Organization
Petroleum Exploration and Production Research Institute, SINOPEC, Beijing 100083, China
摘要
四川盆地海相页岩气已取得勘探开发的重大突破，建成了涪陵、威远、长宁、昭通、威荣、永川6个页岩气田。陆相页岩气资源潜力大，是重要的勘探接替领域。采用全岩X衍射、有机碳含量分析、干酪根碳同位素、有机岩石学、高压压汞—氮吸附联合测定、氩离子抛光—扫描电镜及物性等多种测试分析手段，综合评价了四川盆地侏罗系大安寨段页岩气形成条件，并探讨了页岩气富集主控因素。四川盆地侏罗系大安寨段陆相页岩具有岩相变化快，非均质性强，页岩与砂岩、灰岩频繁互层特征；有机质丰度低，TOC为0.04%~3.89%，有机质类型以Ⅱ2型和Ⅲ型为主；热演化程度低，Ro介于1.10%~1.83%，处于成熟—高成熟阶段，以凝析油和湿气为主。陆相页岩物性较好，孔隙度介于0.95%~8.42%，平均值3.21%，以无机矿物质孔为主，主要为微孔和介孔，现场含气量测试平均为0.96 m3/t。发育于半深湖相、有利的岩相组合、裂缝和保存条件是陆相页岩气富集主控因素。基于主控因素分析，突出陆相页岩品质及热演化程度，结合保存条件和工程技术条件，建立了四川盆地大安寨段页岩气有利区评价标准。采用GIS融合的空间叠合技术，评价出元坝西南部、阆中东南部、仪陇地区、涪陵西北部和建南西北部是四川盆地大安寨段陆相页岩气下一步勘探的有利区带。
Abstract
Productive breakthroughs have been achieved for the exploration and development of marine shale gas in the Sichuan Basin, and 6 shale gas fields have been built including Fuling, Weiyuan, Changning, Zhaotong, Weirong and Yongchuan. Continental shale gas is an important exploration replacement layer series with great potential. By the approaches of whole rock X-ray diffraction, TOC content, carbon isotope of kerogen, organic petrology, combined determination of high-pressure mercury injection and nitrogen adsorption, argon ion polishing and scanning electron microscope, and physical property test, the formation conditions of shale gas in the Jurassic Daanzhai Member of the Sichuan Basin were discussed, and the main controlling factors of shale gas enrichment were proposed. Results show that continental shale in the Jurassic Daanzhai Member in the Sichuan Basin is featured by rapid lithofacies changes, strong heterogeneity, frequent interbedding of shale, sandstones and limestones, low organic matter abundance, TOC ranging from 0.04% to 3.89% with type Ⅱ2 and Ⅲ of organic matters, low degree of thermal evolution with Ro values ranging from 1.10% to 1.83%, producing both condensate oil and wet gas. Continental shale has high porosity, ranging from 0.95% to 8.42%, There are mainly inorganic mineral pores dominated by micropores and mesopores. The average gas content of field test is 0.96 m3/t. It is clear that semi-deep lacustrine facies, favorable lithofacies assemblage, fractures and preservation conditions are the main controlling factors of continental shale gas enrichment. Based on the analysis of main controlling factors, highlighting the quality and thermal evolution degree of continental shale, combined with preservation conditions and engineering technical conditions, an evaluation criterion of favorable areas for continental shale gas in the Daanzhai Member in the Sichuan Basin was established. Combined with GIS integrated spatial superposition technology, several favorable zones were proposed, including the southwest of Yuanba, the southeast of Langzhong, Yilong, the northwest of Fuling and the northwest of Jiannan areas.
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