Environmental Evaluation of the Drill Cuttings at Ologbo Oilfield Wells, Edo State, Nigeria: A Case Study of its Microbiological and Heavy Metals Composition
Abstract
The environmental evaluation with attention on the microbiological and heavy metals composition was carried out on drill cuttings from four different oil and gas wells located at Ologbo community in Edo State. Heterotrophic
bacterial and fungal counts were enumerated using the standard plate count techniques. Heavy metals, oil and grease, pH and electrical conductivity were analyzed using standard analytical procedures. The heterotrophic microbial counts ranged from 7.9x102 ±1.0 cfu/g at 0-610 m to nil at 2745-3660 m for aerobic heterotrophic bacterial counts and 3.7x102 ±0.01 at 0-610 m to nil at 2745-3660 m for the fungal counts. The highest count of 5.2x103 ±1.5cfu/g was recorded for anaerobic heterotrophic bacterial counts. Gram positive bacteria had the highest percentage occurrence among the bacterial isolates. Among the fungal isolates Penicillium spp. and Aspergillus spp. were recorded to have the highest percentage frequency of occurrence. Results of heavy metals showed that copper had the least concentration while iron had the highest concentration. Oil and grease, pH, conductivity showed relative increase along the depth profile. Statistical analysis showed significant differences (P<0.05) for microbial counts and heavy metals. Based on the findings of this study, oil exploration and production companies operating in Ologbo community in Edo State, Nigeria are encouraged to adhere strictly to the procedures and instructions of waste management, so as to avoid unintended environmental pollution.
bacterial and fungal counts were enumerated using the standard plate count techniques. Heavy metals, oil and grease, pH and electrical conductivity were analyzed using standard analytical procedures. The heterotrophic microbial counts ranged from 7.9x102 ±1.0 cfu/g at 0-610 m to nil at 2745-3660 m for aerobic heterotrophic bacterial counts and 3.7x102 ±0.01 at 0-610 m to nil at 2745-3660 m for the fungal counts. The highest count of 5.2x103 ±1.5cfu/g was recorded for anaerobic heterotrophic bacterial counts. Gram positive bacteria had the highest percentage occurrence among the bacterial isolates. Among the fungal isolates Penicillium spp. and Aspergillus spp. were recorded to have the highest percentage frequency of occurrence. Results of heavy metals showed that copper had the least concentration while iron had the highest concentration. Oil and grease, pH, conductivity showed relative increase along the depth profile. Statistical analysis showed significant differences (P<0.05) for microbial counts and heavy metals. Based on the findings of this study, oil exploration and production companies operating in Ologbo community in Edo State, Nigeria are encouraged to adhere strictly to the procedures and instructions of waste management, so as to avoid unintended environmental pollution.
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