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ZADCO Extends Life on Major Offshore Complex in the Persian Gulf by Performing Structural Integrity Assessment

ZADCO Extends Life on Major Offshore Complex in the Persian Gulf by Performing Structural Integrity Assessment
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ZADCO Extends Life on Major Offshore Complex in the Persian Gulf by Performing Structural Integrity Assessment - 1

Project Summary Organization Zakum Development Company (ZADCO) Solution Mining and Offshore Engineering Location Abu Dhabi, United Arab Emirates Project Objectives • Perform structural integrity assessment and requalification for aging jackets at the Zakum Central Complex offshore oil platform to extend the operating life of the facility. • Decouple combined jacket and deck models to improve maneuverability for future structural assessments and modifications. • Identify critical welded nodes for detailed subsea inspection and update risk ranking and risk-based inspection frequency. Products Used SACS, SACS Collapse ZADCO Extends Life on Major Offshore Complex in the Persian Gulf by Performing Structural Integrity Assessment Using SACS to Implement a Substructure Modeling and Analysis Methodology Reduced Costs, Shortened Inspection Times Fast Facts • ZADCO implemented a substructure modeling and optioneering methodology for life extension and requalification of nine jacket structures. • SACS was used to conduct design reviews and nonlinear strength analyses of the jacket structures. ROI Bentley applications improved design efficiency, reduced resource hours, cut costs, and shortened the project schedule. SACS Collapse optimized identification of critical nodes, reducing the total number by 50 percent. Using separated jacket and deck SACS models saved USD 180,000 and halved the duration of subsea inspections of critical nodes, saving USD 165,000 per inspection period. Reliable Operating Life Situated in the Persian Gulf about 80 kilometers off the coast of Abu Dhabi, United Arab Emirates, Zakum oil field is one of the world's largest, most productive oil fields owned and operated by Zakum Development Company (ZADCO) on behalf of Abu Dhabi National Oil Company (ADNOC). The field consists of 450 wells tied to approximately 90 platforms, with Zakum Central Complex as the principal offshore platform accommodating separation facilities, a gas treatment plant, water injection plant, power generation plant, pipeline risers and pigging traps, and associated utilities. A 375-by-46-meter platform, the Zakum Central Complex consists of nine jackets, eight interconnected decks, and three riser support towers. With jackets installed in 1980 now nearing anticipated operating life, ZADCO initiated a structural integrity assessment for requalification of the aging jackets to extend reliable asset life and to support continued operation of the Zakum offshore facility. As part of the life extension process, ZADCO needed to verify and update models independently generated by different engineering contractors and examine their design level assessments. The project required reviewing current loading data, modifications, metocean data, marine growth profiles, and inspection and corrosion information, and upgrading the models accordingly. Structural analyses using SACS and SACS Collapse were integral to ZADCO's methodology for assessing and requalifying the jackets, as well as for identifying critical welded nodes and updating risk-based inspection frequency. A Dynamic Substructure Modeling Approach As ZADCO's main offshore processing complex, the deck platforms at Zakum Central Complex were loaded with numerous process modules, office units, material handling equipment, and safety apparatus, each supported by two independent jackets. The facility models, with deck and jacket models combined, were too large to accurately assess the structural analysis and life expectancy. To allow for more accurate and accelerated analysis, ZADCO separated the combined jacket and deck SACS models. The team generated the deck substructures for each jacket for structural analysis in SACS and carried out nonlinear pushover analysis using SACS Collapse to assess ultimate strength on independent jackets. Since the size of the models was the main hurdle for rapid engineering, separating the originally combined models enabled structural analysis and code checks of the decks in SACS to be completed quickly without losing accuracy. Using SACS and SACS Collapse to implement a dynamic substructure modeling and analysis methodology allowed for modification proposals on a specific deck structure to be easily verified and assessed without the interaction of jacket and pile structure analyses. Overall, the ability to properly decouple the models for accurate assessment of the jackets and decks helped identify individual failure mechanisms, preventing consequential facility failures, improving asset safety, and ensuring code compliance. Optimizing Subsea Inspections As part of the life extension process, ZADCO sought to identify critical welded nodes, which are essential for platform integrity, and update the risk ranking and risk-based inspection frequency. The interoperability of Bentley software enabled the project team to simulate various failure scenarios, allowing them to fully understand the behavior of the structural components and rank the criticality of the nodes. Conducting iterative analyses and ultimate strength assessments using SACS and SACS Collapse on the independent jacket models allowed the team to measure structural redundancy and optimize the number of critical subsea nodes for inspection, reducing the number of inspections by 50 percent. The ability to efficiently explore different strength and mitigation alternatives using Bentley's offshore structural design and analysis capabilities resulted in significant time and cost savings and improved overall lifecycle asset management for Zakum Central Complex. Prior to the project, 17 nodes per jacket, totaling 153 nodes, were identified as critical and requiring inspection. After performing the life extension assessment, ZADCO identified only 76 joints as

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ZADCO Extends Life on Major Offshore Complex in the Persian Gulf by Performing Structural Integrity Assessment - 2

“Bentley SACS provides tools to manage and maintain mega structural models for all lifecycle assessments, thereby mitigating the operational risks to as low as is reasonably practical.” - Wilson John, Structural Integrity Engineer, ZADCO Find out about Bentley at: www.bentley.com Contact Bentley 1-800-BENTLEY (1-800-236-8539) Outside the US +1 610-458-5000 being critical for inspection, half the original amount. This resulted in reducing inspection durations from 40 to 20 days and cutting costs by USD 165,000 per inspection period. Achieving Sustainable Benefits Using SACS and SACS Collapse...

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