库车坳陷大北-克深地区深层致密砂岩气地球化学特征及成因  

Geochemical Characteristics and Genesis of Deep Tight Sandstone Gas in the Dabei-Keshen Zone, Kuqa Depression

作　　者：魏强 李贤庆[1,2] 梁万乐[1,2] 孙可欣 谢增业[3] 李谨 肖中尧 WEI Qiang;LI Xian-qing;LIANG Wan-le;SUN Ke-xin;XIE Zeng-ye;LI Jin;XIAO Zhong-yao(State Key 厶aboratory of Coal Resources and Safe Mining, College of Geoscience and Surveying Engineering, China University of Mining and Technology ( Beijing) , Beijing 100083 , China;College of Geoscience and Surveying Engineering, China Umiversity of Mining and Technology ( Beijing) , Beijing 100083 , China;Research Institute of Petroleum Exploration & Development,PetroChina, Langfang Hebei 065007 , China;Research Institute of Exploration and Development, Tarim Oilfield Company,PetroChina , Korla Xinjiang 841000, China)

机构地区：[1]中国矿业大学(北京)煤炭资源与安全开采国家重点实验室,北京100083 [2]中国矿业大学(北京)地球科学与测绘工程学院,北京100083 [3]中石油勘探开发研究院天然气地质所,河北廊坊065007 [4]中石油塔里木油田分公司勘探开发研究院,新疆库尔勒841000

出　　处：《矿物岩石地球化学通报》2019年第2期418-427,共10页Bulletin of Mineralogy, Petrology and Geochemistry

基　　金："十三五"国家油气科技重大专项课题(2016ZX05007-003);中央高校基本科研业务费专项资金项目(2010YM01)

摘　　要：为探讨库车坳陷大北-克深地区深层致密砂岩气的地球化学特征及成因,对采集的天然气样品进行了组分定量和碳同位素组成分析。结果显示,库车坳陷大北-克深地区深层致密砂岩气中甲烷占绝对优势,为87.30%～98.33%,平均为96.18%;其重烃气含量较低,为0%～3.41%,为明显的干气;天然气的δ^(13)C_1为-31.9‰～-26.5‰,δ^(13)C_2为-24.2‰～-16.1‰,δ^(13)C_3为-31.1‰～-15.7‰;烷烃气碳同位素偏重,主体呈正碳同位素序列,局部出现倒转;天然气成熟度为1.50%～3.62%,平均为2.39%,为高-过成熟天然气;δ^(13)C_(CO2)</sub>主要为-19‰～-10.3‰。研究表明,大北-克深地区深层致密砂岩气中烷烃气属于煤成气成因,同型不同源气或煤成气与油型气的混合是烷烃气碳同位素倒转的主要原因,同时也与深层高温高压条件下烷烃气的形成与成藏过程有关;深层致密砂岩气中CO_2主要为有机成因。In order to study the geochemical characteristics and genesis of deep tight sandstone gas in the Dabei-Keshen zone of the Kuqa depression, components and stable carbon isotopic compositions of natural gas samples were analyzed. The deep tight sandstone gas of Dabei-Keshen zone, Kuqa depression is dominant by methane, ranging from 87.30% to 98.33%, with an average of 96.18%. Samples contain low C2+ from 0% to 3.41%, indicating deep tight sandstone gases in the Dabei-Keshen zone are dry gases. The δ13C1 of natural gases ranges from-31.9‰ to-26.5‰,δ13C2 is-31.9‰ to-26.5‰,δ13C2 is-31.1‰ to-15.7‰. The carbon isotope of alkane gas is heavier, some of which show the positive carbon isotope sequence and others display partial reversal. The natural gas maturity ranges from 1.50% to 3.62% with an average of 2.39%, indicative of high-over matured natural gas.δ13CCO2 is-19‰ to-10.3‰. Therefore, the deep tight sandstone gas of Dabei-Keshen zone, Kuqa depression belongs to coal-derived gas. Carbon isotope reversal of alkane result from the mixing of natural gas from different sources or the mixing of coal-derived gas and oil type gas, and is also possibly related to natural gas formation and accumulation under high temperature and high pressure in deep strata. Moreover, the carbon dioxide in deep tight sandstone gas is mainly organic in origin.

关 键 词：深层致密砂岩气 地球化学特征 碳同位素 成因 大北-克深地区 库车坳陷 

分 类 号：P593[天文地球—地球化学]