河套盆地临河坳陷石油地质特征

CHARACTERISTICS OF PETROLEUM GEOLOGY OF LINHE DEPRESSION IN HETAO BASIN

通过分析认为临河坳陷具备有利的石油地质条件,该坳陷内生烃中心主要位于北部深凹陷,资源规模较大,以高成熟和过成熟生气为主,而中央断隆区烃源岩条件较差;下白垩统和渐新统储层砂体厚度大,深部储层次生孔隙发育,储集性能有明显改善;目的层之上发育多套厚层泥岩,存在有利的封闭层。油源对比分析表明中央断隆区油源以本地生油、短距离运移为主,油源条件差是制约中央断隆区油气富集的主要因素。临河坳陷下一步勘探方向要向生烃条件相对有利的北部深凹陷方向转移,勘探思路以找油为主转为以找气为主,兼顾找油,而临近北部生烃中心的杭后断阶带成藏条件最有利,值得重点关注。

Study shows that Linhe depression has favorable petroleum geologic conditions. The hydrocarbon generating center is mostly located in the northern deep sag with a relatively large resource extent, where the high-mature and over-mature gas predominate in the hydrocarbons generated, while the source rocks in the central faulted uplift zone are poor. The Lower Cretaceous and Oilgocene sandstone reservoirs are thick and secondary pores are well developed in the deep reservoirs, thus the poroperm characteristics are significantly improved. Several sets of thick mudstones are developed on the targets, providing the favorable sealing conditions. Source-oil correlation shows that indigenous hydrocarbon generation and short distance migration would have dominated the central faulted uplift zone, where the poor source rocks are the main factors constraining hydrocarbon enrichment. The future exploration in Linhe depression should be directed to the northern deep sag with relatively good hydrocarbon generating conditions, and the focus of exploration should be changed from previous searching for oil to looking for gas, with some attentions paid to oil at the same time. The Hanghou fault step zone near the northern hydrocarbon generating center has the most favorable reservoiring conditions, thus should be treated as a key exploration area.