Environmental impacts of produced water and drilling waste discharges from the Norwegian offshore petroleum industry

Abstract

Exploratory discharge of produced water and drilling cuttings from oil and gas production has become a major source of pollutant to the biota. The aim of this study is to review previous research on the environmental effect of such exploratory wastes with emphasis on the Niger Delta region. Drilling waste is composed of Aliphatic Hydrocarbon, Polynuclear Aromatic Hydrocarbon (PAH) and heavy metals such as cadmium, chromium, lead, mercury, arsenic , copper, Iron, lead, manganese, zinc, barium and strontium among others which are toxic to the environment. The composition and characteristics of naturally occurring chemical substances in produced water (PW) are closely associated to the geological characteristics of each reservoir. The toxicity of produced water effluent can be reduced when treated before discharging into the sea. Sulphide reducing microorganism which are associated with produced water pose threat to the environment. Barite and bentonite present in most drilling fluid were found to reduce plant growth. Studies in some part of the Niger delta have shown high level of some heavy metals associated with exploratory waste with concentrations higher than world health organization (WHO) standard; these have negative impact on the environment such as massive destruction to aquatic lives and agriculture.

Pollution Impact and Alternative Treatment for Produced Water

“…During oil and gas exploration other forms of wastewater are produced, these include injected water, little quantity of water that is condensed and traces of some chemicals used among which produced water is the highest generated by-product [24]. The physical and chemical properties of produced water vary considerably depending on the geographic location of the field, the geo-logic formation, and the type of hydrocarbon product being produced [24,25]. Dispersed oil, aromatic hydrocarbons and alkylphenols (AP), heavy metals, and naturally occurring radioactive material (NORM) are of particular environmental concern [25,26].…”

“…The physical and chemical properties of produced water vary considerably depending on the geographic location of the field, the geo-logic formation, and the type of hydrocarbon product being produced [24,25]. Dispersed oil, aromatic hydrocarbons and alkylphenols (AP), heavy metals, and naturally occurring radioactive material (NORM) are of particular environmental concern [25,26]. Because the water has been in contact with hydrocarbon-bearing formations, it contains some of the chemical characteristics of the formations and the hydrocarbons.…”

“…It may include water from the reservoir, water previously injected into the formation, and any chemicals added during the production processes. The composition and characteristics of naturally occurring chemical substances in produced water are closely associated to the geological characteristics of each reservoir [25]. Produced water is mostly discharged to the immediate aquatic environment; the organic and inorganic compounds in produced water have higher toxicity to the environment than crude oil.…”

Challenges and Opportunities in Produced Water and Drilling Waste Treatment Techniques to Mitigate the Adverse Environmental Impacts

“…The barite is a primary source of toxic heavy metals in DW discharges [17]. Besides, there is correlation between cadmium and mercury concentrations, and the concentrations of some other trace metals in the barite [18].…”

Utilisation of drilling waste muds from drilling waste dump

“…alkylacrylate sulphonate and polyethylene oxide), pH and shale control agents, and defl occulants. The additives applied vary in diff erent drilling operations and in the course of the drilling itself [1].…”