Energy solutions for offshore platforms

Abstract

This report evaluates the different energy solutions available for operation of an offshore semi-submersible drilling- and accommodation rig today. The focus has been to map the technologies available considering fuel- and emission reductions. A case study has also been carried out for the concept considered most attractive both for newbuildings or retrofit projects today.

The first part of the report consists of a theoretical part which covers the applicable authority regulations for operation in the different offshore oil fields worldwide. Both existing and near future regulations have been considered to address the general motivation for applying new and energy efficient technology for drilling operations. In order to understand the differences of the traditional setup and the new alternative energy solutions, the different technology solutions are presented and considered at current status of availability.

The final part of the report presents the case studies with a fuel calculation model. This model represents an actual operational profile with specific fuel consumption curves. Hence, the actual fuel consumption distribution can be considered and not only the average energy demand over the period. The model produces different engine load profiles and fuel calculations during a drilling operation and is able to consider variables that include weather conditions, number of engines in operation and the type of energy storage system installed. This makes it simple to compare the fuel consumption of the different scenarios and the results are presented for different scenarios.

The different scenarios show a clear advantage of utilizing battery storage systems for both the heave compensation equipment onboard the drilling rig and the dynamic positioning system for both the drilling rig and the accommodation rig. The fuel saving potential for a drilling rig ranged from approximately 7% with battery storage for only the heave compensation system (alternative 1) to approximately 13% for a drilling rig with battery storage for both the dynamic positioning system and the heave compensation system (alternative 2). For operations in the North Sea, the payback time for a battery storage system for the first alternative ranged from 1.8 to 2.7 years and from 1.3 to 1.9 years for the second alternative. Over a ten year period the total fuel and tax reductions were about 13.4 MUSD for the first alternative and 26.2 MUSD for the second alternative. Both alternative 1 and alternative 2 are economically beneficial, and the highest potential has been identified for alternative 2.

For the accommodation unit, battery storage for dynamic positioning operation was considered and gave reduced fuel consumption of approximately 9% and a payback time of 0.9 years. The ten year fuel and tax reduction potential was approximately 10 MUSD. This concludes that fuel reducing measures are available and economically beneficial for drilling and accommodation operations in the offshore industry today.