Wei Bo, Liu Yafeng, Li Xin, Zhao Xinyue, Jie Feilong, Ge Yanyan
School of Geology and Mining Engineering, Xinjiang University, Xinjiang Uygur Autonomous Region, Urumqi 830047, China.
Xinjiang Key Laboratory for Geodynamic Processes and Metallogenic Prognosis of the Central Asian Orogenic Belt, College of Geology and Mining Engineering, Xinjiang University, Xinjiang Uygur Autonomous Region, Urumqi 830047, China.
ACS Omega. 2025 Mar 11;10(11):11359-11374. doi: 10.1021/acsomega.4c11291. eCollection 2025 Mar 25.
Coalbed water participates in the whole process of coalbed gas generation, migration, accumulation, and exploitation, and its hydrogeochemical characteristics play a crucial role in the exploration and development of coalbed gas in mining areas. Taking the Fukang mining area in Xinjiang as the research object, this study tested the conventional cations, anions, trace elements, pH value, and TDS of its aquifer and analyzed the hydrochemical characteristics and evolution process of coalbed gas drainage water. The results show that the drainage water of coalbed gas is generally weakly alkaline, with significant changes in TDS and ion concentrations over time. Among the cations, Na occupies the absolute position, while among the anions, HCO dominates. Sixteen trace elements were detected in the drainage water of coalbed gas, each with varying concentrations. The concentrations of Al, Ti, V, Mn, Cu, As, Mo, Ba, Sb, and other elements exceeded the standard. In the early stages of the drainage process, the concentrations of Na, Cl, and HCO , as well as TDS, were higher near the drainage well but gradually decreased and became more uniformly distributed outward along the wellbore. The distribution trends of Mg, Ca, and SO concentrations were opposite to the former. Vertically, in groundwater within 1000 m, TDS, Na, Ca, Cl, and HCO gradually increased with depth, while SO and Mg showed an increasing trend followed by a decrease with depth. After reaching a burial depth of 1200 m, the TDS, Mg, and Na of the reservoir water gradually stabilized, while Ca and Cl decreased with depth, and HCO increased with depth. The hydrochemical characteristics indicate the influence of external fresh water or upper strata water inflow on the groundwater environment with increasing depth; the drainage activities worsen the closure degree of the groundwater environment, accepting infiltration replenishment and mixing from atmospheric precipitation. The reservoir drainage activities enhance the circulation of groundwater, and during the infiltration process, water-rock interactions such as salt dissolution, cation sorption exchange, and desulfurization occur between groundwater and reservoir. By analyzing the ions, trace elements, and hydrogeochemical characteristics of coalbed gas drainage water, the dynamic characteristics of coalbed reservoir water drainage and the hydrochemical evolution laws were clarified, providing theoretical guidance for coalbed gas exploration and development in the Fukang mining area.
煤层水参与煤层气生成、运移、聚集及开采的全过程，其水文地球化学特征对矿区煤层气的勘探开发起着至关重要的作用。本研究以新疆阜康矿区为研究对象，测试了该矿区含水层的常规阳离子、阴离子、微量元素、pH值及总溶解固体（TDS），并分析了煤层气抽排水的水化学特征及演化过程。结果表明，煤层气抽排水总体呈弱碱性，TDS和离子浓度随时间变化显著。阳离子中，Na占绝对优势，阴离子中HCO₃⁻占主导。在煤层气抽排水中检测出16种微量元素，各元素浓度各异。Al、Ti、V、Mn、Cu、As、Mo、Ba、Sb等元素浓度超标。在排水初期，排水井附近Na、Cl、HCO₃⁻浓度及TDS较高，但沿井筒向外逐渐降低且分布趋于均匀。Mg、Ca、SO₄²⁻浓度分布趋势则相反。垂向上，在1000 m以内的地下水中，TDS、Na、Ca、Cl、HCO₃⁻随深度逐渐增加，而SO₄²⁻和Mg呈先增加后随深度降低的趋势。达到1200 m埋深后，储层水的TDS、Mg、Na逐渐稳定，Ca和Cl随深度降低，HCO₃⁻随深度增加。水化学特征表明，随着深度增加，外部淡水或上层地层水流入对地下水环境产生影响；排水活动使地下水环境封闭程度变差，接受大气降水的入渗补给和混合。储层排水活动增强了地下水循环，在入渗过程中，地下水与储层之间发生盐溶解、阳离子吸附交换、脱硫等水岩相互作用。通过分析煤层气抽排水的离子、微量元素及水文地球化学特征，阐明了煤层储层水排水动态特征及水化学演化规律，为阜康矿区煤层气勘探开发提供了理论指导。
