Hydrocarbon Composition Of Oils Research Articles

The effect of molecular composition on the oxidative behaviour of group I base oils in the presence of an antioxidant additive

AbstractThe response of base oil hydrocarbons to additive molecules is fundamental to any lubricant formulation. To have this understanding it is important to have complete knowledge of the base oil hydrocarbon composition. The work reported here is a study of a series of API Group I base oils showing the effect of various structural parameters during oxidation with an antioxidant additive (zinc dialkyldithiophosphate, ZDDP). To understand this complex base oil‐additive interaction pattern, a combination of chromatographic and spectroscopic methods has been adopted. The results show that certain NMR‐derived base oil structural parameters can be used as an index of the additive response in conjunction with column chromatographic and FTIR absorption data. It is also observed that saturated molecules, i.e., iso‐ and normal paraffins and naphthenes, behave differently towards an antioxidant additive, and the total additive response is the result of all the interactions in the system.

Relation between Bioavailability and Fuel Oil Hydrocarbon Composition in Contaminated Soils

Bioavailability of oil components in contaminated soils is an important regulating factor for biodegradation rates. Changes in the composition of mineral oil can provide information regarding the bioavailability restrictions in contaminated soils. The fate of oil components was studied in a lysimeter experiment and laboratory incubations. A shift in the n-alkane ratios in the range n-C16:n-C20 was observed around 4.0 g kg-1, indicating that two different mechanisms control the bioavailability of the oil. At higher concentrations, the bioavailability was controlled by solubilization from a non-aqueous-phase liquid into the aqueous soil water phase. The ratios remained constant with decreasing oil concentration in this stage. Below 4.0 g kg-1, desorption and diffusion became rate-limiting factors: a shift was observed in the n-alkane ratios, showing that biodegradation rates of n-alkanes increased with decreasing carbon number. The monitoring of n-alkane ratios can be used to improve the efficiency of bior...

Geochemical Analysis of Reservoir Continuity and Connectivity, Arab-D and Hanifa Reservoirs, Abqaiq Field, Saudi Arabia: ABSTRACT

Organic geochemistry and its integration with geologic and reservoir engineering data is becoming increasingly utilized to assist geologists and petroleum engineers in solving production related problems. In Abqaiq Field of eastern Saudi Arabia, gas chromatographic analysis (FSCOT) of produced oils from the Arab-D and Hanifa reservoirs was used to evaluate vertical and lateral continuity within and between these reservoirs. Bulk and molecular properties of produced Arab-D oils do not vary significantly over the 70 km length and 10 km width of the reservoir. Hanifa oils, however, do reflect two compositionally distinct populations that are hot in lateral communication, compatible with the occurrence of a large oil pool in the southern part of the field, and a separate, and smaller northern accumulation. The Arab-D and underlying Hanifa oil pools are separated by over 450 feet of impermeable carbonates of the Jubaila Formation, yet the Southern Hanifa pool and the Arab-D have been in pressure communication since onset of Hanifa production in 1954. Recent borehole imaging and core data from horizontal Hanifa wells confirmed the long suspected occurrence of fractures responsible for fluid transmissibility within the porous (up to 35%) but tight (<10md matrix K) Hanifa reservoir, and between the Hanifa andmore » Arab-D. The nearly identical hydrocarbon composition of oils from the Arab-D and southern Hanifa pool provided the final confirmation of fluid communication between the two reservoirs, and extension of a Hanifa fracture-fault network via the Jubaila Formation. This work lead to acquisition of 3-D seismic to image and map the fracture-fault system. The molecular fingerprinting approach demonstrated that produced oils can be used to evaluate vertical and lateral reservoir continuity, and at Abqaiq Field confirmed, in part, the need to produce the Hanifa reservoir via horizontal wells to arrest the reservoir communication that occurs with existing vertical wells.« less

Influence of secondary factors on the light hydrocarbon composition of oils of the central depression of Cuba

(1982). Influence of secondary factors on the light hydrocarbon composition of oils of the central depression of Cuba. International Geology Review: Vol. 24, No. 1, pp. 99-104.

Susceptibility of petroleum oils to microbial damage in relation to hydrocarbon composition of oils

1. The susceptibility of oils to microbial damage has been shown to depend on their hydrocarbon composition; there is a gradual decrease in the oil's resistance to the action of microorganisms as the severity of the oil treating is increased. 2. Under the influence of microorganisms, changes occur in the oils, causing a deterioration in their physicochemical and service properties. 3. Since the production technology of oils is based on specific requirements imposed by service, microbe-resistant oils must represent products with an adequate severity of treatment, protected by antiseptic additives. 4. A certain similarity has been noted between the mechanisms of chemical and biochemical oxidation of petroleum oils.

On the depth, time and mechanism of petroleum generation

The subsurface petroleum generation process has been studied. In the Los Angeles and Ventura basins, California, hydrocarbon content and hydrocarbon/noncarbonate carbon ratio increase slowly with depth and age in upper and lower Pliocene shales and more rapidly in the deeper and warmer upper Miocene shales. During the oil generation process, and simultaneous with the increase of the hydrocarbon/noncarbonate carbon ratio, the composition of the shale normal paraffins and naphthenes boiling above 325°C gradually changes and eventually becomes very similar to that of the waxy oils of the basin. In the Los Angeles basin as well as in the Ventura basin the bulk of petroleum is generated at depths where the subsurface temperature is above 115°C and where, therefore, the shales are sterile. The conclusion that petroleum is formed from sediment organic matter essentially by thermal, nonbiological processes is inescapable. Because petroleum generation is a chemical process, it is strongly temperature-dependent. This explains the strong increase of the hydrocarbon/noncarbonate carbon ratio at greater depths, where the temperature is higher. It also explains the greater depth of oil generation and of equality of shale and oil hydrocarbon composition in the Ventura basin compared with the Los Angeles basin. This is caused by the smaller temperature gradient in the Ventura basin. The importance of the temperature history of potential oil source rocks is discussed. Appreciable amounts of oil are formed only if the temperature history of the source sediments is sufficiently intense and if the nature and the amount of the organic source material are appropriate. In the Los Angeles and Ventura basins most producing horizons are much shallower than the oil source beds, and vertical migration of petroleum is very common. Evidence is presented that vertical migration of petroleum takes place through faults and fractures, not through the bulk of the shales.