Leistungen
The DeFRIS project aimed to solve the technological needs associated with subsea pipe insulation in future deep water and old marginal oil wells. Experience of the performance of insulation materials in such conditions is limited; few systems have been used beyond depths of 1000m while future developments are planned to 2000m and beyond. These increasing well depths bring with them corresponding increases in the lengths of flowlines which again demands efficient and long term effectiveness of the insulating system in order to prevent cooling of the fluids. Improved functionality over the life of the system will extend the productivity of marginal wells while reducing the requirement for expensive workover treatments, necessary to prevent the formation of hydrate plugs and wax deposits.
Overall, the DeFRIS project has been successful on a number of fronts as indicated by the individual Partner reports. In summary goals have been achieved.
While gathering information from industry end-users, it has been possible to establish a ready network through which project developments can be disseminated.
A further task has enabled a specification of the performance requirements for the thermal insulation systems to be developed. This task involved the identification of the operational requirements of the system. These operational requirements included structural, thermal and mechanical properties. An assessment has also been made of the in-place loads to which the system will be subjected. A review of the options for installation and an identification of the installation performance has also been completed.
Following a full review of all aspects of thermal insulation systems it has been possible to develop empirical based software tools. These will allow easy and efficient design of global insulation systems. The software tool has been calibrated using the results of the local finite element analysis.
In terms of pipe insulation systems, effort has been focused on the development of two new systems System X and System Y. These have each pursued a particular requirement of the project; System X to extend the deepwater performance of foamed polypropylene systems and System Y to explore the use of alternative and novel materials under high temperature fluid conditions. This has been further supported by the work to develop improved design and analysis tools; i.e. to design, develop and install systems for high-duty service applications, and to evaluate existing, and develop improved, screening tests/methodologies.
As a result a several of the new PP grades developed within the DeFRIS project have shown better deepwater and high temperature performance than previous PP materials. Tensile properties are above the requirements for these systems and the partners feel that with further careful tuning of the extrusion process and by lowering the density of the foam, a suitable balance between mechanical and thermal properties can be achieved. The foam structure and the homogenisation of the polymer melt have been optimised and meet the creep specification and the requirements from reel-lay operations.
The new generation of stiff PP polymers has resulted in a significant advance, seen in the PP foam used as thermal insulation in a multilayer pipe coating system. In addition to the stiff PP copolymer, HMS-PP based polymers can be added to improve the homogeneity of the PP foam, increasing the compression strength and improving creep resistance. This has resulted in a product that can withstand a greater hydrostatic pressure, without altering the
thermal insulation performance. Thus the new PP foam can be introduced for use at significantly greater water depths.
Sufficient mixing between BA212E and HMS-PP is of vital importance to obtain PP foams with good mechanical and insulation properties. Therefore the pre-compounded BA150E (70% BA212E/30% HMS-PP) was developed which shows improved foam quality and mechanical properties due to enhanced homogeneity.
A number of full-scale trials have been performed for the prototype (novel) polypropylene (PP) system, which has been identified in the market as Thermotite TDF. The trials have explored and optimised the manufacturing process parameters and polymer ratios, along with a study of foaming techniques. Thermotite has already managed to secure two major contracts, i.e. the BP Thunderhorse and the Statoil Kristin projects through the DeFRIS development efforts.
Materials property tests including comparative thermal property measurement techniques have also been performed. A number of technical papers and journal articles have been published describing the enhancements of the novel PP system, System Y work and its findings, test methodologies, and the analysis tool developments.
Finally from the point of view of installation the main conclusions of the project were that there was a relatively good correspondence between the test results and the outputs of the FE analysis. Some little difference could be observed, but it was generally considered that this model could be used for future simulations of coated pipe reeling, with a reasonable degree of confidence. The main target of the FE analysis will be the study of the steel integrity during the different steps of the pipelay operation. It is considered that modelling the behaviour of the coating material, in order to assess the integrity of the coating material accurately, may still require further work.
Each of the partners� technical knowledge and understanding of the area has increased significantly as a result of the project and each has added to their portfolio of expertise, and in each case their product base.
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