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UWD-15 Wellhead Systems

Rated for working pressures to 15,000 psi, FMC Subsea Drilling Systems offers UWD-15 subsea wellheads for a complete range of shallow and deepwater drilling and production scenarios, including standard, shallow water flow, large bore and rigidized/preloaded operations. The family consists of the following systems:


 System Description

Standard  Rigid Lock  Large Bore  Large Bore-2M
 Designed for drilling and production applications up to 15,000 psi working pressure, the UWD-15 Standard System features a world-proven weight set, metal-to-metal seal design. The Standard System is designed for applications in water depths ranging from a few hundred feet to 6,000 feet. The wellhead systems can also be incorporated with annulus monitoring features. This modular system is designed with maximum flexibility and reliability in mind.

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. 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.  

FMC's Large Bore (LB) is an extension of the RLSD with additional provision to run two casing strings (18" and 16") submudline.

The system includes additional trip-saving tools such as single-trip tools for the submudline equipment where the hanger-packoff assemblies are run in a single trip. The submudline hangers have features to verify proper landing in their respective receptacles. The system also includes bore protectors that can be run and retrieved with drill strings, resulting in additional trip savings.

The Large Bore 2M (LB-2M) Wellhead System is an extension of the LB wellhead. The LB-2M features casing hangers and running tools designed to carry additional casing loads at the systems working pressure. The 16" submudline casing hanger, with a 2M lbs. high-capacity hanger system has a 10,000 psi working pressure rating. The 2M lbs. high-capacity 13-5/8" casing hanger lands inside the high-pressure housing and is rated for 15,000 psi working pressure.


  • 15K psi rated wellhead
  • 7.1M lbs. casing weight and pressure load capacity with passive load shoulder
  • 27" H4 mandrel profile connection
  • Metal-to-metal annulus seal assemblies
  • 16" submudline casing hanger (5K psi pressure rating, 550K lbs. string capacity)
  • 13-5/8" casing hanger (15K psi pressure rating, 1M lbs. string capacity)


The RLSD System features are identical with the Standard System except:

  • Isolation of the 36" x 20" annulus with shallow water flow packoff
  • Additional optional 28"/26" casing string
  • RLSE rigidizes the high-pressure housing to the 36" conductor housing with 2.0M lbs. preload

The Large Bore System features are identical to the Rigid Lock System except:

  • Active load shoulder for 13-5/8" hanger allows for additional 18" submudline hanger

  • Independent 18" and 16" submudline hangers

  • Increased hanger capacity in 16" hanger (6.5K psi pressure rating, 1M lbs. string capacity)

  • Increased hanger capacity in 13-5/8" hanger (1.5M lbs. string capacity)

  • LB-2M wellhead system allows 2M lbs. string capacity for 16" and 13-5/8" hanger


 Ideal Application

Wells located in a few hundred feet to 6,000 feet of water Wells located in deepwater with dynamically positioned vessels, shallow water flow concerns, or a tie-back

Wells located in deep water that require an additional casing string (18"); extra casing string capacity in the 16" and 13-5/8" 


Subsea Drilling Systems