鄂尔多斯盆地石炭系本溪组煤岩气地质特征与勘探突破  

Geological characteristics and exploration breakthroughs of coal rock gas in Carboniferous Benxi Formation,Ordos Basin,NW China

作　　者：赵喆[1] 徐旺林[1] 赵振宇[1] 易士威[1] 杨威[1] 张月巧[1] 孙远实 赵伟波 史云鹤 张春林[1] 高建荣[1] ZHAO Zhe;XU Wanglin;ZHAO Zhenyu;YI Shiwei;YANG Wei;ZHANG Yueqiao;SUN Yuanshi;ZHAO Weibo;SHI Yunhe;ZHANG Chunlin;GAO Jianrong(PetroChina Research Institute of Petroleum Exploration&Development,Beijing 100083,China;Research Institute of Exploration and Development,PetroChina Changqing Oilfield Company,Xi’an 710018,China)

机构地区：[1]中国石油勘探开发研究院,北京100083 [2]中国石油长庆油田勘探开发研究院,西安710018

出　　处：《石油勘探与开发》2024年第2期234-247,259,共15页Petroleum Exploration and Development

基　　金：中国石油科技重大专项“深地煤岩气成藏理论与效益开发技术研究”(2023ZZ18-03);长庆油田重大科技专项“鄂尔多斯盆地深层煤岩气赋存机理、富集规律及有效提产关键技术攻关”(2023DZZ01)。

摘　　要：通过对鄂尔多斯盆地石炭系本溪组煤岩分布、煤岩储层特征、煤质特征、煤岩气特征以及煤岩气资源和富集规律等方面开展系统研究,评价其勘探潜力。研究表明:①煤岩气是有别于煤层气的优质天然气资源,在埋深、气源、储层、含气性、碳同位素组成等方面具有独特特征;②本溪组煤岩分布面积达16×10^(4)km^(2),厚度2~25m,以原生结构的光亮和半亮煤为主,挥发分和灰分含量低,煤质好;③中高阶煤岩TOC值为33.49%~86.11%,平均值为75.16%,演化程度高(Ro为1.2%~2.8%),生气能力强,气体稳定碳同位素值高(δ^(13)C_(1)值为-37.6‰~-16.0‰,δ^(13)C_(2)值为-21.7‰~-14.3‰);④深层煤岩发育气孔、有机质孔和无机矿物孔等基质孔隙,与割理、裂缝共同构成良好储集空间,储层孔隙度为0.54%~10.67%,平均值为5.42%,渗透率为(0.001~14.600)×10^(-3)μm^(2),平均值为2.32×10^(-3)μm^(2);⑤纵向上发育5种煤岩气聚散组合,其中煤岩-泥岩聚气组合与煤岩-灰岩聚气组合最为重要,封闭条件好,录井全烃气测峰值高;⑥构建了广覆式分布的中高阶煤岩持续生气、煤岩基质孔和割理裂缝规模储集、源-储一体赋存、致密岩盖层密闭封堵的煤岩气富集模式,存在煤岩侧向尖灭体、透镜体、低幅度构造、鼻状构造和岩性自封闭5种高效聚气类型。⑦依据煤岩气地质特征评价划分出8个区带,估算埋深超过2000m的煤岩气资源量超过12.33×10^(12)m^(3)。上述认识指导风险勘探部署,两口井实施后分别获得工业气流,推动进一步部署预探井和评价井,获得规模突破,提交超万亿方预测储量和超千亿方探明储量,对中国天然气效益增储和高效开发具有重大意义。To explore the geological characteristics and exploration potential of the Carboniferous Benxi Formation coal rock gas in the Ordos Basin,this paper presents a systematic research on the coal rock distribution,coal rock reservoirs,coal rock quality,and coal rock gas features,resources and enrichment.Coal rock gas is a high-quality resource distinct from coalbed methane,and it has unique features in terms of burial depth,gas source,reservoir,gas content,and carbon isotopic composition.The Benxi Formation coal rocks cover an area of 16×10^(4) km^(2),with thicknesses ranging from 2 m to 25 m,primarily consisting of bright and semi-bright coals with primitive structures and low volatile and ash contents,indicating a good coal quality.The medium-to-high rank coal rocks have the total organic carbon(TOC)content ranging from 33.49%to 86.11%,averaging 75.16%.They have a high degree of evolution(Ro of 1.2%–2.8%),and a high gas-generating capacity.They also have high stable carbon isotope values(δ^(13)C_(1)of–37.6‰to–16‰;δ^(13)C_(2)of–21.7‰to–14.3‰).Deep coal rocks develop matrix pores such as gas bubble pores,organic pores,and inorganic mineral pores,which,together with cleats and fractures,form good reservoir spaces.The coal rock reservoirs exhibit the porosity of 0.54%–10.67%(averaging 5.42%)and the permeability of(0.001–14.600)×10^(-3)μm^(2)(averaging 2.32×10^(-3)μm^(2)).Vertically,there are five types of coal rock gas accumulation and dissipation combinations,among which the coal rock-mudstone gas accumulation combination and the coal rock-limestone gas accumulation combination are the most important,with good sealing conditions and high peak values of total hydrocarbon in gas logging.A model of coal rock gas accumulation has been constructed,which includes widespread distribution of medium-to-high rank coal rocks continually generating gas,matrix pores and cleats/fractures in coal rocks acting as large-scale reservoir spaces,tight cap rocks providing sealing,source-reservoir integration,a

关 键 词：煤岩气 煤层气 中高阶煤 割理 鄂尔多斯盆地 石炭系本溪组 风险勘探 

分 类 号：TE122[石油与天然气工程—油气勘探]