黔北坳陷及周缘下组合油气保存条件研究

Research of Lower Assemblage Preservation Conditions in Qianbei Depression and Its Margin

黔北坳陷及周缘位于上扬子板块西南缘,具备良好的原始油气成藏地质条件,但后期经历了多期构造改造,油气保存条件受到严重破坏,制约了油气勘探进程。研究区内发育中-下寒武统清虚洞组-娄山关群膏盐岩、下寒武统牛蹄塘组泥页岩以及中-下志留统龙马溪组-韩家店组泥页岩三套下组合区域性盖层,盖层分布稳定,封闭性良好;该区构造运动强烈,燕山-喜山运动造成区内区域性抬升剥蚀、断裂发育,是本区早期油气藏破坏的主导因素。整体而言,由北向南,油气保存条件逐渐变差,但黔北坳陷复向斜深层、川南盆缘区仍具备一定勘探潜力。

Qianbei Depression and its margin locate on the southwestern edge of the upper Yangtze plate,with good raw hydrocarbon accumulation geological conditions. While in the late stage it experienced amulti-phase transformation structure, so its oil and gas preservation conditions are destroyed seriouslyand that restricted the process of oil and gas exploration. The study area developed that three sets ofstable gypsum salt rock： the Middle- Lower Cambrian （Qingxudong Formation- Loushanguan Group）gypsum salt rock, the Lower Cambrian （Niutitang Formation） shale and the Middle- Lower Silurian（Longmaxi Formation- Hanjiadian Group） shale seal, with good sealing performance. The tectonicmovement in this area is very strong. Yanshan - Himalayan movement caused the development of a widerange of uplift and denudation areas, where faults developed well that leading to early reservoir damage.As a whole, hydrocarbon preservation condition becomes worse from north to south. However, there isstill exploration potential in Qianbei synclinorium deep depression and southern Sichuan basin marginarea.