基于示踪剂监测和数值模拟的低渗透油藏注采连通性评价

长庆油田作为中国低渗透油藏开发的典型油田,拥有储量巨大的致密油气资源。由于其储集层非均质性强、注采连通性差,油藏采收率普遍不高,亟需对油藏开发单元进行精细描述,以提高中—高含水期井组开发效果。以长庆油田Q011-35井组为研究对象,基于目的层长6₁砂体接触类型划分,采用微量物质示踪剂监测与油藏数值模拟结合的方法,从平面和剖面综合评价井组水驱效果。结果表明：Q011-35井组储集层非均质性较强,平面上,在西北和正西方向发育高渗条带;剖面上,长$6^2_1$砂体较长$6^1_1$砂体水洗程度高,长$6^1_1$剩余油更富集,明确了砂体连通状态和注采对应关系为剩余油分布的主控因素。微量物质示踪剂监测与油藏数值模拟结合的方法克服了采用单一方法评价井间连通性的局限性,结果更加准确可靠,为精细评价低渗透油藏水驱开发效果、制定剩余油挖潜措施提供借鉴。

Evaluation on Injection-Production Connectivity of Low-Permeability Reservoirs Based on Tracer Monitoring and Numerical Simulation

As a typical oilfield developing low-permeability reservoirs in China, Changqing oilfield has huge resources of tight oil and gas. However, strong reservoir heterogeneity, poor injection-production connectivity and low oil recovery make it urgent to describe the reservoir development units in details to improve the development effects of well groups at medium-high water cut stage. Taking well group Q011-35 as a case, this study evaluated the waterflooding development effect of the well group based on the contact types of the target Chang 6₁ sand bodies and the results of tracer monitoring and reservoir numerical simulation. It is concluded that the well group Q011-35 is strongly heterogeneous. Laterally, there are high-permeability zones in the northwest and southwest, while vertically, Chang $6^2_1$ is flooded more completely than Chang $6^1_1$, and the remaining oil in Chang $6^1_1$ is richer, indicating reservoir connectivity and injection-production relationship are controlling factors on the distribution of remaining oil. The combination of tracer monitoring and reservoir numerical simulation eliminates the limitations caused by a single method in evaluating interwell connectivity, therefore the results are more accurate and reasonable. The conclusion is a reference to fine evaluation on waterflooding development effect of low-permeability reservoirs and taking effective measures for potential tapping of remaining oil.