Geochemical characteristics and significance of heteroatom compounds in lacustrine oils of the Dongpu Depression (Bohai Bay Basin, China) by negative-ion Fourier transform ion cyclotron resonance mass spectrometry
Geochemical characteristics and significance of heteroatom compounds in lacustrine oils of the Dongpu Depression (Bohai Bay Basin, China) by negative-ion Fourier transform ion cyclotron resonance mass spectrometry
复制标题
渤海湾盆地东濮凹陷湖相石油杂原子化合物负离子傅里叶变换离子回旋共振质谱地球化学特征及意义
DOI：
10.1016/j.marpetgeo.2018.07.035
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发表时间：
2018-11-01
影响因子：
4.2
通讯作者：
Shi, Quan
中科院分区：
文献类型：
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作者：
Ji, Hong;Li, Sumei;Shi, Quan
采用负离子电喷雾电离（ESI）、傅里叶变换离子回旋共振质谱（FT-ICR MS）对渤海湾盆地东濮凹陷咸水和淡水湖相油进行了表征。ESI-FT-ICR质谱分析发现，油中含有大量的氮、氧化合物，主要包括N-1、O-1、O-2和n101。低成熟油以双键为4的O-1种（DBE = 4，主要为烷基酚类）、DBE = 5-6的O-2种（即藿烷酸、次藿烷酸和类固醇酸）和DBE = 1的脂肪酸为主，表明含氧化合物与其前体存在亲缘关系。成熟度对氮、氧化合物的影响显著，低成熟度油富含O-2，特别是脂肪酸和4-5环环烷，具有生物来源的烃骨架：O-2/N-1 > 0.7；C20-30/ c15-45-dbe1-o-2 > 0.4；DBE5-6/DBE1(2-22)-O-2 > 6.0可能是低成熟度的有用指标。随着成熟度的增加，化合物的缩合度增加，碳数减少。DBE特定碳数范围的N-1和O-1物种相对丰度对成熟度尤为敏感：DBE9-12/DBE15-18-N-1、C20-28/C29-40-DBE12-N-1、C20-30/C31-50-DBE15-N-1、DBE9-12/DBE4-20-O-1和C-20-(30)/C31-50-DEE8-O-1。在某些情况下，FT-ICR MS代理比传统的基于甾烷的成熟度参数提供了更可靠的高成熟度水平指示。然而，其中一些物种对其他影响也有反应，即C20-28/C29-40-DBE12-N-1和C20-30/C31-50-DBE15-N-1比值反映了有机相控制，DBE9-12/DBE4-20-O-1和C20-30/C31-50-DBE8-O-1比值随热化学硫酸盐还原（TSR）而变化，这一点由oss的δ S-34方差证实。考虑到氮氧化合物的多重控制，DBE9-12/DBE15-18-N-1比值似乎不受有机质相或TSR的影响，被认为是最可靠的成熟度指标，其成熟度关系与Ts/(Ts + Tm)相似或更好。除了次生蚀变效应外，淡水样品与盐水样品在组成上存在一些差异，包括O-2和N-1产物丰度普遍较高（特别是低MW）， O-1产物丰度较低且分布差异较大。这些差异表明ESI FT-ICR质谱分析具有区分这些样品类型的潜力。
Saline and freshwater lacustrine oils from the Dongpu Depression (Bohai Bay Basin) were characterized by negative-ion electrospray ionization (ESI) Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS). ESI-FT-ICR MS detected a large range of nitrogen and oxygen compounds in the oils, mostly comprising N-1, O-1, O-2 and N1O1 species. The low mature oils are dominated by O-1 species with double bond equivalent of 4 (DBE = 4; mainly alkylphenols), O-2 species with DBE = 5-6 (i.e., hopanoid, secohopanoic and steroid acids) and DBE = 1 (i.e., fatty acids), indicating a genetic relationship between oxygen compounds and their precursors. The nitrogen and oxygen compounds were significantly influenced by maturity, with the lower maturity oils analyzed enriched in O-2 species, particularly fatty acids and 4-5 ring naphthenes with biologically sourced hydrocarbon skeletons: ratios of O-2/N-1 > 0.7; C20-30/C15-45-DBE1-O-2 > 0.4; and DBE5-6/DBE1(2-22)-O-2 > 6.0 may be useful indicators of low maturity. With increasing maturity, the condensation degree of the compounds increased and the carbon number decreased. The relative abundances of N-1 and O-1 species with the following specific DBE carbon number ranges were particularly sensitive to maturity: DBE9-12/DBE15-18-N-1, C20-28/C29-40-DBE12-N-1, C20-30/C31-50-DBE15-N-1, DBE9-12/DBE4-20-O-1 and C-20-(30)/C31-50-DEE8-O-1. In some instances the FT-ICR MS proxies provided a more reliable indication of high maturity levels than traditional sterane based maturity parameters. However, several of these species were also responsive to other influences, namely C20-28/C29-40-DBE12-N-1 and C20-30/C31-50-DBE15-N-1 ratios reflected an organofacies control and DBE9-12/DBE4-20-O-1 and C20-30/C31-50-DBE8-O-1 ratios changed with thermochemical sulfate reduction (TSR)- confirmed by delta S-34 variances of OSCs. In light of the multiple controls on the nitrogen and oxygen compounds, DBE9-12/DBE15-18-N-1 ratio seems unaffected by organofacies or TSR and was considered the most reliable maturity proxy displaying a similar or better maturity relationship than Ts/(Ts + Tm). Aside from secondary alteration effects, the freshwater samples showed several compositional differences to the saline samples, albeit from a limited data set, including generally higher O-2 and N-1 (particularly low MW) product abundances, lower abundances and quite different distribution of O-1 products. These distinctions suggest ESI FT-ICR MS analysis has potential for distinguishing these sample types.