川南下寒武统筇竹寺组新类型页岩气勘探发现及启示

New Type Shale Gas Exploration Discovery and Enlightenment of the Lower Cambrian Qiongzhusi Formation in the Southern Sichuan Basin

郭彤楼 熊亮 何建华 魏力民 闫亮

GUOTonglou XIONGLiang HEJianhua WEILimin YANLiang

中国石化西南油气分公司, 四川 成都 610041 成都理工大学沉积地质研究院, 四川 成都 610059

Southwest Petroleum Branch, SINOPEC, Chengdu, Sichuan 610041, China Institute of Sedimentary Geology, Chengdu University of Technology, Chengdu, Sichuan 610059, China

四川盆地龙马溪组页岩气累计探明储量3$\times$10$^{12}$ m$^3$，年产量超过250$\times$10$^{8}$ m$^3$，而筇竹寺组才取得商业勘探发现，目前正展开勘探评价。基于川南寒武系筇竹寺组页岩沉积、储层、地化、可压性和含气性等特征的综合研究，大量的基础实验数据，以及与龙马溪组页岩气形成条件的对比分析，结果表明，筇竹寺组页岩气在沉积环境、生烃能力、储集空间、含气性、矿物组成及可压性等方面与龙马溪组页岩气存在显著差异，代表了一种新类型。新类型页岩气主要发育于槽台沉积体系，热液活动较强，成烃生物类型多，生烃能力强；储集空间以无机孔为主，有机孔是有利补充；长英质含量高，整体表现出良好的可压性。综合预测认为绵阳—长宁凹槽是筇竹寺组页岩气有利区带。资阳、井研、威远地区已有多口井获得高产工业气流，证实了从深水到浅水、从高TOC到低TOC页岩，都能富集成藏，是新类型页岩气勘探开发的重点区域。研究成果不仅丰富了页岩气勘探开发的理论基础，还形成了一系列配套的勘探技术，对不同层系、不同地区页岩气勘探开发具有重要示范意义。

The Longmaxi Formation in the Sichuan Basin has a cumulative proven reserve of shale gas of 3$\times$10$^{12}$ m$^3$, with an annual production exceeding 250$\times$10$^{8}$ m$^3$. But the Qiongzhusi Formation, has just achieved commercial exploration discoveries and is currently undergoing exploration evaluation. Based on a comprehensive study of the characteristics of shale deposition, reservoir properties, geochemistry, fracability, and gas content in the Qiongzhusi Formation of the Cambrian System in southern Sichuan, along with extensive basic experimental data and a comparative analysis with the shale gas formation conditions in the Longmaxi Formation, the results indicate that the shale gas of the Qiongzhusi Formation exhibits significant differences from that of the Longmaxi Formation in terms of depositional environment, hydrocarbon generation capacity, storage space, gas content, mineral composition, and fracability, representing a new type. This new type of shale gas predominantly develops in trough-and-platform depositional systems, with strong hydrothermal activity, diverse hydrocarbon-generating organisms, and high hydrocarbon generation capacity. The storage space is dominated by inorganic pores, with organic pores serving as a beneficial supplement. The high content of feldspar and quartz minerals contributes to its overall good fracability. Comprehensive predictions suggest that the Mianyang—Changning trough is a favorable zone for shale gas in the Qiongzhusi Formation. Multiple wells in the Ziyang, Jingyan, and Weiyuan areas have achieved high-yield industrial gas flows, confirming that shale, ranging from deepwater to shallow water and from high to low TOC, can be enriched and form reservoirs. These areas are key regions for the exploration and development of this new type of shale gas. The research findings not only enrich the theoretical foundation of shale gas exploration and development but also establish a series of supporting exploration technologies, providing important demonstrative significance for shale gas exploration and development in different formations and regions.

10.11885/j.issn.1674 5086.2024.11.20.29