哈拉阿拉特山地区构造演化及其石油地质意义

Techtonic Evolution of Hala'alate Mountain Area and Implications in Petroleum Geology

哈拉阿拉特山地区是准噶尔盆地西北缘山前冲断带的一部分,构造演化过程不甚清楚,严重影响着这一地区的油气勘探进程。在三维地震资料解释的基础上,通过野外地质调查及岩心地化分析,重建了哈拉阿拉特山地区构造演化过程,并探讨了其对油气成藏的控制作用。研究结果表明,哈拉阿拉特山地区构造演化主要经历了古洋壳俯冲碰撞(晚石炭世)、伸展裂陷—早期冲断变形(早二叠世)、强烈逆冲推覆(中—晚二叠世)、冲断叠加(三叠纪)、振荡隆升(侏罗纪—白垩纪)、隆升剥蚀兼走滑调整(新生代)6个阶段。早二叠世晚期伸展裂陷构造背景下,研究区发育了厚层的烃源岩;中二叠世到三叠纪,持续强烈逆冲推覆,不仅改善了储集层物性,还形成了大量构造圈闭;侏罗纪以后,构造活动趋于静止,对早期形成的油藏起到了很好的保存作用。

Hala＇ alate mountain area is a part of the piedmont thrust belt in northwestern margin of Junggar basin. The progress of oil and gas exploration in this area is seriously affected for its unclear tectonic process. Based on the 3D seismic data interpretation, field geologic survey and core geochemical analysis, the vertical tectonic evolution process in this area is reconstructed, and the controlling effect on the oil-gas accumulation is discussed. The results show that the tectonic evolution in Hala＇ alate area mainly went through such six stages as ancient oceanic crust subduction and collision （C2）, expanding-rifted and early thrust-deformation （P1）, strong thrust and nappe （P2）, thrust and superimposition （T）, oscilation and upswelling （J-K） and upswelling-erosion and strike-slip adjustment （Cz） ones. In the late Early Permian, under the stretched and rifted tectonic setting, thick source rocks are developed in this area; from Late Permian to Triassic, the strong thrust and nappe allow the reservoir petrophysical property to be improved, thus forming numerous structural traps; since Jurassic, the tectonic activity tends to rest, which plays a good conservation role in early forming reservoirs.