Bacteriological and Physicochemical Evaluation of Petroleum Reservoirs (Flow Stations) in Delta State, Nigeria

Abstract

The chemical and physical characteristics of crude oil are greatly influenced by
microbial activity in petroleum reservoirs, which also affects the oil's economic value
and circumstances of exploitation. The physicochemical and bacteriological
properties of crude oil samples taken from four flow stations in Delta State, Nigeria,
were examined in this study. Total heterotrophic bacteria (THB), hydrocarbonutilizing
bacteria (HUB), and sulfate-reducing bacteria (SRB) were analysed using
standard microbiological procedures. Also, using recognized analytical techniques,
physicochemical parameters including pH, total nitrogen, organic carbon, dissolved
oxygen, and sulfate concentration were ascertained. The findings showed that the
crude oils had a pH ranged from 6.20 to 6.70, that of total nitrogen ranged from 0.05
to 0.08 percent, and that the organic carbon ranged from 9.42% to 11.23 percent.
Potential hazards for microbial corrosion and biofouling were indicated by the
considerable variation in total heterotrophic bacterial counts, which ranged from
1.10×107 to 3.1×107 cfu/ml. Hydrocarbon- utilizing bacterial counts ranged from
0.4×104 to 1.2×104 cfu/ml, indicating active microbial engagement in the
biodegradation of crude oil. The samples were classified as sweet crude because of the
notable absence of sulfate-reducing bacteria, which is consistent with the reported
non-detection of sulfur compounds. The majority of the bacterial isolates found were
Pseudomonas aeruginosa and Bacillus subtilis, which are known to contribute to
biofilms formation, breakdown of hydrocarbons, and biocorrosion. In order to reduce
adverse effects on oil production, environmental integrity, and public health, the
study emphasizes the significance of continuous microbiological surveillance and
reservoir management.