Article: Topsides Weight Control Prevents Project Delays

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ENGINEERING, CONSTRUCTION, & INSTALLATION New approach implemented on Delta House project A ccurate prediction of topsides weight and center of gravity (CG) plays a critical role in the development of of fshore production facilities. In addition to ensuring that an of fshore platfor m remains safe and within allowable str uctural tolerances throughout its lifecycle, employing ef fective weight management practices during design, constr uction, and installation is essential to avoiding schedule delays, preventing cost escalation, and maximizing overall design flexibility. Load budget definition Collaborating with contractors and using historical benchmark data to define initial load budgets in the early planning stages of a project are keys to ef fective weight management. It is in the early stages where the design is not totally fixed, thus allowing for layout and equipment selection to be modified if needed. As a project progresses, the ability to influence weight and CG star ts to diminish and the cost associated with making design modifications to reduce weight increases significantly. In general, poor scope and load budget definition in front-end engineering and design will make cost estimation more dif ficult and increase the likelihood of r unning into issues during detailed design. Early contractor involvement and load budget definition played a critical role in the successful development of LLOG Exploration Co.'s Delta House semisubmersible floating production system (FPS) in the Gulf of Mexico. In order to keep pace with the aggressive schedule to design, fabricate, and install the platform within 30 months, work on Delta House commenced before any detailed reser voir data was available. As a result, the facility had to adopt a flexible "one size fits most" design philosophy that would allow it to handle a wide range of reser voir characteristics and hydrocarbon profiles. This made managing platform weight and CG a challenging task – one that required extreme precision and coordination between the topsides contractor, Audubon Engineering Solutions, hull designer EXMAR Of fshore, and other vendors working on the project. Audubon Engineering Solutions worked closely with EXMAR in the early design phases to establish "Not to Exceed" weight budgets for all stakeholders. CG constraints were provided by EXMAR as a result of a stability analysis on the topsides and hull str ucture. Ver tical CG was an impor tant variable to monitor and control as it directly impacted the overall allowable weight (the higher the CG was above the deck, the lower the allowable weight). The horizontal CG was also closely monitored due to its impor tance during the transit condition, when the facility Taylor Gulotta Audubon Engineering Solutions Topsides weight control prevents project delays LLOG Exploration Co.'s Delta House is a water independent, semisubmersible FPS. It is located in 4,500 ft (1,371 m) of water and entered into production in April 2015. (All images courtesy LLOG Exploration Co.)

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