Organic precipitates in oil production of a Venezuelan oil field

A very light crude oil is being produced in an oil field in Venezuela. Such oils are susceptible to asphaltene precipitation as the reservoir pressure decreases during production. An asphaltene deposit has been found in the tubing of one of the wens and in the bottom sediment of the tanks on site. Dead oil samples from the well head of seven different producers in the field were analyzed by three different companies. The laboratory results covering the following aspects of different solvents show significant differences: asphaltene content, asphaltene/resin ratio, molecular mass of the precipitated asphaltenes, flocculation point, Vanadium/nickel ratio, precipitated asphaltenes, and the Hildebrand parameter. Using different consistency checks and establishing correlations among the results, the analysis of one lab is strongly favored against the others. The analytical results are discussed in detail, including the correlation between asphaltenes and the well situation regarding perforation depth and the phase behavior of the produced oil.