延川南地区水文地质条件及煤层气成藏  

Groundwater conditions and relative CBM accumulation feature in Yanchuannan area

作　　者：余林 YU Lin(East China Branch Company, SINOPEC, Nanjing 210011, China)

机构地区：[1]中石化华东油气分公司,江苏南京210011

出　　处：《煤田地质与勘探》2017年第2期69-74,共6页Coal Geology & Exploration

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(NaHCO_3)和氯化钙型(CaCl_2),谭坪构造带以NaHCO_3为主,矿化度较低,为4×10~3mg/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700m;万宝山构造带以CaCl_2型为主,矿化度较高,为4×10~4mg/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700m。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。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 feature,influence,CBM reservoir formation and saturation.Typical accumulations are proposed according to hydrogeochemistry conditions.Two types of groundwater exist in Yanchuannan area.NaHCO3of acid low salinity(4×103mg/L)is located in Tanping belt.Isotope fractionation proves powerful and carbon value is-36‰.Water head reaches as high as more than700m.CaCl2of weak alkali and high salinity(4×104mg/L)is distributed in Wanbaoshan belt.Fractionation works subtle and the value is-32‰.Head is no more than700m.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.

关 键 词：煤层气 水文条件 成藏特征 成藏模式 

分 类 号：TE12[石油与天然气工程—油气勘探]