基于相渗曲线的油藏注入水利用状况评价方法

针对现有油藏注入水利用状况评价方法不能适应油藏阶段注采比不断变化的问题,提出了基于相渗曲线的油藏注入水利用状况评价方法。首先,根据油藏归一化相渗曲线,确定油藏含水上升规律描述方程。其次,根据油藏不同阶段实际可采储量采出程度,采用由归一化相渗曲线确定的油藏含水上升规律描述方程,计算对应的理论含水率,再结合油藏不同阶段实际注采比,进而计算油藏不同阶段的理论阶段存水率和理论阶段水驱指数偏离量。然后,根据油藏不同阶段实际注采比和实际含水率,计算油藏不同阶段的实际阶段存水率和实际阶段水驱指数偏离量,绘制实际(理论)阶段存水率和实际(理论)阶段水驱指数偏离量随时间的变化曲线。最后,通过对比理论曲线和实际曲线,评价油藏的注入水利用状况。采用该方法对老君庙L油藏西区注入水利用状况进行了评价。结果表明:1970年以前,注入水利用状况较差;1970年以后,注入水利用状况较好。

EVALUATING METHOD OF THE INJECTED WATER UTILIZATION CONDITIONS FOR THE OIL RESERVOIR BASED ON THE RELATIVE PERMEABILITY CURVES

Aiming at the problem that the existing evaluating methods of the injected water utilization condition for the oil reservoir are not suitable for the constant changing of the stage injection-production ratio,the new evaluating method was proposed based on the water-oil relative permeability curves.Firstly,according to the normalized relative permeability curves of the reservoir,the describing equation about the watercut rising laws was established for the reservoir.Secondly,according to the actual recovery degree of the recoverable reserves in different stages of the oil reservoir,with the help of the normalized relative permeability curves,the characterizing equation of the rising laws was determined;the corresponding theoretical water cut was calculated,and moreover integrating with the actual injection-production ratio of the reservoir in different stages,the theoretical stage water storage rate and deviation amount of the theoretical stage water drive index were computed.Thirdly,according to the actual injection-production ratio and water cut in different stages,the actual stage water storage rate and deviation amount of the actual stage water drive index were calculated,and then the changed relations between the actual (theoretical) stage water storage rate as well as the deviation amount of the corresponding actual (theoretical) stage water drive index were drawn with the time.Finally,by means of the comparison between the theoretical and real curves,the utilized conditions of the injected water were evaluated.With the help of the method stated above,the injected water utilization conditions were evaluated for West Reservoir L in Laojunmiao Oilfield.The achievements show that the injection water utilization conditions were poorer before 1970 comparing with those after 1970.