ALIGNING THE NEEDS OF FLOATING DRILLING AND THE CAPABILITIES OF ICE MANAGEMENT

摘要

Floating drilling operations in dynamic Arctic sea ice will require an ice management program to reduce ice loads to levels that are within the capacity of the protected vessel's stationkeeping system (dynamically positioned or moored). Since some conditions cannot be adequately managed by current icebreaker capabilities, the ability to safely suspend operations, secure the well and disconnect the marine drilling riser must be accounted for as a part of normal operations for floating drilling in ice. Ice management operations should be structured in order to deliver, with confidence, alerts consistent with the required warning times for suspension of drilling operations and disconnection. Planned disconnections under normal operations are typically executed to leave the well in "optimal" condition for quickly resuming drilling activities. Disconnections within shorter timeframes maintain well integrity, but may result in increased time to resume normal operations. Achieving high drilling uptime without compromising safety requires harmonization of the functional requirements and capabilities of both drilling and ice management operations. It is necessary to balance the ability of ice management to deliver alerts consistent with well integrity objectives with the need to minimize the time required to resume operations upon reconnection. This paper discusses functional requirements to ensure safe well suspension for varying target disconnection frequencies. Based on assumed drilling systems and scenarios, the practical capabilities of ice detection and ice management are also described in this context. Ice drift records from the Canadian Beaufort Sea and realistic icebreaker performance characteristics are used to compare the practical capabilities of ice surveillance methods to the minimum requirements for target drilling disconnection alert times. It is shown that these objectives can be attained, but may require the aid of airborne ice monitoring, advanced ice drift forecasting and one or more scouting icebreaker(s) to test ice breakability sufficiently far ahead of the rig in dynamic ice environments.