南堡凹陷盖层封闭油气有效性的定量评价

Quantitative evaluation for sealing effectiveness of cap rocks in Nanpu Sag

沈群¹ 孙同文¹ 樊树峰² 汪振杰³

东北石油大学地球科学学院，黑龙江 大庆 163318 延边大学理学院，吉林 延吉 133002 中国地质大学（武汉）资源学院，湖北 武汉 430074

College of Geosciences, Northeast Petroleum University, Daqing 163318, China College of Science, Yanbian University, Yanji 133002, China Faculty of Resources, China University of Geosciences, Wuhan 430074, China

为了研究南堡凹陷盖层在油气成藏中的作用，文中利用烃源岩演化、成藏期与盖层排替压力等的对应关系对南堡凹陷盖层天然气封闭时间有效性进行评价，利用南堡凹陷现今盖层排替压力测试资料及油气藏剩余压力计算对盖层封闭天然气的能力有效性进行评价，并且分析了盖层排替压力与油气藏剩余压力的差值及天然气相态和产能之间的关系。结果表明：盖层形成封闭能力的时间均早于沙三段烃源岩大量排气期或与之同期，在时间上封闭油气是有效的；盖层排替压力大于储层剩余压力时，具有能够有效的对油气进行封闭的能力；压力差不同，天然气在地下的相态也不同，并且压力差与天然气产能成反比。盖层封闭油气有效性决定了其下富集油气量。

In order to study the role of cap rock for hydrocarbon accumulation in Nanpu Sag, the sealing effectiveness of cap rocks was evaluated in Nanpu Sag by analyzing the relationship of the evolution of hydrocarbon source rocks, accumulation period and cap rock displacement pressure, it was also evaluated by present cap rock displacement pressure test and reservoirs residual stress calculation. Relationship of the difference between cap rock displacement pressure and remaining reservoir pressure and gas phase-yielding capacity was studied. Results show that formation time of cap rock sealing ability is earlier than Es3 hydrocarbon expelling period or in the same period, oil-gas can be broad-scale accumulated, so it is effective to seal oil-gas in the time; when cap rock displacement is greater than the residual pressure of reservoirs, it can effectively seal oil-gas; with the different pressure, gas phases are different in the ground, and the pressure difference is inversely proportional to gas capacity. The sealing effectiveness of cap rock determines that it can be rich in oil and gas.

10.6056/dkyqt201504002