Distribution and geochemical significance of alkylbenzenes for crude oil with different depositional environments and thermal maturities  

作　　者：Bing-Kun Meng Dao-Fu Song Yuan Chen Sheng-Bao Shi 

机构地区：[1]School of Petroleum Engineering and Environmental Engineering,Yan'an University,Yan'an,716000,Shaanxi,China [2]State Key Laboratory of Petroleum Resources and Prospecting,College of Geosciences,China University of Petroleum,Beijing,102249,China

出　　处：《Petroleum Science》2024年第2期777-790,共14页石油科学（英文版）

基　　金：supported by Doctor’s Scientific Research Initiation Project of Yan’an University(YAU202213093);National Natural Science Foundation of China(Grant No.41503029)。

摘　　要：A total of 45 alkylbenzenes were detected and identified in crude oils with different depositional environments and thermal maturities from the Tarim Basin,Beibuwan Basin,and Songliao Basin using comprehensive two-dimensional gas chromatography time-of-flight mass spectrometry(GC×GCTOFMS).By analyzing the distribution characteristics of C0-C5alkylbenzenes,it is found that the content of some alkylbenzenes varies greatly in crude oils.Based on the distribution characteristics of 1,2,4,5-tetramethylbenzene(Te MB)and 1,2,3,4-Te MB,the ratio of 1,2,4,5-Te MB to 1,2,3,4-Te MB is proposed to indicate the organic matter origin and depositional environment of ancient sediments.Oil samples originated mainly from lower hydrobiont,algae,bacteria and source rocks deposited under reducing/anoxic conditions have low 1,2,4,5-/1,2,3,4-Te MB values(less than 0.6),while oil samples originated mainly from terrestrial higher plants and source rocks deposited under oxic/sub-oxic conditions have higher 1,2,4,5-/1,2,3,4-Te MB values(greater than 1.0).The significant difference of 1,2,4,5-/1,2,3,4-Te MB values is controlled by 1,2,4,5-Te MB content.1,2,4,5-Te MB content in oils derived from source rocks deposited in oxidized sedimentary environment(greater than 1.0 mg/g whole oil)is higher than that in oils from source rocks deposited in reduced sedimentary environment(less than 1.0 mg/g whole oil).1,2,4,5-/1,2,3,4-Te MB ratio might not or slightly be affected by evaporative fractionation,biodegradation and thermal maturity.1,2,4,5-/1,2,3,4-Te MB ratio and 1,2,4,5-Te MB content can be used as supplementary parameter for the identification of sedimentary environment and organic matter input.It should be noted that compared to the identification of organic matter sources,the 1,2,4,5-/1,2,3,4-Te MB parameter is more effective in identifying sedimentary environments.

关 键 词：1 2 4 5-Tetramethylbenzene GC×GC-TOFMS Organic matter origin Depositional environment 

分 类 号：O657.63[理学—分析化学]