Isotopic compositions and biomarkers in crude oils from the Tarim Basin: Oil maturity and oil mixing

The effect of oil expulsion or retention on further thermal degradation of kerogen at the high maturity stage: A pyrolysis study of type II kerogen from Pingliang shale, China

“…There were few variations in dD values of n-alkanes with the EasyRo values ranging from 0.9% to 1.1%, but a rapid increase of dD (by 50‰) during the oil cracking process (Tang et al, 2005). D enrichments in n-alkanes, by 30-40‰, have also been reported for natural oil samples at various maturity stages (Li et al, 2001;Jia et al, 2013). However, n-alkanes in extracts from natural sediments and rocks might display more complicated variations in hydrogen isotopes during maturation, although a general trend of D enrichment for n-alkanes has been observed (Dawson et al, 2005(Dawson et al, , 2007Radke et al, 2005;Pedentchouk et al, 2006;Schimmelmann et al, 2006;Kikuchi et al, 2010).…”

Carbon and hydrogen isotopic compositions of n -alkanes as a tool in petroleum exploration

“…Early H isotope studies by Yeh & Epstein (1981) and Schoell (1984) conducted on bulk oil have shown minimal exchange of C-bound H over geological timescales. More recent studies Wang et al 2009aWang et al , b, 2013 involving H isotope investigation at the compound-specific level, however, do show that H exchange can take place. A broad range of δ 2 H values typical of organic compounds from different compound classes (H in n-alkyl and aromatic structures, and H bound to and adjacent to heteroatoms), and thus a different degree of susceptibility of these compounds to H exchange reactions (both the extent and rates), provide ample opportunity for investigating the extent of H isotope exchange over geological timescales.…”

“…This and related studies show that the Alpine foreland Bjorøy et al (1994) and Odden et al (2002) in the North Sea were among the first to use CSIA data for correlation and then for additional follow-up investigations. Studies in other basins (Tarim, Niger, Barents and Western Canada Sedimentary) are further excellent examples of integrated geochemical basin analysis (Li et al 2001(Li et al , 2010Samuel et al 2009;Jia et al 2010Jia et al , 2013He et al 2012;Murillo et al 2016). Other basin studies are examples of investigations that have focused on particular applications, such as charge evaluation (West Sak, Masterson et al 2001), source rock correlation (Austria, Bechtel et al 2012;Sirte Basin, Aboglia et al 2010), and the interplay of maturity and in-reservoir processes (Perth Basin, Dawson et al 2005;Potwar Basin, Asif et al 2009;Liaohe Basin, Sun et al 2005). basin provides an excellent natural laboratory to study the impact of source and maturity variations as well as migration on compound-specific isotope compositions and to further develop these tools in petroleum exploration.…”

“…Large variations in stable C isotopic composition of n-alkanes in fluid compositions reflect mixing from many distinct source rocks (Jia et al 2010;Li et al 2010). More recently, using both C and H CSIA of n-alkanes, Jia et al (2013) untangled complex source contributions in the Tabei and Tazhong uplift areas and ultimately distinguished oils from the same source rock at different maturity levels as well as contributions from different sources also at different maturity levels (Jia et al 2013).…”

De-convoluting crude oil mixtures from Palaeozoic reservoirs in the Tabei Uplift, Tarim Basin, China

“…Second, such basins contain a range of petroleum types, including dry gas, wet gas, condensate, light oil, heavy oil and solid bitumen. Multiple oil generation and filling stages and a number of post-accumulation processes, e.g., mixing, biodegradation, fractionation, have been proposed to explain the diverse oil occurrence and formation (Zhang, 2000;Wang et al, 2008;Pan and Liu, 2009;Jia et al, 2010Jia et al, , 2013Zhang et al, 2011Zhang et al, , 2014Zhang et al, , 2015Li et al, 2012Li et al, , 2015Tian et al 2012a,b;Zhu et al, 2012Zhu et al, , 2013Zhu et al, , 2014b.…”