临邑凹陷辉绿岩中石油包裹体形成条件与油气成藏研究

Petroleum inclusions in diabase: Implications to the formation of oil and gas pools in Linyi sag

在临邑凹陷商河地区,商52井浅成辉绿岩侵入体中发现大量黄色和黄绿色荧光的石油包裹体,主要赋存在长石解理、裂隙中,多数为十分细小的纯液态的石油包裹体。测得其中部分粒径较大的石油包裹体的均一温度th=79～82℃,表明这些石油包裹体是辉绿岩体侵入Es3地层冷却以后受地层水作用在发生的多种蚀变反应的过程中长石的节理、裂隙愈合带封存了渗入的烃类物质而形成的。石油包裹体的PVTsim模拟计算结果表明,捕获温度ttr为88.6～92.1℃,捕获压力ptr为22.2～23.0MPa。与本区沙三段地层砂岩储层中石油包裹体捕获温度、捕获压力的对比结果表明两类石油包裹体的成藏条件基本相似。本区玄武岩-辉绿岩中的油气藏,实际上是特殊岩性储层的油气藏,其勘探前景主要受临邑凹陷多孔隙、裂隙的火成岩分布规模与沟通烃源岩的断裂和各种圈闭的控制。

A lot of petroleum inclusions are observed in the intrusive diabases in Well Shang-52 in Snangne reg,on, Linyi sag. The petroleum inclusions, formed in joints and fractures of feldspars, have yellow and green yellow fluorescence. Most of them are tiny and have a unique liquid phase. The homogenization temperature measurements are conducted on some larger petroleum inclusions with two phases （oil and gas） and yield a temperature range of 79 -82℃. The low homogenization temperatures indicate that the petroleum is encapsulated at the cooling stage of the diabases that have intruded in the Es3 strata when the interaction between ground water and the feldspars resulted in alteration. The trapping pressure and temperature of petroleum inclusions are calculate by PVTsim software as follows： ttr = 88.6- 92. 1℃, and ptr = 22. 2 -23.0 MPa. This is consistent with the results of the petroleum inclusions in the adjacent sandstone, indicating that the formation conditions of accumulation of petroleum are similar. As a matter of fact, the volcanic reservoir is a special reservoir and its potentials are controlled mainly by the distribution of porous and fissuring volcanic rocks, the source rocks-linking faults and the proper traps.