Coalbed methane (CBM) well-produced water contains abundant geochemical information that can guide productivity predictions of CBM wells. The geochemical characteristics and productivity responses of water produced from six CBM wells in the Yuwang block, eastern Yunnan, were analyzed using data of conventional ions, hydrogen and oxygen isotopes, and dissolved inorganic carbon (DIC). The results showed that the produced water type of well L-3 is mainly Na-HCO3, while those from the other five wells are Na-Cl-HCO3. The isotope characteristics of produced water are affected greatly by water-rock interaction. Combined with the enrichment mechanisms of isotopes D and 18O, we found that the water samples exhibit an obvious D drift trend relative to the local meteoric water line. The 13C enrichment of DIC in the water samples suggests that DIC is mainly produced by the dissolution of carbonate minerals in coal seams. The concentration of HCO3-, D drift trend, and enrichment of 13CDIC in produced water are positively correlated with CBM production, which can be verified by wells L-4 and L-6.

中文翻译：

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滇东禹王区块煤层气井采出水地球化学特征及产能响应

煤层气（CBM）采出水含有丰富的地球化学信息，可以指导煤层气井产能预测。利用常规离子、氢氧同位素和溶解无机碳（DIC）数据，分析了滇东禹王区块6口煤层气井产出水的地球化学特征和产能响应。结果表明，L-3井采出水类型以Na-HCO3为主，其余5口井采出水类型为Na-Cl-HCO3。采出水的同位素特征受水-岩相互作用影响很大。结合同位素D和18O的富集机制，我们发现水样相对于当地大气水线表现出明显的D漂移趋势。水样中 DIC 的 13C 富集表明 DIC 主要是由碳酸盐矿物在煤层中溶解产生的。采出水中HCO3-浓度、D漂移趋势和13CDIC富集与煤层气产量呈正相关，L-4井和L-6井可以验证这一点。