Tong Chuanxia, Huang Huazhou, He Huan, Wang Bo
Key Laboratory of Coalbed Methane Resources and Reservoir Formation Process, School of Resources and Geosciences, and School of Chemical Engineering & Technology, China University of Mining and Technology, Xuzhou 221008, China.
ACS Omega. 2019 Oct 9;4(17):17561-17568. doi: 10.1021/acsomega.9b02562. eCollection 2019 Oct 22.
Coalbed methane (CBM) is an unconventional natural gas resource. CBM mining releases a large amount of coproduced water, and the trace elements of CBM coproduced water can provide a basis for the exploration and development of CBM. The contents of eight major trace elements in the produced water from wellhead were tested and analyzed based on seven CBM wells in Tiefa Basin. The research indicates that Sr and Ba are the dominant trace elements with the highest concentrations in produced water. There is a positive correlation among Li, Sr, and Rb by cluster analysis and correlation analysis, which may be affected by the total dissolved solids and pH in the groundwater. The contents of Li, Sr, and Ba increase with the burial depth of coal seam and could be influenced by the fault. The gas production of CBM wells is affected by the depth of the coal seams, and there is no significant correlation between water production and the coal seam depth. However, faults have an important impact on gas and water production. The productivity of coalbed methane is affected by hydrogeological conditions and structure because the productivity of CBM wells located in different tectonic locations varies with the change of Li, Sr, and Ba contents.
煤层气是一种非常规天然气资源。煤层气开采会产生大量伴生水，煤层气伴生水中的微量元素可为煤层气的勘探开发提供依据。基于铁法盆地的7口煤层气井，对井口产出水中8种主要微量元素的含量进行了测试与分析。研究表明，锶（Sr）和钡（Ba）是产出水中含量最高的主要微量元素。通过聚类分析和相关性分析发现，锂（Li）、锶和铷（Rb）之间存在正相关关系，这可能受地下水中总溶解固体和pH值的影响。锂、锶和钡的含量随煤层埋藏深度增加而升高，且可能受断层影响。煤层气井的产气量受煤层深度影响，而产水量与煤层深度无显著相关性。然而，断层对产气和产水有重要影响。由于位于不同构造位置的煤层气井产能随锂、锶和钡含量的变化而变化，所以煤层气的产能受水文地质条件和构造的影响。
