Abstract
Chemometrics has been widely used to cope with the problems of oil-oil and oil-source correlations because of its unique advantages in the comprehensive consideration of multiple parameters and the classification of samples or variables. In this paper, three chemometric methods, especially multidimensional scaling, were used to revisit the genetic oil family and the relationship between the crude oil and the source rock, because the oil source in the Wushi Sag, a significant petroliferous sag in the Beibu Gulf Basin of South China Sea, is still controversial. Two genetic families of crude oils, namely group A and group B, have been identified based on chemometric results. Group A oils are characterized by relatively higher Pr/Ph ratios and a high abundance of C27 ααα 20R steranes and C30-methylsteranes than those of group B oils, suggesting that this group of oils was deposited under a more oxic condition with more contribution of algae organic matter. Group A oils have been interpreted to be a mixture derived from the member 2 and member 3 of the Liushagang Formation (LS-2 and LS-3), whereas group B oils can be ascribed to the LS-2 member. The contribution of LS-3 mudstone member to the Wushi oils in previous studies may have been underestimated to some extent, which was inferred from the chemometric oil-source correlation results. The results of oil-source rock correlation may be used to guide future petroleum exploration activities with the incorporation of geological evidence. The spatial distribution of oil and gas reservoirs varies with burial depth. Taking into consideration other geological evidence, we may infer that the reservoir in eastern Wushi Sag was mainly distributed in the deep of Liushagang Formation, whereas the reservoir in southeast Wushi Sag was likely located in the shallow Liushagang Formation.
Highlights
Chemometrics is a useful tool for recognizing patterns and extracting useful information from measure data (Peters et al, 2005; Kumar et al, 2014)
Three sets of source rocks are present in the Wushi Sag: the first, second, and third members of the Liushagang Formation, i.e., LS-1, LS-2, and LS-3 (Liu et al, 2018; Li et al, 2021)
The LS-1 mudstone member of the studied sample is a fair source rock, whereas the LS-2 and LS-3 mudstone members of the studied sample have good to excellent hydrocarbon generation potential
Summary
Chemometrics is a useful tool for recognizing patterns and extracting useful information from measure data (Peters et al, 2005; Kumar et al, 2014). HCA calculates the distance matrices of the studied data objects, and organize objects with similar features into clusters (Cheong et al, 2016) Both PCA and MDS transform multiple correlated variables (i.e., biomarker ratios) into a small number of new uncorrelated variables (principal component). The LS-2 member was formed in a deep water body during the maximum of lake expansion, with a set of high-quality source rock developed (Li et al, 2021) This member is composed of interbedded fine-grained sandstones and shales (Liu, 2004).
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
