When drilling through formations where unconsolidated shallow water flow sands are anticipated, an additional casing string is often used to isolate the zone. The UWD-15 Rigid-Lock Stack Down (RLSD) system allows for the addition of a 26" casing string without changing standard drilling procedures or components required for running subsequent casing strings. A rigid-lock seal assembly installed between the 36" and 20" casing strings contains any shallow water flow present. The rigid-lock seal assembly is set to contain the flow and “rigidize” the 36" and 18-3/4" housings together to provide high fatigue resistance in deepwater applications. The UWD-15/RLSD preloaded system handles the higher bending, fatigue, and torsional loads generated by TLP, Spar, DP drill ships, and DP semisubmersible applications. This unique stackable system is also used in many subsea tree applications where fatigue and torsional loads are expected. The UWD-15/RLSD system, with or without 26" conductor, is recommended for water depths up to 10,000 feet.
-
Modular design operates with or without 26" casing string for added flexibility during offshore operations
-
Full cement returns are allowed back to the mudline in 36" x 26" and 26" x 20" annuli for improved structural foundation
-
Rigid lock between the lowpressure and high-pressure housings accomplished using a remotely retrievable preloaded seal assembly
-
Rigid-lock seal assembly is run with the 18 3/4" high-pressure housing, the 20" casing string is cemented and the seal assembly is set and pressure tested with positive confirmation back to the rig floor in a single trip
-
The rigid-lock seal assembly can be retrieved, re-run, and tested with the 18-3/4" housing in place
-
Optional 16" casing string is installed submudline
-
Large flow-by area between the 26" casing hanger and the 36" low-pressure housing
-
All internal tools are identical to the standard system
-
Guideline or guidelineless configurations available
-
Bit run and retrievable wear bushings are available with this system
More Features and Benefits - More system specific features