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A common method of enhanced oil recovery is alkaline-surfactant-polymer (ASP) flooding where a solution of alkali, surfactant, and polymer is injected followed by a polymer drive. Many crude oils contain naphthenic acids that react with the alkali to form soap in-situ. With the proper selection of an injected surfactant that mixes with the soap in-situ, a sufficiently low interfacial tension can be achieved to mobilize the residual oil. However, ASP flooding is complex since it involves chemical reactions that depend on the oil composition, water composition, rock mineralogy, temperature, pH, etc. Mechanistic simulations of ASP flooding typically involve a large number of reactions to calculate the consumption of alkali due to ion exchange reactions with the clay and micelles as well as other reactions with the minerals and brines. This approach is computationally intensive. After a full mechanistic model of ASP flooding was developed and validated, a simplified ASP model was implemented in a 3D chemical flooding reservoir simulator. In the simplified ASP model, the amount of soap is calculated using the total acid number of the crude oil. A phase behavior mixing rule model was developed to calculate the optimum salinity and solubilization ratio of the soap and surfactant mixtures. Other key mechanisms modeled are alkali consumption and surfactant adsorption as a function of alkali concentration. Several ASP corefloods were successfully modeled using the simplified ASP model. Based on these results, 3D simulations of an ASP field pilot were performed. In this particular case, the results were comparable to those obtained from ASP flooding simulations using a more complete set of geochemical reactions. The simplified ASP flooding model is a more practical and convenient way to simulate field applications of ASP flooding for such cases.

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Our team has developed a new simulation model for an upcoming 5-spot Alkaline-Surfactant-Polymer (ASP) pilot in the Sabriyah Mauddud reservoir in Kuwait. We present new pilot simulation results based on new data from pilot wells and an updated geocelluar reservoir model. New cores and well logs were used to update the geocellular model, including initial fluid distributions, permeability and layer flow allocation. From the updated geocellular model a smaller dynamic sector model was extracted to history match field performance of a waterflood pattern. From the dynamic model a yet smaller pilot model was extracted and refined to simulate the 5-spot ASP pilot. We used this pilot model to evaluate injection composition, zonal completions, observation well locations, interwell tracer test design and predicted performance of ASP flooding. A sensitivity analysis for some important design variables and pilot performance benchmarks is also included. We used multiple interwell tracer test simulations to estimate reservoir sweep efficiency for both water and ASP fluids, and to help us understand how well operations will affect this unconfined ASP pilot. This work details some crucial aspects of pre-ASP pilot design and implementation.