This paper presents the extensive work performed to propose to the LNG industry an offloading solution fully compliant with EN1474 standard requirements using floating hoses. Between 2009 and 2013, a tandem offloading system using floating cryogenic flexible hoses developed and qualified to be able to transfer LNG in open seas. This arrangement was selected in order to combine the safety and the availability brought by the tandem configuration with the wide operational envelope provided by the use of floating hoses. This system is composed of an innovative and compact hose storage system on the LNG Terminal allowing to store the hoses between two offloading operations, of a connection head (hose end termination piece) to ease the deployment/retrieval of the hoses and of a storage and maintenance platform for the connection head at the aft of the LNG Terminal, also allowing to replace a hose section in offshore conditions. On the LNG Carrier side, a bow loading platform is installed to ensure hoses connection even in exposed environmental conditions. The 20" ID cryogenic floating hoses to be used with this system has been developed and qualified in parallel with the development of the tandem system. A red line for this development was to keep a similar level of safety, integrity and performance to onshore offloading operations. To fulfill this requirement, simple, robust and proven technologies have been considered for the main items of the system. The system incorporates a comprehensive panel of safety layers through monitoring, hardware, procedures and control philosophy providing protection for people and material during all steps of the offloading sequence. Regarding the performance, the system can transfer LNG at a flowrate of 10, 000 to 12, 000 m3/h using three hoses, which gives redundancy to transfer LNG even with one hose unavailable. To offer a high availability, dedicated solutions have been implemented in the system to withstand sea states with Hs up to 3.5 m for hoses connection and 4 m for cargo transfer and hoses disconnection. This solution will help unlocking offshore stranded gas resources in many areas around the world through FLNG development.

The installation of flowlines in ever deeper and remote areas requires the usage of specific technologies in order to carry out pre-commissioning operations. As the water depth increases, the weight of the conventional equipment to be deployed to perform the required operations becomes a major issue and alternate solutions are thus required. An option lies in using Coiled Tubing. Coiled Tubing consists of continuous pipe that has been coiled around a reel and can be deployed and recovered according to operational needs. So far, offshore operation of coiled tubing has been limited to small diameters and to short operational duration. The pre-commissioning operations can require the Coiled Tubing to be deployed several times for durations sometimes exceeding a month, and also requires larger diameters (typically 3.5"). As the duration of operations increases, a suitable way of assessing and mitigating the fatigue of Coiled Tubing is required. To that extent SAIPEM has carried out an extensive testing campaign aiming at better understanding the mechanism underlying plastic and elastic fatigue. Once enough confidence in the models has been gathered, the Coiled Tubing has been deployed offshore for the pre-commissioning operations of several Brazilian projects. This paper reports the lessons learnt from an innovative pre-commissioning method based on Coiled Tubing that was successfully implemented on four ultra-deep offshore pipelines in 2015. All these projects were located offshore Brazil in water depth around 2200 m. The paper will provide feedback on the engineering and operations associated with the use of large diameter Coiled Tubing for pre-commissioning in deep water. A first section will highlight the specificities of the projects while subsequent sections will provide more details on offshore operations.

As more complex oil reservoirs are discovered, innovative flow assurance solutions are required to make the development of new discoveries both technically and economically feasible. Indeed, depending on the size of the field, a long distance tie-back might be relevant to avoid the economic impact of a dedicated production platform. If the tie-back is too long, the water depth too deep and/or the fluid temperature at the wellhead too low, conventional flow assurance solutions might not be applicable. In addition, the size of the reservoir might not justify the installation of a service line or a second production line to generate a loop to allow preservation by mean of flushing the line with dead oil in order to avoid the formation of wax and or hydrates during shutdown. Active heating of the flowlines efficiently covers this gap. Among the available technologies, Heat Tracing appears as being an interesting technology as it features very high efficiency when compared to other solutions. To this date, this solution was limited to reel lay. This paper will present a design suitable for J-laying installation methods thus enabling the technology for larger diameters and remote locations, removing the need for a spool base. This new solution is based on a sliding pipe in pipe concept that has been adapted and improved in order to include a heat tracing capability while optimizing laying rates and offering enhanced monitoring capability including both temperature and stress surveillance. As in any other heat traced pipe in pipe concept, the electrical cables are spirally winded around the inner pipe and, covered with insulating material and enclosed in an outer pipe. Optical fibers are added in order to monitor stress and temperature. In the case of this technology, several innovations aiming at improving the concept have been implemented and tested. The concept mainly relies on a specific connector designed for the simultaneous connection of all electrical wires and fiber optic cables in a single and reliable operation. The concept of sliding pipe in pipe has also been improved, relying on packers and specific pipe end design that simplify the handling of quad joints. The performed qualification testing includes: Full scale fabrication; Testing of the connection system; Testing of the fiber optics; Testing of the packers to validate their holding capacity. All tests have been performed at full scale and included deformation and temperature testing. They allowed to demonstrate that all components can be easily integrated with a conventional Pipe in Pipe design while significantly facilitating offshore operations. The present paper will provide insight on the main features of the technology in addition to details on the performed qualification campaign.

This paper presents the experience made with the engineering and execution of the tie-in of flexible risers to rigid pipelines on a project recently completed in West Africa. Five production and injection pipelines (10” and 6”) were tied back to the host platform with flexible risers, in Lazy wave configurations, in ∼600m water depth. The risers are directly connected to the terminations structures (PLETs) of the rigid pipelines, through horizontal connection systems. The structures forming the tie-in (risers, PLETs and pipelines) have been designed to accommodate axial displacements of the pipelines in the range 0.3m to 1.0m, as positive displacements (expansions) and −0.1m to −0.7m as negative displacements (contractions) of the pipelines, respectively towards and away from the risers, due to pipelines thermal expansions and pipe walking. Note that along some of the lines anchoring structures have been installed to control pipe walking. The tie-in interface loads were to be limited, in order not to threaten the flexible pipe, the PLETs and the connectors, and, despite the small pipeline end displacements, keeping the interface loads within allowable values, was a challenge. The positive displacements were causing interface loads as high as 80% of the allowable values, while the negative displacements were causing up to 90% utilization of the capacity of the connectors and 95% of the allowable loading of the foundations of the PLETs. The main drivers of such high loadings are the stiffness of the flexible pipe, combined with the layout of the tie-in. Extensive in place analyses were done to simulate the effects of progressive displacements of the pipelines, the pipe-soil interactions and the specifics of the behaviour of the flexible pipes (hysteretic stiffness). Full 3D FE analyses of the foundations (mud mats) of the PLETs were done, to circumvent the limitations of a classical bearing capacity analysis approach. As built information were also used, to remove some conservatisms in the assumptions initially taken in the design. A special installation procedure was implemented, to achieve a layout of the riser at the approach of the pipeline capable to better relieve the displacements of the pipelines and reduce interface loads. Feedbacks from the installation are given in the paper. The lessons learned are also presented: a “flexible” pipe is a “stiff” structure and a direct tie-in to the pipeline may become an issue, if not addressed early enough during the execution of the project, when it can be too late to add mitigation structures, like intermediate tie-in spools, or to change significantly the routing of the risers and pipelines.