莱阳凹陷烃源岩中的石油包裹体及油气初次运移研究

Investigation of Petroleum Inclusion and Primary Migration of Petroleum of Source Rocks in the Laiyang Depression

莱阳凹陷莱孔2井下白垩统莱阳组水南段暗色泥岩为富含藻类体和无定形体的优质烃源岩。用高倍荧光显微镜观察,在这些暗色泥岩的砂质碎屑矿物和自生矿物中,发现丰富的微石油包裹体群。这些石油包裹体的均一温度较集中,为78～82℃。根据莱孔2井水南段古地温演化历史,进一步推算出烃源岩中这些石油包裹体的形成时间为74～77Ma。根据PVTsim模拟计算,这些石油包裹体的捕获压力为305～307bar。莱阳凹陷水南段暗色泥岩石油包裹体的发现,说明该凹陷在第三纪抬升以前水南段暗色泥岩曾经历过深埋与生排烃作用,为本区重要的烃源岩。

The dark mudstone in the Shuinan Section, Laiyang Formation of the Cretaceous age from the Laiyang Depression belongs to a type of fine source rock with dominant source matter of aglinite and amorphinite. With high magnification of microscopy, a lot of petroleum inclusions were found, which occur in the fissures of sand grains and authigenic minerals in the source rock. The petroleum inclusions have a narrow range of homogenization temperature of 78 - 82 ℃. Combined use of the geothermal evolution history of the Shuinan Section in the borehole LK2 and the trapping temperature of the petroleum inclusions, its formation time was deduced to be 74 -77 Ma. According to the PVT simulation calculation, the trapping pressure of the petroleum inclusions was in the range of 305 - 307 bar. The occurrence of the petroleum inclusions has shown that the source rock underwent a deep burial and petroleum generation and expulsion before the uplifting of the Laiyang Depression in Tertiary, and the Shuinan section is the important source rock in this depression. This result has provided important information for further evaluation and exploration of this depression.