摘要
确认大规模生烃中心、发现大规模的孔隙性储层,是启动四川盆地西部坳陷二叠系气藏勘探的两个关键因素。为此,采用层拉平技术研究了该区震旦系一寒武系的地层结构,编制下古生界厚度图以描述二叠系的生烃中心;进而结合地震相分析和野外生物礁露头发现,预测了该盆地中二叠统礁滩相储层的分布;最后,根据断层特征分析了礁滩相储层白云岩化的有利条件。结果表明:①在拉平二叠系底反射界面的剖面上,震旦系顶为一个巨大的洼陷,洼陷两侧发育正断层,其内充填巨厚的下古生界沉积,由此可以确认,川西坳陷发育一个在兴凯地裂期形成的坳拉槽,其内巨厚的寒武系可形成生烃中心,使得二叠系具备形成大型气藏的物质条件;②川西坳陷中二叠统存在明显的礁滩相异常响应特征,发育3个大型异常条带,结合地表中二叠统生物礁露头的发现,预测为生物礁滩相复合体;③礁滩相的边缘发育有深大拉张断层,具有发育白云岩储层的有利条件。结论认为,四川盆地川西坳陷中二叠统圈闭天然气资源量达7 400×10~8 m^3,具有良好的天然气勘探前景,目前中石化已部署实施了1口风险探井。
Confirming thick hydrocarbon generation center and discovering thick porous reservoirs are two key factors to start the Permian gas exploration of the Western Sichuan Depression. In this paper, the Sinian- Cambrian structures of this area were studied by adopting the layer-flattening technology and the Lower Paleozoic thickness map was prepared in order to describe the Permian hy- drocarbon generation center. Then, combined with seismic facies analysis and field outcrop bioherm discovery, the distribution of Middle Permian reef flat reservoirs were predicted. Finally, the favorable conditions for reef flat reservoir dolomitization were ana- lyzed based on fault features. The study indicates that： （1） Sinian top represents a huge depression in the profile flatted by the reflec- ting interface of Permian bottom, with normal faults filled by thick Lower Paleozoic sediments at both sides, revealing that a aulaco- gen formed during the Khanka taphrogeny exists in the Western Sichuan Depression, where very thick Cambrian strata may contain hydrocarbon generation center, making Permian strata have the material conditions for the formation of large gas pools~ （2） the Middle Permian strata in the Western Sichuan Depression exhibit obvious abnormal response in reef flat facies, where three large ab- normal bands are developed, which are predicted as bioherm complex combined with the Middle Permian bioherm outcrop discoveries in surfacel and （3） deep and large extensional faults are developed in reef flat margin, manifesting as favorable conditions for the de- velopment of dolomite reservoirs. The results show that the Middle Permian traps in the Western Sichuan Depression contain resources up to 740 X 109 m3, showing significant natural gas exploration prospects. By far, one risk exploration well has been deployed.
出处
《天然气工业》
EI
CAS
CSCD
北大核心
2015年第7期17-26,共10页
Natural Gas Industry
基金
国家科技重大专项"四川盆地碎屑岩储层识别与预测技术研究"(编号:2008ZX05002-004-003)
关键词
四川盆地
川西坳陷
中二叠世
礁滩相
生物礁
白云岩
储集层
坳拉槽
兴凯地裂运动
.. Sichuan Basin
Western Sichuan Depression
Middle Permian
Reef flat facies
Bioherm
Dolomite
Reservoir
Aulacogen
Khanka taphrogeny
