Study on Key Technology of Tapping Potential and Adjustment at High Water Cut Stage in Offshore Delta Oilfield

In view of the complex water flooding law, serious interlayer interference and prominent non-Newtonian fluid characteristics of heavy oil faced by offshore delta S Oilfield in Bohai Sea at the "Double High" stage of high water cut and high recovery degree, how to lock the remaining oil enrichment area and realize the efficient production of heavy oil in this area is the key to the potential tapping and adjustment of the oilfield. In this paper, firstly, a large number of core sampling, seismic, logging and other data are used, combined with the type of lateral contact of single sand body, to quantitatively describe the plane configuration boundary and lock the remaining oil area formed by imperfect injection and production. Secondly, the mathematical model of dynamic change of water flooding sweep thickness is established by introducing the influencing factors such as heterogeneity and water injection /polymer injection in single sand body. Based on this, the main controlling factors of water flooding sweep thickness are analyzed, and the water-line advancement charts of different types of estuary dam are established. The actual drilling water flooding data of S oilfield are used for comparison and verification. Finally, the quantitative relationship between seepage velocity and viscosity of heavy oil is obtained by using indoor experimental data, and the equivalent numerical simulation of non-Newtonian characteristics of heavy oil in the remaining oil enrichment area is realized. The results show that after the offshore delta facies oilfield enters the high water cut stage, there are still many remaining oil enrichment areas formed by imperfect injection and production in the plane of single sand body. In the vertical distribution of remaining oil, due to different geological factors and development conditions, the thickness of water flooding will be quite different. The larger the formation heterogeneity, the larger the injection pore volume multiple, the smaller the reservoir thickness, the higher the proportion of the water flooding thickness to the single layer thickness. In the remaining oil enrichment area, the heavy oil recovery of the horizontal well infilled well pattern will be 10% higher than that of the basic well pattern. Based on this study, the error of the water flooded thickness distribution map is less than 20%, and the new wells used for guidance are in good condition. The above technologies effectively guide the research on the adjustment scheme of S Oilfield of Bohai Sea, and also provide technical guidance and direction for the stable and upper production of the same type of offshore oilfield in the high water cut stage, which has good application value.