OTIMROTA-Multiline: Computational Tool for the Conceptual Design of Subsea Production Systems

Abstract

This article presents a computational tool oriented to develop subsea layouts of oil production system focused on design concepts associated with wet completion. The OTIMROTA-Multiline has been developed by Petrobras in partnership with UFRJ; its goal is to comply with the needs and requirements to develop conceptual design of several subsea systems currently being studied in the Brazilian pre-salt scenarios. Considering that subsea projects are intrinsically complex, multidisciplinary and comprising of several interfaces, the OTIMROTA-Multiline tool follows two approaches to achieve an optimal solution. The first is based on deterministic methodologies, intended to systematically reproduce design experience with logical restrictions; thus, a large number of candidate solutions can be quickly analyzed, greatly reducing the time to complete the design. The second approach is based on evolutionary algorithms such as Genetic Algorithms to solve the optimization aspects. Both approaches have a large search space, with several interdependent design variables, with complex and quite unpredictable interactions. The final goal is to reduce the overall project costs. Initially, the computational tool includes facilities to find the best position for a floating production unit (FPU), and to interactively integrate satellite wells in an optimized subsea layout. Compliance with the many design criteria, parameters and requirements is automatically checked, including marine geology and environmental constraints; pre-existent obstacles; simultaneity of offshore operations; risers anchoring, and so on. Information is available to the designer throughout the tool iterative execution, including acquisition and installation costs for the equipment and flowlines, and expected oil flow rates for each candidate solution. As a final deliverable, the tool automatically provides a formatted report with all relevant results for a proper project selection. The tool also exports a file that can be employed in 2D/3D modeling programs, enabling the best alternative selected to be subsequently detailed by the specialists. One of the main contributions of developed automation tool will be to enhance the integration among the technical teams through less complex analyses; this will contribute to a more reliable and robust alternative selection, leading to more efficient solutions. Further developments are currently underway, including new subsea architectures (including production ring, trunkline, manifolds), along with their costs, production flow modeling and the interface with well and topside design to have a more robust tool for evaluation of new architectures.