Drilling riser is a conduits to transfer materials from the seafloor to production and drilling facilities atop the water's surface, as well as from the facility to the seafloor, subsea risers are a type of pipeline developed for this type of vertical transportation. Whether serving as production or import/export vehicles, risers are the connection between the subsea field developments and production and drilling facilities.
Similar to pipelines or flow lines, risers transport produced hydrocarbons, as well as production materials, such as injection fluids, control fluids and gas lift. Usually insulated to withstand seafloor temperatures, risers can be either rigid or flexible.
Types Of Risers
Deployed on fixed platforms, compliant towers and concrete gravity structures. Attached risers are clamped to the side of the fixed facilities, connecting the seabed to the production facility above
Pull tube risers
Used on fixed structures. Pipelines or flow lines that are threaded up the center of the facility.
Steel catenary risers
Used to connect the seafloor to production facilities above, as well as connect two floating production platforms, steel catenary risers are common on TLPs, FPSOs and spars, as well as fixed structures, compliant towers and gravity structures
Used on TLPs and spars. completely vertical riser system that terminates directly below the facility. Although moored, these floating facilities are able to move laterally with the wind and waves.
Riser towers and flexible riser configurations
Riser towers are ideal for ultra-deepwater environments, this riser design incorporates a steel column tower that reaches almost to the surface of the water, and this tower is topped with a massive buoyancy tank. The risers are located inside the tower, spanning the distance from the seafloor to the top of the tower and the buoyancy tanks.
Flexible risers can withstand both vertical and horizontal movement, making them ideal for use with floating facilities. There are a number of configurations for flexible risers, including the steep S and lazy S that utilize anchored buoyancy modules, as well as the steep wave and lazy wave that incorporates buoyancy modules
While production and import/export risers transfer hydrocarbons and production materials during the production phase of development; drilling risers transfer mud to the surface during drilling activities. Connected to the subsea BOP stack at the bottom and the rig at the top, drilling risers temporarily connect the wellbore to the surface to ensure drilling fluids to not leak into the water.
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