A Management Plan for the Offshore Disposal of Drilling Muds and Cuttings in Brunei: A Receiving Environment Based Approach

An offshore survey and environmental assessment was conducted on the Brunei continental shelf offshore oil and gas concession area in 2000–2001. The results of the comparison of the environmental effects of previous ocean disposal of oilbased mud (OBM), water-based mud (WBM) and ester-based synthetic mud (ESBM) was used to prepare guidelines for atsea disposal of mud and cuttings based on the sensitivity of the receiving environment. The ranking, in terms of sensitivity of environmental components are as follows: 1) Shallow coral reefs; 2) Deep reefs; 3) Juvenile shrimp nursery areas; 4) Adult shrimp shallow coastal areas; 5) Adult shrimp mid-shelf areas; 6) the Brunei continental shelf; and, 7) Continental slope and deep water. Detailed instructions are presented for the handling and disposal of WBM and ESBM for each offshore zone. The guidelines are presented in a user-friendly format and provide: description of the environmental zone and it’s sensitivity; the disposal management strategy including options for disposal in order of preference; and requirements for planning, disposal and recommended monitoring and follow-up.