Private Forums
Slot Recovery
24 September 2012
Slot recovery, Well is vertical We have the following:
  • 30” conductor set at 300 ft MD (200 ft below sea bed) (ID of Conductor 28”)
  • 13 â…œ” set at 4500 and cemented to surface. (13â…œ” 68 LB/FT)
  • 9 ⅝” CSG set at 8500 ft MD, cemented to surface.
The plan to sidetrack the well below the 30” conductor shoe, drill new hole 17"” hole, set new 13â…œ”. In fact we did so far 8 wells by milling both casing (9⅝" and 13â…œ")from surface to 50 ft below the 30” conductor shoe, but we are still looking to improve the cost because each job of milling is costing us 2.5MM$ to clear enough room below the conductor shoe.

The milling also took 15 days to mill ±300 ft of 13â…œ” and 9 ⅝” casing. We found the above method is costly (money and days). Next year one of the wells will be vertical and we need to do some is different and we need your advice.

  1. We will remove the well head after abandonment the old hole.
  2. Cut all casing (9⅝” and 13â…œ”casing) to 50 ft below the conductor shoe.
  3. the clearance between the 30” conductor and 13â…œ” CSG is enough to wash over the cement (drill the cement) ,we will use especial core head or special rotary wash pipe shoe
  4. We will put 16” casing or 18⅝” as extension above the bit.
  5. We will continue drilling to 10 ft below the conductor shoe.
  6. run with 9⅝” CSG spear and latch into CSG and Pull the casing and L/D same.

May be the Casing is not centric inside the 30” Conductor, so will make drilling the cement with rotary shoe  very difficult. Therefore Can we use 3â…›” bit with 3"” drill pipe or 2⅞” to clean the cement in the biggest side of the clearance between the 30” conductor & 13â…œ” casing.
7 answer(s)
Well Control Specialist - Senior Drilling Supervisor
Total Posts: 31
Join Date: 04/11/07
Having extensive slot recovery experience in the SNS and on the NW Hutton Decommissioning in the past, I have found that rather than milling and trying to washover the redundant casing, it was much quicker and much less messy for the rig equipment to go in, cut short sections of casing and jar that free, especially in shallow holes where the tripping times are short.
Good luck.
Drilling Services Consultant
Clyde Drilling
Total Posts: 10
Join Date: 05/11/14

You can cut the all the strings including the 30" in one cut just above the 30" shoe using a sub-surface abrasive cutter SABRE from Claxton in Dubai. Then you can install your whipstock on the stump and off you go.

OR cut everything at / near seabed using SABRE, or diamond wire and then set a casing whipstock on the stump. You can later correct the well back to vertical if necessary.

Well Construction Manager
Applied Drilling Technology International
Total Posts: 3
Join Date: 11/02/10
Try these folk, they might be able to supply a better way to cut.
Drilling Specialist/Well Engineer/Training Consultant
Kingdom Drilling
Total Posts: 361
Join Date: 10/01/05
This is from a Jack up I presume?
why not simply cut all casings with a one triptool i.e. 10ft below mud line. Note: One company has a four bladed casing cutter, this is considered the most superior.

then run drill or drive a bent curved conductor to give you the new well kick off and Trajectory required.

I am sure, We used to run curved conductors I recall in the 90's from North Sea platforms so this may be doable.
The Gulf of Suez Petroleum Company
Total Posts: 3
Join Date: 08/08/12

All what you need is to cur the 30", 13-3/8" and 9-5/8" casing with Multi String cutter or diamond wire as generally the 13-3/8" casing will not be centralized in the 30" conductor and break the knifes,  so the diamond wire cutter is more efficient.  Then L/D the cemented string in sections.

 After that you can use a deflecting sleeve to drive 24” conductor or you can pull the conductor but it will be a risky operation.

You have many collogue X Gupco in ADMA performed this job before. This is a short hint and if you need more detail you can contact me.  

DSL (Drill Site Leader)
Abu Dhabi Marine Operating Company
Total Posts: 48
Join Date: 20/04/11
first of all thanks SamehHussin for your replay Exactly, this is the one of slot recovery technique if you have depleted reservoir , also it is suitable for driven new conductor by using deflecting tool. but it is difficult in case drilling 36” hole, then run & cemented 30”condcouter because the sea bed is hard, the idea from my new technique to keep the old conductor as it is.
Senior Drilling Engineer
The Gulf of Suez Petroleum Company
Total Posts: 3
Join Date: 08/08/12

You can cut 30", 13-3/8", 9-5/8" with internal or external cutter 6-8' above sea bed, run with 30" deflecting tool (This tool use here in Egypt to drive new conductor beside the old one) drive new 30" conductor, drill new well.

Sameh Hussein

Jump to top of the page