渤中坳陷天然气地球化学特征及部分气源浅析

渤中坳陷位于渤海海域中部，是海上独立的一个一级负向构造单元，面积约19800km2，坳陷东界为辽东－鲁东隆起区，南界以索南凸起的南侧断裂与济阳坳陷分隔，西与埕宁卫起为斜坡过渡，东北与辽河坳陷相通，陷由3个凹陷（秦南凹陷，渤中凹陷及渤东凹陷）和5个凸起（秦南凸起，石臼坨凸起，渤东低凸起，庙西凸起及渤南凸起）组成。

Geochemical characteristics and natural gas sources of Bozhong depression, Bohai Bay basin

Among the natural gases discovered in Bozhong depression, hydrocarbon gas is dominant and non hydrocarbon gas is small. Of the gases found below the Dongying cap rocks, most are wet gas and a few are dry gas. This dry gas was formed by pyrolysis. But among the gases found beneath the Minghuazhen cap rocks, most are dry gas and a few are wet gas. This dry gas was formed by biodgradiation. The gases from Shahejie and Dongying source rocks are mostly oil type gas. The gas of QHD30 1 is mixed gas and mainly from the coal derived gas from pre Tertiary source rocks. The formation of natural gas in the Bozhong depression is characterized by multiple sources, multi periods and continuous generation and expulsion. So its exploration potential is good in Bozhong depression. The regions where the Dongying cap rocks well developed are the major exploration targets of natural gas.