Hybrid Well Riser Risk of Failure and Prevention. Study Report

摘要

The MMS contracted MCS to perform an investigation into the causes and probabilities of top-tensioned riser (TTR) failures from workover and drilling operations through existing single and dual casing production risers with a surface Blow-Out Preventer (BOP). Specific attention was paid to potential wear issues due to rotating drill pipe within riser systems that have already been in service for a substantial period of time, and that may have been subject to corrosion and VIV fatigue. Performing drilling operations through any production TTR poses a critical hazard which must be addressed prior to the start of the operation. If the riser has not been designed to handle the additional fatigue and wear associated with drilling, then an engineering assessment should be completed to determine the risers suitability. For risers not designed to be drilled through, mitigation measures such as wear sleeves and non-rotating protectors may be implemented to achieve an acceptable level of risk. Additionally, inspection and monitoring measures can help to detect warning signs of potential failure modes which allows operators to take action to prevent them.