渤海石油地质的几个问题

Several problems about petroleum geology in the Bohai Sea.

渤海是郯庐断裂经过的地带 ,对于渤海湾盆地的形成起着很大作用。根据构造力学和古地质研究成果判断 ,郯庐断裂和沙垒田、石臼坨两凸起向东延伸部分 ,把渤中凹陷分成五个洼陷。渤中凹陷应是早断晚衰型 ,因此凹陷中的烃源岩层位齐全。下含油组合 (Ek2 —Es4)以高熟油为主 ,可能有凝析油和天然气 ;中含油组合 (Ek3 —Es1)以成熟油为主 ,可能有高熟油 ;上含油组合 (Ed—N)以低熟油为主 ,可能有成熟油。目前海域中的上第三系浅层油层勘探工作 ,应当注意寻找正常的成熟油油田 。

The Bohai Sea plays major role in the formation of Bohai Bay Basin for Tanlu fracture crossed. Bozhong sag is divided into five subsags by the extended part of Shaleitian and Shijiutuo arch toward east and Tanlu fracture, which is judged by the research results of tectonics mechanics and palaeogeology. Bozhong sag should belong to the early-fracture and later-depletion type, so the horizons of source rock in it are complete. Highly mature crude oil is dominant, gas condensate and natural gas exist probably in lower petroliferous assemblage (Ek 2-Es 4); mature crude oil is dominant, highly mature exists probably in middle petroliferous assemblage (Ek 3-Es 1); low-mature crude oil is dominant, mature crude oil exists probably in upper petroliferous assemblage (Ed-N). The present exploration of shallow oil reservoir in Neogene system in sea area should center on seeking the oilfield of normal mature oil, the predicted distribution zone is near fracture zone that is divided into five subsags.