Due to commercial interests the client has requested to remain anonymous.
Uninterruptible power supply (UPS) units that provide emergency backup power to the control system for an Intervention Riser System (IRS) onboard a semi-submersible production platform rig.
Mitigated risk to the safety of personnel, equipment, and the environment.
Our client, a world-leading resources company with more than 80,000 employees and contractors, primarily located in Australia and the Americas. While operating in the Gulf of Mexico, our client was required to comply with the regulatory requirements in the Code of Federal Regulations Title 30 Part 250. As part of these requirements, a compliance verification of the well control equipment had to be performed prior to deployment. This verification process is conducted to provide assurance that the well control equipment was designed, tested, and maintained to perform under the maximum environmental and operational conditions anticipated to occur at the well. To accomplish this, ModuSpec was commissioned to perform a pre-deployment Well Compatibility Verification (WCV) assessment of the IRS.
How we helped
During a WCV assessment in June 2016, our controls surveyor conducted an inspection of the UPS units that provides backup power to the IRS control system aboard the semi-submersible production platform rig.
During this inspection, it was noted that the IRS control system was not equipped with an integrated UPS system to provide battery backup to the entire system in the event of a power loss. Instead, the system utilised a subsea UPS module to provide backup power to the subsea control module and individual/localised UPS units for the individual assemblies within the surface control system.
Based on the requirements from the American Petroleum Institute (API) RP 17G Recommended Practice for Workover Risers Second Edition, July 2006, a UPS shall be provided to maintain control during loss of main electrical power supply.
The uninterruptible power supply is required to ensure normal control for 30 minutes and successful emergency shutdown and emergency disconnect within 1 hour from loss of power.
To verify compliance with these guidelines, it was confirmed that routine drawdown testing was being conducted on the subsea UPS module to verify functional integrity with no deficiencies observed. However, the attending surveyor noted that there was no evidence that a drawdown test of the surface UPS units had not been performed. The surveyor raised the concern that without verification of the surface UPS units, there was no assurance that the control system would be able to maintain normal control of the IRS following a power loss, as required by API RP 17G. A recommendation for corrective action was communicated to all involved parties onboard and it was agreed that this testing would be performed prior to deployment.
While performing the recommended UPS drawdown testing on the Superintendent’s Control Panel, the associated UPS unit immediately failed to adequately maintain battery backup, losing over 30% of output power within the first two minutes of the test. A replacement UPS was installed, tested, and verified to be capable of providing backup power to the control panel for 30 minutes as required by API RP 17G.
The attending surveyor’s recognition of a deficiency in the existing UPS test procedures and equipment performance and the subsequent recommendation for corrective action mitigated the risks of commencing intervention operations with an emergency system that was not fully operational. Failure to maintain control of this intervention well control equipment during an emergency could have resulted in a potentially catastrophic event.
ModuSpecTM also recommended a follow up testing program that would mitigate risk to the safety of personnel, equipment, and the environment.
Our technical expertise and knowledge of the applicable standards and regulatory requirements aided us in effectively identifying and mitigating the risks to our client’s operation associated with commencing intervention operations with an emergency system that was not fully operational.