摘要
煤层气在温度、压力和应力等敏感地质要素的作用控制下形成煤—气—水强耦合系统,深刻理解该系统对加快发展煤层气赋存地质理论、高效推进煤层气勘探开发具有重要意义。为此,提出了煤层气系统的基本概念,并在明确煤层气系统的基本要素基础上,研究了煤层气系统形成过程及基本特点,总结分析了煤层气系统储层压力、地层温度、地下水化学特征和煤层气的赋存状态、构成、含气饱和度以及生产特征,最后以鄂尔多斯盆地煤层气为例,分析了煤层气系统在空间上的展布规律。研究结果表明:①煤层气系统应考虑的基本要素包括煤层及其与之相关联的地层压力系数相近的煤系其他岩层、盖层系统以及相近地层压力系数下的煤层气/水流体系统。②储层—盖层—流体3大要素与系统环境演化的耦合决定了不同深度煤层气系统的煤—气—水的赋存状态。③以煤层气赋存状态等为主要依据将煤层气系统划分为“两带”,两带为改造带和原生带,其中改造带对应于通常意义上的浅层煤层气,原生带对应于深层煤层气;原生带进一步划分为吸附气为主带(原生A带)、游离气—吸附气带(原生B带)、吸附气—游离气带(原生C带)。结论认为:①改造带煤层气主要以向斜控气模式为主,原生带煤层气特别是原生B带、原生C带应重视圈闭区的勘探;②鄂尔多斯盆地石炭系—二叠系煤层气系统自东西两翼至中部由改造带—原生A带—原生B带—原生C带依次转变,盆地中部主要为原生B带及原生C带煤层气。
Under the control of sensitive elements such as temperature,pressure and stress,coalbed methane(CBM)forms a coal-gaswater strong coupling system.Understanding this system is of great significance for accelerating the development of the CBM occurrence geological theories and promoting CBM exploration and development efficiently.In this paper,the basic concept of CBM system is defined,and the basic elements are determined.Then,the formation process and basic characteristics of CBM system are studied,and the reservoir pressure,formation temperature and groundwater chemical characteristics of CBM system and the occurrence state,composition,gas saturation and production performance of CBM are analyzed.Finally,the spatial distribution patterns of CBM system are identified with the CBM in the Ordos Basin as an example.The following results are obtained.First,the basic elements which should be considered in CBM system include coal seams and their associated strata in coal measures with similar formation pressure coefficient,caprock system,and CBM/water fluid system with similar formation pressure coefficient.Second,the coal-gas-water occurrence states of CBM system at different depths are determined by the coupling of three major elements(reservoir,caprock and fluid)with the evolution of the system environment.Third,based on the occurrence state of CBM,the CBM system is divided into two zones,i.e.,reworked zone and primary zone.The reworked zone corresponds to the shallow CBM in the usual sense,and the primary zone corresponds to the deep CBM.The primary zone is subdivided into main adsorbed gas zone(primary A zone),free gas-adsorbed gas zone(primary B zone),and adsorbed gas-free gas zone(primary C zone).The CBM in the reworked zone is dominated by a syncline controlling gas mode,and as for the CBM in the primary zone,especially in the primary B and C zones,attention shall be paid to the exploration of trap areas.What's more,the Carboniferous–Permian CBM system in the Ordos Basin transforms from reworked zone to primary A zone,then primary B zone and to primary C zone in turn from eastern and western flanks to the middle,and in the center of t he basin,the CBM of primary B zone and primary C zone is domin ant.
作者
孙粉锦
周国晓
田文广
邓泽
申建
SUN Fenjing;ZHOU Guoxiao;TIAN Wenguang;DENG Ze;SHEN Jian(PetroChina Research Institute of Petroleum Exploration&Development,Beijing 100083,China;Exploration and Development Research Institute,PetroChina Changqing Oilfield Company,Xi'an,Shaanxi 710018,China;Key Laboratory of Coalbed Methane Resources&Reservoir Formation Process,Ministry of Education//China University of Mining and Technology,Beijing 100083,China)
出处
《天然气工业》
EI
CAS
CSCD
北大核心
2024年第7期42-53,共12页
Natural Gas Industry
基金
国家自然科学基金项目“深部煤系造穴激活储层地质约束机理与优化”(编号:42272198)、中国石油天然气股份有限公司科技专项“深地煤岩气成藏理论与效益开发技术研究”(编号:2023ZZ18-01)、“煤岩气富集规律与开发机理研究”(编号:2021DJ23-01)。
关键词
煤层气系统
温度
压力
地下水化学特征
赋存状态
鄂尔多斯盆地
CBM system
Temperature
Pressure
Chemical characteristics of groundwater
Occurrence state
Ordos Basin
