Yan Xinlu, Chang Suoliang, Tang Shuheng, Meng Yanjun, Yan Taotao, Zhang Sheng, Zhao Dekang
College of Mining Engineering, Taiyuan University of Technology, Taiyuan 030024, China.
China United CBM (Shanxi) Ltd., Taiyuan 030032, China.
ACS Omega. 2024 Sep 16;9(38):40019-40033. doi: 10.1021/acsomega.4c05859. eCollection 2024 Sep 24.
Aquifer leakage recharge poses a prevalent challenge in coalbed methane (CBM) development, severely impeding its efficient production. This study focuses on the Sanjiao Block, located on the eastern margin of the Ordos Basin, and provides a comprehensive evaluation of the impact of aquifer leakage recharge on CBM well productivity, employing hydrochemical characteristics and numerical simulation. Fisher's discriminant analysis reveals a close association between external water sources for CBM wells in the Taiyuan Formation and the hydrodynamic environment: in the western stagnant zone, hydrochemical characteristics resemble those from the Shanxi Formation; in the eastern strong runoff zone, water from the Taiyuan Formation directly contributes to CBM well development; in the central weak runoff zone, hydrochemical characteristics suggest mixed water sources from the Shanxi Formation and Taiyuan Formation. The numerical simulation employs orthogonal experiments to quantify the sensitivity of aquifer geological parameters to CBM production, ranked from strong to weak for aquifer types, leakage channel properties, and aquifer physical properties. The fundamental reason for disparities in the efficacy of leakage recharge lies in categorizing aquifers into finite and infinite recharges based on their water supply capacity. The properties of leakage channels, including the location and scale, manifest as effects on the magnitude and shape of gas production characteristics in infinite and finite recharge aquifers, respectively. Furthermore, a discriminant flowchart of CBM production is presented, delineating the production characteristics of CBM wells under the influence of aquifer leakage recharge into six patterns and illustrating their distribution in the study area. This discriminant process provides scientific guidance for analyzing CBM production characteristics and evaluating potential under the influence of aquifer leakage recharge.
含水层渗漏补给是煤层气开发中普遍存在的挑战，严重阻碍了其高效开采。本研究聚焦于鄂尔多斯盆地东缘的三角区块，利用水化学特征和数值模拟，全面评估了含水层渗漏补给对煤层气井产能的影响。费舍尔判别分析表明，太原组煤层气井的外部水源与水动力环境密切相关：在西部滞流区，水化学特征与山西组相似；在东部强径流区，太原组的水直接为煤层气井开发提供补给；在中部弱径流区，水化学特征表明存在来自山西组和太原组的混合水源。数值模拟采用正交试验来量化含水层地质参数对煤层气产量的敏感性，按敏感性从强到弱依次为含水层类型、渗漏通道性质和含水层物性。渗漏补给效果存在差异的根本原因在于根据含水层的供水能力将其分为有限补给和无限补给。渗漏通道的性质，包括位置和规模，分别表现为对无限补给和有限补给含水层中气产量特征的大小和形状的影响。此外，还给出了煤层气产量判别流程图，将含水层渗漏补给影响下煤层气井的生产特征划分为六种模式，并说明了它们在研究区域内的分布情况。这一判别过程为分析含水层渗漏补给影响下的煤层气生产特征和评估潜力提供了科学指导。
