三塘湖盆地油气勘探前景

Exploration Potential in Santanghu Basin.

三塘湖盆地的主要生油凹陷是条湖凹陷和马朗凹陷,按油气资源量它们属于中等丰度偏高的凹陷。研究认为,由于对源岩成熟度认识不足等原因,资源量的计算值是偏高的。盆地内的盖层与输导层的规模不大,不利于油气的长距离运移。对有机质包裹体的研究也表明,油气运移的水动力条件比较弱,油气以短距离垂向运移为主,仅可以形成自生自盖式的油藏。经计算,盆地内源岩潜力指数比较低,只能获得中小型规模的储量。勘探目的层应以上二叠统芦草沟组为主,山前掩覆带是有利勘探区。

Tiaohu sag and Malang sag are primary source depressions in Santanghu basin.They are depressions with above medium abundance in petroleum resources.This study showed that a little too high appeared for their esti-mated value of resources for reasons of insufficient understanding of source-rock-richness in them;the cap rock and car-rier rock in the basin are not large in size,so it is not favorable to long-distance hydrocarbon migration.Also,study of the organic matter inclusion enclave showed that hydrodynamic conditions for petroleum migration are relatively poor,dominated by short-distance vertical migration,and only reservoirs with both source and seal are formed.The computed value showed that the source potential index in Santanghu basin is lower,possibly providing medium-and small-sized reserves.Therefore,the target zone should be explored dominantly in Upper Permian Lucaogou formation,and paying at-tention to its piedmont and foothill overthrust belts for exploration.At present,to understand the piedmont geologic structures is very difficult because the seismic data are insufficient and there exist some problems in interpretations.