M.C. Onojake

Multivariate analysis of source and maturity biomarker indices of crude oils from SW Niger Delta

Saturated biomarker source and maturity parameters obtained from Gas chromatography-mass spectrometry were analyzed using multivariate statistical methods to maximize diagnostic information on the hopanes and sterane spectrum. This statistical method provided the identification of structural relationships (similarities and differences) between various fingerprint descriptors for the crude oil samples. The results emphasized the separation of the oil samples in regards to their locations into two genetic families. This separation pattern is more evident when principal component analysis was applied to biomarker data compared with the standard biomarker cross-plots. Such compositional differences are commonly attributed to unique source rock paleodepositional environments. The plotted source and maturity diagnostic parameter in a dendrogram separated the oils into two families both having terrestrial input. The group that have higher terrestrial input contain more oleananes, and have the highest Pr/Ph ratio. They are generated from source rocks with a high abundance of terrestrial organic matter. The second groups of oils have mixes of terrestrial and marine organic matter with lesser amount of oleananes.

The Effect of the Adulteration of Premium Motor Spirit (PMS) on Automotive Engines

Ten samples of premium motor spirit were collected at different dispensing points and analyzed to determine the extent at which the adulteration of this petroleum product affects automotive engines. Results of the analyses shows, research octane number values from 60.10 to 93.30, specific gravity from 0.7523 to 07885, Reid vapor pressure from 0.28 to 0.60 kgf/cm2, while atmospheric distillation ranges from 189 to 251°C. The result of this research reveals that most of the products are highly adulterated and this is not desirable for spark-ignited engines, as it may lead to the problem of detonation, insufficient supply of engine power, slow rate of deflagration experienced by most consumers, and consistent knock of spark-ignited engines.

Source, depositional environment and maturity levels of some crude oils in southwest Niger Delta, Nigeria

A suite of crude oil samples, that had not been previously characterized geochemically, was collected from two oil fields in the southwest Niger Delta Nigeria. The saturate biomarkers were used to evaluate geochemical characteristics such as depositional environments, sources of organic matter and extent of biodegradation using gas chromatography–flame ionization detector and gas chromatography–mass spectrometry. Distribution of n-alkanes (Pr/Ph, and isoprenoide/n-alkanes ratios), the abundance of hopanes, oleanane skeleton and C27–C29 steranes in the oils indicate that they were formed from mixed sources (marine and terrestrial kerogen) deposited in an oxic paleoenvironment with no particular maturity trend. These parameters also permit the source grouping of the oils into two families.

Bulk Geochemical Characteristics of Crude Oils From the Umutu/Bomu Fields, Niger Delta, Nigeria

The bulk properties of seven crude oil samples from two oil fields in the Niger Delta were investigated. Results show °API gravity with the range of 29.00–85.00°, specific gravity 0.65–0.88, Reid vapor pressure 3.00–9.00 kPa, kinematic viscosity 0.90–10.10 cSt, dynamic viscosity 0.70–8.90, moisture content 0.13–126.00%, gum content 6271–45846 mg/100 mL, cloud point 3.00–12.00°C, pour point 7.00–4.00°C, and flash point <30.00°C. Values of aliphatic biomarkers were used as supporting tool to deduce the geochemical characteristics such as thermal maturity, depositional environments, source OM, and extent of biodegradation.