川西北地区双鱼石区块栖霞组膝折褶皱的发现及其油气意义  

Kink folds discovered in Qixia Formation of the buried structural belt,northwestern Sichuan Basin: Their significance to oil and gas

作　　者：梁瀚[1] 冉崎[1] 狄贵东 曾鸣[1] 韩嵩[1] 王跃翔 Liang Han;Ran Qi;Di Guidong;Zeng Ming;Han Song;Wang Yuexiang(Exploration and Development Research Institute,PetroChina Southwest Oil&Gasfield Company,Chengdu,Sichuan 610041,China)

机构地区：[1]中国石油西南油气田分公司勘探开发研究院

出　　处：《天然气勘探与开发》2019年第4期1-7,共7页Natural Gas Exploration and Development

基　　金：国家科技重大专项“四川盆地二叠系—中三叠统天然气富集规律与目标评价”（编号：2016ZX05007-004）;中国石油天然气股份有限公司科技重大专项“四川盆地碳酸盐岩地球物理关键技术研究与应用”（编号：2016E-0604）

摘　　要：四川盆地西北部中二叠统栖霞组台缘滩相白云岩储层广泛发育,油气储集条件好,新近发现①号断层下盘的隐伏构造带可延续并包含了双鱼石构造,栖霞组勘探有利面积增大,是四川盆地勘探开发领域的战略接替区。但隐伏构造带的构造变形机制复杂,以前仅有地震资料,没有实钻井钻进隐伏构造带的复杂翼部,故认为背斜-向斜之间发育高角度逆冲断层,栖霞组气藏是断块型气藏,该认识限制了对栖霞组气藏的整体认识和油气勘探开发部署。但近期,构造复杂带双鱼石区块的实钻井倾角测井和高分辨地震精细成像攻关结果表明:①川西北地区隐伏构造带栖霞组大范围发育膝折褶皱,褶皱之间以高角度膝折带相连,并不发育大规模、延伸远的高角度逆冲断层;②膝折带为构造剪切带,膝折带内的储层裂缝发育,连通性强,是背斜和向斜的栖霞组储层的良好沟通渠道;③不仅双鱼石构造,整个①号断层下盘的栖霞组储层都具有连片分布的地质特征。结论认为:川西北地区隐伏构造带栖霞组气藏具备形成大型岩性-构造整装气藏的潜力。With better oil and gas accumulation condition, dolomite reservoirs of marginal platform beach facies are widely developed in Middle Permian Qixia Formation, northwestern Sichuan Basin;moreover, a buried structural belt, newly discovered at the footwall of No.1 fault, extends to and contains Shuangyushi structure, expanding a favorable exploration area for Qixia Formation. The Qixia Formation in the buried structural belt becomes a strategic replacement area of exploration and development domains in Sichuan Basin. However, for this belt, the tectonic deformation mechanism is complex;in addition, there is a little available seismic data and no wells actually drilled into its complex flank. As a result, some previous study deemed that a high-angle thrust fault developed between anticline and syncline and Qixia Formation belongs to fault-block gas reservoirs. These points limit an overall understanding on Qixia reservoirs and their exploration and development deployment. Based on some dip data from actual drilling and logging into Shuangyushi structure and high-resolution fine seismic imaging, it’s shown that,(1) in the buried structural belt, there are many kink folds connecting through kink bands, which are widely developed in the Qixia Formation instead of large-scale, extensive, and high-angle thrust faults;(2) inside these kink bands, also structural shear zones, fractures are developed with strong connectivity, which are better connecting pathway for Qixia reservoirs in both anticline and syncline;and(3) there are Qixia reservoirs massively developed not only in Shuangyushi structure but also at the footwall of No.1 fault. It’s concluded that gas reservoirs of Qixia Formation in the buried structural belt, northwestern Sichuan Basin, have great potential to form large-scale monoblock lithologic-structural ones.

关 键 词：逆冲断块 构造变形 膝折带 中二叠世 整装气藏 四川盆地 双鱼石区块 龙门山前带 

分 类 号：P61[天文地球—矿床学]