Experimental Studies of Oil Recovery After Alkali-Surfactant-Polymer (ASP) Flooding with West Salym Cores

Abstract

Abstract Chemical EOR project in Salym Petroleum Development (SPD) aims to increase oil recovery factor by applying a mixture of alkali, surfactants and polymer (ASP). In West Salym field it is expected to gain increase in oil recovery of 10–20%. A successful ASP pilot was conducted by Shell in 1989 in several wells of White Castle field, LA, where 38% of oil left after water-flood was recovered by ASP flooding. ASP method was first developed in early 80s in Shell, in Bellaire Research center, Houston, as a result of field testing of different chemical methods. Surfactant in the mixture reduces interfacial tension between oil and water, which leads to mobilization of resudual oil in porous medium of the rock. For efficient mobilization of oil the value of interfacial tension should be lowered down to extra-low values of 10-3 mN/m. Alkali is added in order to reduce adsorption of surfactant into the formation, which helps to bring down consumption of expensive surfactants. Polymer increases viscosity of the mixture, which helps to stabilize flow, improve sweep and displace viscous emulsion created in the formation. Several companies are involved in the SPD project: surfactant selection is done by research department of Shell, core experiments are conducted in the Laboratory of Reservoir Physics in JSC TomskNIPIneft, Salym Petroleum Development N.V. manages and coordinates the project. Recently GazpromNeft Research Center joined the work on surfactant selection. The objectives of the experiments conducted in JSC TomskNIPIneft were: Determination of the optimal salt concentration for creation of the maximum volume of micro-emulsion in the mixture of oil and ASP cocktail based on phase behavior tests.Modeling of reservoir conditions of West Salym field and expected technological operations during injection of ASP solution in the core flood experiments.Determination of residual oil after ASP flood and its distribution along core column at various volumes of ASP slug, various concentrations of salt and alkali, and various polymer viscosity.