柴达木盆地东部石炭系海陆过渡相煤系页岩气地球化学特征及成因  

Geochemical characteristics and genesis of shale gas for Carboniferous marine-continental transitional facies coal measure strata in Eastern Qaidam Basin

作　　者：曹军[1,2] 刘成林[1,2] 马寅生[1,2] 李宗星[1,2] 杨元元[1,2] 王国仓[3] 彭博[1,2] 张旭[1,2] 顿超[4] 

机构地区：[1]中国地质科学院页岩油气调查评价重点实验室,北京100081 [2]中国地质科学院地质力学研究所,北京100081 [3]中国科学院地质与地球物理所兰州油气资源研究中心,甘肃兰州730000 [4]中国石油大学(北京)地球科学学院,北京102249

出　　处：《地学前缘》2016年第5期158-166,共9页Earth Science Frontiers

基　　金：国家自然科学基金面上项目(41272159;41572099);中国地质调查局地质调查项目(1212011120964)

摘　　要：为了弄清柴达木盆地东部石炭系海陆过渡相页岩气特征和成因,选取柴页2井石炭系克鲁克组泥页岩和页岩气样品展开地球化学研究。通过对泥页岩样品热解和镜检实验,页岩气现场解析、室内气体组分测试和碳同位素分析,取得以下认识:柴达木盆地上石炭统海陆过渡相煤系地层发育暗色泥页岩、碳质泥页岩、煤和泥灰岩4类富有机质沉积,TOC含量平均值分别为3.46%、12.34%、77.62%和1.89%,以Ⅲ型和Ⅱ2型干酪根为主,处于高成熟演化阶段,具备生成大量页岩气的物质基础。柴页2井现场解析气中氮气含量较高,含极少量Ar和He,烃类气体以甲烷为主,总体为干气;甲烷稳定碳同位素组成主要分布在-48.6‰^-39.8‰,介于海相和陆相页岩气之间,随深度增大,呈现碳同位素偏重的现象;页岩气以热成因气为主,其次是生物成因气。For the purpose of figuring out the characteristics and genesis of shale gas from the Carboniferous marine-continental transitional facies strata in the eastern Qaidam Basin, the research was carried out by extracting the shale and shale gas from the Carboniferous Keluke group of the Well Chaiye 2, through the rock-eval pyrolysis experiments and microscopic examination for the shale samples, shale gas field desorption, gas composition testing and carbon isotope analysis indoor. The research results indicate that Carboniferous marine-continental transitional facies coal measure strata developed 4 types of organic rich sediments of dark shale, carbonaceous shale, coal and marl in the Qaidam Basin. The mean values of TOC are 3. 460//oo, 12.34%, 77.62% and 1.89%, respectively. The kerogen is mainly of type l]I and type llz, which is at highly mature stage with the organic material to generate considerable amount of shale gas. The level of nitrogen is higher than others in the Well Chaiye 2 according to the shale field analysis of shale gas which also contains considerably small amount of Ar and He. Methane contributes the largest part of hydrocarbon gases and they are generally dry gas. The distribution percentage of methane stable carbon isotope ranges from --48.6% to --39. 8%, which is between marine and continental shale gas, having a bias towards carbon. Shale gas contains thermogenic gas as its largest amount of composition and biogenic gas as the second.

关 键 词：页岩气 成因 海陆过渡相 石炭系 柴达木盆地 

分 类 号：P618.13[天文地球—矿床学] P534.45[天文地球—地质学]