Good day - I have a challenge I’d like to have some input on.
I need to cut several casing strings as part of an onshore well abandonment.
The strings I need to cut are:
178mm 34.2 kg/m J55 – cemented to surface
244.5mm 79.6kg/m L-80 – cemented to surface
“Inner conductor” 406mm OD - 16” 0.312” wall line pipe (40 ksi?)
“Outer Conductor” 509mm OD - 20” 0.375” wall
line pipe (40 ksi?)
no cement between the conductor pipes
Cut depth is about 10 meters (33 feet) below ground.
This is a very difficult to access location and since the
well is already abandoned downhole, the client would like to evaluate a rig-less
approach – likely helicopter borne (about a 5000lb weight limit per load).
Due to the cement sheath I assume that the first three
casing strings must be cut & pulled together.
I have the following concerns/issues.
The limitations of about a 156mm (6”) ID and a
cut to 406mm (16”) diameter will mean stand-off issues for abrasive/water jet
The traditional casing cutting methods that I am
familiar with all require the rotation/torque capabilities of a rig (which I’m
trying to avoid due to huge logistics issues).
Does anyone in the community have any experience
with this kind of problem, or suggestions regarding tools/techniques/suppliers?
Thanks in advance
Sounds like a fun project.
Oceaneering has multi-string abrasive cutting capabilities with a 5.913" drift for the smallest tool size. With one tooling run, all the casings could be cut. The biggest obstacle would be the weight limit imposed for the heli lifts.
Another option would be a diamond wire or guillotine saw, both of which Oceaneering can provide as well. This would be preferred, especially if you can get approval to cut at a shallower depth.
Feel free to email me with any questions...firstname.lastname@example.org
Laser cutting tech, developed by Foroenergy , has been used successfully in the North Sea for multiple strings cutting, it is wroth getting in touch with them to explore the options and viability. .
Have a look at the AXE Tool from Helix.
It is originally an offshore application, may be you can make it work onshore as well.
The alternative ... a large explosive charge should do the job.
I would have to first ask why they need casings cut at 10m/33 ft BGL rather than bottom of cellar? : some local regulation ? But if that is what they want to pay for , then ....hard to access location, you say ? !
The construction industry may have some solutions. I know specialist foundation companies can do foundation pile removal and may be worth a look. Their smaller construction drilling rigs may also be able to be broken down and heli-portable. Maybe some food for thought on link here...http://www.bauertech.co.uk/QuietPileRemoval.html
Going a little sideways, do ground conditions allow you to excavate down to the required depth?
If so, this would logistically make things much easier, as all that would be needed are gas axe equipment, some wire rope, sheaves & shackles, an 'A' frame, a Bulldozer, a BackHoe and an explosive charge.
I know Caterpillar have Bulldozers and BackHoe's that can be easily broken down to be heli-transportable.
The general sequence would be to first set off a large explosive severing charge at the required depth.
If this then allows you to pull the inner three strings (using the A frame, sheaves and bulldozer) that's a bonus, but the principle purpose is to destroy the cement in that area.
Excavate around the conductor with the bulldozer & back hoe to the required depth.
You should then be able to flame cut and recover the 20" over the other casings.
After that is recovered, the cement being shattered by the explosive charge should make it much easier to cut the remaining casing strings and recover those.
An alternative to flame cutting could be a method used by the well control companies. They sometimes use a wire rope coated in an abrasive material, which is then pulled against the casing and wound backwards and forwards by two winches to saw the wellhead off.
All the Best
Diamond cutters as used by Rovs on Subsea well during rifles abandonment.
This is an external tool that should be able to cut all strings externally like a saw blade cutting through a large tree.
Not sure if access to well you may need to excavate some area around wellhead to access tool.
Suggest you seek out companies who have these tools