AFFINITIES OF OILS

Origins and Source Affinities of Oils and Their Associated Asphaltenes from a Fields in the Gulf of Mexico

Origins and Source Affinities of Oils and Their Associated Asphaltenes from a Fields in the Gulf of Mexico

Introduction

The works in this thesis is to evaluate the origin and source of the affinity of various oils and their associated asphaltenes from the Gulf of Mexico. Six crude oil correlation studies were analyzed. Asphaltenes precipitated from the oil samples with n-hexane, and heated using an aqueous pyrolysis for the production of pyrolysis products of hydrocarbons. Samples of oil and associated asphaltene pyrolysates were separated into saturated hydrocarbons, aromatic hydrocarbons and polar fractions. Saturated, separated from the heated oil and asphaltene pyrolysates were analyzed by GC and GC-MS. Sterane and hopane isomer relationship was analyzed at maturity, sedimentation, and organic matter input. The main purpose of the report is to analyse the research paper critically.

The autohor of the paper presents results which are complex and difficult to interpret for example C27 aaa 20R / C28 aaa 20R steranes relations, low oil sample for 8672 and asphaltene profligate 8675, 0.76 and 0.65, respectively, and very high oil sample in September 8675 which, 95, but in aggregate, the results show that the oil samples and their corresponding asphaltenes were obtained from marine carbonate rock source. All oils and their corresponding asphaltenes were obtained from the similar maturity of source rocks containing a mixture of marine and terrigenous organic matter.

Discussion

The paper argues that oil is a complex mixture of hydrocarbons having different chemical, physical and compositional behaviour. This mixture contains the simple to the complex structures of carbon, hydrogen, heteroatoms and metals. These can be divided into different groups, such as alkanes, branched alkanes, alkenes, branched alkenes, aromatic hydrocarbons and monocyclic aromatic, and so on. In the oil of different compounds of varying solubility in particular solvents. These compounds can be separated from each other depending on their molecular weight. There are four main classes of compounds in the oil mixture of saturated hydrocarbons, aromatics, resins and asphaltenes (CREEK, 2005). Aliphatic and monoaromatic hydrocarbon fractions, as a rule, lighter fractions of petroleum. Naphhtenic and aromatic structures are with more than six alkylated ring in the heavy fractions of oils.

The perspective suggests that aromatic fraction and the number of aromatic rings increase with the boiling point. Asphaltene is the heaviest and most polar fraction of crude oil, which consists of conjugated polyaromatic ring system. Heavy oil fractions contain more than 25 carbon atoms and their molecular weight, density, viscosity, refractive index, polarity, and structural complexity increases with the boiling point. Heavy oil is generally enriched in resins and asphaltenes (MCBRIDE, 1998).

Whaereasm it is necessary for the author to to consider that in the process of biodegradation, bacteria destroy and change the oil, including some important biomarkers, which features the oil changed (BEARSLEY, 2004). Thus, in connection with these changes, it is difficult to establish any link between the oil or petroleum source ...