Research On Reservoir Geological Properties For Horizontal Well Application

In recent years, horizontal well is paid more attention for enhancing swept volume and improving development results. Following water injection, the field test of horizontal well was performed in SaZhong developing areas in 2004, and the test result of N1-2-P25 well was very satisfying, indicating that it is feasible to develop the oil residued on the top of main reservoirs by drilling horizontal well. However, the present challenge for Daqing Oil Field is that there are still considerable portion of residual oil in thick channel sands, where the polymer solution has been injected. Therefore, it is essential to find a way to produce the residual oil developed by polymer flood. Although horizontal well has been applied to develop the oil residued on the top of main reservoirs, there is no case for the technology to be used to produce the residual oil after polymer flood.On the basis of wide investigation on technical reference and study results from the domestic and abroad, the paper describes geological characteritics of river channels, combining with core data and well test logging information. Meanwhile, the heterogeneity within the resevoirs, the most important key factor that causes residual oil formation after polymer flood, is studied, and the description method for the heterogeneity within the reservoirs is obtained. With the analysis on geological properties, the method used to analyze residual oil distribution is completed by injection-prodution relationship analysis, performance data, well test logging data of new drilled well. Form the analysis aforementioned, it is feasible for the horizontal well to develop the oil residued on the top of main reservoirs after polymer flood and in well damage areas as well. The paper presents a set of method with respect to potential analysis of horizontal well and optimization, fine reservoir description for horizontal well application area, 3D modeling formation, residual oil description, well location optimized for horizontal well and etc. The research will provide technical support for improving the oil recovery of mature oilfields and offer valuable experience for future horizontal well's design and application.