Legislation worldwide and current technologies used in the treatment of offshore oil and gas/condensate produced water are mainly aimed at the removal of dispersed hydrocarbons (dispersed oil). From the beginning of this century, new insights in the North Sea area revealed that specific contaminants in produced water are toxic and their impact on the environment was assessed. This insight was later supported by work in the Philippines. A comparison of water with the same total organic carbon (TOC) levels showed in one case that the unknown toxic content was higher with an unexpected disastrous effect on the biocultures. Overall parameters like biological, chemical and total oxygen demand (BOD, COD and TOC) are of no value in identifying and managing the toxic content of waste and produced water streams. New extraction based technologies such as the Macro Porous Polymer Extraction (MPPE) technology appear to remove dispersed and dissolved toxic constituents and reduce the environmental impact. Industrial applications show a >99% toxic content reduction in produced water streams. A recent application (at Woodside Petroleum's Pluto LNG project) is described where the ultimate reuse of produced water was as demineralised water in an LNG plant. Emerging potential is presented for floating LNG plants currently investigated in conceptual studies by the oil and gas industry. Finally, fundamental technological mechanisms are presented that are required to meet zero harmful discharge legislation.
At the moment, technologies used in the treatment of offshore produced water on oil and gas platforms are mainly aimed at the removal of dispersed hydrocarbons (dispersed oil). The focus on the removal of dispersed hydrocarbons is due to past and still current legislation that aims to reduce dispersed oil emissions. In the late 1990s and at the beginning of this century, attention has shifted towards the effect of other constituents of the produced water. This has led to a better understanding of the impact of the individual toxic constituents on the environment and the development of new technologies to abate them. Extraction technologies like C-tour and the Macro Porous Polymer Extraction (MPPE) technology have shown very good performance reducing harmful discharge.
This paper will deal with: present emission regulations; produced water composition and environmental issues; technological mechanisms reducing the environmental impact factor; MPPE technology; environmental impact toxicity reduction with MPPE; analytical parameter and approach to produced water treatment; and, the future and reuse of produced water.
To view the full article, click here.