Comparison of an Improved Compositional Micellar/Polymer Simulator With Laboratory Corefloods

Abstract

Summary In this paper, we compare numerical simulations made with our previously reported simulator with both our own and literature experiments. The most significant improvement concerns the phase behavior model used in the simulator. The new model approximately represents the phase behavior of pseudoquaternary mixtures containing surfactant, cosurfactant, oil, and brine. The different effects of sodium and calcium cations in the mixtures are accounted for with a new cation exchange model allowing for exchange with both clays and micelles. A tertiary oilflood experiment is reported that includes a more complete analysis of phase compositions and properties than generally available previously. Produced samples were analyzed for surfactant, alcohol, sodium, calcium, polymer, tritium, water, carbon-14-tagged decane, and decane. These analyses and pressure drop were compared with simulated behavior. Supporting physical property data were used as much as possible to estimate simulator property data were used as much as possible to estimate simulator input parameters rather than adjusting or "history matching" the results. Agreement with the most important features of the experiment was good. This agreement and good agreement with an experiment from the literature lead us to conclude that a significant improvement over previous efforts has been achieved. Especially noteworthy is our previous efforts has been achieved. Especially noteworthy is our capability to account for the chromatographic separation of surfactant and alcohol. Introduction We have had a program for several years to investigate systematically the phenomena needed for compositional simulation of the micellar/polymer process. Several comparisons of laboratory coreflood experiments with micellar/polymer or chemical flood simulators have been reported. Although significant progress has been made, these efforts have been limited by the lack of complete experimental data for even one system and by the incompleteness or inaccuracy of numerous physical property models used in the simulators. Although significant uncertainties remain in some aspects, especially regarding three-phase relative permeability and dispersion, Which continue to be investigated, permeability and dispersion, Which continue to be investigated, the treatment of several other phenomena has been significantly improved, resulting in much better agreement with oil recovery experiments. In this paper, we emphasize the application of the two most important improvements: the phase behavior and cation exchange of sodium and calcium with micelles. One of our most recent and complete oil recovery experiments is briefly reported here. Camilleri and Lin have reported more details and other experiments, and more comparisons with our simulator can be found in these and Refs. 4 and 17. We also compare our simulations with an experiment of Gupta, one of the most completely reported experiments in the literature, which has been previously analyzed and serves as a good illustration of the separation of alcohol and sulfonate in the core. Alcohols are often used as cosolvents or cosurfactants in surfactant formulations to improve the phase behavior. They can prevent or minimize gels, emulsions, liquid crystals, precipitation, prevent or minimize gels, emulsions, liquid crystals, precipitation, and polymer/surfactant interaction. They can also decrease surfactant retention, alter the optimum salinity, and increase the size of the active region. The integrity of surfactant slugs containing alcohol used for oil recovery therefore depends on the relative transport of the surfactant and alcohol. An obvious but difficult objective is to design the chemical flood so that the surfactant and alcohol will transport without separation. This is promoted by close association of alcohol and surfactant and by situations that minimize selective partitioning and adsorption. Both our theoretical understanding of these partitioning and adsorption. Both our theoretical understanding of these phenomena and our capability to simulate them have been limited phenomena and our capability to simulate them have been limited in the past. For this reason a more generalized phase behavior model was developed based on the pseudophase theory, which assumes principally that the compositions of brine and oil in the principally that the compositions of brine and oil in the microemulsion phase are identical to those of the excess brine and excess oil, respectively. In particular, the alcohol content is the same for a given pseudophase, although different for brine, oil, and membrane pseudophases. The last refers to the surfactant or interfacial region.