大宁-吉县区块深层煤岩多尺度孔缝结构特征  

Characteristics of Multi-Scale Pore-Fracture Structure of Deep Coal Rocks in the Daning-Jixian Block

作　　者：杨秀春 宋柏荣[3] 陈国辉 何睿 赵浩阳 杨潇 Yang Xiuchun;Song Bairong;Chen Guohui;He Rui;Zhao Haoyang;Yang Xiao(PetroChina Coalbed Methane Co.,Ltd.,Beijing 100028,China;China United Coalbed Methane National Engineering Research Center Co.,Ltd.,Beijing 100095,China;PetroChina Liaohe Oilfield Company,Panjin,Liaoning 124010,China;Beijing Runze Innovation Technology Co.,Ltd.,Beijing 100120,China)

机构地区：[1]中国石油煤层气有限责任公司,北京100028 [2]中联煤层气国家工程研究中心有限责任公司,北京100095 [3]中国石油辽河油田分公司,辽宁盘锦124010 [4]北京润泽创新科技有限公司,北京100120

出　　处：《特种油气藏》2022年第5期94-100,共7页Special Oil & Gas Reservoirs

基　　金：中国石油煤层气有限责任公司重大科技项目“煤系储层精细表征基础实验研究”(2022KJ17)。

摘　　要：针对单一技术手段难以定量表征大宁-吉县区块深层煤岩储层复杂的多尺度孔缝结构问题,基于全直径CT扫描、微米CT扫描、FIB-SEM电镜扫描、氩离子抛光场发射扫描电镜等多种实验方法,利用多尺度的数字岩心技术对煤岩样品进行扫描及分析。结果表明:大宁-吉县区块深层煤岩发育多尺度孔缝系统,纳米尺度以气孔和组织孔发育为主,微米尺度以微裂缝和矿物溶孔发育为主,毫米尺度发育有高角度裂缝和割理组合;全直径CT扫描技术可有效识别毫米级的裂缝、割理及溶孔;建立了D20井煤岩段岩心孔-缝模型,计算得到裂缝孔隙度为1.55%,裂缝密度为22.5条/m,裂缝平均开度为1.1 mm;微米孔隙平均半径为2.99~4.15μm,微米喉道平均半径为1.16~1.80μm;微裂缝平均开度为3.75~4.84μm;纳米孔隙平均半径为51.21~80.65 nm,纳米喉道平均半径为19.44~32.06 nm;通过微、纳米孔隙数据拼接,获得多尺度分布特征,小孔数量最多,平均表面积占比为63.68%,大孔(大于103 nm)数量少但贡献了大量的孔隙体积。研究成果可为深层煤层气勘探开发提供技术支撑。In response to the problem that it is difficult to quantitatively characterize the complex multi-scale pore-fracture structure of deep coal rock reservoirs in the Daning-Jixian Block with a single technical method,a multi-scale digital core technology is adopted to scan and analyze coal and rock samples based on full-diameter CT scanning,micro-CT scanning,FIB-SEM scanning,and argon ion polishing field emission scanning electron microscopy and other experimental methods.The result shows:The multi-scale pore-fracture systems develop in the deep coal rocks in the Daning-Jixian Block.The nano-scale development is dominated by stomatal and tissue pores,the micro-scale development is dominated by micro-fractures and mineral dissolved pores,and the millimeter-scale development is high-angle fractures and cleat assemblages.The full-diameter CT scanning technology can effectively identify millimeter-scale fractures,cleats and dissolved pores.The core hole-fracture model of the coal section of Well D20 is established,and the calculated fracture porosity is 1.55%,the fracture density is 22.5 pieces/m,and the average opening of fractures is 1.1mm;the average radius of micro-pores is 2.99-4.15μm,the average radius of micro-throat is 1.16-1.80μm;the average opening of micro-fractures is 3.75-4.84μm;the average radius of nano-pores is 51.21-80.65 nm,the average radius of the nano-throat is 19.44-32.06 nm;the multi-scale distribution characteristics are obtained through the splicing of micro-and nano-pore data.The number of micro-pores is the largest,with the average surface area accounting for 63.68%,while the number of macro-pores(greater than 103 nm)is small but contributes a large amount of pore volume.The research results can provide technical support for the exploration and development of deep coalbed methane.

关 键 词：深层煤岩 多尺度孔缝结构 数字岩心技术 煤层气压裂选层 大宁-吉县区块 

分 类 号：TE135[石油与天然气工程—油气勘探]