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.

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.

A subsea line clamp assembly (1) has a body (10) having an axis and a clamp member (50), assembled in segments around a subsea line (3), and tethered to a subsea anchor (5). The clamp member (50) is movably located within the body (10). The inner surface of the body (10) and the outer surface of the clamp member (50) have respective tapered portions as part of teeth (32, 72) arranged to inter-engage. Adjacent teeth (32, 72) may be separated by axis-parallel portions. The clamping force on the subsea line (30) can be maintained at a consistent clamping force throughout the service life of the subsea line (3), despite the actions of creep and compression acting to reduce the outer diameter of the line (3).

A riser assembly and method of installing a riser assembly are disclosed. The riser assembly includes a first attachment element connected to a first portion of flexible pipe and a second attachment element connected to a second portion of flexible pipe. The first attachment element and second attachment element are connected by at least one tether element, via a fixed structure in a configuration such that, in use, in response to movement of the first and second portions of flexible pipe, the tension load at any moment in time, at each attachment element, remains substantially equal.

A method and apparatus are disclosed for supporting a flexible pipe. The method includes the steps of responsive to a change in at least one condition experienced by a flexible pipe, varying an amount of support provided at at least one location on the flexible pipe.

A clamp for a flexible pipe is provided that provide a load bearing flange on the flexible pipe permitting buoyancy jackets to be joined thereto. The clamp has a longitudinal axis arranged to extend along the length of the flexible pipe and a radial axis being perpendicular to the longitudinal axis. The clamp includes: a plurality of separate clamp elements being supported together in a radial array extending at least partially around the longitudinal axis; engagement means located between neighboring clamp elements to movably interconnect the clamp elements; and a strap being adapted to surround the clamp elements, in use for exerting a compressive force thereon. Also provided is a clamp element for use in the aforementioned clamp.

A riser assembly for transporting fluids from a sub-sea location is disclosed. The riser assembly includes a riser having at least one segment of flexible pipe and a plurality of buoyancy compensating elements connected to the riser and connected together in an in-line configuration to form a mid-line buoyancy section. The riser assembly also includes at least one buoyancy aid connected to the riser at a position above and spaced apart from the mid-line buoyancy section. The at least one buoyancy aid forms a first distributed buoyancy section and is sufficiently buoyant to maintain a tension load on the riser between the first distributed buoyancy section and the mid-line line buoyancy section. The riser assembly further includes at least one further buoyancy compensating element connected to the riser at a position above and spaced apart from the first distributed buoyancy section to form a second distributed buoyancy section. The second distributed buoyancy section is configured to support a portion of the riser in a wave configuration.

The invention relates to an offshore top site system comprising a subsea facility, a floating unit arranged above the subsea facility and at least one transportation line extending between the subsea facility and the floating unit. The transportation line comprises a catenary riser section and comprises an uppermost end and a top site section with a lowermost end. The catenary riser section and the top site section are in flow connection with each other. The transportation line further comprises a connecting portion preferably arranged within a vertical floating unit zone and between the top site section and the uppermost end of the riser section. The connection portion is pivotally connected to the floating unit. The connection portion is preferably pivotally connected to the floating unit such that at least a major part of pulling force from the riser section is alleviated by the connection to the floating unit.

A method for constructing a tubular connection assembly includes forming a first tubular having a first inner diameter, a first wall thickness, and a first connection end, forming a second tubular having a second inner diameter, a second wall thickness, and a second connection end, and increasing the first wall thickness of the first connection end, increasing the first inner diameter of the first connection end, increasing the second wall thickness of the second connection end, and increasing the second inner diameter of the second connection end. The first tubular and the second tubular are attached at a weld point between the first connection end and the second connection end so as to form a tubular connection assembly with a target amount of fatigue performance. A metallic riser, such as a steel catenary riser or a steel lazy wave riser, can be formed of a plurality of tubular connection assemblies.

Disclosed are riser assemblies for connecting a topside structure and a subsea production facility. The assembly includes an upper riser having an upper end terminating at the topside structure, a flow diverting structure having an upper interface configured to connect to the upper riser and a lower interface configured to connect to at least two lower risers such that the upper riser is in communication with the at least two lower risers. Methods of deployment of the riser assemblies are also disclosed. The method includes connecting an upper riser to the topside structure, and connecting a first lower riser to a lower bore of the flow diverting structure such that the upper riser, the flow diverting structure and the first lower riser are connected, and the upper riser is in fluid communication with the first lower riser. Additional lower risers can be installed at a later time if desired.