentration. This is then utilized to couple a non-isothermal multi-phase flow and transport simulator with a geomechanics simulator. Our results propose that reservoir pressure depletion, temperature changes, and water weakening play important roles in controlling the reservoir's performance. Our study confirms that accounting explicitly for the coupled THMC processes in reservoir simulations of water flooding in chalk is necessary for reliable prediction of reservoir behavior. Besides improving hydrocarbon recovery by injection of modified salinity water, the results show that MSW flooding greatly reduces the compaction of high-temperature reservoirs.
Chapter 5 presents the main challenges of upscaling modified salinity waterflooding in chalk reservoirs. It reviews the mechanisms controlling the MSW injection at the chalk surface, stemming from the interactions between calcite, brine, and crude oil. The chapter also presents the history matching of our in-house experiments conducted at core scale to obtain a salinity-induced shift in the relative mobility of the aqueous and oleic phases. Further, the chapter addresses the current difficulties in upscaling the observed benefit of MSW measured from core flood experiments to field-scale models for chalk reservoirs. It demonstrates how our findings can be used to predict performance of MSW flooding in a sector model of a Danish North Sea chalk reservoir
Chapter 2 reviews the importance of measuring the secondary drainage and imbibition saturation curves in the field scale simulation of modified salinity waterflooding of water-flooded reservoirs with highly non-uniform saturation history. Since oil-bearing chalk exhibits a long capillary transition zone, we address the challenge of wettability alteration modeling by preserving the saturation history (hysteresis) through relative permeability functions. To that end, three models are proposed for characterizing the interplay among wettability alteration, hysteresis effect, and fluid flow transport in porous media. The models capture the wettability alteration impact that causes a change in the saturation curves for imbibition and secondary drainage versus salinity. It is found that including hysteresis with the wettability alteration process can better quantify the re-trapping of the oil that is mobilized due to the wettability alteration of the reservoir.
Chapter 3 investigates the impact of dynamic wettability alternation (moving from non-water-wet to water-wet condition) on the saturation front stability. It is shown that the wettability alteration during an immiscible two-phase flow can cause the growth of fingers due to not only the viscosity ratio but also the new shape of relative permeability curves and their end-point values. This is an important observation since this may result in delayed oil mobilization in hydrocarbon reservoirs.
Chapter 4 provides the state-of-the-art modeling and simulation of coupled Thermo-Hydro-Mechanical-Chemical (THMC) processes during water injection in chalk reservoirs. First, we quantify the experimental observations of hydrostatic pore collapse strength and bulk modulus of water-saturated chalk specimens as a function of temperature and sulfate concentration. This is then utilized to couple a non-isothermal multi-phase flow and transport simulator with a geomechanics simulator. Our results propose that reservoir pressure depletion, temperature changes, and water weakening play important roles in controlling the reservoir's performance. Our study confirms that accounting explicitly for the coupled THMC processes in reservoir simulations of water flooding in chalk is necessary for reliable prediction of reservoir behavior. Besides improving hydrocarbon recovery by injection of modified salinity water, the results show that MSW flooding greatly reduces the compaction of high-temperature reservoirs.
Chapter 5 presents the main challenges of upscaling modified salinity waterflooding in chalk reservoirs. It reviews the mechanisms controlling the MSW injection at the chalk surface, stemming from the interactions between calcite, brine, and crude oil. The chapter also presents the history matching of our in-house experiments conducted at core scale to obtain a salinity-induced shift in the relative mobility of the aqueous and oleic phases. Further, the chapter addresses the current difficulties in upscaling the observed benefit of MSW measured from core flood experiments to field-scale models for chalk reservoirs. It demonstrates how our findings can be used to predict performance of MSW flooding in a sector model of a Danish North Sea chalk reservoir
Original language | English |
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Publisher | Technical University of Denmark |
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Number of pages | 137 |
Publication status | Published - 2023 |
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Temperature effects on recovery processes in chalk reservoirs
Hosseinzadeh, B. (PhD Student), M. Nick, H. (Main Supervisor), Eftekhari, A. A. (Supervisor) & Feilberg, K. L. (Supervisor)
01/10/2019 → 14/06/2023
Project: PhD