Their Assets in Exploration/Production of Hydrocarbons
Reduce the installation costs by minimizing the time spent offshore
Push the technical limits of the exploration and production of subsea hydrocarbon fields
Polymer solution Inspired by this certainty, the engineers at BARDOT Group quickly became committed to develop and indicate Technical Polymers capable of conserving high level properties even after very demanding underwater use:
Submersion in seawater
Hydrostatic working pressure of several hundreds of bars
Temperature ranging from 3° to 40° Celsius
25 years minimum of use under these conditions
Accredited with fully documented qualification certificates from the Centre of Experimental Development (Centre de Développement Expérimental) in La Ciotat, some of these materials are now known under the trademarks BarDeep® for compact polymers and Deepfloat® for the syntactic polymers and are offered alongside other field proven Technical Polymers. For a number of years, the following technical requirements have been added to the aforementioned preliminary organizational imperatives, with regards to:
HPHT fields with a need for materials resistant to extremely high temperatures
Arctic fields with a need for materials storable in air at extremely low temperatures
Finally, for the past number of years, the “REACH” regulations established by the European Chemicals Agency have formed an additional requirement taken into account by our teams in the development and adaptation of BarDeep® and DeepFloat® formulas. Thanks to their steady development in polymer expertise over the past number of years, the engineers at BARDOT Group have already designed solutions to deal with these new constraints.
The Structure of Polymers
We call a solid polymer an organic material whose molecular mass is greater than 5000 grams per mole. These materials are the result of complex formulations from high-quality crude oil refining products, or naphtha, and are based on propylene, toluene, benzene, ethylene or even xylene. BARDOT Group works with the two matrix families of solid polymers:
Thermosetting materials (principally urethane, epoxides, rubber, silicone, but also polydicyclopentadiene PCPTD, polytetrafluoroethylene PTFE) are characterized by a three-dimensional cross-linked network whose intermolecular links are intensified by a supply of calories. These are the result of a chemical transformation, called polymerisation or vulcanisation, and offer high mechanical performances.
Thermoplastics (principally polyethylene, polypropylene, polyamides, but also polyether ether ketone PEEK, Polyvinylidene fluoride PVDF), are easily fusible and recyclable. These are in turn the result of a chemical-free transformation, by a simple phase change linked to the temperature.
These matrices can be formulated, transformed, and used as such, pure, or combined with filler or reinforcement, which can be fibrous or particulate: carbon fibres, aramid fibres, glass fibres, mica fibres, but also glass flakes, micro and macro elements, hollow or solid, heavy-duty… Then these matrices, isotropic or not, can be surface modified again by specific thermal or mechanical treatments (such as vacuum nitriding), or at the core by the introduction of flame retardant or antistatic additives for example, whether or not linked to the matrix as well as tracers.
Utilisation Properties of Polymers
The utilisation properties are defined by the sum of mechanical and physical properties. For example, the simple reference to a polymer family and a hardness, as “Polyurethane 95 Shore A”, surely does not suffice to completely define a material, not only because there are numerous chemical sub-families of polyurethane (eight basic chemical structures: TDI-Polyether-polyol, TDI-Polyester-polyol, TDI-Polyester-amine, PPDI-polyester-polyol, TDI-Polyether-amine, MDI-Polyether-Polyol, MDI-Polyester/Polyol, PPDO Polyether-Polyol, etc.) which are more or less subject to a continued use in seawater, but also because an identical Shore hardness can show very different mechanical properties. See the real example below:
Polyurethane 95 Shore A "X"
Polyurethane 95 Shore A "Y"
Module at 100%
Module at 300%
Elongation at break
Tear Resistance to D-470
This is why each polymer material is characterized by many other properties, such as:
Rigidity or modulus of elasticity
Resistance or ultimate constraint properties
Hardness or resistance to the penetration of an independent object
Resiliency, shock resistance
Endurance, fatigue resistance by a rotating pressure
Long term wear, under very low pressure but long time periods
Please do not hesitate to ask our teams for any additional information.
Their expertise in structural relationships – utilisation properties of polymer materials, combined with the strong integrated capabilities of macromolecular engineering, now allows BARDOT Groups to identify infinite possibilities and technological opportunities day after day, and to choose from this group of possible materials the most promising according to an extended underwater use, in very specific conditions of exploration and production of marine energy, and also according to the LowPex® philosophy of the group, which aims to provide our clients with a better control of their CAPEX and OPEX. These materials, connected to their process and recipe of composition, after undergoing and fulfilling the complete challenging qualification procedures, form the established product range of BarDeep® and DeepFloat® materials, basis deemed reliable from designing many mechanical systems, manufactured and commercialised by BARDOT Group, among other “field proven” Technical Polymers. For example, these materials are characterized by their excellent resistant properties to bacterial colonization, even without additives prone to migrate during the period of use. A portion of BARDOT Group’s resources is also devoted to a prospective analysis on reactive and active materials, which will play an important part in the future technologies of the group, based, among other things, on nano mechanics.
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In the present context, the world is pursuing the development of renewable energies. One promising solution is marine renewable energy. In this field, Ocean Thermal Energy Conversion (OTEC) has the opportunity of becoming an essential contributor in using the temperature gradient between warm sea surface and cold deep sea water to run a heat engine and/or air conditioning (SWAC). Actually, those technologies are only at their beginning and there is room for major improvements thus major advantages can be highlighted compared to existing solutions.
Bardot Group is a renowned world Polymer specialist for subsea solutions. Our new concepts based on polymer materials allow significant cost reductions and efficient solutions for OTEC & SWAC technologies. Bardot Group experience relies on a solid knowledge of the HDPE (High Density Polyethylene) material, based upon 10 years of subsea projects and in house laboratory material qualification. Bardot Group has also developed and delivered its own Water Intake Riser (WIR) for cold water pumping for production process. Nowadays our design is based on a mix of structural and hydrodynamic analysis. In the past of the industry, studies remained focused in modelling the pipe/riser behaviour under waves and current mainly for steel structure. The use of HDPE pipes for SWAC and OTEC now brings new challenges that leads to develop specific material behaviour programs.
The aim of this paper is to present, in the first part, our testing program on HDPE mechanical properties. As a second part the paper will present the innovative Bardot concept for pumping cold water for Offshore systems and its applications to OTEC and SWAC.
For HDPE Pipes, specific material tests have been developed to assess the following mechanical properties: * Tensile * Compression * Abrasion tests to demonstrate the possible friction between two riser intakes or with the seabed. * Ageing process in seawater to model the variation of mechanical behaviour * Tensile uniaxial fatigue * Flexure fatigue
A full-scale test program is also scheduled to define: * Full-scale impact tests in case of interference with another material * Axial stiffness test * Hoop stress tests
In 2015, Bardot has developed a HDPE Water Intake Riser for the Total/Saipem Kaombo FPSO project (built in Singapore). The aim of the WIR is to use cold water for the FPSO process and to reduce the use of heat exchanger.
Thanks to using HDPE Riser, the loads applied on the hull and during the installation of the system are significantly reduced compared to steel Riser. Intensive hydrodynamic FEA on the global HDPE structure have been carried out. These FEA analysis showed that the HDPE light weight and low stiffness allows to decrease stress, moment reaction and impact in the line. Furthermore, our test campaign have also qualified the HDPE concept in fatigue using our SN Curve for HDPE.
Bardot is now exploring deep WIR for process cooling solutions.
Indeed today, HDPE material appears like a competitive solution also for OTEC. The main challenge in OTEC system is pumping water into deep water. Based on our experience and bringing our test campaign solutions, Bardot Group is developing innovative concepts for OTEC and SWAC system. Our knowledge gained on WIR is applied onto more important flow rates and deeper water depth for OTEC. HDPE riser also presents all necessary characteristics (low weight to reduce tension in top structure, good capacity in flexure...). At last, Bardot is applying its technology also to SWAC system including pipeline stabilisation system but also anti friction devices.
As a conclusion, the HDPE technology for designing, building and installing a deep water and large diameter riser for water pumping is a key element in the success of OTEC, SWAC and WIR. The proper material definition but also tests are key milestones in the development of this technology. Association of polymer specialist, hydrodynamic and use of HDPE can move OTEC/SWAC from research to industrial and competitive solutions.