断层气密性定量评价方法及其在油田开发中的应用

Quantitative assessment of fault gas-sealing capacity and its application in oilfield development

吴义志,王建,武刚

WU Yizhi, WANG Jian, WU Gang

中国石化胜利油田分公司勘探开发研究院，山东 东营 257000

Research Institute of Exploration and Development, Shengli Oilfield Company, SINOPEC, Dongying 257000, China

胜利油田复杂断块油藏已进入特高含水开发阶段，由于断块面积小，剩余油规模小，通过新井挖潜，经济效益较差。油藏开发过程中，提出了在断块构造高部位注氮气形成“人工气顶”，以置换高部位剩余油的技术方法，这就要求开发地质研究中要定量、准确地评价控油断层对注入氮气的封堵能力。文中综合应用断层破碎带内幕密闭取心及围岩普通取心等资料，开展了测试与对比分析；在此基础上，创新性地提出了基于成岩等效类比的断层气密性定量评价方法——通过对围岩普通取心样品排替压力的测试分析，回归建立排替压力公式，据此转换计算得到断层岩的排替压力，并通过“断储压差”的计算，定量评价断层的气密性。该方法在胜利油区“人工气顶驱”开发先导试验工区的应用，为优化特高含水期提高原油采收率方案设计奠定了基础。

Complex fault block reservoir of Shengli oilfield has entered the stage of ultra-high water cut development. Due to the small area of fault block and small scale of remaining oil, the economic benefit of tapping potential through new wells is poor. In the reservoir development, the technique of replacing residual oil at high position by artificial gas cap formed by nitrogen injection at high structural position of fault block is proposed, which requires quantitative and accurate evaluation of sealing ability of oil-control fault to nitrogen injection in development geological research. Based on the data of closed coring in fault fractured zone and common coring in surrounding rocks, the test and comparative analysis are carried out. On this basis, the quantitative evaluation method of fault gas-sealing capacity based on diagenetic equivalent analogy is innovatively proposed. Through the test and analysis of displacement pressure of surrounding rocks common coring samples, the displacement pressure formula is established by regression, and the fault rock displacement pressure is obtained through conversion calculation. The fault gas-sealing capacity is evaluated quantitatively by the "pressure difference between fault and reservoir". The method has been applied to the pilot of "artificial gas cap drive" test area in Shengli Oilfield, which lays the foundation for optimization design of EOR in ultra-high water cut stage.

10.6056/dkyqt202202021