倾斜多层油藏注N2非混相驱合理注气速度研究

注气速度对非混相驱的采率有很大的影响。在注气非混相驱替理论模型的基础上，分析了注水开发后单一储层注N2非混相驱界面稳定条件，给出了倾斜多层油藏注水开发后注气非混相驱考虑渗透率级差和有效吸气厚度影响的合理注N2速度界限的确定和注气动态分析方法，并对某实际油藏剖面进行注氮动态分析，用数值模拟进行了对比分析验证。结果表明：所给出的合理注气速度界限的确定方法和倾斜多层油藏的注N2动态分析方法是合理的。

Reasonable Velocity of N2 Injection Nonmiscible Flooding in Tilting Multilayer Reservoir

Gas injection velocity has strong effected on oil recovery for non-miscible flooding. Based on theoretical model of two-dimensional displacement in porous media and interface stability condition of N 2 non-miscible flooding after waterflooding, the determination method of reasonable N 2 injection velocity limit and the performance analysis ways as to tilting multilayer reservoir have been presented in this paper by taking both permeability and effective gas imbibition thickness into account. It has been found that reasonable N 2 injection velocity is proportional to the product of permeability by effective gas imbibition thickness, and reasonable N 2 injection velocity must be less than minimum value of maximum N 2 injection velocity in all layers. Partial stability will occur when N 2 injection velocity is greater than minimum velocity and less than maximum velocity. Oil recovery will gradually decrease in such situation. Comparing results from N 2 injection performance analysis of actual reservoir with that of simulation indicated that methods presented in the paper are reasonable and effective ways for determining reasonable N 2 injection velocity and analyzing injection performance in tilting multilayer reservoir.