Systems Engineering of Subsea Production Systems
Authors: Marcotulli Amedeo , Wilkinson David 
Published: April 2022

Abstract
Subsea production systems (SPS) are widely used throughout the upstream oil and gas industry, and can range in complexity from simple, single well tiebacks, in shallow water, through to multi-well developments (involving subsea processing), linked back to purpose-built host facilities, in deep water and/or harsh environments. As the complexity (and cost) of the SPS being deployed has increased over the past few decades, the requirement for a more rigorous and systematic approach toward the engineering of such systems has increased.
Whilst it is true that many SPS are based on "industry standard" components (when viewed at a sufficiently granular level), the reality is that every SPS is in some way unique, primarily due to the large number of boundary conditions that drive the design – be it the reservoir characteristics, produced fluid properties, water depth, seabed topography/soil conditions, environmental conditions, etc.
SPS are also somewhat unusual in the upstream oil and gas industry, insofar as they typically involve the transport of multiphase flowstreams over relatively long distances, which directly impacts the complexity of the system. The inherent complexity of managing multiphase flowstreams (and/or operating subsea processing facilities) using remotely operated equipment, leads to systems where many elements of the design are "tightly coupled", as a minor change in one part of the system has the potential to significantly impact the design and operation of another part of the system, even though these "system components" may be widely separated physically.
Similarly, complex systems used in other industries have been found to greatly benefit from the application of formal systems engineering (SE) processes. Whilst it is acknowledged that SE has been informally practiced in the upstream oil and gas industry for many years, the approach has typically been relatively unstructured as the various SE processes are scattered throughout existing engineering and project management processes, and therefore the SE is performed in a sub-optimal manner. Systems engineering practitioners, such as they are, have learned the trade over many years of multidisciplinary experience and have developed the holistic top-down thinking required, but to date there are no publically available documents that provide specific guidance on the systems engineering of subsea production systems.
A systems engineering guidance document, specifically written to be applicable to SPS, is currently being developed by members of API Sub-Committee 17 and will soon be available. The publication of this document is intended to advance the understanding of SE theory and to foster more efficient and rigorous implementation of the various SE processes, in order to improve project outcomes.
The objective of this paper is to make potential users of the guidance document aware of its existence and of the benefits associated with the use of formal systems engineering processes when designing complex facilities. The guidance document will be in the format of a Technical Report and therefore is not intended to be directive in nature, and can be tailored for use as seen fit by the Project Management Team and systems engineering personnel using it.