地震泵抽吸作用与油气运聚成藏物理模拟

Suction Role of Seismic Pumping and Physical Simulation on Hydrocarbon Migration and Accumulation

地震泵抽吸作用是在断裂活动开启过程中,引发流体进入断裂带,并发生垂向运移的作用方式。在裂隙递进扩张形成优势裂隙并进一步发展成大的断裂面的演化过程中,地震泵抽吸作用发生,围岩中的流体在相对负压抽吸作用下进到断裂带中,之后主要在构造应力和异常高孔隙流体压力的共同作用下向上运移,并向着邻近断裂的封闭程度差、体积大、物性好的储层中充注运移,运移效率远远高于达西流和扩散流。断裂周期性破裂活动的特征决定了油气沿断裂的垂向泵吸运移呈周期性、间歇性和脉动的特点,同时也决定了油气易于在断裂错开的最新层位聚集成藏。通过克拉2气田天然气运聚成藏过程物理模拟实验结果表明,紧邻圈闭的盐下断裂为有效的天然气运移通道,穿盐断裂为无效的天然气运移通道,天然气在地震泵抽吸作用下沿断裂运移速度快、效率高,在断裂活动的短时间内可以大规模运聚成藏。

The suction role of seismic pumping can induce fluid flowing into fault zone and further migrating into the fault zone. When micro-fractures develop and become dominant fractures, further form fault, the suction role of seismic pumping occurs. At the same time, fluid inside surrounding rock flows into fault zone as a result of relative negative pressure suction role. Afterward, fluid migrates upwards along fault zone as a result of tectonic stress and abnormal pore pressure, and flows into a reservoir with bad sealing, large volume and good physical property, where migrating efficiency is much higher than that of Darcy flow and diffusion flow. Because of periodically faulting hydrocarbon pumping migration along fault zone is periodic, intermittent and pulsant, and hydrocarbon migration and accumulation often locates the newest strata. The physical simulation results on the process of gas migration and accumulation in Kela 2 gas-field indicate that the fault below salt near trap is effective migrating passage of natural gas, whereas the fault cutting salt is noneffective migrating passage of natural gas. It also indicates that the natural gas migration along fault zone is characterized by high speed and high efficiency under the suction role of seismic pumping, and natural gas can migration and accumulation at large scale in the short time of faulting.