An exploration drilling is planned on the Struten field in the Norwegian Sea. The present report shows the results from calculation of concentrations in the water column and depositions on the sea floor caused by the discharges from the planned drilling operations. The report considers two different alternatives for discharges to sea, Alternative 1 and Alternative 2. For Alternative 1, discharges are assumed to take place at the sea floor for the top hole sections (36” and 17 ½”) combined with discharges from the drilling rig for the deeper drilling sections (12 ¼” and 8 ½”).For Alternative 2, all discharges are assumed to take place from the drilling rig only. All calculations are carried out with the DREAM model version 4.0 operated by SINTEF.