东濮凹陷白庙地区古近系超压成因机理

综合超压成因机理的各种分析方法,从压实不均衡、生烃作用两方面对白庙地区的超压成因机理进行了系统的分析.研究结果表明,泥岩声波时差曲线表现为两段式线性演化,其拐点深度为3 100 m左右.一方面,白庙地区实测超压顶界面深度约为2 800～3 050m,说明是压实不均衡作用导致了该区超压的形成;另一方面,超压顶界面埋深与生烃高峰深度表现出良好的一致性,在3 050 m深度其镜质体反射率R0值为1.0%,说明生烃作用对白庙地区超压的发育亦具有一定的贡献,由此认为,压实不均衡和生烃增压作用是白庙地区超压发育的主要机理.

Eogene Overpressure Mechanism in Baimiao Area of Dongpu Depression

Dongpu depression lies in the southwest of Bohaiwang Basin,and is a tensional pull fault basin developed in Paleogene. While Baimiao structure is located in the southern part of the sag , and it has an absolute response of the overpressure. In the Baimiao area the overpressure mechanism was studied by every aspect of possibility, such as the compaction disequilibrium and hydrocarbon generation. The result indicates that the Paleogene formation of Baimiao area shows a compaction disequilibrium situation where mudstone acoustictime curve present a two parts linear evolvement, with the inflexion depth about 3 100 m. Meanwhile, the measured top depth of overpressure is 2 800-3 050 m. This verifies that the compaction disequilibrium causes the overpressure in the area. On the other hand, there is a good coherence between the top depth of the overpressure and the hydrocarbon generation fastigium ,and the Ro is 1.0% at the depth of 3 050 m, which verifies the contribution of the hydrocarbon generation to the overpressure de- velopment. Therefore, it can be concluded that hydrocarbon generation and the compaction disequilibrium are the main mechanism of the overpressure development.