RIGSDOMRIGSDOM · H₂S sour service drilling rigs
Sour serviceH₂S sour service drilling rigs
Drilling a sour well is a materials problem before it is an operational one. Units in the fleet carry H₂S spools to NACE MR-01-75, and the sour service programme, detection layout and contingency plan can be prepared for your well before the rig moves.
What sour service actually requires
H₂S attacks steel through sulphide stress cracking, and the failure mode is sudden. Compliance is not a single certificate but a chain of decisions:
- Materials — wellhead, spools, BOP body and elastomers selected to NACE MR-01-75 and ISO 15156, with hardness limits verified rather than assumed.
- Detection — fixed sensors at the flowline, shakers, cellar, rig floor and living quarters, with set points typically at 10 and 15 ppm and a defined action at each level.
- Respiratory protection — SCBA sets and escape sets in counted quantities, fit tested, with a cascade system for extended work.
- Mud chemistry — pH control and sulphide scavenger at monitored concentration, checked on a schedule rather than on suspicion.
- Layout — briefing areas placed against prevailing wind, windsocks visible from the floor, and an evacuation discipline everyone has drilled.
Which units are suited to sour work
Two units carry H₂S spools per NACE MR-01-75 as standard, both with mud gas separators and gas detection fitted. Where a well requires sour service on a unit not currently equipped, the modification scope and cost can be quoted with the rig.
The judgement to make is not simply which rig is labelled sour, but whether the whole system — materials, detection, mud, layout and crew training — matches the concentration you expect. A rig with the right spool and untrained crew is not ready.
Preparing the sour programme before you spud
The engineering suite on this site prepares an H₂S contingency plan and sour service programme covering detection set points by location, alarm levels with the action for each, SCBA counts, briefing area placement, NACE materials verification, scavenger treatment, drill schedule, medevac routing and a pre-spud checklist an auditor can walk.
It is written to API RP 49 and API RP 55 with the standards cited by number, and issued as a watermarked PDF.
Matching units
Common questions
Which rigs are certified for H₂S service?
Units carrying H₂S spools per NACE MR-01-75 are marked H₂S service in the fleet listing. Both are equipped with mud gas separators and gas detection.
Can a rig be upgraded for sour service?
In most cases yes. The scope covers wellhead and BOP materials, spools, elastomers, detection and mud system provision. The scope and cost are quoted with the unit.
Can RIGSDOM prepare the H₂S contingency plan?
Yes. The engineering suite prepares a full sour service programme to API RP 49, including detection set points, alarm response levels, SCBA counts, materials verification and a pre-spud checklist.
Talk to the desk
Tell us the well, the location and the timing, and we will come back with the units that fit, the delivered price or day rate, and the technical data pack.