富油凹陷不同洼陷烃源岩的热演化及生烃特征差异性

渤海湾盆地富油凹陷通常发育多个生烃洼陷,每个洼陷往往为相对独立的生烃中心;由于沉积埋藏史的差异,不同洼陷及其不同构造部位烃源岩的热演化和生烃特征存在明显差异。以渤海湾盆地东濮凹陷和东营凹陷古近系沙河街组主要烃源岩系为例,对比分析了两凹陷中主要生烃洼陷烃源岩的热演化及生烃史特征,并探讨了其对油气藏形成及分布的控制作用。研究认为,在发育多个生烃洼陷的富油凹陷,以毗邻陡坡带大断裂的洼陷埋藏最深,烃源岩最发育、热演化程度最高、生烃能力最强、资源量最丰富;由于母质条件和埋藏热史的差异,同一层系不同亚段烃源岩、同一洼陷不同构造部位烃源岩的生烃特征具有较大差异;不同富油凹陷烃源岩埋藏演化生烃也存在明显差异性。 

Diversity in the thermal evolution and hydrocarbon generation of source rocks in different sub-depressions of rich oil depression

Every rich oil depression in the Bohai Bay Basin generally consists of several sub-depressions which are commonly independent hydrocarbon-generating centers. Due to the differences in sedimentary-burial history of these sub-depressions, there are obvious differences in thermal evolution and hydrocarbon generation of source rocks between different sub-depressions and their different structural positions. Taking the main source rocks of Paleogene Shahejie Formation in Dongpu Depression and Dongying Depression of the Bohai Bay Basin for example, the article demonstrated a comparative analysis in the thermal history and hydrocarbon generation history of source rock between major sub-depressions in two depressions, and the control effects on the reservoir formation and distribution were illustrated in detail. The result shows that, in rich oil depression which consists of several hydrocarbon generation sub-depressions , the source rock in the most deep buried sub-depression adjacent to fault in steep slop is the best, which is widely distributed with high thermal evolution degree, great hydrocarbon generation potential and rich resources. Because of the distinction of the conditions of source rock and burial-thermal history, the hydrocarbon-generating cha-racteristics of source rock in different members of the same strata series and different structural positions in the same sub-depression show relatively large diversity. There are obvious diversities in hydrocarbon generation of source rock in different rich oil depressions.