| In addition to the natural severe heterogeneity of middle and high permeability reservoir in ShenLi Oilfield, the divergences of vertical, areal and interlayer permeability become serious, due to long term waterflooding, repeated perforation, forced injection and forced production, which makes the process of water shutoff and profile modification more and more difficult, and the effect of treating worse and worse. After the analysis of this realistic problem in detail, it was conducted that enlarging the plugging radius, researching economical plugging agent, optimizing the agents combination with different properties and matching the profile modification parameters and formation conditions can enhancing the treatment effects obviously. Four cheap blocking agents with different strength were studied, including weak gel, water swelling polymer combined gel, particulate combined gel and cationic starch. According to the strength of gel from weak to strong and the sequence of plugging depth near and far away, the profile modification agent is designed into preflush slug, major slug and sealing slug. The weak gel can be used as preflush slug. The gel, combined water swollen gel and combined particulate gel can be used as major slug. The cationic starch, water swollen combined gel and particulate combined gel can be used as sealing slug. All plugging parameters, including the slug volume, injection rate, injection pressure and displacement volume, were optimized according to the field reality of ShenLi Oilfield. These research results were applied in the field case in Gudao, Hekou and Shenli oil plants respectively, leading to the obvious improvement of the injection, to the general enhancement of the injection pressure and to the improvement of the intake profile. The production condition of the producer became better dramatically, which indicates a good effect of decreasing water production and increasing oil product.
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