基于煤层结构数字井筒反演的有机质丰度评价方法及应用  

Practice of Digital Wellbore Inversion of Coal Seam Structure and Evaluation Method of Organic Matter Abundance

作　　者：黄红星 杨秀春[1,2] 陈国辉 朱文涛 师斌斌 何睿 赵浩阳 Huang Hongxing;Yang Xiuchun;Chen Guohui;Zhu Wentao;Shi Binbin;He Rui;Zhao Haoyang(PetroChina Coalbed Methane Co.,Ltd.,Beijing 100028,China;China United Coalbed Methane National Engineering Research Center Co.,Ltd.,Beijing 100095,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]北京润泽创新科技有限公司,北京100120

出　　处：《特种油气藏》2024年第3期11-17,共7页Special Oil & Gas Reservoirs

基　　金：中国石油煤层气有限责任公司科技项目“煤系储层数字化精细评价研究”(2023-KJ-19)。

摘　　要：煤层气是典型的自生自储型气藏类型之一,甲烷气体主要由煤层中的有机碳热演化生成并大量吸附于孔隙表面,有机成分的含量对于煤层生气及储气能力十分重要。但煤层气储层结构复杂,有机煤岩和无机夹矸层交互叠置发育,层内非均质性强,单井纵向煤层结构可视化难度大,制约了煤层气单井有机质丰度评价及高效开发。全直径CT扫描是近年来针对大尺度岩心的一种重要实验技术,应用该技术扫描得到的煤岩灰度值与其构成关系密切,灰度值越高则煤岩灰分、密度以及矿物含量越高,反之则越低。以大宁—吉县区块目的煤层为研究对象,通过全直径CT扫描技术与测井解释技术相结合,探究了岩石灰度与伽马、密度以及声波时差等测井数据的关系,建立了煤层结构数字井筒反演数学模型,并结合灰度与有机组分的关系,提出了全直径CT扫描单井有机质丰度评价方法。将研究区A1井反演获得的纵截面与全直径CT扫描真实灰度截面对比,二者相似度高,反演灰度值与CT真实灰度值散点图分布规律一致,表明反演模型能够有效反映煤层内部非均质性结构变化。数字井筒反演及有机质丰度评价方法可为研究区煤层气井压裂选段及产能预测提供有力的技术支撑。Coalbed methane is one of the typical types of self-generated and self-stored gas reservoirs.Methane gas is mainly generated by the thermal evolution of organic carbon in coal seams and adsorbed in large quantities on the surface of pores.The content of organic components is crucial for the gas generation and storage capacity of coal seams.However,the reservoir structure of coalbed methane is complex,with interbedded development of organic coal-rock component structures and inorganic leat.The strong heterogeneity within the layers and the difficulty in visualizing the longitudinal coal seam structure in a single well greatly hinder the evaluation of organic matter abundance and efficient development of coalbed methane in single wells.Full-diameter CT scanning is an important experimental technique for large-scale core analysis in recent years.The grayscale values obtained by this technique are closely related to the composition of coal and rock.The higher the grayscale value,the higher the ash content,density,and mineral content of coal and rock,and vice versa.Taking the Daning-Jixian Block as the research object,this study combines full-diameter CT scanning technology with wellbore interpretation technology to explore the relationship between rock grayscale and logging data such as gamma,density,and sonic transit time.A mathematical model for digital well logging inversion of coal seam structure is established,and combined with the relationship between grayscale and organic components,a method for evaluating organic matter abundance in single wells using full-diameter CT scanning is proposed.The comparison between the inverted cross-section of Well A1 in the study area and the real grayscale cross-section obtained by full-diameter CT scanning shows a high degree of similarity,and the distribution pattern of inverted grayscale values is consistent with that of real CT grayscale values,indicating that the inversion model can effectively reflect the heterogeneity structure changes within the coal seam.The digital w

关 键 词：煤层气 全直径CT扫描 测井解释 数字井筒 单井有机质丰度 

分 类 号：TE135[石油与天然气工程—油气勘探]