摘要
为了阐明煤层气排采过程中的水岩耦合作用机理及对产能的影响,针对实际生产过程中的不同类型产气井,按照相似性原则开展了基于水力冲洗的煤层气排采过程水岩作用模拟试验,对比分析了试验前后产出离子的变化特征,结合实际生产数据,揭示了产出水地球化学特征与产能的响应关系。结果表明:不同的矿化度和流速条件下,水岩作用的反应程度不同,较高的矿化度和较小的流速有利于水岩作用的进行,水岩反应产出溶液的矿化度和pH值均增加,且在矿化度2000 mg/L,流速0.3 mL/min条件下矿化度增量最大。整体上,Na^(+)+K^(+)和Cl^(-)均随着原始溶液矿化度增加而增加;且特定的矿化度和流速范围有利于Ca^(2+)、Mg^(2+)产出;较高的矿化度和流速都会抑制HCO_(3)^(-)离子产出,当矿化度和流速超过某一阈值时,SO_(4)^(2-)会大量产出。煤层气井的高产受原始矿化度和排采水耦合作用的共同影响,樊庄区块高产井对应的矿化度范围为1800~2200 mg/L,多属中、低产水,相应模拟试验条件的水岩作用最强。3号煤层煤层气井产出水的Ca^(2+)浓度和产气量呈现良好的正相关性,但不同产水-产气模式下Ca^(2+)的产能响应机制不同。高产水中产气模式中Ca^(2+)产出主要受底板砂岩含水层水岩作用影响,低产水高产气模式中Ca^(2+)产出主要受煤中方解石溶解影响。
To clarify the water-rock coupling mechanism and its influence on productivity during Coalbed Methane(CBM)extraction,a series of hydraulic-flushing-based simulation experiments were conducted on different types of production wells following similarity principles.The variations in ionic composition of produced water before and after the experiments were systematically analyzed.By integrating field production data,the response relationship between the geochemical characteristics of produced water and CBM productivity was elucidated.The key findings are as follows:The extent of water-rock interactions varies under different salinity levels and flow rates.Higher salinity and lower flow rates enhance water-rock reactions,leading to increased salinity and pH in the effluent.The maximum salinity increment was observed at 2000 mg/L and 0.3 mL/min.Overall,Na^(+)+K^(+)and Cl-concentrations increase with rising initial salinity.Specific salinity and flow rate ranges promote the release of Ca^(2+)and Mg^(2+),whereas elevated salinity and flow rates suppress HCO_(3)^(-)generation.When salinity and flow rate exceed a critical threshold,SO_(4)^(2-)becomes significantly enriched.The high productivity of CBM wells is co-controlled by the coupling effect of initial salinity and drainage conditions.In the Fanzhuang block,high-yield wells correspond to a salinity range of 1800−2200 mg/L,mostly exhibiting medium-to-low water production rates,under which the simulated experimental conditions demonstrated the most intensive water-rock interactions.A strong positive correlation exists between Ca^(2+)concentration in produced water and gas production in the No.3 coal seam.However,the productivity response mechanism of Ca^(2+)differs under varying water-gas production regimes.In high-yield water and medium gas production mode,Ca^(2+)release is predominantly governed by water-rock interactions in the underlying sandstone aquifer.Conversely,in low-yield water and high gas production mode,Ca^(2+)mobilization is primarily driven by calcite dissolution within the coal matrix.
作者
王勃
徐凤银
张傲翔
王立龙
王文龙
李志
屈争辉
王硕
史鸣剑
WANG Bo;XU Fengyin;ZHANG Aoxiang;WANG Lilong;WANG Wenlong;LI Zhi;QU Zhenghui;WANG Shuo;SHI Mingjian(Information Research Institute of Emergency Management Department,Beijing 100029,China;College of Energy(College of Modern Shale Gas Industry),Chengdu University of Technology,Chengdu 610059,China;State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation,Chengdu University of Technology,Chengdu 610059,China;Shanxi CBM Branch of Huabei Oilfield,Changzhi 046000,China;CITIC Guoan Xinjiang Tianyuan Energy&Chemical Co.,Ltd.,Hami 839300,China;Key Laboratory of Coalbed Methane Resource&Reservoir Formation Process,Ministry of Education,China University of Mining&Technology,Xuzhou 221116,China;School of Resources and Geosciences,China University of Mining&Technology,Xuzhou 221116,China)
出处
《煤炭学报》
北大核心
2025年第8期4008-4021,共14页
Journal of China Coal Society
基金
国家自然科学基金面上资助项目(41872179)。
关键词
煤层气
水岩作用
水力冲洗
产出水地球化学
产能控制
coalbed methane
water-rock interaction
hydraulic flushing
produced water geochemistry
productivity control
作者简介
王勃(1979-),男,陕西蓝田人,正高级工程师,博士。E-mail:wangbo1230038@163.com。
