塔里木盆地古生界原油中高丰度C_(29)规则甾烷的分布及意义  

Distribution and significance of high abundance C_(29) regular sterane in the crude oil of Lower Paleozoic in Tarim Basin

作　　者：张敏 程青松 ZHANG Min;CHENG Qingsong(College of Resources and Environment,Yangtze University,Wuhan 430100,Hubei;Exploration and Development Integration Center,Zhejiang Oilfield Company,Petro China,Hangzhou 310023,Zhejiang)

机构地区：[1]长江大学资源与环境学院,湖北武汉430100 [2]中国石油浙江油田分公司勘探开发一体化中心,浙江杭州310023

出　　处：《长江大学学报（自然科学版）》2021年第1期11-29,共19页Journal of Yangtze University(Natural Science Edition)

基　　金：国家自然科学基金项目“地质体中异常分布规则甾烷类化合物的成因机制与石油地质意义”(41772124)。

摘　　要：通过对塔里木盆地(塔中和塔北)61个来源于寒武奥陶系烃源岩的原油样品进行色谱质谱(GC-MS)分析后发现,大部分原油样品中含有高丰度的C_(29)规则甾烷。依据C_(29)/C_(27)(规则甾烷)(C29规则甾烷与C27规则甾烷的比值)将原油划分为3类:C_(29)/C_(27)(规则甾烷)<1,1<C_(29)/C_(27)(规则甾烷)<1.5,C_(29)/C_(27)(规则甾烷)>1.5。C_(29)/C_(27)(规则甾烷)跟甲基菲比值(F_(1))和姥鲛烷/植烷比值(Pr/Ph)无相关性,但与甾烷和藿烷的相对含量正相关,而与三环萜烷的相对含量无关;同时,C_(29)规则甾烷的绝对含量也与甾烷的绝对含量和藿烷的绝对含量有着极好的正相关关系,而与三环萜烷的绝对含量相关性差。甾烷的异构化参数与C_(29)/C_(27)(规则甾烷)无相关性,但是重排甾烷与规则甾烷的比值(Dia/Re(甾烷))与C_(29)/C_(27)(规则甾烷)负相关。此外,Dia/Re(甾烷)也与热演化参数无关,与甾烷和藿烷的相对含量负相关,与三环萜烷的相对含量正相关。重排甾烷与三环萜烷的绝对含量具好的正相关关系,而与藿烷及甾烷的绝对含量相关性较差。值得注意的是,相关参数表明,C_(29)规则甾烷与伽马蜡烷的绝对含量正相关,同时伽马蜡烷(G)的相对含量和绝对含量与热演化参数和沉积环境参数无关,而与生源参数有关。因此,研究区原油中高丰度C_(29)规则甾烷主要受控于生物母质来源,且其生物母质可能是以细菌和藻类为食的微型浮游动物。随着硫芴相对含量上升,甾烷和藿烷以及伽马蜡烷的相对含量和绝对含量都降低,而三环萜烷和重排甾烷的相对含量反而增加。表明随着水体硫化的增强,海洋生物的生存受抑制,但是细菌和浮游动物受影响更显著。因此,研究区下古生代原油中高丰度的C_(29)规则甾烷可能来自以藻类和细菌为食的浮游动物。动物也是C29规则甾烷的来源之一,虽然微型浮游动物一直被人们所忽视,但是By gas chromatographer-mass spectrometry(GC-MS)analysis of 61 crude oil samples from Cambrian-Ordovician source rocks in Tarim Basin(Tazhong and Tabei),it is found that most of the crude oil samples contain high abundance of C_(29) regular sterane.According to the ratio of C_(29) regular sterane to C_(27) regular sterane(C_(29)/C_(27)(regular sterane)),the crude oil can be classified into three categories:C_(29)/C_(27)(regular sterane)<1,1<C_(29)/C_(27)(regular sterane)<1.5 and C_(29)/C_(27)(regular sterane)>1.5.C_(29)/C_(27)(regular sterane)has no correlation with methyl phenanthrene ratio(F 1),pristane/phytane ratio(Pr/Ph),and the relative content of tricyclic terpenes,but has a very good positive correlation with the relative content of steranes and hopanes.At the same time,the absolute concentration of C_(29) regular sterane has an excellent positive correlation with that of steranes and hopanes,while its correlation with the absolute concentration of tricyclic terpanes is poor.The isomerization parameters of sterane are not correlated with C_(29)/C_(27)(regular sterane),but the ratio of diasteranes to regular sterane(Dia/Re(sterane))is negatively correlated with C_(29)/C_(27)(regular sterane).Dia/Re(sterane)is also independent of thermal evolution parameters,but it is negatively correlated with the relative content of gonanes and hopanes,and positively correlated with the relative content of tricyclic terpenes.Moreover,the absolute concentration of diasteranes has a good positive correlation with that of tricyclic terpenes,but its correlation with absolute concentration of hopane and sterane is poor.It is worth noting that the relative parameters show that the absolute concentration of C_(29) regular sterane is positively correlated with that of gammacerane.Meanwhile,the relative content and absolute concentration of gammacerane(G)are independent of thermal evolution parameters and sedimentary environment parameters,but related to source parameters.Therefore,the high abundance C_(29) regular sterane in the c

关 键 词：下古生代 C_(29)规则甾烷 重排藿烷 伽马蜡烷 浮游动物 塔里木盆地 

分 类 号：P618.13[天文地球—矿床学]