Abstract
Subsea chemical storage and injection systems are a new technology that moves the chemical units from topside to subsea locations, close to the wells. It has been conceived for application on field development projects with long tiebacks, whenever the objective is to replace the expensive hydraulic umbilicals for chemicals distribution. Conversely, the new subsea technology needs only a power and communication link to the existing topside facilities.
So that this can occur, a dedicated industrialisation programme was launched for developing all the building blocks of the technology to achieve a sufficient readiness level for the first industrial application. The core of the industrialisation has been the extensive qualification campaign, mostly based on experimental testing carried out in laboratory and workshop environments, as well as in simulated deep-water conditions. Due to the nature of the treated fluids, specific attention has been paid to the chemical compatibility testing of materials and fluids for long term applications in harsh environments.
The available technologies have been reviewed through a comprehensive market assessment, to spotlight the gaps as well as the elements of novelty of the intended application. Several industrial partners have been engaged to jointly define and carry out relevant qualification plans.
The basis of design for the development and qualification of equipment has been defined considering a range of possible applications in the subsea field development and subsea processing context. The information was used to build a map of the technology requirements including the chemical fluids to be managed, flowrate and injection pressure ranges. The map, combined with a set of process data and IMR scenarios, has been further elaborated to define the storage unit size, modularization philosophy and to set relevant reliability requirements.
The qualification philosophy was based on the framework set by the international guidelines for technology qualification, i.e. DNV RP A203 and API 17 Q, through a documented risk-based approach. Whenever applicable, the components have been qualified to specific relevant standards, for instance API17 F and ISO 1817 for the electronic components and the effect of liquids on polymeric materials respectively.
Programme execution included the construction of several prototypes of the key equipment: the subsea pump & motor unit, electrical actuator for small-bore valves, flowmeter and the storage unit. Most of the components were subject to endurance and cycle testing to provide quantitative data to support the results of the RAM analyses. In addition, the programme leveraged the control system components that have been industrialised as part of a previous qualification initiative addressing the requirements of several subsea processing applications.
The paper will introduce the elements of technological novelty of the equipment and will describe the methodology, challenges and main results of the programme. The qualification activities will be completed by the end of 2020.
