渤海湾盆地南堡凹陷地层压力演化及其成藏意义

渤海湾盆地南堡凹陷2 900 m以下超压现象较普遍，然而超压成因演化研究较为薄弱.基于数值模拟技术对南堡凹陷古超压的形成与演化进行了恢复，结合沉积速率演化、生烃演化及孔隙度演化研究了超压的成因演化特征，并进一步探讨了地层压力演化的成藏意义.研究表明，南堡凹陷地层压力演化经历了原始积累(东营组剥蚀期以前)、超压释放(东营组抬升剥蚀期)及超压重新积累(东营组末期至今)3个阶段；东营组剥蚀期以前超压成因以欠压实为主，超压幕式排放利于油气幕式排出，东营组剥蚀期发生超压卸载，超压卸载使得早期形成的油气藏进行一定程度的调整，东营组末期至今以生烃增压为主，生烃增压期与2次重要成藏期及油源断层活动增强期相耦合，一方面大量油气沿断裂及岩性通道运移形成源内成藏组合，另一方面在源储剩余压力差作用下，油气沿活化的油源断层运移形成源上成藏组合；油气有利聚集区与压力分布密切相关，在相应层段油层压力系数分布区间内，总体油层厚度与压力系数具有正相关关系，因此建议将勘探重点放在相应层段压力系数分布区间内的压力系数高值区. 

Pressure Evolution and Its Effect on Petroleum Accumulation in Nanpu Sag,Bohai Bay Basin

This article aims to discuss the evolution of genetic mechanisms of overpressure, based on the numerical situation technique to recover the paleopressure formation and evolution, and combined with the evolution of sedimentation rate, hydrocarbon generation and porosity. And further study the accumulation significance of pressure evolution. The forward modeling indicates that the overpressure evolution in the sag is divided into three stages: original forming (before the erosion of Dongying Formation), release (during the erosion of Dongying Formation) and reform (since the end of Dongying Formation). Compaction disequilibrium is the main cause of overpressure before the erosion of Dongying Formation, which is beneficial to hydrocarbon emission. Overpressure release occurred during the erosion of Dongying Formation, which leads to the early reservoir adjustment to a certain extent. Hydrocarbon generation is the main cause of overpressure since the end of Dongying Formation, and coupling of the hydrocarbon generation, two hydrocarbon accumulation periods and fault activities played an active role in hydrocarbon accumulation. On one hand, a large quantity of hydrocarbon migrated along with fracture and sandstone to form inner-source plays. On the other hand, hydrocarbon migrated along with oil-source faults to form above-source plays under the high residual pressure difference between source rock and reservoir providing. The beneficial hydrocarbon accumulation regions are closely related to the stress distribution. Generally, the depth of oil reservoir and pressure coefficient is positive correlation under different plays of pressure coefficient distribution. The present study suggests that the future exploration would focus on higher value of pressure coefficient under different plays of pressure coefficient distribution.