渤海湾盆地东濮凹陷压力演化与超压形成机制

通过实测压力、泥岩声波时差、流体包裹体古压力恢复及盆地模拟,对东濮凹陷北部地区地层压力的演化和现今压力特征进行分析,结合岩心观察解析超压的形成机制,探讨不同机制对超压的贡献率。结果表明:剩余压力的演化经历"超压原始积累-超压释放-超压重新形成"3个阶段,两次超压的形成时期与油气成藏的时期相对应;古今超压的空间展布均受构造格局、断裂活动和膏盐岩分布的控制,洼陷带以及盐下、盐间地层的剩余压力较大;超压的形成主要为欠压实作用、生烃作用及膏盐岩作用的结果,生烃作用对超压的贡献率与烃源岩的热演化相关。

Pressure evolution and formation mechanism of overpressure in Dongpu depression,Bohaiwan Basin

The pressure evolution and present pressure characteristics in north part of Dongpu depression were analyzed based on the measured pressure, mudstone sonic log interval, the pressure recovery by fluid inclusions and basin modeling. The overpressure formation mechanism was analyzed combined with core observation, and the contribution rate of hydrocarbon generation on the overpressure caused by different mechanisms was discussed. The conclusions are as follows. Firstly, that residual pressure evolution experienced three stages:primitive accumulation-release-reform, and two overpressure formation periods are corresponded with the oil and gas accumulation period. Secondly, the distribution of paleo-pressure and present pressure are controlled by tectonic framework, fault activity and plaster salt-gypsum rock distribution. Moreover, the formation in subsag belt or below/between the salt-gypsum rock developed larger residual pressure. Lastly, overpressure formation is mainly caused by compaction disequilibrium, hydrocarbon generation and salt-gypsum rock effect. In addition, the contribution rate of hydrocarbon generation on the overpressure is related to the thermal evolution of source rocks.