Monitoring discharges of drill cuttings and mud

A Joint lndustry Project called ERMS Environmental Risk Management System) has been initiated to develop tools for evaluating impacts from discharges of drill cuttings and mud during drilling of offshore exploration and production wells. SINTEF is coordinating the project, which so far is funded by Statoil, Norsk Hydro, Agip, Total, ConocoPhillips and ExxonMobil.

An important element in the ERMS project is to measure concentrations of particulate matter in the water column, as well as deposits on the seabed, from an offshore drilling operation. At the same time, effects from the discharges on the sedimentary fauna will be investigated. These data are needed to calibrate/tune numerical models for simulation of the environmental impacts during drilling operations.
It was decided to do the measurements associated with the Statoil drilling of 4 production wells at the gas and condensate field “Sleipner Vest Alfa Nord” in the North Sea, located some 18 km NW of the Sleipner Vest main production field area. Sampling and analysis of bottom sediments in 2002 confirmed that this area has not been contaminated prior to the production drilling program.

In September 2003 a field survey was performed at the drilling platform “Transocean Searcher” during surface
discharges of drill cuttings with water based mud. The activities included:

• Test discharge with the use of the tracer Rhodamine for the prediction of dilutions
• Current, temperature and stratification measurements of the water column
• Turbidity measurements to determine concentrations of particulate matter
• Deployment of sediment traps
• Deployment of caged organisms as bio sensors (mussels and sea scallops)
• Bottom sediment sampling (multi corer, grab) for chemical and biological analysis
• Sampling of the drill cuttings/mud discharge on board the drilling rig
• Seawater sampling in the water column to measure concentrations of particulate matter
• Observations of discharge and particle properties in the water column from ROV

These field activities were performed by SINTEF in cooperation with Akvaplan-niva, Tromsø, and RF-Akvamiljø, Stavanger. The active involvement from Statoil assured that the field activities had sufficient priority on board the drilling rig. The rig personnel showed a great deal of interest in the activities, and contributed both with ROV observations and any other assistance requested.

In 2004, after the drilling program on this site has been finished, potential biological impacts on the benthic fauna will be investigated through the collection of a new series of bottom sediment samples from the same locations as used in the 2003 survey.

Contact at SINTEF Materials and Chemistry: Henrik Rye or Alf Glein Melbye