摘要:
【研究目的】通过分析RX1井五峰组-龙马溪组页岩有机地化、物性和孔隙特征，明确桴焉向斜页岩气成藏基础地质条件，探讨盆外复杂构造区超浅层页岩气勘探开发潜力。【研究方法】本次研究利用黔北地区RX1井的岩心，开展现场解吸、地化测试、现场压裂效果以及储层特征等综合实验分析，结合邻区勘探资料，探索埋深、构造保存环境对黔北超浅层页岩气富集的影响。【研究结果】 RX1井五峰组-龙马溪组优质烃源岩段厚度14.78m，总有机碳含量均值4.43%，有机质成熟度处于2.36%~2.78%，干酪根类型为II1型，具备良好的生烃基础；优质页岩段孔隙度均值为3.30%，脆性矿物含量高，平均脆性指数达69，为页岩气提供了良好的储集空间；井区构造相对稳定，地层倾角小，整体页岩气基础地质条件好，获得良好含气性显示及压裂效果。【结论】 RX1井勘探实践的成功，证实了盆外复杂构造区目的层埋深1000m以浅的向斜构造单元内，页岩气可富集成藏，具有较好的建产潜力，可作为下一步有利勘探目标。结合区域地质资料分析认为，受新生代构造叠加改造形成的压扭性构造系统是盆外复杂构造区页岩气富集成藏的重要场所，压扭性构造控藏作用应是下一步勘探研究的重点。
Abstract:
[Objective] By analyzing the organic geochemistry, physical properties, and pore characteristics of the Wufeng-Longmaxi Formation in well RX1, the basic geological conditions of the Fuyan yansynclinal shale gas accumulation are clarified, and the exploration and development potential of ultra-shallow shale gas in the complex structural area outside the basin is discussed. [Methods] This study utilizes the core of Well RX1 in northern Guizhou to conduct comprehensive experimental analysis such as on-site desorption, geochemical testing, on-site fracturing effect, and reservoir characteristics. In combination with exploration data from neighboring areas, it explores the impact of burial depth and the structural preservation environment on the enrichment of ultrashallow shale gas in northern Guizhou. [Results] The results show that the thickness of the high-quality hydrocarbon source rock section in the Wufeng-Longmaxi Formation of the RX1 well is 14.78m, the average content of total organic carbon is 4.43%, the maturity of organic matter is between 2.36% and 2.78%, and the kerogen type is II1, which has a good hydrocarbon generation basis; the average porosity of high-quality shale is 3.30%; and the content of brittle minerals is high, with an average brittleness index of 69, which provides a good reservoir space for shale gas. [Conclusions] The successful exploration practice of well RX1 confirms that shale gas can be enriched in the synclinal structural unit with a depth less than 1000m in the target layer of the complex structure area outside the Sichuan basin, which has good potential for construction and production and can be used as a favorable exploration target in the next step. Based on the analysis of regional geological data, it is believed that the compression-torsional structural system formed by the superposition and transformation of Cenozoic structures is an important place for shale gas accumulation in complex structural areas outside the basin. The reservoir-controlling effect of the compression-torsional structural system should be the focus of the next round of exploration and research.
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