More than 80% oil reservs is heavy oil in Bohai Bay of China.This paper describes the practice and research for comprehensive adjustment of SZ oil filed which is a large scale multi-layer sandstone heavy oil reservoir in China Offshore.In order to explore the potential of the reservoir, based on the fine geological studies, dynamic data of production and testing, we got water-cut contour of sub-layers by reservoir engineering method. Quantitative description of the remaining oil in the vertical and plane direction was gained by reservoir numerical simulation method, which could be the foundation for deployment of infilling wells and adjustment program of the oilfield. All the above were verified by the pilot well. Based on these studies, we designed infill wells between the edge and corner production wells and the the well network of the oilfield changed from nine-spot pattern to line drive well network. And in the comprehensive adjustment plan we designed 52 wells, the recovery of the oilfield will increase 7.8% compared to basic program.Combined with scaled corning data and the inversion of original resistivity, we established perforating program on the basis of fine numerical model and similar oilfield experiences. Water-cut of the new drilled wells were decreased, the potential productivity of them was fully released, and the effect of the water flooding was improved. Untill Dec 2011, 48 wells have been drilled, and the cumulative oil production of the new wells was about 174 × 104m3, the recovery is expected to be enhanced more than 10.4%.The production performance of the new wells shows that the direction of the adjustment for the heavy oilfield and the method for studying the remaining oil distribution are scientifical and reasonable. The research ideas during this comprehensive adjustment and the method for studying the distribution of remaining oil in the vertical and plane direction of the reservoir can be taken as a reference for similar oilfields, such as JZ and QHD oilfields in Bohai bay.

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