Geochemistry of alkylbenzenes in the Paleozoic oils from the Tarim Basin, NW China

Biomarkers and C and S Isotopes of the Permian to Triassic Solid Bitumen and Its Potential Source Rocks in NE Sichuan Basin

“…Although it is impossible to prove that these compounds are syngenetic, their occurrence and distributions are consistent with other observations. Aryl isoprenoids have been detected in the Tarim Basin from the Cambrian overmature anoxic source rocks and highly mature oils derived from these sources, although their concentrations and carbon number decrease with increasing maturity [13,15,16,42,45]. The NE Sichuan Basin study area is similar to the Tarim Basin in that both are characterized by rapid burial [6,8,12,23]; thus, some molecular markers in the study area may be related to the deposition environment and/or OM sources although it is hard to be proved.…”

Application of the monoterpane ratio (MTR) to distinguish marine oils from terrigenous oils and infer depositional environment in northern Tarim Basin, China

“…Previous studies have reported that the Paleozoic marine oils from the northern Tarim Basin have experienced multiple secondary alteration processes including biodegradation (Zhang et al, 2014a), evaporative fractionation (Ma, 1995;Zhang et al, 2014b), thermal maturation (Wang et al, 2006;Zhang et al, 2011b) and mixing (Wang et al, 2008;Zhang et al, 2014a), while the terrigenous oils and condensates from the Kuqa depression have been altered by evaporative fractionation (Zhang et al, 2010b;Gong et al, 2014) and thermal maturation (Zhang et al, 2011a).…”

Ratios of low molecular weight alkylbenzenes (C0–C4) in Chinese crude oils as indicators of maturity and depositional environment

“…The derived condensates are enriched in light n-alkanes and depleted in light aromatics, and usually accumulate at shallower depths. In contrast, residual oils are enriched in light aromatics and naphthenic hydrocarbons, such as toluene, cyclohexane and methylcyclohexane, and usually occur in deep reservoirs (Zhang et al, 2014). Two ratios toluene/n-heptane (B) and n-heptane/ methylcyclohexane (F) were proposed to recognize the evaporative fractionation process (Thompson, 1987(Thompson, , 1988.…”

“…With increasing thermal maturity, a prominent trend of demethylation of alkylbenzenes accompanied by the shortening of alkyl side chains was observed (Lis et al, 2008;Zhang et al, 2014). Lis et al (2008) found that dimethylbenzene/toluene (DMB/Tol) and ethylbenzene/toluene (EB/Tol) decline with increasing vitrinite reflectance (%Ro).…”

“…Alkylbenzenes (C 0 -C 4 ) are important components in crude oils, source rock extracts and pyrolysates of kerogen, coal and asphaltene (Douglas et al, 1991;Hartgers et al, 1994a;Hoefs et al, 1995;Clegg et al, 1997;Koopmans et al, 1997;Kissin, 1998;Pedentchouk et al, 2004;Lis et al, 2008;Zhang et al, 2014). The origin of these compounds has been investigated in numerous studies.…”