Geochemical Modeling of Oil-Brine-Rock Interactions during Brine-Dependent and Brine-CO2 Recovery Technique in Carbonate Petroleum Reservoirs
Date
2019-04-24
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Abstract
The brine-dependent recovery process involves the tweaking of the ionic composition and strength of the injected water compared to the initial in-situ brine to improve oil production. The recovery process has seen much global research efforts in the past two decades because of its benefits over other oil recovery methods. In recent years, several studies, ranging from laboratory coreflood experiments to field trials, admit to the potential of recovering additional oil in sandstone and carbonate reservoirs and has been well-explored on two frontlines, namely, brine dilution and compositional variation. However, many challenges have saddled the recovery process, such as disputes over the fundamental chemical mechanisms; difficulty with construction of a representative model to give reliable interpretation and prediction of the process, and these necessitate applicable solution. Therefore, this study explores the formulation of theory based on experimentally-observed behavior to couple equations of multicomponent transport and geochemical reactions. Mechanisms such as dispersion/diffusion, advection, instantaneous equilibrium reactions, and non-equilibrium rate-controlled reactions are captured in the construction of the numerical models. The DLVO theory of surface forces was also applied to rationalize potential determining ion interactions and to evaluate the contribution of each force component to the wettability change in the oil-brine-rock system and the characteristic oil recovery improvement. The model was applied to interpret recently-published results on the different approaches that have been explored in the application of brine-dependent recovery process in carbonate reservoir rocks. The focus being that identifying the dominant mechanisms responsible for the observed improved recovery will help substantiate the field application of the process. The study demonstrates that injected brines, containing potential determining ions depleted in NaCl, are more effective at improving recovery when it, and wettability alteration is much more pronounced at high temperatures. It was also illustrated that potential determining ion concentrations play a more significant role as compared to brine salinity reduction. The magnitude of the contribution of the electrostatic force to sustaining a stable water film increases with decreasing ionic strength, either through reduction of NaCl, Ca2+ or brine dilution, or increasing SO42- concentration. Mineral dissolution/precipitation is necessary for the pursuit of re-establishing equilibrium and should not be ignored in modelling different mineralogical carbonate rocks. The derived optimized thermodynamic parameters are demonstrated to be widely applicable. Although chalk and limestone differ by surface area and reactivity, the same thermodynamic parameters are applicable in modeling the recovery process in their respective reservoir rocks. There is a significant increase in relative injectivity for brine-CO2 recovery mainly due to more exposure to a higher amount of CO2-saturated-brine
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geochemical modeling, surface sorption and complexation, oil-brine-rock interactions, low-salinity-water-CO2, water film stability, interfacial mechanisms, potential determining ions, smart waterflooding, carbonate rocks, wettability alteration
Citation
Awolayo, A. N. (2019). Geochemical modeling of oil-brine-rock interactions during brine-dependent and brine-CO2 recovery technique in carbonate petroleum reservoirs (Doctoral thesis, University of Calgary, Calgary, Canada). Retrieved from https://prism.ucalgary.ca.