Research on Strategies for Tapping Potential of Low Oil Column and Strong Bottom Water Reservoirs in the Middle and Late Stages of Development
Authors: Xie Yue , Gan Liqin , Gong Tianhao , Wang Gongchang , Deng Jingfu , Lv Zuobin 
Published: February 2025

Horizontal wells are an effective well type for developing low oil column and strong bottom water reservoirs. In the early stages of development, they can effectively increase the drainage area and slow down the rate of water cut increase. However, in the later stage of development, there are problems such as unclear water outlet points in horizontal wells, difficulty in controlling water, and low oil recovery rate and recovery rate. Based on fine reservoir characterization and production dynamic data, this study accurately predicts the water flooding mode of horizontal well, and propose corresponding production measures to achieve stable oil and water control. Firstly, based on forward simulation and multi-attribute comparison, the minimum amplitude attribute is selected to predict the spatial distribution of reservoir. Secondly, four amplitude attributes that are highly correlated with interlayer thickness are optimized, and the weight coefficient is automatically obtained under interlayer thickness supervision, then the seismic attribute fusion is obtained to predict the spatial distribution of interlayer. Then, based on dynamic data, three modes of linear waterflood, point waterflood and multi-point waterflood are proposed. Linear waterflood is common in homogeneous reservoirs, and the production dynamic curve can be divided into three stages, namely, the long water-free oil production period, the slow rise in water content period and the high water cut period. And the quadratic derivative curve of water cut has no obvious jump point. For linear waterflood mode, increasing pressure can be used to maintain stable production with high fluid volume. Point and multi-point waterflood are common in areas with strong heterogeneity and intercalation, where remaining oil is enriched. The water breakthrough time and number can be determined by quadratic derivative curve of water cut.Then, the water breakthrough position is determined by combining the reservoir distribution, oil column height, interlayer distribution and numerical simulation. Finally, the intelligent subcompartment water control technology of horizontal wells is used for subsection water control to achieve water control and oil stability.This method has been successfully applied in L oilfield. L oilfield is a shallow water delta deposit, with oil column height of 20m, water body multiple of 60. The daily oil production of 22 wells is 1274 stb/day, and comprehensive water content is 97%. Based on the above study, the operation of stabilizing oil and controlling water in 5 horizontal wells was successfully implemented, resulting in an additional oil quantity of 1596 stb/day and water cut down to 80%, which successfully reversed the development situation of the oilfield.The successful stabilization of oil and controlling water in L oilfield shows that the above strategy is effective. This method provides a new approach for tapping potential of similar reservoirs.