Platform Drilling Life Cycle Assessment of Drilling Waste Handling

Abstract Different methods to handle oil wet drill cuttings in a field development offshore Canada has been evaluated. The governing requirement is an upper limitation of 6,9% oil on cuttings for discharge to sea when an environmentally acceptable base oil is chosen. Methods that ensure that cuttings remain below this are evaluated primarily with respect to their environmental impact on air, sea and sea bottom. The conclusions are derived from a study including literature review, interview of relevant industry experts, and evaluation of existing reported studies and relevant equipment. Relevant equipment in this sense means equipment with impact on solids control and handling that there exists experience data from in conditions that can be compared to those this location. Dispersion modelling of relevant scenarios is performed. The dispersion modelling findings represent a key part of the conclusion. Five scenarios are evaluated. These include: 1. Skip and ship for onshore cuttings treatment 2. Shaker solution and dryer for additional treatment 3. Shaker and dryer with additional dryer in series 4. Thermal Desorption Unit (TDU) with partial direct disposal to sea instead of storage units 5. TDU processing for all generated cuttings in synthetic-based drilling fluid In the paper it is shown how, based on the review of the five scenarios, the best option for drilling platform wells offshore Newfoundland is scenario 2, shaker and dryer. This gives low emission to air, comparable marine discharge as well as requiring the lowest footprint on a platform.