Polymer microsphere flooding test and application effect evaluation of Sai 392 ultra-low permeability reservoir in Jing’an Oilfield

Abstract The Sai 392 reservoir in Jing ‘an Oilfield is a typical ultra-low permeability reservoir with dense lithology. With the advancement of reservoir development, the profile control operations of conventional injection wells struggle to reach the deep formations. Moreover, after multiple rounds of profile control, the effectiveness gradually diminishes[10]. Polymer microsphere profile control and flooding is a new type of deep profile control, oil displacement, and water shutoff technology developed in recent years[2]. Microsphere has good dispersion, low system viscosity, temperature and salt resistance, small initial particle size, water absorption and expansion, elastic deformation and self cementation ability. It can enter the deep formation and block step by step, and can be injected online without changing the established water injection system, The purpose of deep profile control, which cannot be achieved by conventional methods, is to enhance the swept volume of water drive and to control the ineffective circulation of injected water, thereby diverting the flow of liquids, pilot field tests were carried out on four water injection trunk lines in the southern part of Chang 6 reservoir in Sai 392 of Jing’an oilfield. After injection, the injection pressure, formation energy and water drive conditions of the test well group were analyzed, and the plugging effect was obvious. Through analyzing dynamic changes and effectiveness, the impact of oil increase under various conditions was assessed. The EOR effect of the test well group is evident. Polymer microsphere flooding demonstrates a favorable application effect in the early stages of low-permeability reservoirs in the Jing’an oilfield. This test is the first test of polymer microsphere flooding in ultra-low permeability reservoir of Jing’an oilfield[15]. Through the evaluation of this experimental effect, polymer microsphere profile control and flooding will continue to be carried out in other poor development blocks of Sai 392 reservoir.