Subsea Operations
Where the day-to-day operation of a subsea asset is done in-house, we can provide additional support to breakdowns, specific campaigns or other high-workload events. The benefits of using a consultancy such as Stramach for ad-hoc workscopes is that the right solution can be deployed for a package of work with little burden on the existing organisation and no obligation of continued work commitment.
Effective surveillance of a subsea system is an area where attention to detail can pay dividends in minimising unplanned failures, and maximising uptime. Examples might be fluid cleanliness of an HPU, condition monitoring of electrical insulation resistance, vacuum testing of flexible risers, and material mapping / compatibility studies. These activities tend to be low cost yet, when implemented proactively, can avoid costly repair interventions and production deferment. Alongside such a strategy might be assessments of spares holdings to optimise repair lead times.
We can also provide advice on all matters relating to the specification, operation and reliability of subsea systems.
Some examples of our experience in subsea operations support include the following:
- Following identification of defective pipework within a production manifold, a number of repair options were identified and early engineering progressed. These included pipework replacement and engineered permanent repair clamps. Alternatives to subsea repairs (mothballing, well re-routing, further inspection) were also presented. By working closely with the client, a preferred strategy was devised to assess serviceability of the manifold through a targeted inspection scheme, with further contingency operations made available.
- An analysis of the status of an FPSO-based subsea control system was undertaken, to identify vulnerabilities and operational risks, and provide recommendations on actions required to ensure operability through to end of field life. Particular focus was applied to the degraded subsea electrical system and the threat it presented to continued production.
- As a result of the blockage of several chemical cores in a subsea umbilical, a scheme was devised to transfer service to spare cores and replace jumper hoses where possible. This scope was urgently required due to the field being shut in. Method statements were developed for the attempted recovery of the blocked cores, flushing of spare cores, isolations, installation of replacement hoses, and system reconfiguration. Fluid and material compatibility testing was also required before spare cores could be put into service. This complex scope was executed successfully within a few weeks of the initial blockage, and production restored.
- Management of an obsolete subsea control system on behalf of the client. A phased approach was taken whereby the short-term threat was mitigated by the strategic management of spares, and selective component upgrades; for example, the obsolete MCS VDU was replaced with a 1U rack-mounted IPC (running emulation software) and standard VGA monitor, which had the added benefit of providing an alternative means of system back-up in place of obsolete tape drives. In parallel, the long-term solutions were explored with the OEM, and a replacement MCS proposal developed.
- Following the failure of a gas lift flexible flowline, a review was carried out on all of the client’s flexibles in order to understand areas of risk. This led to the development of a spares strategy identifying the most cost-effective way of reducing lead times of critical items. A selection of adaptable spares was procured in line with the strategy, including a length of unterminated flexible pipe and a selection of end fittings.
- Management of the transition of a subsea asset during change of ownership. All asset data, work management and integrity management systems were reviewed, with a view to rationalising, and ensuring compliance with legislative requirements.
