For this USD 150 million project, jacket platforms operated by Oil & Natural Gas Corporation (ONGC) offshore of Mumbai, India, were assessed for extended “fit for use” and strengthened as required to meet industry safety requirements. Carrying out analysis studies for structural adequacy posed a significant challenge, as many of the jackets had exceeded their 25-year design lifecycle—in addition to having undergone modifications, mitigations, and strengthening due to revamping for enhanced oil recovery. Moreover, the platforms needed to be kept operational during any strengthening work, so safety was of paramount importance. To address the complex challenges and thoroughly evaluate its options, ONGC needed flexible, interoperable offshore design and analysis applications.
ONGC leveraged SACS (design level) and SACS Collapse (ultimate strength analysis) to perform multiple analyses with parametric variations and optimize the strengthening/mitigation measures. The project team conducted an effective section calculation and member strength assessment using SACS’ dent modeling capability, which resulted in significant time savings. Using SACS and SACS Collapse for member/joint component strengthening, OGNC carried out analysis with different strengthening options, making it easy to ascertain the failure modes of jacket structures. The adoption of an iterative optioneering methodology for additional pile modeling also ensured an effective selection of pile sizes for providing support capacity.
The structural analysis studies carried out using Bentley software ensured continued operation and revenue generation from the platforms. Conducting customized, simultaneous analyses in SACS and SACS Collapse not only saved at least 12 resource hours per platform, but also avoided installation of a new platform at a net cost of USD 25 million. The requalification and recertification of the offshore jacket structures is expected to add an additional 10-15 years of life to the structures, as well as ensure the continued average production of around 1000 barrels of oil per day.
Deploying Bentley software to carry out multiple analysis with parametric variations provided OGNC an effective solution for optimizing remedial measures. The interoperability of SACS and SACS Collapse enhanced the team’s ability to effectively explore different strengthening/mitigations variations, resulting in a significant time and cost savings. The requalification of the platform structures ensures continued safety to marine life, the offshore property, and the working environment.