琼东南盆地松南—宝岛凹陷特殊成因天然气及油气源分析  

Characteristics and origin analysis of a unique genetic type of natural gases in Songnan-Baodao sag,southeast Qiong basin

作　　者：丁文静 侯读杰[1,2,3] 陈立 甘军 梁刚[4] 马潇潇[1,2,3] 吴飘 王慧 冯信荦 

机构地区：[1]中国地质大学(北京)海相储层演化与油气富集机理教育部重点实验室,北京100083 [2]中国地质大学(北京)页岩气勘察与评价国土资源部重点实验室,北京100083 [3]煤层气开发利用国家工程研究中心中国地质大学(北京)煤储层物性实验室,北京100083 [4]中海石油(中国)有限公司湛江分公司,广东湛江524057 [5]中国石油塔里木油田分公司库车油气开发部,新疆库尔勒841000 [6]中国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：《东北石油大学学报》2018年第3期1-15,共15页Journal of Northeast Petroleum University

基　　金：国家自然科学基金项目(41472108)

摘　　要：分析天然气碳同位素、组分、轻烃,伴生凝析油轻烃、全油及单体烃碳同位素、生物标志物,以及渐新统—中新统烃源岩生物标志物及显微组分,研究琼东南盆地松南—宝岛凹陷天然气和凝析油的生烃母质和成熟度。结果表明:琼东南盆地松南—宝岛凹陷天然气可划分为4种成因类型,即生物气与特殊低熟气的混合气(Type A)、特殊低熟气(Type B)、成熟煤型气(Type C)和特殊低熟气与成熟煤型气的混合气(Type D)。Type B特殊低熟气干燥因数小(0.65~0.91),富含有机成因CO_2,为较低温度12C—12C键优先断裂而形成的轻质烃类;低成熟的(Ro<0.6%)陵水组一段上部泥岩地层中有机质腐泥组体积分数逐渐增大,藻类及低等水生生物的贡献大于陆源高等植物输入的。Type B天然气伴生凝析油碳同位素较轻,奥利烷、杜松烷和扁枝烷等高等植物来源的生物标志物丰度低,三环萜烷丰度及低甾烷/藿烷比较高,显示菌藻类生源优势,轻烃显示偏腐泥型母源及低成熟特点。特殊低熟气是琼东南盆地海陆过渡相—海相天然气的一种新的成因类型,是典型煤型气的极大补充,表明琼东南盆地陵水组一段上部地层有较好的低熟气勘探潜力。The source and maturity are analyzed based on the compositions,δ^(13) C ratios,light hydrocarbons of natural gases and biomarker,stable carbon isotope ratios of individual n-alkanes and whole oil in the concomitant condensate,along with the macerals and biomarkers analysis in Oligocene-Miocene source rocks.Four genetic types of natural gases are classified in study area:mixture of biogenic gas and special low-mature gas(Type A);special low-mature gas(Type B);mature coal-type gas(Type C)and mixture of special low-mature gas and mature coal-type gas(Type D).Type B natural gas is different from typical coal-type gas with lighter stable carbon ratios,lower dry coefficient,more abundant organic CO_2,which are caused by two factors:the lighter hydrocarbons generated from the preferred cracking of ^(12) C—^(12) C bonds in lower temperature;greater proportion of sapropelinite in strata overlying 1 st member of Lingshui formation with corresponding Roless than 0.6%.Type B natural gases are characterized with higher content of tricyclic terpane,extremely low content of sterane/hopane ratio and terrestrial biomarkers such as oleanane,cadinane,phyllocladane.Light hydrocarbons indicate the sapropel-prone and low-mature genesis as well.The special low-mature gas is a new genetic type of natural gases generated from transitional-marine shale,which is also a supplement resource of typical coal-type gases,indicating agood exploration potential in previously neglected low-mature shale overlying 1 st member of Lingshui formation of Songnan-Baodao sag and adjacent deep waters in southeast Qiong basin.

关 键 词：特殊低熟气 成因分析 油气源对比 松南—宝岛凹陷 琼东南盆地 

分 类 号：TE112.1[石油与天然气工程—油气勘探]