川东北五宝场地区须家河组和沙溪庙组天然气地球化学特征及其勘探意义  

Geochemical characteristics and exploration significance of natural gas in Xujiahe Formation and Shaximiao Formation in Wubaochang area,Northeast Sichuan

作　　者：陈沁 谢增业[2,3] 张璐 李剑[2,3] 国建英 杨春龙[2,3] 李谨 田继先[2,3] CHEN Qin;XIE Zengye;ZHANG Lu;LI Jian;GUO Jianying;YANG Chunlong;LI Jin;TIAN Jixian(Northeastern Sichuan Gas Mine of PetroChina Southwest Oil&Gasfield Company,Dazhou 635000,China;Research Institute of Petroleum Exploration&Development,Beijing 100083,China;Key Laboratory of Gas Reservoir Formation and Development,CNPC,Langfang 065007,China)

机构地区：[1]中国石油西南油气田公司川东北气矿,四川达州635000 [2]中国石油勘探开发研究院,北京100083 [3]中国石油天然气集团有限公司天然气成藏与开发重点实验室,河北廊坊065007

出　　处：《天然气地球科学》2022年第10期1648-1660,共13页Natural Gas Geoscience

基　　金：国家科技重大专项“大型油气田及煤层气开发”(编号:2016ZX05007-003);中国石油股份公司科技项目“大气田(区)成藏规律与勘探关键技术研究”(编号:2021DJ0604);中国石油西南油气田公司科技项目(编号:20210301-22)联合资助.

摘　　要：川东北五宝场地区上三叠统须家河组天然气勘探获重要突破,中侏罗统沙溪庙组勘探也有重大进展,但天然气地球化学特征与川中地区典型须家河组自生自储天然气有较大差别。基于天然气组分、碳同位素、氢同位素、轻烃等实验分析数据,结合具体的地质条件,对五宝场地区须家河组和沙溪庙组天然气成因进行了系统研究,明确下一步的勘探方向。结果表明:(1)五宝场地区须家河组和沙溪庙组天然气均为以烃类气体为主的干气,干燥系数分别为0.984~0.990和0.950~0.960。(2)较之于川中须家河组自生自储天然气,五宝场地区须家河组和沙溪庙组绝大多数天然气甲烷碳同位素组成重、乙烷碳同位素组成轻、甲烷氢同位素组成重。(3)五宝场地区须家河组天然气轻烃组成有以正构烷烃为主,也有以环烷烃为主,沙溪庙组天然气以正烷烃为主,芳烃含量低,其特征均介于须家河组自生自储天然气与川东长兴组—飞仙关组天然气之间。结论认为,川东北五宝场地区须家河组天然气为上三叠统须家河组源岩和二叠系龙潭组源岩共同供烃,但混源比例在不同地区有差异;沙溪庙组天然气主要是源于下侏罗统和须家河组烃源岩,可能有少量下伏海相天然气的贡献。在川东北地区应围绕深层通源断裂发育的地区,寻找有效的储—盖组合,以发现下一步勘探的有利区。Important breakthroughs have been made in the natural gas exploration of Upper Triassic Xujiahe Formation in Wubaochang area,Northeast Sichuan,and significant progress has been made in the exploration of Middle Jurassic Shaximiao Formation. However,the geochemical characteristics of natural gas in this area are quite different from the self-generated and self-stored natural gas of typical Xujiahe Formation in Central Sichuan. Based on the analysis and experimental data of natural gas composition,carbon isotope,hydrogen isotope and light hydrocarbon,combined with specific geological conditions,the genesis of natural gas in Xujiahe Formation and Shaximiao Formation in Wubaochang area is systematically studied to clarify the next exploration direction. The study show that:(1)The natural gas of Xujiahe Formation and Shaximiao Formation in Wubaochang area is dry gas which is dominated by hydrocarbon gas,and the dryness coefficient is 0.984-0.990 and 0.950-0.960 respectively.(2)Compared with the self-generated and self-stored Xujiahe Formation natural gas in Central Sichuan,most natural gas in Wubaochang area is higher in methane carbon isotope value and methane hydrogen isotope value and lower in ethane carbon isotope value.(3)The light hydrocarbon composition of the Xujiahe Formation natural gas in Wubaochang is mainly n-alkanes or cycloalkanes,and the natural gas of Shaximiao Formation is mainly n-alkanes with low aromatic hydrocarbon content. Its characteristics are between the self-generated and self-stored natural gas of Xujiahe Formation and the natural gas of Changxing-Feixianguan formations in eastern Sichuan. It is concluded that the natural gas in Wubaochang area of Northeast Sichuan is the mixed hydrocarbon supply of source rocks of Xujiahe Formation and Permian Longtan Formation,however,the proportion of mixed sources varies in different regions. The natural gas of Shaximiao Formation mainly comes from the source rocks of Lower Jurassic and Xujiahe Formation,and may be contributed by a small amount of unde

关 键 词：致密砂岩 天然气 地球化学特征 须家河组 沙溪庙组 四川盆地 五宝场地区 

分 类 号：P618.13[天文地球—矿床学]