罗胜元, 陈孝红, 李培军, 唐协华. 鄂西宜昌地区寒武系常规、非常规天然气显示及勘探意义[J]. 地质通报, 2020, 39(4): 538-551.
    引用本文: 罗胜元, 陈孝红, 李培军, 唐协华. 鄂西宜昌地区寒武系常规、非常规天然气显示及勘探意义[J]. 地质通报, 2020, 39(4): 538-551.
    LUO Shengyuan, CHEN Xiaohong, LI Peijun, TANG Xiehua. Characteristics of conventional and unconventional shale gas displays of the Cambrian strata in Yichang area, West Hubei, and their exploration significance[J]. Geological Bulletin of China, 2020, 39(4): 538-551.
    Citation: LUO Shengyuan, CHEN Xiaohong, LI Peijun, TANG Xiehua. Characteristics of conventional and unconventional shale gas displays of the Cambrian strata in Yichang area, West Hubei, and their exploration significance[J]. Geological Bulletin of China, 2020, 39(4): 538-551.

    鄂西宜昌地区寒武系常规、非常规天然气显示及勘探意义

    Characteristics of conventional and unconventional shale gas displays of the Cambrian strata in Yichang area, West Hubei, and their exploration significance

    • 摘要: 鄂西寒武系具有良好的油气成藏条件,但由于地层时代早、经历构造运动次数多,勘探成果不理想。近期在宜昌地区寒武系水井沱组获得页岩气流,并在寒武系天河板组、石龙洞组等多套层系获得了天然气显示,表明鄂西宜昌地区是寒武系页岩气、天然气的有利勘探区。以储集层为核心划分出水井沱组页岩气、天河板组-石龙洞组常规天然气成藏组合。寒武系水井沱组页岩生烃潜力大、含气性高,以页岩中的有机质孔和微裂缝作为储集空间,构成自生自储的页岩气藏;水井沱组页岩气测试获工业气流,气体组分中甲烷含量超过90%。宜地2井天河板组发生井喷,气体成分以甲烷为主,储集空间主要为半充填状裂缝和溶孔,地层水为氯化镁型,保存条件中等。石龙洞组砂屑云岩储层具有累计厚度大、低孔中低渗并局部发育高孔渗段的特点。以水井沱组富有机质页岩为烃源岩,以天河板组灰岩裂缝和石龙洞组白云岩孔洞为储集空间,以覃家庙组含膏云岩和云质膏岩为盖层,组成垂向供烃的生储盖组合。油气成藏演化史分析表明,寒武系烃源岩在早志留世开始生油,早二叠世开始生气,晚三叠世达到生气高峰期,经历了多期次构造运动的改造,现全部转化为气态烃。宜昌地区为页岩气有利区,也是天河板组-石龙洞组常规天然气勘探的有利区。上述认识对鄂西地区寒武系天然气勘探领域的拓展具有重要指导意义。

       

      Abstract: The Cambrian strata in west Hubei have favorable hydrocarbon accumulation conditions, but it is difficult to obtain substantial breakthrough in exploration due to multiple tectonic movements and old strata.Recently, industrial gas flow was tested in the Cambrian Shuijingtuo Shale and a large quantity of natural gas was discovered in multiple formations, which represent an enormous potential gas resource in Yichang area.The proved and possible reserves of Cambrian formations include Shuijingtuo shale and Shilongdong-Tianheban carbonate, which represent the shale gas and conventional gas system respectively.Black rock series of the Shuijingtuo Formation has high hydrocarbon potential and shale gas content.Micropores in organic matter and microcracks in shale are reservoir space, which resulted in a self-generation and accumulation for shale gas.The test of Shuijingtuo shale revealed an industrial gas flow after horizontal well fracturing.Methane is the main constituent of gas sample with concentration exceeding 90%.Considering the well blowout with methane and formation water in the carbonates of the Tianheban strata, the carbonate reservoir must be semi-filled fracture and dissolved pores.The formation water is of magnesium chloride type and the storage conditions are medium.Sand-clastic dolomite of the Shilongdong Formation is characterized by large cumulative thickness, low porosity and low permeability with partly high reservoir property.The sedimentation of Cambrian strata in Yichang slope developed the gas play with organic shale of the Shuijingtuo Formation as the source rock, and the fractures inlimestone of Tianheban Formation and dissolved pore in dolomite of Shilongdong Formation serve as the main reservoirs.Gypsum dolomite and shale constitute the main cap rock of the conventional gas system.All this constitutes a vertical gas system.An analysis of the evolution history of oil and gas accumulation shows that the Cambrian source rocks began to generate oil in the early Silurian, generated gas in the Early Permian, and reached the gas peak in the Late Triassic.After undergoing transformation of multiple stages of tectonic movement, all the petroleum reservoirs have been converted into gaseous hydrocarbons.All this shows thatthe study areamight be the favorable area for shale gas accumulation in the Middle Yangtze region, and it is a new area for shale gas exploration outside the Sichuan Basin.The above understanding will play an important guiding role in the exploration of Cambrian shale gas and natural gas in west Hubei.

       

    /

    返回文章
    返回