Techniques for monitoring the recovery of deep, cold-qater habitats following physical disturbance from drilling discharges

Jones, Daniel O.B., Park, Iain F.J. and Gates, Andrew R. (2008) Techniques for monitoring the recovery of deep, cold-qater habitats following physical disturbance from drilling discharges. In SPE International Conference on Health, Safety, and Environment in Oil and Gas Exploration and Production, 15-17 April, Nice, France. Society of Petroleum Engineers. 111629-MS .

Abstract

Recovery of deep, cold-water benthic habitats following physical disturbance caused by discharges of cuttings and water-based mud (WBM) from drilling have been measured using Remotely Operated Vehicle (ROV) sampling techniques. Video data were collected from a well site in the Laggan field in the Faroe-Shetland channel immediately after discharge and again two years after discharge. Data were also collected on baseline conditions and from a nearby well site to provide data on recovery ten years after discharge. Faunal abundance and diversity parameters were quantified from the video and used to assess the community-level disturbance and recovery. Initial disturbance resulted in a reduction in faunal diversity and density from baseline levels close to drilling activity (<100 m). After two years and within 100 m of the drilling activity assemblages were still significantly different in composition and lower in diversity and density. Recovery was observed after ten years as increases in faunal density and diversity close to the site of previous drilling activity. In the area completely covered by cuttings (approx. 30 m radius), there were few megafauna observed in any survey. This work was carried out opportunistically as part of an environmental impact assessment and in stand-by time from a drilling rig. The use of existing technology in stand-by time provides oil and gas operators with opportunities to integrate routine environmental monitoring into normal operations providing a cost-effective and scientifically robust monitoring method.

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