乌马营潜山天然气藏地质地球化学特征和成藏过程

WUMAYING BURIED HILL GAS RESERVOIR GEOLOGICAL AND GEOCHEMICALCHARACTERS AND ORIGIN ANALYSIS

乌马营潜山是黄骅坳陷南区凹陷内深埋的潜山。鸟深1井在奥陶系顶部风化壳钻遇了具工业价值的古生古储的潜山天然气藏。探讨了该气藏的成因后指出:乌马营潜山天然气主要来源于石炭—二叠系煤系地层;天然气碳同位素与环烷指数显示出天然气不同成分间存在较大的成熟度差异,且天然气同位素发生倒转;乌深1井天然气为同源多阶天然气复合注入的产物。根据古构造恢复及包裹体研究认为,乌马营潜山天然气藏显示出两期成藏特征——早期(中生代)古气藏的改造和晚期(第三纪)少量天然气的混入。

Wumaying buried hill is a deeply buried one situated in south of Huanghua depression. Commercial gas reservoir originated and stored in Paleozoic was found at the weathering crust on the top of Ordovician when drilling Wushen-1 well. It's natural gas mainly originated from coal-bearing formation of C-P; Carbon isotope analysis, gas drying coefficient and naphthene index show that there is diversity in maturity of different component of the gas and the reverse carbon isotope series of gas, which indicate that the gas from Wushen-1 well is mixed by those in different maturation stages from the same source; Combined with the research on Wumaying paleo-structural restoration and Wushen-1 well fluid-inclusion it is found that Wumaying buried hill gas reservoir shows lately formed features, a result from early gas trap suffering destruction migration and getting mixed with lately generated gases.