Development of Isotherm Polymer/Surfactant Adsorption Models in Chemical Flooding
Cuong T.Q. Dang, Zhangxing Chen, Ngoc T.B. Nguyen, Wisup Bae, Thuoc H. Phung
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The injection of chemical solutions plays an important role in increasing the recovery factor of mature fields. For many reservoirs, polymer or surfactant flooding is an attractive alternative to conventional waterflooding; it can improve the area swept efficiency not only in the macro scale but also in the micro scale.
Adsorption of polymer/surfactant on reservoir rock is an extremely important parameter for chemical flooding. Adsorption represents a loss of a chemical agent from solution, and consequently, a net reduction in the surfactant-polymer slug. Therefore, the efficiency of chemical flooding will be significantly diminished not only in technical aspects but also in terms of economics. However, adsorption is usually measured in laboratory scale with high uncertainties, and numerical simulation of multi-component adsorption is still limited. The adsorption process in a polymer/rock system has not yet been well developed, especially for highly heterogeneous reservoirs. In this paper, the polymer and surfactant adsorption processes are modeled by the Langmuir isotherm theory for various chemical flooding approaches including polymer, surfactant, micellar polymer and alkaline/surfactant/polymer flooding. The simulation results indicate that polymer adsorption strongly depends on the polymer concentration, shear rate, pH, salt concentration, and reservoir heterogeneity. An effective controlling of such parameters can reduce the effect of polymer adsorption so that it helps minimize mass of chemical loss and improve economic efficiency of the chemical flooding process.