Experimental Study On Slug Combination And Injection Method Optimization Of ASP Flooding

The ASP flooding technology is widely used in major oil fields in my country and has achieved relatively ideal results.With the gradual deepening of research on ASP flooding technology,the existing problems have gradually emerged.In the second-class oil layer,affected by the heterogeneity of the reservoir development,the production is uneven among the layers,and the production degree of the middle and low permeability layers is relatively low.In the layer,the bottom of the positive rhythm is mainly used,and the breakthrough time of the front edge of the high permeability layer is early,which affect the overall development effect and causes waste of compound flooding chemicals.A large number of studies have shown that the different slug combinations and injection methods of ASP flooding have obvious effects on the improvement of oil recovery.Therefore,the research carried out in this article has theoretical guiding significance for enriching the application of ASP flooding and giving full play to the synergy between chemical agents.This paper firstly determined the types and concentrations of polymers,surfactants and alkalis suitable for ASP flooding through experiments to provide a material basis for later research.In view of the heterogeneity of the reservoir,a strip core model and a flat core were designed and produced for the physical simulation experiment of intralayer and interlayer heterogeneity.The core model adopts a well layout method of one injection and one mining.The difference of the model is that it can simulate various injection and production methods,and the pressure plate and electrode accessories are designed to ensure accurate spatial coordinates while simultaneously making,accurately control the value of permeability,and have good parallelism.Using the core model,the effects of conventional injection methods with different pre-slugs and three-way main slugs and alternate injection methods on the effect of ASP flooding were carried out.By comparing the degree of recovery,pressure changes,remaining oil distribution,and produced fluid detection results,the influence of different injection parameters on the development effect is summarized,and the most efficient injection method and slug combination are finally determined.The research results show that the alternative injection of ASP flooding has a better displacement effect than conventional injection.In the core model,the viscosity and injection volume of the conventionally injected ASP flooding front slug and the ternary main slug affect the increase in injection pressure and the pressure transmission in the core.Considering the injectability of the front slug and the main slug and the effect of alleviating the contradiction between the layers,the injection viscosity is not easy to be too high.Since there is no interlayer channeling in the interlayer heterogeneous model,it is difficult to form interlayer disturbance and pressure communication,and the interlayer of the core affects the interlayer flow.Therefore,the sweep efficiency of the middle and low permeability layers is low,and the enhanced oil recovery value of ASP flooding is relatively small.The alternative injection of ASP flooding in the heterogeneous core model with a coefficient of variation of 0.65 has a better displacement effect.Alternate injection adopts a high-viscosity polymer slug + low-viscosity ternary slug alternately injecting 4 rounds of injection,and the degree of recovery is the best.Because the high-viscosity polymer slug fully exerts its fluidity control ability,the low-viscosity ternary slug can better flow into the middle and low-permeability layers to expand the volume.The 4rounds of alternate injection avoids the situation of too few injection rounds and large slugs,and at the same time avoids the situation of too many alternate injection rounds and the length of the slugs is small.It can effectively play the role of fluidity control without destroying the polymer slug,effectively reduce the chemical agent adsorption and dilution loss,and give full play to the synergistic effect between the chemical agents.