The reduction of viscosity of heavy crude with micro-organisms

Abstract

ABSTRACT This research investigates use of microorganisms (Pseudomonas aeruginosa, Bacillus subtilis and, Klebsiella spp) to reduce viscosity of heavy crude oil. It focuses on determination of abilities of microorganisms singly and in association to reduce viscosity of heavy crude oil, effects of secondary microbial injections and the significance in MEOR projects. At constant temperature of 29°C and within a 7-min investigative duration, microorganisms were injected twice into 9 Erlenmeyer flasks containing 50 ml sterile heavy crude oil (initial viscosity of 382cP) with changes in viscosities recorded 2 and 3 minutes after inoculations. The short investigative duration supports key assumptions of zero growth and death rates of microorganisms. The 10th flask without any microorganism served as control and was subject to the same environmental conditions as test flasks. Three minutes after initial inoculation of Klebsiella sp, Pseudomonas sp, and Bacillus sp into heavy crude, viscosities were reduced to 155 cP, 170 cP, and 188 cP, respectively; a reduction of more than 50% of original viscosity. With two bacteria mixtures (Pseudomonas sp + Klebsiella sp, Bacillus sp + Pseudomonas sp and Bacillus sp + Klebsiella sp), increase in average rate of change in viscosity were noted (3.00, 5.00 and 11.00 Cp/minutes, respectively), in all samples, except Pseudomonas sp + Klebsiella sp. The effect of second injection of microbes, were less effective (3.26–14.67%) and impacts on overall reductions were less. The correlation, r, after first and second inoculations were −1.00 and −0.98, respectively; a strong negative relationship between viscosities of heavy crude (Cp) and concentration of microbes.