摘要
鄂尔多斯盆地东部大宁—吉县区块2024年煤岩气产量达到19.6×10^(8) m^(3),建成了世界首个年产200×10^(4) t油气当量煤岩气田,标志着煤岩气已深刻影响中国天然气产业格局。为了更好地推动中国煤岩气产业发展,保障国家能源安全,在系统梳理全球煤层气到煤岩气探索历程的基础上,对比了全球典型盆地煤层(岩)气地质特征,明确了煤岩气概念的科学内涵、富集机理、应用价值及实践意义。研究结果表明:(1)煤岩气指以煤作为储集岩且处于煤炭开采经济技术极限深度以深煤层中的天然气。(2)煤岩气概念立足煤岩学属性,突出了煤层作为储集岩的科学内涵;区分了煤层气(瓦斯)的伴生资源属性,明确了作为独立天然气资源的应用价值;超越了煤层吸附气为主的传统认识,具备勘探开发思路转型的实践意义。(3)煤岩气概念实现了3方面突破:深层煤岩割理裂缝和微孔喉发育,突破了煤层气开发埋深下限;深层煤岩吸附气+游离气共存,突破了吸附气为主的煤层气相态认知局限;深层煤岩气压后排液即高产,突破了“排水—降压—生产”理论模式局限。(4)提出了“连续稳定的优质煤岩是成烃控储基础、良好的保存条件是成藏控产关键”的深层煤岩气“二元富集”理论以及“原生沉积连续稳定的煤层在构造稳定区、转折区和复杂区依次形成了‘顶底封存、原位滞留’‘挤压封堵、斜坡残留’‘水力封堵、构造调整’”3种控气模式。结论认为,针对鄂尔多斯盆地大宁—吉县区块2 000 m以深煤岩气的勘探开发形成的煤岩气“二元富集”理论认识,已成功引领煤岩气勘探开发在中国的拓展,有望推动中国天然气格局发生革命性变化。
The Daning-Jixian block,eastern Ordos Basin,achieved a coal-rock gas production up to 19.6×10^(8) m^(3) in 2024,setting the world's first coal-rock gas field with an annual output of 2 million tons of oil and gas equivalent,and marking the practical and profound impact of coal-rock gas on the pattern of China's natural gas industry.In order to better promote the development of coal-rock gas industry and ensure national energy security in China,this paper systematically reviews the global exploration course from coalbed methane(CBM)to coal-rock gas.On this basis,the geological characteristics of CBM and coal-rock gas in the typical basins globally are compared,and the scientific connotation,enrichment mechanism,utilization value,and practical significance of coal-rock gas are clarified.The following results are obtained.First,coal-rock gas refers to the natural gas which is preserved in the coal seams below the economic and technological depth limits of coal exploitation.Second,the concept of coal-rock gas is based on the attribute of coal petrology,and highlights the scientific connotation of coal as reservoir rock.It tells the properties of CBM(gas)as an associated resource,and clarifies the utilization value of CBM as an independent natural gas resource.It overrides the traditional understanding that focuses primarily on coalbed adsorbed gas.Thus,this concept is of practical significance to the transformation of exploration and development ideas.Third,the concept of coal-rock gas breaks through:(1)the burial depth limit in CBM development,by confirming the presence of cleat fractures and micro-pore throats in deep coal rocks;(2)the limited knowledge that CBM primarily exists in the state of adsorbed gas,by proposing the coexistence of adsorbed gas and free gas in deep coal rocks;and(3)the theoretical model of"drainage–depressurization–production",by demonstrating the possibility of high production rate of deep coal-rock gas through drainage immediately after fracturing.Fourth,the"binary enrichment"theory of deep coal-rock gas is proposed,i.e.,continuous and stable high-quality coal rocks are the foundation of hydrocarbon generation and reservoir control,while favorable preservation conditions are the key to hydrocarbon accumulation and production control.In addition,three gas control models,i.e.,top-bottom sealing and in-situ retention,compressive sealing and slope residual,and hydraulic sealing and structural adjustment,are established for the primarily deposited,continuous and stable coal seams in stable,transitional and complex structure zones,respectively.In conclusion,the binary enrichment theory of coal-rock gas for the exploration and development of deep coal-rock gas below 2000 m in the Daning-Jixian block has successfully led the expansion of coal-rock gas exploration and development in China and is expected to promote a revolutionary shift in the natural gas pattern in China.
作者
周立宏
熊先钺
丁蓉
李勇
ZHOU Lihong;XIONG Xianyue;DING Rong;LI Yong(China United Coalbed Methane National Engineering Research Center Co.,Ltd.,Beijing 100095,China;PetroChina Coalbed Methane Company Limited,Beijing 100028,China;College of Geoscience and Surveying Engineering,China University of Mining and Technology-Beijing,Beijing 100083,China)
出处
《天然气工业》
北大核心
2025年第3期1-15,共15页
Natural Gas Industry
基金
中国石油天然气集团有限公司科技项目“全国陆上煤层气资源评价”(编号:2023YQX20117)。
