The Middle East faces a substantial challenge to keep hundreds of ageing offshore oil and gas structures operating safely and legally beyond original design life. “There are at least 700 to 800 fixed platforms and bridges in the region,” said Anupam Ghosal, regional manager for Middle East and India, DNV GL - Oil & Gas. “More than 70% are older than 25 years; some exceed 40 years. United Arab Emirates (UAE) alone has about 450.”
Life extension of ageing structures ensures continued operation within regulatory requirements, and helps to limit future operational expenditure (opex). “Constraining opex is vital to economically viable but safe operations,” he added. Operators in the Middle East are at different stages of implementing controlled approaches to asset integrity management (AIM) and structural integrity management (SIM) systems. Ghosal observed: “Several are in the planning stage. DNV GL is engaged in the process with quite a few customers in the region.”
The Abu Dhabi Marine Operating Company (ADMA-OPCO), a major producer of oil and gas from offshore Abu Dhabi, is in the vanguard of Middle East operators addressing life extension opportunities; some of its earliest structures are more than 50 years old. “We have an extensive fleet of structures undergoing continuous brownfield project developments to ensure sustainable oil production over the extended field-life,” explained Dr Tarek Omar, civil/structural engineering team leader, ADMA-OPCO. “Of these assets, 70% have already reached design life, and ADMA has taken a strategic decision to lead in the area of managing their integrity.”
Case study: ADMA-OPCO
ADMA-OPCO has developed a comprehensive structural management system (SMS) framework based on a fully quantitative approach. All changes are monitored and managed through an in-house developed management of change (MOC) system for structures which meets all the company’s requirements. ADMA's SMS uses a fleet management system (FMS) to manage the quantification and risk ranking of its fleet.
“This SMS works with different database systems,” said Ebrahim Saleh AL-Shehhi,
ADMA-OPCO’s project manager for the integrated database management system, which covers asset integrity for structures, pipelines and critical safety equipment. “DNV GL’s Synergi™ Structure software is used for storing all structural characteristics data, inspection findings and reports, and risk ranking information. The Synergi dashboard presents results interactively showing main highlights across all assets.”
Continuous improvement is important, Ghosal agreed: “Technological advances provide opportunities to produce more hydrocarbons economically from existing structures. Low oil prices create the need to extract best value from current facilities. Other drivers include improved data on reservoirs, heightened regulation, updated design standards and knowledge, advances in risk management, and enhanced focus on safe operations.”
ADMA-OPCO plans to further increase effectiveness of SIM by: mandating use of the management of change system company-wide; continuously updating structural assessment methods; and continuous interaction and joint innovation with industry partners.
Greater activity around asset and structural integrity will generate substantial know-how for the Middle East and elsewhere. ADMA-OPCO’s structures, for example, are forecast to be among the industry’s longest lasting, Omar said. The company is actively taking key initiatives in joint industry R&D projects, and in adopting international standards for structural management. One key learning from ADMA-OPCO’s SMS is the importance of an effective MOC process and sophisticated inspection in capturing the risks, Omar said. “This earned continuous support from company management to make it a company-wide culture.”
One solution does not fit all
Another lesson is that one-size does not fit all when developing an SMS, he added. “Each company and region has its own special requirements and a structural management system needs to cater for these.” Ghosal commented: “Operators here face challenges encountered elsewhere in the world, but also ones that are specific to, or more pronounced, in this region, such as sour gas. DNV GL has had a presence here for more than 30 years and understands local needs.”
DNV GL’s software, database, quantitative and qualitative approaches, and other expertise in capturing, analysing and managing information for SIM assists customers to scope, design and implement life extension strategies. The company’s ‘missing data methodology’ addresses the absence of historic documentation, a common challenge for operators in the region.
Key structural integrity goalsEngineering experts at oil and gas companies operating in the Middle East see ageing effects in grouted piles as one of the top structural integrity management (SIM) challenges. This emerged from interviews by DNV GL, and in a survey at its annual Ageing Structures Day in September 2015.
Some operators also expressed a desire to see regional acceptance criteria formulated for SIM of existing fixed structures, but with operators having flexibility to respond to local circumstances.
For offshore Abu Dhabi, they wanted to know: how lateral pile capacity might be enhanced in carbonaceous rocks; more about the seismic vulnerability of platforms; and, how a spectrum of site-specific responses might be formulated.
Others were interested in the implementation of online health-monitoring. Respondents saw a need for engineering studies to verify requirements for replacement of degraded appurtenances such as riser- and conductor-protectors.
Region-specific guidance on the below elements is useful when developing life extension strategies for ageing offshore structures.
- Wave spectra suitable for benign sea conditions in the Arabian Gulf to predict fatigue reliability and to assess the remaining fatigue life of structures.
- Corrosion mitigation strategies for structures and critical appurtenances to optimize the operating expenditure of ageing offshore structures.
- New technology to acquire missing data on actual pile penetration depth and ageing grout strength to assure drilled and grouted foundation integrity.