Optimum Design of Field-Scale Chemical Flooding Using Reservoir Simulation




Wu, Wei-Jr

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Chemical flooding techniques for improved oil recovery are not widely applied in large-scale projects due to the high cost of chemical and uncertainty of oil price. An optimum design was constructed with new techniques and innovations such as high-efficiency chemicals, horizontal well technique, and advantage from the chemical reactions and interactions that is necessary to improve the cost-effectiveness of chemical floodings. A series of systematic sensitivity simulations with a realistic fluids and reservoir properties was adopted as the optimization process. The sensitivity factors included reservoir properties, injection fluid physical properties, the chemical reactions, and fluid/rock interactions. The simulations were perfo1med by a three-dimensional, multiphase, multicomponent chemical flooding simulator, UTCHEM, developed in the center for Petroleum and Geosystems Engineeling at The University of Texas at Austin. In the course of the optimum design construction, the competitive adsorption and dynamic adsorption model and the modifications of geochemical model for UTCHEM was made and validated. The optimization process was applied to three reservoirs each representative of low, moderate, and high heterogeneous permeability distributions for surfactant/polymer flooding. Several factors such as amount of chemicals, chemical adsorption, cation exchange, salinity gradient design, temperature effect on surfactant phase behavior, and low tension polymer injection scheme were studied in detail. A complete economic analysis was done on the typical on-shore U.S. oil reservoir case. We also investigated the alkaline/surfactant/polymer (ASP) flooding for a pilot with an inverted five-spot pattern and a total of 13 vertical wells and history matched three core flood results. This is the first time field-scale alkaline/surfactant/polymer flooding simulations with detailed reaction chemistry have been done. A tracer test simulation to obtain the pattern balance and optimum production rate for each producer was performed. A comparison of different improved oil recovery processes such as water, polymer, alkaline/polymer, surfactant/polymer, and alkaline/surfactant/polymer flooding was made. Finally, a series of sensitivity simulations was performed to approach the optimum design for the pilot. From these results, injection of high-efficiency surfactant and utilization of polymer for mobility control along with benefit of competitive adsorption and alkaline/surfactant/polymer process has high potential to improve the cost-effectiveness of chemical flooding.


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