二连盆地吉尔嘎朗图凹陷煤层气成因类型及勘探方向  

Genetic Types and Exploration Prospect of Coalbed Methane in Jiergalangtu Depression, Erlian Basin

作　　者：陶俊杰 申建[1] 王金月[1] 李叶朋[1] 李超[1] TAO Junjie;SHEN Jian;WANG Jinyue;LI Yepeng;LI Chao(CME’s Key Laboratory of CBM Resources and Reservoiring Process, School of Resources and Geosciences, China University of Mining and Technology, Xuzhou 221116, China)

机构地区：[1]煤层气资源与成藏过程教育部重点实验室中国矿业大学资源与地球科学学院,徐州221116

出　　处：《高校地质学报》2019年第2期295-301,共7页Geological Journal of China Universities

基　　金：国家重大科技专项"低煤阶煤层气富集规律及有利区块预测"(2016ZX05044-02)资助

摘　　要：低煤阶煤层气地球化学特征及成因判识是勘探选区重要基础。通过解剖煤层气井气、水组成及其碳、氢同位素特征,探讨了二连盆地吉尔嘎朗图凹陷煤层气成因。结果表明:煤层气组分中甲烷占93.41%,重烃及二氧化碳含量低,为典型干气;甲烷碳同位素(δ^(13)C)值介于-62.5‰～-60.1‰之间、氢同位素(δD)值介于-275.1‰～-270.2‰之间、二氧化碳碳的同位素(δ^(13)C)值介于5.1‰～6.2‰之间,反映其为生物成因气。煤层水来源于大气降水,呈弱碱性、较低矿化度。煤层气井气、水氢同位素特征表明研究区97%左右生物成因气形成于二氧化碳还原机制。生物气藏是吉尔嘎朗图凹陷重要煤层气勘探方向,适宜地下水环境是勘探选区关键因素。Geochemical characteristics and genetic identification of low-grade coalbed methane are important foundations for exploration targets. The origin of coalbed methane in Erlian Basin is discussed by dissecting the composition of gas and water in coal-seam wells and the characteristics of carbon and hydrogen isotopes. The results show that methane content in coalbed methane components is 93.41%, and the content of heavy hydrocarbons and carbon dioxide is low, indicating a typical dry gas. The carbon isotope values of methane are between-62.5‰and-60.1‰,and the hydrogen isotope values are between-275.1‰and-270.2‰. The carbon isotope values of carbon dioxide range from 5.1 to 6.2‰, suggesting that it is biogas. Coal bed water originated from atmospheric precipitation, showing weak alkalinity and low salinity. The gas and water isotope characteristics of coalbed methane wells indicate that about 97% of biogas in the study area was formed by carbon dioxide reduction. The biogas reservoir is an important exploration target for coalbed methane in the Jiergalangtu depression. The suitable groundwater environment is a key factor in the exploration targets.

关 键 词：吉尔嘎朗图凹陷 煤层气 同位素 生物气 二氧化碳还原 

分 类 号：P618.11[天文地球—矿床学]