Indian Journal of Science and Technology

Abstract

The environmental impact of exploratory wastes (drilling muds & cuttings) generated during the drilling of Igbokoda X and Igbokoda Y onshore oil wells, was studied by analyzing its total hydrocarbon (TPH), aliphatic hydrocarbon (AH), polycyclic aromatic hydrocarbon (PAH) using gas chromatography-mass spectrophotometry (GC-MS) method and metal contents using atomic absorption spectrophotometry (AAS). The aim was to determine their toxicity and possible impacts on their immediate environments of disposal. These drilled wastes generated from the drilling of Igbokoda X and Igbokoda onshore wells indicated an exceedingly very high values of AH compared with the values of PAHs in both the oil based and water based muds and cuttings respectively. These values of aliphatic is generally >5000 mg/kg in all oil based sample types analyzed for the drilled muds and generally >4000 mg/kg in all the sample types analyzed for the drilled cuttings. However, these values of the AH varied according to sample types with the water based drilled mud collected at the depth of 4121-10171 feet having values of >6000 mg/kg while the value in the water based drilled cuttings is generally <5000 mg/kg. Both the oil based drilled mud and cuttings have higher values of PAHs at the drilled samples collected between 0-4121 feet than deeper depth and composite samples. Iron (Fe) has the highest concentration followed by calcium (Ca), magnesium (Mg) with varying level of toxic metals like lead (Pb), Nickel (Ni), Manganese (Mn) and Chromium (Cr) in both the oil and water based drilled mud and cuttings from Igbokoba X and Igbokoba Y wells. Most of the analyzed parameters (AH, PAHs, TPH) and metals like Pb, Mn, Cr, etc. generally have values higher than that of the United States Environmental Protection Agency, Federal Environmental Protection Agency and Directorate of Petroleum Resources Standards in some cases thereby implying possible negative impacts on the immediate environments.
Keywords: Total hydrocarbon; aliphatic hydrocarbon; polycyclic aromatic hydrocarbon; Igbokoba.