Baseline and Environmental Monitoring in Deep Water – A New Approach

Abstract The offshore oil and gas industry in Norway is obliged to establish a firm and publicly accepted baseline regarding environmental parameters in new areas of activity. These baseline studies include an examination of the sediments to identify the background level of physical, chemical and biological parameters. The monitoring stations in a survey are typically located at fixed distances along a "cross", where the longest axis is downstream along the main current, and where several replicate samples are collected at each station (OSPAR recommendations and Norwegian HSE regulations). The design of the monitoring programme is quite rigid, and does not take into account knowledge regarding the sediment characteristics of an area, like whether it is soft or hard, erosion, accumulation etc. It is well established that the characteristics of the sediment is one of the most important parameters regarding both the possibility to accumulate chemical contaminants, and the structuring of the benthic community. The sediment characteristic is therefore a parameter, which should be taken into consideration during the planning of the environmental monitoring programme. By doing this it is possible to get a more cost effective survey and more comprehensive results. This is relevant both for shallow as well as for deep water. The present paper will outline how a first attempt was made to incorporate knowledge of the sediment characteristics, and integrate the knowledge from the various relevant disciplines involved in the planning of a well i.e. geologists working on Holocene sediments, oceanographers and biologists. The well was situated in block 6405/7 on the Norwegian continental shelf, with a water depth of approx. 1200 m. Input data to the environmental survey came from geological interpretation and samples collected with gravity corer, data from seismic and multi-beam echo-sounder, video footage from ROV, and box corer samples for biology.