Recent discoveries of oil reservoirs off the northwest corner of Australia have prompted a flurry of oil and gas exploration activity. But the area is also environmentally sensitive. Large tracts of the North West Shelf and Timor Sea regions are made up of shoal areas and island chains with wide fringing reefs, and the area also supports rich benthic and demersal fisheries. Because oil spills and leaks from drilling and production pose a potential risk to local biology and habitats, Australian regulations require oil and gas companies to perform quantitative risk-assessment studies prior to drilling, or in planning new facilities. In the past, studies have focused on risks to shorelines from surface slicks. However, oil companies and their government regulators are now increasingly focusing on the risks presented to the subsurface environment by dissolved and entrained components of oil slicks.
Recently, Asia-Pacific ASA have been commissioned by a number of clients, including BHPP, Chevron, Apache Energy and Woodside Energy, to quantify potential risks to sub-tidal habitats using ASA's three-dimensional oil spill fates and biological effects model, SIMAP. SIMAP's physical fate model is being applied to estimate potential concentrations of dissolved and entrained components of spills within the water column and to estimate rates of sedimentation to the seabed. SIMAP's sub-surface release capabilities have also been used to quantify risks to submerged habitats generated by blowouts at the seabed and corrosion leaks from submerged pipelines. The example figure shows a detail of a SIMAP application to a blowout study in the Timor Sea.
SIMAP's ability to separately predict the path of submerged and surface-bound spill components and to estimate hydrocarbon dosage rates as a product of concentration and duration of exposure have proven to be particularly helpful to resource companies aiming to better understand and describe environmental risks associated with their activities.
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