Techniques and systems to reduce deflection of a riser extending from an offshore platform. A device may include a main tube disposed along a length of the device. The device may also include a support member that may be coupled to the main tube, wherein the support member may surround the main tube. The device may include a buoyancy assembly that may at least partially surround the main tube, wherein the buoyancy assembly may have an elongated non-circular and non-cylindrical shape. The buoyancy assembly may also include buoyancy foam.

A flotation system includes one or more floatation modules, each having a first section and a second section, each having an internal core made of a buoyant material. The first section includes two end faces and a projection extending from one of the end faces. The projection has a contoured profile. The second section includes two end faces and a reciprocal recess in one of the end faces. The end faces of the first section engage the end faces of the second section such that the projection engages the reciprocal recess in a mating engagement. A stop collar may be disposed adjacent each end of the floatation module. The floatation system may be attached to a tubular string that is lowered into a marine riser to reduce a load applied to a rig disposed over the marine riser.

A riser or jumper assembly for transporting production, exportation or injection fluids is disclosed as is a method for providing buoyancy to such an assembly. The riser or jumper assembly includes a first segment of flexible pipe comprising a portion of flexible pipe body and a first and second end fitting, a further segment of flexible pipe comprising a portion of flexible pipe body and a first and second end fitting and an intermediate segment of flexible pipe comprising a portion of flexible pipe body and a first and second end fitting and at least one buoyancy element.

Apparatus and method for supporting a riser are disclosed. The apparatus includes an anchoring element for anchoring a riser to a fixed structure, and a supporting portion configured to support a section of flexible pipe, the supporting portion having a bearing surface for the section of flexible pipe to bear against to thereby restrain the flexible pipe from upward movement.

A marine riser system, a buoyancy system, and a method of buoying a body. A riser joint includes a body, a buoyancy module, a thrust collar, and a reaction collar. The buoyancy module is coupled around the body and configured to produce a buoyant force when submerged at a subsea location. The thrust collar is coupled around the body and engaged with the buoyancy module to transfer the buoyant force to the body. The reaction collar is engaged with the body such that movement of the buoyancy module is restricted by the reaction collar.

An installation of bottom-to-surface connections of at least two undersea pipes (11-1, 11-2) resting on the sea bottom (10), and a rigid pipe (1-1, 1-2) constituted by a vertical riser having its bottom end (1a) fastened to a base (9-1, 9-2) at the sea bottom (10), and having its top end (1b) tensioned by an immersed float (4-1, 4-2); and a flexible connection pipe (2-1, 2-2) providing the connection between a common floating support (12) and the top end (1b) of the vertical riser via a junction device (3-1, 3-2; wherein two hybrid towers are connected together by at least one rigid separator bar (5) having a length not less than the diameter of the larger-diameter float.

A buoyant apparatus and method of use buoyancy to offset the weight of a load during immersion of the load in a fluid medium such as a payload manipulated by a cable and crane or by a remotely operated undersea vehicle. Buoyancy modules that can be of different size and shape have elongated supports that are attachable via complementary connection fixtures at the ends. The attached supports form a skeleton of the array. The connection fixtures are axially resiliently compressible and maintain the buoyancy modules in abutment notwithstanding shrinkage or expansion of the buoyant material due to hydrostatic pressure that increases with depth.

A buoyancy device (1) comprises a support structure 2, 4 which can be connected to an underwater application (3) and one or more buoyancy spheres (4) having a specific weight of less than 500 kg/m.sup.3 connected to the support structure (2) and having a light metal spherical shell (5) defining a spherical inner volume (6) and which has an outer diameter (d) greater than 0.5cm, and a radial thickness (t) greater than 0.08mm, wherein the spherical shell (5) is obtained in one piece in nano-crystalline metal with an average grain size of less than 1000 nanometers.

A flotation system includes one or more floatation modules, each having a first section and a second section, each having an internal core made of a buoyant material. The first section includes two end faces and a projection extending from one of the end faces. The projection has a contoured profile. The second section includes two end faces and a reciprocal recess in one of the end faces. The end faces of the first section engage the end faces of the second section such that the projection engages the reciprocal recess in a mating engagement. The outer surface of the flotation module include one or more grooves providing a pathway for the flow of circulation fluid. The floatation system may be attached to a tubular string during inner string cementing operations to reduce the load applied to the platform.

The disclosure relates to a method for detecting water in a tensioning buoy of a riser column of an installation located in an aquatic environment, the method including, in succession, steps of: defining a representative standard echo; emitting the ultrasonic signal on a wall of the buoy; measuring a representative response echo due to the reflection of the ultrasonic signal in the buoy; comparing the representative response echo to the representative standard echo; and determining whether water is present in or absent from the buoy from the comparison.