The geochemical information of produced water from coalbed methane (CBM) wells is abundant in geological significance. Based on the conventional ions, hydrogen and oxygen isotopes (δD and δ¹⁸O) and trace element tests of 27 produced water samples from CBM wells, the geochemical identification of the source and environment of produced water from CBM wells and its productivity significance have been analysed. The following conclusions have been drawn: CBM produced water can be divided into three categories, namely, polluted water from frac fluids, polluted surface water and formation water. The formation water has low Cl^- concentration, low total dissolved solids (TDS) concentration, and light δD and δ¹⁸O. The water polluted by frac fluid has high Cl^- and TDS concentrationt, and heavy δD and δ¹⁸O. The polluted surface water has high SO₄^2- and light δD and δ¹⁸O. CBM groun dwate r environments can be divided into confined and unconfined systems. The confined system is characterized by low Na⁺/Cl^- value, high (Cl^- - Na⁺)/Mg²⁺ value, a general absence of SO₄^2-, high Sr and Ba and low F. The unconfined system is characterized by high Na⁺/Cl^- value, low (Cl^- - Na⁺)/Mg²⁺ value, low SO₄^2-, low Sr and Ba and high F. Constructing a cross plot with the new D drift index (d') value and Cl^- concentration can further identify four types of source-water environments: an unconfined formation water system, an unconfined surface water system, a confined system heavily polluted by frac fluids, and a confined system only slightly polluted by frac fluids. The unconfined system often produces more formation water and has high CBM production. The confined system often produces water more heavily polluted by frac fluids and is low in CBM production. The fitting formulas of hydrochemical productivity have been established for daily CBM and water production of CBM wells.

中文翻译：

---

煤层气井采出水水源和环境的地球化学识别及其生产力意义-以云南东部和贵州西部典型煤层气井为例

煤层气井的采出水的地球化学信息具有丰富的地质意义。基于传统的离子，氢，氧同位素（δD和δ ¹⁸ O）和从煤层气井27个产生的水样微量元素的测试中，源的地球化学识别和产生的水环境从煤层气井和其生产力显着性已分析。得出以下结论：煤层气采出水可分为三类，即压裂液中的污水，地表水和地层水。地层水具有低的氯^-浓度，低的总溶解固体（TDS）浓度，光δD和δ ¹⁸ O.通过压裂流体污染的水具有高氯^-和TDS concentrationt和重δD和δ ¹⁸ O的污染的地表水具有高的SO ₄ ^2-和光δD和δ ¹⁸ O. CBM groun dwateř环境可分为密闭和无约束系统。密闭系统的特征在于低的Na ⁺ /氯^-值，高（CL ^- -钠⁺）/镁²⁺值，一般不存在的SO ₄ ^2-，高Sr和Ba和低F.无侧限系统的特征在于由高的Na ⁺ /氯^-值，低（CL ^- -钠⁺）/镁²⁺值，低SO₄ ^2-，低Sr和Ba和高F.构建与新的d漂移指数（的交叉曲线d”）的值和Cl ^-浓度可以进一步识别四种类型的源极-水环境的：非限制地层水系统，非限制地表水系统，被压裂液严重污染的密闭系统和仅被压裂液轻微污染的密闭系统。无限制系统通常会产生更多的地层水，并具有较高的煤层气产量。密闭系统经常产生的水被压裂液污染更严重，煤层气产量低。已经建立了每天的煤层气和煤层气井水产量的水化学生产率的拟合公式。