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The connection of the electrical and hydraulic umbilicals to the Exxon Zincsubsea production template was accomplished using first-end connection systemsdesigned to be diverless and utilize guidelines for deployment.
This paper describes the design, testing and installation of the umbilicalconnection systems developed for the Zinc subsea production system.
The Zinc subsea production system is a gas development in 1460 feet ofwater, located in the Mississippi Canyon area of the Gulf of Mexico. Separateelectrical and hydraulic umbilicals are used to control the Zinc subseaproduction system from the Alabaster platform, located six miles to the west in468 feet of water. The umbilicals provide the electrical power, communicationlink and hydraulic/chemical injection supply to the multiplex subsea controlsystem on Zinc.
Each umbilical installation was initiated at Zinc using guidelines forlowering and landing an umbilical termination assembly onto its receiver on thesubsea template. After the umbilical termination assembly was landed, theumbilical was laid to the Alabaster platform where a second-end J-tube pull wasperformed to complete the installation.
Final connection of the umbilicals to the subsea template/ manifold wascompleted after the umbilicals had been installed and tested. For the hydraulicumbilical, the connection tool utilized a mechanical clamp to make-up theumbilical connection to the hydraulic fluid distribution system on the subseamanifold. The electrical umbilical connection was completed by attaching anelectrical jumper assembly from the control skid on the manifold to thetermination assembly on the electrical umbilical using a Remote OperatedVehicle (ROV).
Selection of Connection Systems
The umbilical connection systems were selected to feature a first-endconnection at Zinc. The first end connection method allowed close routing ofthe umbilicals to the flowlines near the template, which minimized mooringdifficulties for subsequent drilling operations. After installation wascomplete, the subsea electrical and hydraulic umbilical connections to the Zinccontrol system were made-up. A slack loop near the Alabaster Platform wasincluded in the route to accommodate excess umbilical length prior to thesecond-end J-tube pull. This allowed both umbilicals to be installed withoutmodifying their length in the field.
Since the first umbilicals were developed and installed to control and preserve subsea equipment they have continued to evolve to ensure effective operation in an increasingly challenging subsea environment. New material technologies, complex analysis tools and umbilical designs, such as in , have been developed to ensure umbilical systems operate through-out their service life irrespective of the ambient temperature, fatigue loading, hyperbaric pressure and tensile loads applied. Typical Control and Chemical Injection Umbilical Arangement The subsea industry needs to adapt to the challenge of reducing capital expenditure (CAPEX) costs due to reduced oil price. The potential cost savings could be realised through adapting the subsea processing system to treat processed fluids on the seabed together with utilising longer step out systems from existing facilities. This could drive a new step in umbilical evolution. To support the potential evolution of subsea processing systems, the conventional control umbilical must evolve to incorporate the supply of electrical power and potentially electrical control to replace hydraulic control over long step out distances. This has a significant influence on the design of the umbilical system, introducing several new challenges which need to be addressed through material selection and advanced analysis techniques. This paper will provide an overview of the potential evolution of the Next Generation All Electric umbilical and outline the design challenges and methods developed to maximise the reliability of the umbilical system.
The current industry trend towards very long length tieback umbilicals for Mediterranean gas fields puts a strong cost focus on the subsea control umbilical system because the cost is approximately proportional to length.
The super duplex tubes contribute the majority of cost of a steel tube umbilical and optimising the wall thickness, to minimise material required, can deliver significant cost savings. The wall thickness is calculated based on service conditions and allowable utilisations as defined by ISO-13628 part-5. The tube manufacturing process and tolerances can also provide further optimisations. Vallourec Umbilicals Super Duplex Seam welded tube produced on a state of the art manufacturing line offers high guaranteed material yield and tighter manufacturing tolerances, enabling more cost effective tube designs without increasing operational risk or compromising safety.
This presentation charts the steps taken to introduce this technology through to successful installation of the first project, an 18km long tieback umbilical for TOTAL’s Glenlivet project in the UK North Sea and demonstrate the benefits it can bring to future long length tieback umbilicals. The new tube manufacturing process has been developed via an extensive qualification program with collaboration between Tube supplier, Operators, Umbilical manufacturers and third party type approval bodies, proving suitability for umbilical use.
The transition from R&D to Industrialisation was a success for all parties involved who collaborated to move the manufacturing into full scale project production requirements. Early planning through a risk assessment focused approach to umbilical lay-up was fundamental for a smooth manufacturing phase and installation campaign. The first project delivery has grown confidence and provided valuable experience. The technology can now be considered well proven and can offer significant cost benefits to future long length tieback prospects.
The Oil and Gas industry driven by cost savings have developed growing interest for field architectures where the tieback of the field, even with long distances to the main operating production facility are considered. Operating conditions lead to new philosophy in the design of subsea umbilicals, which are evolving to answer the needs in terms of functionalities and injection capacity.
Abstract This paper attempts to shed some light on the deepwater performance capabilities of subsea umbilicals incorporating thermoplastic hoses as fluid conduits and for provision of hydraulic power, by reporting and discussing the significance of the empirical findings derived from a case study of a section of thermoplastic-hose (TPH) umbilical salvaged after deployment in the deepwater Zafiro field offshore Equatorial Guinea for more than a decade. It is of utmost environmental and economic importance for an umbilical to perform safely and reliably throughout the productive life of a subsea oil and gas project. Offshore oil and gas producers have used TPH umbilicals beneficially for more than 30 years to link remote and/or subsea wells with operating facilities. As offshore E&P has moved into ever deeper water, the performance capabilities of TPH umbilicals increasingly have been challenged, both in the field and in the minds of deepwater operators, despite steady improvements in umbilical construction methods and materials of construction, alike. Today, TPH umbilicals are manufactured to exacting technical design standards and quality is carefully monitored and verified throughout the manufacturing process. However, uncertainty about TPH umbilical capabilities persists in part because of a dearth of publicly available, scientific data evaluating their performance in the field. This case study contributes such hard-to-get credible scientific data to the public record by documenting the extent of physical and chemical degradation suffered by a TPH umbilical following extended deployment in deep water. The author describes the physical design, dimensions, and technical characteristics of a salvaged TPH umbilical and the conditions under which it was utilized, including the water depth in which deployed, the role played in the Zafiro field, and operating conditions during deployment. The author describes the testing methodology and the results of various tests performed upon the umbilical to determine its physical and chemical condition to establish a scientific basis for drawing conclusions about the safety and reliability of TPH umbilicals in deep water. Introduction TPH umbilicals and steel-tube (ST) umbilicals containing no thermoplastic hoses are engineered to design standards embodied in API 17E/ISO 13628-5 Specification (API, 2003) (ISO, 2002). Yet, the two basic types of umbilicals exhibit widely differing performance characteristics, so selecting the right subsea production umbilical system for a given deepwater application is not straightforward. Modeling umbilical performance is a complex task and offshore producers must take into account a wide range of demanding performance criteria--fluid-conduit bore size, anticipated working pressures, internal chemicals or fluids to be transported, and hose-end fitting requirements--as well as a host of site-specific logistical and installation factors. In most cases, the selection process favors the umbilical system that will perform reliably and efficiently under expected operating pressures and temperature extremes in the most cost-effective manner. The superior fatigue-resistance of TPH umbilicals enables them to claim the advantage in most dynamic applications. However, there are no clear cut rules that can dictate the optimal subsea umbilical design for all deepwater and ultra-deepwater applications.