| Light hydrocarbon as an important part of crude oil, contains a lot of geochemical information, and has attracted much attention .Total of 29 marine oils and terrigenous oils samples were analyzed by comprehensive two-dimensional gas chromatography. The results show that 13 pairs of covalent peaks are detected in C5?C10 light hydrocarbons by comprehensive two-dimensional gas chromatography, which has the advantage of effectively eliminating the conjugation of compounds compared with conventional gas chromatography. Based on the previous studies, combined with the C5?C7 light hydrocarbon composition characteristics, comparative analysis of typical marine facies oil C5?C10 light hydrocarbon composition and composition ratio.It was found that the typical naphthenic content and I/P value, while the typical continental crude oil has a relatively high naphthenic and aromatic hydrocarbon content and A/P value. A new parameter for determining the depositional environment and maturity was established for C8 light hydrocarbon monomer compounds. The sedimentary environmental parameters of Cs has good correlation with commonly used geochemical parameters such as 4-MDBT/DBT, Pr/Ph, Ph/nC18-Pr/nC17, C21/C23TT and DBT/P, and on each plate can be clearly distinguished. According to paraffin index and heptane value chart. It has good correlation with the maturity parameters of C30M / C30H, MNR, TNR1 and CPI, further proved that the new parameters to evaluate the maturity of crude oil is feasible. In the detection of C9 light hydrocarbon fraction, 32 compounds were identified and the relative composition of C9 light hydrocarbon fraction of typical sea-land crude oil samples was dominated by five-member ring, while the six-member ring and benzene were in the crude oil. Based on this difference,a new parameter for determining the depositional environment was established. The parameters were compared with the classical biomarker parameters Pr/Ph, 4-MDBT/DBT, 1-MDBT/DBT and(C21+C22) /(C28+C29), it was found that the linear relationship between the new parameters and the classical biomarker parameters was normal, but the typical sea-land crude oil could be distinguished. Therefore, whether the parameters were related to the source of organic matter or source rock Still need further proof. In the process of analysis of 23 C10 light hydrocarbon compounds, six kinds of monoterpene compounds with different abundance in crude oil samples were found. Based on the research idea of monoterpene hydrocarbon parameter MTR, the new monoterpene hydrocarbon parameters for the determination of sedimentary environment were proposed: 2,6-DMO/1,1,2,3-TeMCHx, and this parameter was found has good correlation with the MTR?Pr/Ph?DBT/P?4-MDBT/DBT?(2+3 )-MDBT/DBT. and marine crude oil has a relatively low MTR1 value,which is due to the marine crude oil has a more abundant 1,1,2,3 Tetramethylcyclohexane, it is proved that MTR1 can be used as a supplementary parameter to judge the deposition environment of crude oil or source rock. |
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