Identifying methods for coal measure aquifers and multi-coal seam commingled drainage water sources:A case study of the Baode block in Shanxi Province
ZHANG Qingfeng
ZHANG Jikun
LI Ziling
YAO Yanbin
DU Fengfeng
SUN Xiaoguang
HAO Shuai
LI Junhui
Abstract：The success of coalbed methane(CBM)drainage in multilayered coal seam gas wells depends on the precise identification of water sources and gas contributions from each produc-tive layer.Current methods for identifying water sources exhibit deficiencies,presenting sig-nificant challenges in optimizing layer combinations and designing drainage systems for multi-coalseam gas wells.To address this,this study leveraged exploration and development data from 85 CBM wells in the Baode block,coupled with chemical testing,to identify aquifer stra-ta and establish criteria for classifying drainage water types.Using principal component analy-sis(PCA)and Bayes discriminant analysis,a model for identifying drainage water sources in multi-coal seams is constructed,yielding methods for aquifer identification,drainage water type classification,and drainage water source identification within multi-coal seam integrated mining.Validation using 27 drainage water samples confirmed the accuracy of the model and assessed the interlayer interference strength under varying drainage water source conditions during integrated mining.The results indicate stable and thick aquifer strata at the top and bottom of coal seams 4+5 and 8+9,significantly impacting well production.Both the classifi-cation of drainage water types and the drainage water source identification model are useful for analyzing the origins of drainage water.The classification is based on geological engineering characteristics and provides a preliminary qualitative division of the drainage water sources.This approach is particularly effective for identifying recharge water sources throughout the life cycle of coalbed methane wells.The drainage water source identification model integrates con-ventional ion characteristics of the produced water to dynamically pinpoint the source of the drainage water.This approach offers insights for analyzing interlayer interference intensity in combined layer drainage.Single-coal-seam water sources in integrated development wells re-sult in severe interlayer interference and poor gas production,whereas a mixture of coal seams and aquifer water leads to moderate interference and average gas production.Solely integrated coalseam water sources exhibit weak interlayer interference and improved gas production.This study offers a viable method for identifying drainage water sources in integrated coal seam min-ing,providing insights into interlayer interference evaluation and facilitating adjustments to drainage equipment and work systems for multi-coal seam integrated mining.
Keywords：coalbed methaneidentification of water source in production and drainageprinci-pal component analysisBayes discrimination methodinterlayer interference
Publication Date：2025-01-29
Online Publishing Date：2025-08-15(First online date of this platform, not the publication date of the document)
Pages：12( 115-126 )