Chemical Structure and Biomarker Content of Jinghan Asphaltenes and Kerogens

Abstract

The compound classes and biomarker compositions of immature Jinghan crude oil asphaltenes and their potential respective source rock kerogens have been investigated by chemolysis. The C-S-, C-O-, and C arom -C-bound appendages have been liberated by Ni 2 B reduction, BBr 3 hydrolysis, and ruthenium-ions-catalyzed oxidation. Measured were the saturate, aromatic, and polar (+ asphaltene) compound classes and the homologous series of hydrocarbon biomarkers: n-alkanes, regular isoprenoids, steranes, 4-methylsteranes, hopanes, gammacerane, their monocarboxylic acid derivatives, and R,ω-di-n-alkanoic acids. The nature and distribution of the biomarkers in shallower depths reveals a good correlation between the crude oil asphaltene and the kerogen, manifesting a crude oil-source rock relationship. In deeper strata, the correlation is less convincing but there is no indication of incompatibility. The biomarker composition confirms the immaturity of this deposit, and the huge (53%) yields of C-S plus C-O bond cleavage products from the high-sulfur asphaltene set this type of asphaltene aside from mature crude oil asphaltenes. Also, the biomarker composition points to a strongly reducing, lacustrine depositional environment for this deposit.

Distribution of acids and nitrogen-containing compounds in biodegraded oils of the Liaohe Basin by negative ion ESI FT-ICR MS

“…Typically, asphaltenes were defined as the crude oil fractions that are insoluble in aliphatic solvents but soluble in aromatic solvents; thus, asphaltenes separated from crude oil by low molecular weight alkanes contain the most polar and the highest molecular weight species of crude oil (Chang and Fogler, 1994). Peng et al (1999) also indicated that low molecular weight asphaltenes usually comprise chemisorbed and coprecipitated resins along with low molecular weight asphaltene fragments. Since it may be difficult to completely ionize asphaltene fractions by ESI due to the wide molecular weight range, the species analyzed by FT-ICR MS may only account for lower molecular weight compounds in asphaltene fractions.…”

Geochemical quantification of mixed marine oils from Tazhong area of Tarim Basin, NW China

“…Meanwhile the occluded hydrocarbons inside the asphaltenes were released, which can be distinguished from the adsorbed hydrocarbons obtained from the initial asphaltenes by acetone extracting (Liao et al, 2006b;). The hydrocarbons occluded inside the asphaltenes were well protected from secondary alterations in the reservoir due to the macromolecular structures of asphaltenes, therefore they retain the early generation information of crude oils (Behar et al, 1984;Ekweozor, 1984Ekweozor, , 1986Peng et al, 1997Peng et al, , 1999. Thus, the geochemical features of the compounds adsorbed and occluded inside asphaltenes can provide useful information concerning the charging or mixing processes of oils.…”

Adsorption of asphaltenes from toluene on mineral surface

“…Sulphur atoms are essentially present in thiophene and organic sulphur [5][6][7]. However, the composition of asphaltenes depends upon the origin of crude oil and the method of extraction [8][9][10][11][12][13].…”