Diamondoid hydrocarbon ratios as indicators of biodegradation in Australian crude oils

Oil–source correlation for the paleo-reservoir in the Majiang area and remnant reservoir in the Kaili area, South China

“…Therefore, some biomarkers with high resistance to these secondary alterations, such as diamondoid hydrocarbons (Wingert, 1992), triaromatic steroid hydrocarbons (Peters and Moldowan, 1993a;Williams et al, 1986), pregnane and homopregnane (Peters et al, 2005b;Wenger and Isaksen, 2002), were selected for the oil-source correlations. Since diamondoid hydrocarbons are highly resistant to severe thermal alteration and biodegradation after oil expulsion (Wingert, 1992;Grice et al, 2000), they are useful for oil-oil correlation in cases where the oil and bitumen have suffered severe biodegradation or thermal cracking (Schulz et al, 2001). Pregnane and homopregnane are also highly resistant to biodegradation.…”

Quantitative analysis of diamondoids in crude oils using gas chromatography–triple quadrupole mass spectrometry

“…Since adamantane (the simplest diamondoid) was first discovered in petroleum in 1933, more diamondoids have been detected in many crude oils (Bender et al, 1986;Williams et al, 1986;Wingert, 1992;Chen et al, 1996;Dahl et al, 1999;Grice et al, 2000;Azevedo et al, 2008), petroleum products (Wang et al, 2006), coals and sedimentary rocks (Imuta and Ouchi, 1973;Aczel et al, 1979;Schulz et al, 2001;Wei et al, 2006a), and gas condensates (Lin and Wilk, 1995;Stout and Douglas, 2004;Sassen and Post, 2008). Furthermore, some higher diamondoids (more than three diamond cages) have been separated and identified from petroleum (Dahl et al, 2003).…”

“…Diamondoid hydrocarbons are more stable than most other hydrocarbons and are resistant to thermal and biological destruction (Aczel et al, 1979;Williams et al, 1986;Wingert, 1992;Grice et al, 2000). Therefore, they have been widely used to determine the thermal maturity of highly mature crude oils (Chen et al, 1996;Li et al, 2000;Zhang et al, 2005), assess the extent of oil cracking (Dahl et al, 1999) and investigate the secondary alteration of crude oils, such as mixing, biodegradation and thermochemical sulfate reduction (TSR) (Dahl et al, 1999;Grice et al, 2000;Wei et al, 2007aWei et al, , 2011. Because of their stability and resistance to biodegradation, diamondoid hydrocarbons have also been utilized to identify the sources of oil spills (Stout and Douglas, 2004;Wang et al, 2006).…”

“…In addition to ratios based on their distribution (Chen et al, 1996;Grice et al, 2000;Li et al, 2000;Zhang et al, 2005), the abundance of diamondoids has proven to be very useful. For example, methyldiamantane concentration (4-+ 3-methyldiamantane) can be used to estimate the extent of oil cracking (Dahl et al, 1999) and the relative abundance of diamondoids in light petroleum and gas condensates is an important ''fingerprinting'' tool to identify the sources of oil spills (Stout and Douglas, 2004).…”

“…Therefore, before introducing oil samples into the gas chromatograph, a preparative group separation step is usually employed to eliminate the matrix interference. In such preparation procedures, hexane or pentane eluates are concentrated by evaporation to a small volume prior to sample injection to improve analytical sensitivity (Wingert, 1992;Chen et al, 1996;Grice et al, 2000;Li et al, 2000;Schulz et al, 2001;Zhang et al, 2005). Moreover, the sensitivity of diamondoid analysis can be enhanced by using selective ion monitoring (SIM) mode of GC-MS, such as monitoring m/z 136, 135, 149, 163, 177 and 191 for adamantanes, m/z 188, 187, 201, 215 and 229 for diamantanes, and m/z 240, 239, 253, 267 and 281 for triamantanes (Wingert, 1992;Schulz et al, 2001).…”