Comparative Study Between an Integrated All-Electric Subsea Production System, Including Subsea Chemical System Injection, and a Standard Electro-Hydraulic System
Authors: Manach Julien , Verdeil Julien , Bouzard Vincent , Hiron Stephane , Sommer Burkhard , Beristain Mario , Manson Greg 
Published: April 2023

This representative case study for a greenfield development compares traditional subsea field architecture to an all-electric alternative. The evaluation highlights the benefits of the subsea integrated all-electric system (iAES) for a long-tieback gas field development. Increased production of decarbonized natural gas through all subsea tiebacks to shore is a key enabler to lower carbon dioxide (CO2) emissions.

The main objective of this case study is to improve the development plan of a remote large gas field with a low power requirement to achieve improved performance, cleaner energy production, and cost- effective implementation.

The optimization of the field architecture enabled by the iAES relies on a combination of technology bricks: subsea electrical power distribution, digitalization, all-electric production systems, and a subsea chemical storage and injection (SCSI) system.

The evaluation compares field architectures based on a traditional electro-hydraulic design versus an iAES with optimized field layout and power requirements, operating modes, a combination of field-proven solutions and innovative technologies, and balance between new equipment and cost.

Digitalization built on those advancements enables the required in-depth optimization. The electric actuators used to operate valves on trees, manifolds, and pipeline end terminations (PLETs) remove the need for the large hydraulic tubes in the control umbilical. Chemical delivery is still required during production for low-dosage inhibitors (such as scale, corrosion, and wax inhibitors) and for hydrate inhibitors during preservation and restart operations. This can be done most efficiently by an infield smart SCSI system that accurately doses chemicals for each application. Because this optimized system requires vessel-based refilling, it is important that dosage rates are administered precisely based on a variety of sensors distributed across the field layout. These sensors create in-depth knowledge of the process parameters to avoid overinjection and delaying replenishing while optimizing power consumption of the overall system to a minimum necessary level and maximizing uptime.

This representative case study demonstrates not only the feasibility of an iAES but especially its benefits for a developer with a focus on cost reduction, decarbonization, standardization, and safety improvement. An iAES extends the limits of traditional field development and enables very long distance stepouts with a lower carbon footprint.

The results of this study are directly applicable to many other developments and can readily be transferred to other projects and commercialized as a standard package.

This in turn confirms the viability of new field architectures and new ways of operating. The iAES is a feature that introduce the opportunity for a transformative business model of phased development.