东营凹陷坨庄地区T165油藏低压充注的流体包裹体记录

东营凹陷坨庄地区深部储层中发育被方解石充填的构造裂缝,方解石脉中油气包裹体丰富。方解石脉中包含2种不同结晶形态的颗粒,它形细晶颗粒和自形中晶颗粒,且2种晶体颗粒中流体包裹体特征也有所差异。通过流体包裹体的镜下观察、显微测温以及PVT模拟恢复了包裹体被捕获时的温压条件,分析了油气成藏的特点:①流体包裹体只记录了一期油气成藏,主要在明化镇组沉积时期;②油气成藏早期,储层压力系数小于1,表现出低压成藏的特点,断层活动产生的泵吸作用是油气充注的主要动力。此外,研究结果表明,不能简单根据储层自生矿物的岩相学特征划分成藏期次。

Low-pressure accumulation of hydrocarbon recorded by fluid inclusions in T165 reservoir,Tuozhuang area,Dongying Sag

Some fractures filled with calcites were found in the deep reservoirs in Tuozhuang area of the Dong-ying Sag. Large numbers of oil-bearing inclusions were contained in the calcite veins. The calcite veins contain two different morphologic crystals, which are fine xenomorphic crystal and medium-crystalline automorphic crystal, and the features of fluid inclusions in the two kinds of crystals are different. Based on optical observation, microthermometry and PVT simulation, this paper revealed the P-T trapping conditions of fluid inclusions, and also analyzed the characteristics of hydrocarbon accumulation. a) The fluid inclusions only recorded one period of accumulation, mainly during Nm. b) In the early accumulation, the pressure coefficient was less than 1, presenting the characteristic of low-pressure migration and injection. The seismic pumping caused by fault activities was the dominant dynamic force of hydrocarbon injection. In addition, it is not reliable to distinguish different accumulation periods by the petrographic characteristics of authigenetic minerals.