High-Resolution Environmental Survey around an Exploration Well Drilled with Formate Brine in the Barents Sea, Norway

摘要

The present paper gives an overview of the environmental impact of cuttings discharges on the bentic sediments, three years after drilling an exploration well (7122/7-1) with formate brine (mixture of potassium and sodium formate) in Production Licence 229 in the southwestern part of the Barents Sea. Eni conducted a high resolution environmental survey on the physical, chemical and biological conditions of the benthic sediments, in the vicinity of well 7122/7-1 drilled in 2000 in PL229. The cuttings and mud from the well were released to the environment as the drilling operation was conducted before the political decision to restrict the discharge of cuttings and mud from operations using water based mud (WBM) in the Barents Sea1. The aim of the study was to verify findings in a life cycle assessment (LCA) that had been conducted for formate brine, which concluded with: “The findings of the study indicate that the discharge of moderate amounts of Formate Brines is not likely to lead to potentially significant negative impacts on the marine environment.” 2 Samples were collected from 27 stations surrounding well 7122/7-1. Apart from the reference station, all stations were within 500 meters of the well head (reference station about 3 km to the south of the well head). Samples from 22 stations were analysed physically/chemically and 19 stations were analysed biologically, in addition to the reference station. As stations were very close to each other, very high sampling accuracy was of crucial importance. The findings in this study are in line with the conclusion in the LCA as only minor environmental impact in the vicinity of the drilling location was detected.