Study and application of in situ low interfacial tension foam flooding technology:taking A20 well group in Bohai KL oil-field as an example
Aiming to the problems such as plane flooding,uneven longitudinal water absorption and the diffi-culty of injection in conventional profile control system of A20 well group in KL oilfield of Bohai,the evalua-tion experiment of in-layer self-generated low interfacial tension foam flooding control performance was carried out.In this study,the interfacial rheometer,the foam scanner and the static evaluation device of the foam regu-lating drive were used to screen and optimize the composition agents and the optimal mixture concentration ra-tio of the self-generated low interfacial tension foam system.The dynamic regulating and flooding performance of the system was investigated by a multifunctional physical simulation displacement device.Results showed that the optimized composition and the ratio of 10%gas agent A+10%gas agent B+2%gas release agent C+0.5%surfactant PA-5+0.3%polymer PJ(mass concentration).The composite system could stabilize the bub-ble formation in the visualized sand filled tube.The oil displacement efficiency of one-dimensional sand filled pipe could be increased by 19.1%on the basis of water flooding.In the case of parallel displacement of hetero-geneous sand fill pipes,the injection complex system could further wash the residual oil of high permeability sand fill pipes and effectively block the high permeability channel,expand the sweep coefficient of low perme-ability sand fill pipes,and increase the fraction of liquid from 0 to 34%.From the field practice,the produc-tion curve of A20 well group showed a decrease in water cut and an increase in oil production after the imple-mentation of self-generated low interfacial tension foam flooding operation,with a cumulative oil increase of 2 007.29 m3 within 3 months.It preliminarily proved that the technique of self-generated low interfacial tension foam flooding had broad application prospect in this kind of reservoir.
Bohai oilfieldin situ foam systemlow interfacial tensionprofile control and flooding perfor-manceoilfield chemicals
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