Environmental Efficiency in Water Use in Offshore Platforms in Campos Basin-RJ-Brazil

Abstract

In drilling and production of oil at sea, potable water is most commonly transported to oil platforms using offshore supply vessels (OSV). This transport generates a series of environmental impacts, such as the emission of greenhouse gases and risks to human health. Furthermore, transporting high volumes of water requires large vessels and consequently, very high fuel consumption. To minimise the environmental impacts, water supply options were studied. The desalination of seawater and the reusing of streams from grey water (light and dark) and black water were evaluated and compared with the characteristics of the current supply via OSV. The amount of fuel consumed was collected in the logistics department of the oil company that used the OSVs. Air emissions were quantified using the methodology that the IPCC recommended. The information on the types of sewage treatment was found in the technical manuals from the manufacturers. It was concluded that the reused water could achieve up to 70% reduction in atmospheric emissions, the use of chemicals in the water treatment plant, sludge generation and the consumption of marine diesel fuel for the transport of water. On the other hand, the same reduction can be observed both from the effluent disposal at sea and in the chlorine of the sewage treatment plant. Therefore, the source of water used and the reduction of air emissions can be maintained without impairment of the normal water use in offshore platforms in the Campos Basin. The objective of this study was to diagnose problems related to the current form of water supply, to quantify them and to propose measures for increasing environmental efficiency.