西藏羌塘盆地鸭湖地区天然气水合物成藏条件

发布时间：2018-03-22 11:31

本文选题：天然气水合物　切入点：成藏条件　出处：《地质通报》2017年04期 　论文类型：期刊论文

【摘要】：近年来中国陆域冻土区天然气水合物调查研究结果表明,气源条件是制约羌塘盆地天然气水合物找矿突破的关键因素。为明确鸭湖地区天然气水合物成藏潜力,基于近年来的钻探调查成果,从陆域冻土区天然气水合物成藏系统理论出发,系统分析了影响天然气水合物成藏的冻土、气源、储集、构造等地质因素。分析结果显示,鸭湖地区局部具有较好的冻土、地温、气源、储集、构造及水源条件,具备一定的天然气水合物成藏潜力,继续寻找充足的烃类气源是下一步天然气水合物调查的主要方向。同时,选取钻探调查获取的地温梯度、气体组分等参数,结合音频大地电磁测深(AMT)冻土厚度调查成果,对鸭湖地区天然气水合物稳定带的厚度和底界深度进行了预测。结果显示,当甲烷为85%、乙烷为9%、丙烷为6%时,天然气水合物稳定带厚度与冻土厚度分布变化基本一致,稳定带厚度400~630m,底界深度400~680m。当甲烷为98%、乙烷为2%时,天然气水合物稳定带厚度急剧减薄,大部分地区仅有0~30m,最厚仅有150m,局部地区稳定带底界最深仅为240m。结合气测录井结果,认为渐新世唢呐湖组比上三叠统土门格拉组更具备天然气水合物成藏潜力,土门格拉组自身具备较强的生排烃能力,可作为寻找常规油气或页岩气的一个重要层位。
[Abstract]:In recent years, the results of gas hydrate investigation in permafrost regions of China indicate that the gas source conditions are the key factors restricting the breakthrough of gas hydrate prospecting in Qiangtang Basin. Based on the results of drilling investigation in recent years, based on the theory of gas hydrate formation system in continental frozen soil region, the geological factors affecting gas hydrate formation, such as permafrost, gas source, reservoir, structure and so on, are systematically analyzed. There are good permafrost, ground temperature, gas source, reservoir, structure and water source in the area of duck lake, so it has the potential of forming natural gas hydrate reservoir. To continue to search for sufficient hydrocarbon gas sources is the main direction of gas hydrate investigation in the next step. At the same time, selecting the parameters of geothermal gradient and gas composition obtained from drilling investigation, combining with the survey results of thickness of frozen soil obtained by Audio magnetotelluric sounding (AMT), The thickness and the bottom boundary depth of the gas hydrate stability zone in the Yahu area are predicted. The results show that when methane is 85, ethane is 9 and propane is 6, the thickness of gas hydrate stability zone is basically consistent with the thickness distribution of frozen soil. The thickness of the stable zone is 400 ~ 630m, and the depth of the bottom boundary is 400-680m.When methane is 98 and ethane is 2m, the thickness of the stable zone of natural gas hydrate decreases sharply. In most areas, the thickness of the stable zone is only 0 ~ 30m, the thickest is only 150m, and the deepest of the local stable zone is only 240m. combined with the results of gas logging, It is considered that the Oligocene Suona Lake formation has more potential for gas hydrate formation than the Upper Triassic Tumengra formation, and the Tumen Gela formation has a strong hydrocarbon generation and expulsion capacity, which can be used as an important horizon for searching for conventional oil and gas or shale gas.
【作者单位】：中国地质调查局油气资源调查中心;中国地质调查局成都地质调查中心;中国地质科学院勘探技术研究所;中国地质科学院地球物理地球化学研究所;中国科学院力学研究所;中石化胜利石油工程有限公司地质录井公司;
【基金】：中国地质调查局项目《青南藏北冻土区天然气水合物调查》(编号:DD20160222)
【分类号】：P618.13

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