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.
Valves and actuators are key building blocks to realize subsea processing plants. Both isolation and control valves are key elements for operating processes such as water treatment and injection, boosting and separation. In order to increase the performances and to eliminate the hydraulic lines within the umbilicals, a retrievable configuration to drive both types of valves sharing the same electric actuator has been developed. For a subsea water treatment application, and to manage its backwashing function, a dedicated development and qualification plan has been implemented, to cater for the associated high number of cycles. This requirement was new considering that common subsea applications call for a total number of actuations in the order of around one hundred, while to implement these backwash sequences, isolation valves need to be capable of thousands of complete cycles and control valves of hundreds of thousands of small adjustments. This paper addresses how the design of subsea valves and actuators has been qualified to TRL4 through both analysis and test campaigns on dedicated prototype units in compliance with API 17N or DNV RP A203, API 17F, API 6A and API 17D. Saipem performed a market review to map the existing technologies and understand potential gaps against the needed performances for isolation valves, control valves and relevant actuations. Based on the results of this review, the key providers were selected to undertake the technology qualifications required to close the identified gaps. Working in team with the technology providers, three dedicated technology qualification plans were defined to ensure the suitability of each technology. The activities identified in these plans include both analyses and performance/endurance tests on prototypes. These activities were considered to mitigate risks associated with the failure modes identified during the FMECAs. The envelope of the performance set as the basis of each technology qualification plan allows the extension of the deployment of these technologies in different subsea processes. The isolation valve qualification plan was successfully completed in 2018, while the control valve and the electric actuator qualification plans will be completed by end of 2019, establishing a new reference for the utilization of subsea valves in complex subsea processes, such as subsea water treatment and injection systems or subsea separation systems. The presentation and paper will introduce the elements of novelty and will describe the process, the challenges and the results of the technology qualification. The technology qualification plans will be presented, including the initial readiness level assessment, the outcomes of the FMECAs and the qualification activities, which include: high-cycling isolation valves: analyses, mock-up tests, prototypes hyperbaric and endurance tests; high-cycling control valves: analyses and endurance tests; high-cycling all electric actuators analyses, mock up tests, temperature of electronic boards, pressure, shock and vibrations tests (API 17F) and prototype functional and endurance tests.
The exploitation of subsea hydrocarbons fields as well as large subsea gas to market infrastructures often requires pipelines to route across sharp slope transitions. Site conditions are sometime so critical to represent a severe design concern and to require costly seabed preparation works, extremely challenging and environmentally impacting. This paper presents an innovative solution that allows avoiding any preparation work as well as a novel installation method for its effective and safe implementation. Specifically, the paper presents a design case study for a gas export pipeline crossing a severe escarpment at the intersection between the Continental Shelf and the Continental Slope (Shelf Break). The rigid pipeline installed by normal continuous pipelay across such sharp slope transition would be subject to excessive bending due to localized imposed curvature that requires mitigation. Two alternative design solutions have been developed and compared: one based on excavation (trenching) to shape the escarpment edge and one introducing vertical bends on the pipeline string. The design solution based on trenching results in large excavation volume with associated environmental impact in term seawater turbidity and damaged seabed surface (biocenosis). The analysis results also show that the solution is very sensitive to trenching profile accuracy and profile long term stability. Constructability is discussed in terms of availability of technology vs water depth, soil uncertainties, excavation volume, excavation tolerances. The alternative design based on bends allows avoiding any seabed preparation works and all the associated issues. The analysis results demonstrate much higher performances in terms of pipeline integrity and safety throughout the pipeline life. However, its implementation requires special installation solutions as bends are not installable with the normal continuous pipelay method. The paper presents a new installation method (Saipem patented) that allows realizing vertical cold bends safely and effectively on the pipeline profile with no interruption of the continuous pipelay process. The novel idea is to realize the bends underwater, when the pipe is landing or close to landing on the seabed, by means of a remotely operated Underwater Bending Machine purposedly designed. The paper describes the new Underwater Cold Bending technology, presenting the engineering work done to support the demonstration of its robustness and reliability. The paper also presents a case study for escarpment crossing design developed according to two alternative design concepts, the standard and the novel one. The two solutions are compared, listing pros and cons of each one, highlighting relevant design issues as well as construction criticalities and risks.
Subsea pipeline repair connectors have been used in the oil & gas industry for many years and are considered a valid and safe way of repairing major damages and restoring the original pipeline condition in case of an emergency repair; they can also be used for tie-ins to allow extensions by connection of new pipeline sections to an existing one and they have an extensive track record mainly on carbon steel pipelines but are fit also for stainless steel and duplex pipelines. The increasing number of subsea pipelines with internal CRA cladding which have been deployed in recent years and are foreseen in the future poses new technological challenges since conventional sealing solutions are not suitable for or have limitations in this specific application: in this case the repair connector not only needs to be designed to be compliant with the sour product but it also needs to protect the pipeline carbon steel wall from coming into contact with the internal fluid. This paper presents a new concept of a pipeline repair connector that has been developed from the beginning specifically to target repairs on sour service lines and in particular on clad lines. This innovative repair connector is based on a metal to metal sealing technology that offers permanent repair without any reduction of the pipeline's internal diameter, provides a versatile diver/diver-less solution, can deal with multiple wall thicknesses and can also be applied to other types of pipelines, such as those for sour service with internal corrosion allowance since it can manage pipe wall thickness reduction over time. The design of the mechanical connector has been carried out in compliance with DNV pipeline codes after a comprehensive technology qualification testing campaign under DNV certification and focused on medium size pipes. A full-scale 26″ prototype connector has been designed and fabricated for completing the qualification testing program including all required pressure and loading conditions. FEM analyses of the testing configurations have been carried out for comparison with test data so to validate the FEM models and extend results to other sizes within a predefined range. The matching between the experimental data and FEM calculations has allowed setting up a Type Approval process with DNV and, after a design effort covering various pipeline sizes and types, the connector will be certified for a wide range of large bore pipelines and design conditions and be ready for release to the market.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.