Department of Chemical & Petroleum Engineering

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Browsing Department of Chemical & Petroleum Engineering by Author "Adeosun, T."

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    Open Access
    Experimental Study of Viscosity as a Criterion for Determination of Onset Asphaltene Flocculation in Nigeria,s Crude
    (Petroleum and Coal publishers, 2015-07) Adeyanju, O.; Adeosun, T.; Obisanya, A.
    Asphaltene are heavy hydrocarbon molecules that exist naturally in petroleum reservoir fluids. Asphal-tene precipitation may occur during pressure depletion or during gas injection process for Improved Oil Recovery (IOR). It is an important problem during oil production because it can result in formation damage and plugging of wellbore and surface facilities. In this experimental study, the rheological behaviors of Nigeria’s crude oil sample were reported. This research used a typical Nigeria’s oil sample to generate information on the asphaltene deposition tendency of a heavy crude oil sample using the standardized test as described by American Society for Testing and Material Method (ASTM) D-3279-90. The results obtained show that the amount of asphaltene precipitated out of a crude sample is dependent upon the type of solvent used. Generally, the lower the number of carbon atoms in the solvent, the greater the amount of asphaltene precipitated. Also contrary to the general belief, that since Nigeria’s crude is known for its low asphaltene content, the nation’s oil industry needs not to take the asphaltene precipitation effect into consideration, it was observed that asphaltene concentration as low as 1% (percentage weight) is enough to change the rheological behavior of crude samples from Newtonian to Non-newtonian flow. It was also observed that the flocculation and not precipitation of asphaltene was responsible for the change in the rheological behavior. These changes in rheological properties can lead to reduction in the rate of crude oil flow in a petroleum reservoir, and hence reduced productivity.