摘要
煤系是中国天然气勘探开发的重要领域,天然气资源类型多样。针对煤系全油气系统和煤岩中天然气成藏演化的特殊性,通过系统梳理煤系全油气系统中的天然气主要类型和地质特征,揭示煤岩气的形成、富集特征和分布规律。研究取得的主要认识:(1)将煤系全油气系统中天然气按赋存特征和成藏机理划分为2种基本类型(常规气和非常规气),再按天然气的源储关系和储层岩性划分为6种类型(远源碎屑岩气、特殊岩性类气,远源/近源致密砂岩气,源内致密砂岩气、泥页岩气和煤岩气等),将煤岩储层中赋存的天然气统一称为煤岩气。现有资料表明,同一地区煤岩气在勘探开发地质特征上存在浅层、深层显著差异性,转换深度界限一般在1 500~2 000 m。基于当前煤岩气认识并充分尊重煤层气术语的应用历史习惯,煤岩气按照埋藏深度可以划分为深层煤岩气和浅层煤层气。(2)按照煤系全油气系统理论“全过程成藏”的研究思想,基于典型煤岩气成藏演化剖析,煤岩气可以进一步划分为原生型煤岩气、再生型煤岩气、残留型煤岩气和生物型煤岩气4种主要类型,前两种主要属于深层煤岩气,后两种主要属于浅层煤层气。(3)煤岩气成藏演化研究表明,浅层煤层气主要是原生型煤岩气经地质改造后形成的残留型煤岩气或生物型煤岩气,埋藏较浅,具有“低地层压力、低含气饱和度、吸附气为主、排水降压采气”等主要特征;深层煤岩气主要为原生型煤岩气和再生型煤岩气,埋藏较深,具有“高地层压力、高含气饱和度、富含游离气、气藏不含水或少水”等特征;原生型煤岩气分布广,资源量大,气藏品质好,是煤岩气中最为有利的勘探开发类型。
There are various types of natural gas resources in coal measures,which are the main areas of natural gas exploration and development in China.In view of the particularity of the whole petroleum system of coal measures and the reservoir-forming evolution of natural gas in coal,this study reveals the formation,enrichment characteristics and distribution laws of coal-rock gas by systematically sorting out the main types and geological characteristics of natural gas in the whole petroleum system of coal measures.First,natural gas in the whole petroleum system of coal measures is divided into two types,conventional gas and unconventional gas,according to its occurrence characteristics and accumulation mechanism,and into six types,distal detrital rock gas,special rock gas,distal/proximal tight sandstone gas,inner-source tight sandstone gas,shale gas,and coal rock gas,according to its source and reservoir lithology.The natural gas present in coal rock reservoirs is collectively referred to as coal rock gas.Existing data indicate that there are significant differences in the geological characteristics of coal rock gas exploration and development between shallow and deep layers in the same area,with the transition depth boundary generally around 1500-2000 meters.Based on the current understanding of coal rock gas and full respect for the historical usage habits of coalbed methane terminology,coal rock gas can be divided into deep coal rock gas and shallow coalbed methane according to the burial depth.Second,according to the research concept of“full-process reservoir formation”in the theory of the whole petroleum system of coal measures,based on the formation and evolution of typical coal rock gas reservoirs,coal rock gas is further divided into four types:primary coal rock gas,regenerated coal rock gas,residual coal rock gas,and bio coal rock gas.The first two belong to deep coal rock gas,while the latter two belong to shallow coal rock gas.Third,research on the coal rock gas reservoir formation and evolution shows that shallow coal rock gas is mainly residual coal rock gas or bio coal rock gas formed after geological transformation of primary coal rock gas,with the reservoir characteristics such as low reservoir pressure,low gas saturation,adsorbed gas in dominance,and gas production by drainage and depressurization,while deep coal rock gas is mainly primary coal rock gas and regenerated coal rock gas,with the reservoir characteristics such as high reservoir pressure,high gas saturation,abundant free gas,and no or little water.In particular,the primary coal rock gas is wide in distribution,large in resource quantity,and good in reservoir quality,making it the most favorable type of coal rock gas for exploration and development.
作者
张君峰
李国欣
贾承造
赵群
ZHANG Junfeng;LI Guoxin;JIA Chengzao;ZHAO Qun(PetroChina Research Institute of Petroleum Exploration&Development,Beijing 100083,China;CNPC Key Laboratory of Gas Reservoir Formation and Development,Beijing 100083,China;PetroChina Company Limited,Beijing 100007,China;PetroChina Oil,Gas and New Energy Company,Beijing 100007,China;CNPC Key Laboratory of Coal-rock Gas,Langfang 065007,China;China National Petroleum Corporation,Beijing 100007,China)
出处
《石油勘探与开发》
北大核心
2025年第4期792-803,共12页
Petroleum Exploration and Development
基金
新型油气勘探开发国家科技重大专项《深层煤岩气成藏机理与效益开发技术》项目(2025ZD1404200)
中国石油天然气股份有限公司前瞻性基础性项目(2024DJ23)
中国石油勘探开发研究院科学研究与技术开发项目(2024vzz)资助。
关键词
煤系全油气系统
煤系气
煤层气
煤岩气
煤岩气成藏演化
煤岩气分类
whole petroleum system of coal measures
coal measure gas
coalbed methane
coal rock gas
coal rock gas reservoir formation and evolution
coal rock gas classification
