内蒙古东北部拉布达林盆地冻土天然气水合物钻探地质启示:以ST-1井为例  

Geological Indicators of Permafrost-associated Gas Hydrates in the Labudalin Basin,Northeastern Inner Mongolia

作　　者：张朝辉 刘显正 冯岩 李洪亮 李磊 杨才 夏宁 卢振权 张运波 刘国 孙丽 林子杨 李青 ZHANG Zhaohui;LIU Xianzheng;FENG Yan;LI Hongliang;LI Lei;YANG Cai;XIA Ning;LU Zhenquan;ZHANG Yunbo;LIU Guo;SUN Li;LIN Ziyang;LI Qing(Geological Exploration Company,Coal Geological Exploration Group of Inner Mongolia,Hohhot,Inner Mongolia 010020,China;Geological Survey and Research Institute of Inner Mongolia,Hohhot,Inner Mongolia 010020,China;Oil&Gas Survey,China Geological Survey,Beijing 100083,China;No.231 Limited Company,Coal Geological Exploration Group of Inner Mongolia,Hulun Buir,Inner Mongolia 021000,China)

机构地区：[1]内蒙古煤炭地质勘查(集团)地质勘查公司,内蒙古呼和浩特010020 [2]内蒙古自治区地质调查研究院,内蒙古呼和浩特010020 [3]中国地质调查局油气资源调查中心,北京100083 [4]内蒙古煤炭地质勘查(集团)二三一有限公司,内蒙古呼伦贝尔021000

出　　处：《现代地质》2024年第5期1383-1399,共17页Geoscience

基　　金：内蒙古自然资源厅本级综合研究类项目“内蒙古自治区呼伦贝尔市天然气水合物(可燃冰)靶区优选及验证”(2022-TZH02)。

摘　　要：内蒙古东北部拉布达林盆地是我国陆域高纬度冻土型天然气水合物重要潜在分布区,有望成为祁连山木里高海拔冻土型天然气水合物的互补类型,具重要调查研究价值。目前该区天然气水合物调查研究程度较低,2023年内蒙古自治区地质调查研究院首次在该区部署两口天然气水合物探井。以资料较为齐全的ST-1井为例开展综合分析与区域对比研究,旨在总结各种可能与天然气水合物相关的异常现象,分析天然气水合物形成的有利条件,指出研究区天然气水合物-浅层气系统的共生模式。研究显示:(1)本次钻探中发现岩心表面冒泡现象、井涌现象、烃类气测和岩心解吸气高含量异常现象、自生方解石伴生产出现象等,可能与天然气水合物直接或间接相关。(2)岩心解吸气组成主要为CH_(4),次为CO_(2),还含少量C_(2)H_(6),主要以煤型气来源为主,可能还含少部分微生物成因气及热解成因混合气。(3)钻遇的下白垩统大磨拐河组(K_(1)d)有机碳含量在3.16%~31.19%间,平均12.48%,生烃潜量在1.50~113.78 mg/g间,平均45.50 mg/g;有机显微组分以镜质组和腐泥组为主,有机质类型为Ⅱ_(2)-Ⅲ型,干酪根镜质体反射率Ro值在0.63%~0.80%间,为低熟-成熟阶段,具备良好生烃条件。可能是天然气水合物主要的潜在气源岩,对比区域上5套烃源岩,上侏罗统满克头鄂博组(J_(3)m)烃源岩有望成为天然气水合物另一重要潜在气源岩;(4)钻后30 h、54 h、78 h的温度测井数据在200 m以浅一直难以稳定下来,特别是43.45~70.55 m间深度段测井温度波动较大,可能与部分深度段地层破碎或断裂发育而形成局部热融作用有关,致使此次温度测井数据可能难以真正代表地层本身的地温特征,但是研究区仍然具有良好的天然气水合物形成条件和潜力;(5)本次钻井现场气测录井烃含量多个深度段达11.95%~16.65%,解吸气含量0.95~3.19 m^(3)/t,平均为1.84 The Labudalin Basin in Northeastern Inner Mongolia is an important land-based area for the potential formation of high-latitude permafrost-associated gas hydrates in China.It is expected to become an important complement to the high-altitude permafrost-associated gas hydrates in the Qilian Mountain,offering significant research value.Currently,investigations and studies on gas hydrates in this area are relatively limited.In 2023,the Geological Survey and Research Institute of Inner Mongolia deployed two exploration wells for gas hydrates in this region for the first time.This study uses the ST-1 well,which has more comprehensive data,as an case study to conduct an thorough analysis and regional comparison.The aim is to investigate anomalies related to gas hydrates,identify favorable conditions for their formation,and establish a symbiotic model for the shallow-gas and gas hydrate system in the study area.The study results indicate that:(1)During drilling,phenomena such as bubbling on the core surface,well-fluid eruptions,high anomalies in hydrocarbon gas measurements,elevated desorbed gas content from the core samples,and the occurrence of authigenic calcite were observed,all of which may be directly or indirectly related to gas hydrates.(2)The composition of the desorbed gas from the core samples is primarily CH_(4),followed by CO_(2),with a small amount of C_(2)H_(6).This gas is mainly sourced from coal-type gas and may also contains a small portion of microbial-derived gas and mixed pyrolytic gas.(3)The organic carbon content of the Lower Cretaceous Damoguaihe Formation(K_(1)d),encountered during drilling,ranges from 3.2%to 31.2%,with an average of 12.5%.The hydrocarbon generation potential varies from 1.50 to 113.78 mg/g,with an average of 45.50 mg/g.The organic maceral components are primarily vitrinite and sapropelinite,indicative of Ⅱ_(2)-Ⅲ organic matter.The reflectance of kerogen vitrinite(Ro)ranges from 0.63%to 0.80%,indicating a stage from low maturity to maturity,which provides favorable condition

关 键 词：内蒙古东北部 拉布达林盆地 冻土 天然气水合物 钻探 地质启示 

分 类 号：P618.1[天文地球—矿床学]