TL;DR
A leaking wash pipe seal causes mud loss and can spray drilling fluid onto rig personnel. Replace the wash pipe packing at the earliest drill pipe connection.
What you might see
- drilling mud leaking from wash pipe area
- pressure drop at swivel during drilling
- mud volume gain in the active system
- wash pipe union showing wet marks
Likely causes
Wash pipe packing wear from abrasive drilling fluid
Wash pipe surface scoring creating a bypass path for fluid
Packing retainer loose or backed off from vibration
Wrong packing material grade installed for the mud weight and pressure
Required tools
- LOTO kit
- Torque wrench (for packing retainer)
- Replacement wash pipe packing kit
- PPE: face shield, chemical gloves, coveralls
Safety first
- Drilling mud is at high pressure at the wash pipe. Do not approach from below. Shut down mud pumps before any seal work.
- The rig floor is a dropped object hazard zone. All tools used at top drive height must be tethered.
- Lock out the top drive rotation and confirm zero rotation before touching any component of the wash pipe assembly.
Procedure
- 1
Identify the leak location at the wash pipe. Distinguish between the upper and lower packing areas.
Warning: Drilling mud is under high pressure at the wash pipe. Do not approach the leak from directly below. Wear face shield and chemical splash protection. - 2
At the next drill pipe connection, shut down the mud pumps and lock out the top drive rotation.[1]
- 3
Inspect the wash pipe body for scoring, grooves, or pitting. A scored wash pipe will not seal reliably even with new packing.[1]
- 4
Remove the packing retainer and old packing rings. Clean the packing chamber.
- 5
Install new packing of the correct grade for the mud weight and standpipe pressure. Torque the retainer to specification.
- 6
If the wash pipe body is damaged, replace the wash pipe assembly.
- 7
Restore pressure to the mud system and confirm the leak is eliminated before continuing to drill.
Sources
NOV (National Oilwell Varco) NOV TDS-11SA / Ideal Drilling Rig / Top Drive general technical documentation, NOV (National Oilwell Varco)
NOV TDS-11SA / Ideal top drive general wash pipe packing and seal replacement procedures (general)
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