延川南地区水文地质条件及煤层气成藏 |
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引用本文: | 余林.延川南地区水文地质条件及煤层气成藏[J].煤田地质与勘探,2017,45(2):69-74. |
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作者姓名: | 余林 |
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摘 要: | 水文地质条件是煤层气富集、成藏以及产出过程中的重要控制因素。通过分析延川南地区水化学与水动力条件,结合排采数据,明确了延川南地区煤层的水文地质条件分布特征,研究其对煤层气含气性、成藏等影响,并划分出相应的成藏模式。研究结果表明,延川南地区2号煤层水属于碳酸氢钠型(NaHCO3)和氯化钙型(CaCl2),谭坪构造带以NaHCO3为主,矿化度较低,为4×103 mg/L左右,偏酸性,甲烷碳同位素分馏作用强,为-36‰左右,水头高普遍高于700 m;万宝山构造带以CaCl2型为主,矿化度较高,为4×104 mg/L左右,偏碱性,甲烷碳同位素分馏作用弱,为-32‰左右,水头高一般低于700 m。研究区存在3种水文条件:万宝山为高压封闭滞留区,谭坪为弱径流区,研究区中北部局部断层发育的渗流区。煤层气成藏模式主要为承压水动力和断层封堵复合型煤层气藏。
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关 键 词: | 煤层气 水文条件 成藏特征 成藏模式 |
收稿时间: | 2016-11-25 |
Groundwater conditions and relative CBM accumulation feature in Yanchuannan area |
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Abstract: | Groundwater plays a controlling role in enrichment, accumulation and yield of coalbed methane. With production data, hydrochemistry and geochemistry are taken into account to study hydrodynamic occurrence and hydrochemistry fea-ture, influence, CBM reservoir formation and saturation. Typical accumulations are proposed according to hydrogeochemis-try conditions. Two types of groundwater exist in Yanchuannan area. NaHCO3 of acid low salinity (4×103 mg/L) is located in Tanping belt. Isotope fractionation proves powerful and carbon value is -36‰. Water head reaches as high as more than 700 m. CaCl2 of weak alkali and high salinity (4×104 mg/L) is distributed in Wanbaoshan belt. Fractionation works subtle and the value is -32‰. Head is no more than 700 m. Three types of groundwater conditions occur as follows:high pressure stagnant flow in Wanbaoshan, weak runoff flow in Tanping and seepage in the north and midst dominated by faults. Confined water and fault block lead to accumulations. |
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