高古4井及其与邻区煤成气藏的比较研究——兼论临清坳陷东部煤成气勘探方向

Comparative study on coal-derived gas reservoir between well Gaogu 4 and its adjacent areas——Exploration direction of coal-derived gas in eastern Linqing depression

临清坳陷煤成气藏资源潜力大,但至今仍未取得大的突破。从源岩的埋藏史、生排烃史、断层的活动历史以及由此造成的侧向封堵性入手,通过对临清坳陷东部,尤其是高古4井的解剖,结合渤海湾盆地典型煤成气探井的对比,认为早期(早白垩世末期)没有进入生烃门限而古近纪末或新近纪初才达到二次生排烃的地区是煤成气勘探的有利区带。二次生排烃高峰期晚、断层活动与二次生排烃高峰时期相匹配是油气大规模运聚成藏的前提。后期构造运动的强弱及侧向封堵条件的好坏是油气成藏的关键。

Although Linqing depression has great potential of coal-derived gas resource, there is no major brea- kout hitherto. Based on the studies of the burial history of source rock and its hydrocarbon generation and ex- pulsion, this paper analyzes the geological conditions of eastern Linqing depression, especially well Gaogu 4, in the comparison with typical coal-derived gas wells in Bohai Bay Basin, by combining the process of fault ac- tivity and its lateral sealing. It is revealed that the favorable zones of coal-derived gas exploration are locations where an early stage（ at the end of the early Cretaceous） did not enter the threshold of hydrocarbon generation and a late stage （ late Paleogene or early, Neogene） reached the second hydrocarbon generation. The late peri- od of second hydrocarbon generation and expulsion, as well as the fault activity and its matching with the peak of the second hydrocarbon generation and expulsion are the premise of the large-scale hydrocarbon migration and accumulation. The strength of late tectonic movement and its effectiveness of lateral sealing conditions are the key factors to reservoir development.