Saturates in heavy organics precipitated from crude oil at different locations of the production line

Abstract

The saturate hydrocarbon composition of the nC₅:nC₆ heavy organics precipitated from different locations of petroleum production line were studied. The heavy organics (HOs) were precipitated by gravimetric titration of the crude oils samples from three locations of the production line (wellhead, flowline and separator) with nC5:nC6 precipitant binary mixture. The saturate fractions of the HOs were obtained by column chromatography and the hydrocarbon type compositions were analyzed by gas chromatographic-flame ionization detection. The results showed that gas chromatographic-flame ionization detector (GC-FID) has 100% efficiency in quantifying the saturate hydrocarbon composition of the HOs. From one of the wells studied, the wellhead showed the highest total saturate hydrocarbon concentration with 28,497ppm, followed by the flowline with 23,512ppm and separator with 19,346ppm. The order of total saturate hydrocarbon concentration was wellhead > flowline > separator. However, the second well showed an opposite trend: separator (20,686ppm) > flowline (7,580ppm) > wellhead (3,778ppm) while others were completely inconsistent. This may imply that the amounts of saturate hydrocarbon composition at the different locations of the production line do not necessarily translate into the quantity of HOs or wax precipitated at that location of the production line

Key words: GC-FID, Heavy Organics, Asphaltenes, Precipitation, Saturate hydrocarbons, Crude oil.