CERASPHERE · Development of a Low Cost Ceramic Buoyancy Sphere

Oil and gas exploration is being carried out in ever deeper water, as more readily-exploitable reserves become depleted. And whilst previously uneconomical deep-water oilfields are now becoming financially viable, accessing them remains difficult due to the technical challenges associated with extreme operating conditions.When working in water at depths of up to 5000m the water pressure is above 500atm. Components and systems for extracting oil and gas need to be neutrally buoyant, in order to maintain them in the desired position. Buoyancy modules for drill risers used in exploration lines are currently made from syntactic foams using micro and macro-spheres. Macro-spheres offer buoyancy advantages, but become increasingly unreliable at greater depths due to manufacturing inconsistencies. A typical deep-water buoyancy module will contain thousands of tightly packed spheres, and when a buoyancy module fails this can necessitate costly repairs and lead to environmental harmThe current technology for buoyancy modules operating at less than 3km uses spheres made of Expanded PolyStyrene (EPS) balls which are then coated with a shell of epoxy resin. The epoxy coating acts as the load bearing structure withstanding water pressure. Spheres from each batch are pressure tested and rated for performance which determines the depth at which the batch can be usedThis proposal concerns development of a perfectly spherical, low-cost coated ceramic macrosphere manufacturing process. The ceramic spheres will be designed and manufactured in more than one size for improved packing density and rated for higher compressive strength allowing use at greater depths. A further development of this project is to address the sphere contact issues within the current syntactic foams. Point contact between spheres can contribute to failure from stress concentrations. We propose to coat the higher strength ceramic spheres with an elastomeric resin, reducing stress and the risk of failure.