东濮凹陷异常高压油气藏形成机理

The Formation Mechanism of Abnormal High Pressure Reservoirs in Dongpu Sag, Bohai Bay Basin

研究了东濮凹陷异常高压油气藏的特征后指出,东濮凹陷内的异常高压可分为烃源岩层异常高压和储集层异常高压。导致烃源岩层异常高压的主要原因是晚期生烃作用;造成储集层异常高压的主要原因是的盐岩或致密泥岩的有效封堵作用、油气充满度及油气成熟度。二次生烃是造成深层异常高压油气藏晚期成藏的原因,具有成藏形成时间晚,运移距离短,气油比高,油气藏压力系数较大,分布在隆起带翼部或构造斜坡带,埋深一般小于4 300 m的特点。

The study of the distribution characteristics of abnormal high pressure reservoirs in Dongpu sag in Bohai Bay basin shows that the measured abnormal high pressure in this sag can be divided into source rock abnormal high pressure and reservoir abnormal high pres- sure. The main reason of the former is the late hydrocarbon generation, and that of the latter includes effective plugging effect caused by salt or shale, its oil and gas saturation and maturity. The secondary hydrocarbon generation served as the material basis for its late hydrocar- bon accumulation in condition of deep abnormal high pressure. Such a reservoir is characterized by late formation time, short oil-gas migra- tion distance, high gas-oil ratio and big reservoir pressure factor, etc., and generally distributed in slope zone and sides of an uplift belt, with buried depth of less than 4 300 m.