Program Optimizayion And Effect Evaluation Of High Concentration Polymer Flooding In Sa-nan Oilfield

Polymer flooding technology is a traditional technology for enhancing oil recovery, and has already become the important method for sustainable development of Oilfield. The field test indoor experiments indicate that polymer flooding makes oil recovery factor enhanced by 12%; but ASP compound flooding enhances oil recovery factor higher, but the technology is still in the process of development. How to obtain one new technology for EOR with wide applications is a big challenge to the researchers and technicians. The research results of a number of research groups show that visco-elasticity of polymer can increase the recovery factor significantly. The indoor experiments indicate that the high concentration polymer, which has good visco-elasticity, high shearing strength and good dilution ability, can improve recovery factor to the level of ASP compound flooding. Therefore, injecting high concentration polymer is the important way to further enhance recovery factor and economic efficiency.The high concentration polymer flooding field test of main reservoir has been developed for several years in Daqing Oilfiled and obtained primary recognize. The idea of developing high concentration experiment in north of Oilfield and increasing injection concentration in industrialization block of our factory indicate: the visco-elasticity of high concentration polymer can enhance flooding efficiency obviously. The oil layer or oil droplet can be stretched by high visco-elastic property of polymer solution to increase lifting ability, thereby, the microcosmic flooding efficiency has been enhanced. The recovery can be enhanced through injecting high concentration polymer in different polymer flooding period. Indoor research indicates that injecting high concentration polymer according to different time can enhance more recovery than that of ordinary polymer flooding, and the sooner the better. The high concentration polymer is fit for the wells of more channel sand multi-connection. Whatever high concentration has been injected prior to injecting polymer or during injecting polymer, the better economic efficiency can be always gained under fluctuant oil price.This paper presents that the researches of injection property of super high molecular weight polymer by core displacement in indoor experiment simulation, and polymer types have been determined.25000 thousands molecular weight polymer single slug, combinatorial slug, and plane model polymer flooding experiments have been performed to optimize injection concentration and choose the best slug combination. Based on combinatorial slug experiment, the optimized experimental program is used to carry on the separate injection experiment with three pipe parallel for researching influence on recovery from separate layer and in different injection period, so as to optimize separate layer injection opportunity. Through high-concentration polymer flooding experiments in Sanan block, with the help of reservoir sediment feature, oil layer producing condition and remaining oil distribution, and applying reservoir numerical simulation method, the injection parameter designs have been optimized and chosen, the dynamic change law of high concentration polymer in injection process and response features of production well have been analyzed, and primary effect has been evaluated. After high concentration polymer is injected, the injection pressure of injection wells rising smoothly, resistance factor being big, injection performance being better, the injection profile adjusting obviously, producing state being improved, response ratio of produced well being big, and the effect of increasing oil and decreasing water being obvious, especially the area of high water cut saturation has been improved significantly.Thereby, the researches in this paper will provide guides for operations of high concentration polymer flooding in other blocks.