Frac Systems and Services
Offshore Exploration
Shallow Water Solutions
Contact Us
Offshore Exploration Overview

Offshore Exploration

OBS-II Exploration Wellhead Systems

The OBS-II drill-through rental wellhead system can run mudline hanger systems much faster and safer than conventional wellhead systems. This new rental wellhead system has saved between 21 and 29 hours of jackup rig time during exploration drilling. More importantly, the OBS-II system reduces operational risk and improves safety for rig workers. Both the time savings and safety improvements come from FMC’s Unihead through-bore technology.


  • Exploration jackup drilling
  • Shallow water wells with mudline suspension systems
  • Predrilled development wells for tieback to platform
  • Drilling program:
       30” (26”) x 20” (18-5/8”) x 13-3/8” x 9-5/8”
       30” (26”) x 13-3/8” x 9-5/8" 


  • Drill-through system saves rig time
  • Less BOP handling reduces exposure to hazardous operations
  • Speedloc-II connectors reduce nipple up time
  • Safer operations:
       No welding
       No cutting casing strings
       No open-well exposure
       No working under suspended BOPs
  • Complete 24-hour service support


  • 10,000-psi pressure rating
  • Large 8-in. space out tolerance
  • Proven sliplock technology
  • Industry standard clamp hubs and ring gaskets
  • Standard FMC 100 series gate valves
  • Full range of crossovers to fit all BOP configurations

OBS-II Adjustable Wellhead

FMC Technologies’ OBS-II drill-through wellhead system has a revolutionary design that allows adjustment and tensioning of two casing strings inside the wellhead. The system is designed for typical 13-3/8” and 9-5/8” casing strings, but this can vary according to your casing program.

The system is available in a full hole design, 30” x 20” x 13-3/8” x 9-5/8”, and a minimal configuration, 30” x 13-3/8” x 9-5/8”. The principle application of this system is for drilling exploration wells using mudline suspension equipment without having to break the stack, set slips, add another spool and nipple up again. Thus, operators benefit from significant time savings over conventional wellhead systems and reduced exposure to hazardous operations. The spaceout of all the casing strings is achieved within an 8-inch range. The 13-3/8” string is adjusted mechanically, and the 9-5/8” string is run on a mandrel hanger with tension retained by hydraulically actuated slips.

The OBS-II system has been designed in accordance with API 6A, validated by in-house testing, and field proven in many locations.

SD-1 Mudline Suspension

FMC’s OBS-II system is used in conjunction with the SD-1 mudline suspension system, which suspends casing weight at the mudline for wells drilled with a jackup rig. The SD-1 system provides economical, efficient drilling, abandonment and tiebacks for offshore exploratory wells. The SD-1 is a fully field-proven system with more than 20 years of worldwide use. It is available in all popular casing and conductor sizes. The system is a compact stack down design, provides improved cement washout, and meets NACE requirements for H2S service. The SD-1 system is rated for 10,000 psi working pressure and can be supplied to 15,000 psi upon request.