河套盆地临河坳陷油气成藏过程解剖及勘探潜力分析

河套盆地属于我国中西部地区中小型陆相含油气盆地,近期于临河坳陷西南部吉兰泰构造带发现亿吨级大油田。工区地质条件复杂且勘探程度低,油藏动态演化过程研究有待深化。针对吉西凸起带和中央断垒带已发现油藏,应用地质、地震和分析化验等资料,在石油地质综合分析的基础上,采用“九史”分析方法对油藏进行动态解剖,取得了以下三点认识:(1)油气晚期成藏并表现出“三晚”,即烃源岩晚期生烃、断裂晚期活动及油气晚期充注;(2)第四纪走滑活动影响油气富集,负花状构造不发育且晚期强烈反转地区有利于成藏;(3)优选出西南部凸起带和中央断垒带两大油气有利勘探区带。

Hydrocarbon Accumulation Process and Exploration Potential in Linhe Depression,Hetao Basin

The Hetao basin is a small-medium continental petroliferous basin in Midwest China. A million-ton oilfield was recently discovered in the Jilantai tectonic belt in the southwestern Linhe Depression. Due to the complex geological conditions and low degree of prospecting, the reservoir dynamic evolution is yet to be well understood. The reservoirs in the Jixi uplift belt and the central fault-barrier belt are taken as the main research target. Geological and seismic data were collected from comprehensive petroleum geological analysis, whilst dynamic analysis of the reservoir was performed by the “nine histories” analysis method. Three major findings are obtained: (1) the hydrocarbon accumulation timing was late and comprises three stages, i.e. the hydrocarbon generation, fault activity, and oil filling; (2) Quaternary strike-slip tectonism affected the oil accumulation. Negative flower-like structure was not developed, and the area with strong tectonic inversion in the late period is favorable for hydrocarbon accumulation. Meanwhile, the area with intense uplift and minor negative flowery structure is favorable for oil accumulation; (3) the southwest uplift belt and the central fault-barrier belt are selected as favorable exploration zone.