Molecular characterization of sulfur compounds in some special sulfur-rich Chinese crude oils by FT-ICR MS

LU Hong¹, SHI Quan2^*, MA QingLin³, SHI Yang³, LIU JinZhong¹, SHENG GuoYing¹ & PENG PingAn¹

¹State Key Laboratory of Organic Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China; ² State Key Laboratory of Heavy Oil, China Petroleum University, Beijing 102249, China; ³ Southern Petroleum Exploration and Development Ltd. (CNPC), Guangzhou 510240, China

*Corresponding Author: Quan Shi − E-mail:  sq@cup.edu.cn

DOI: 10.1007/s11430-013-4789-9

Keywords: ESI, FT-ICR MS, organic sulfur compounds, sulfur-rich oil, Jianghan Basin, Jinxian Sag

Abstact: Routine GC/MS analysis may apply to the volatilized Low-Molecular-Weight compounds in saturate and aromatic hydrocarbon fractions; thus, relative studies using this technique inevitably bring about some limitations on distribution of miscellaneous sulfur atom. In this article, Fourier Transform Ion Cyclotron Resonance Mass Spectrometry (FT-ICR MS) with high resolution is employed to investigate the distribution of organic sulfur compounds (OSCs) in the crude oil typically derived from the Eogene carbonate-evaporite sediments with further chemical compositional characterization in molecular level by miscellaneous atomic type, carbon number, and double bond equivalent (DBE). A variety of miscellaneous atomic types with S₁, S₂, S₃, OS, OS₂, O₂S, O₂S₂, NS, and NOS etc. (S₁ means those OSCs with one sulfur atom in a molecule) were identified in OSCs in these oil samples. High levels of alkyl thioether series compounds with one ring structure were presented mainly in the crude oil in the Jianghan Basin whereas high amounts of benzothiophene, dibenzothiophene etc. compounds with higher values in DBE and carbon number range occurred in the sulfur-rich heavy oil in the Jinxian Sag. Although carbonate-evaporite sediments deposited in the saline lacustrine facies in the Eogene basin both occurred in the Jinxian Sag and Jianghan Basin, obviously, they possess different chemical diagenetic pathway of sulfur under various microbial reactions, leading to diverse distributional characteristics on biomarkers, OSCs, and even different hydrocarbon generation mechanism of immature crude oil.