Helical coil annular access plug and abandonment
A method for creating access to annular spacing during P&A operations is described. Specifically, helical coils are cut into one or more casings before the plugging material is set. The plugging material is able to exit the helical coils, forming multiple, small rock-to-rock seals.
1. A method of sealing an annular space in a hydrocarbon well, said method comprising:
a) deploying a cutting tool downhole to cut a helical coil opening in one or more casings at a section of an annular space in a well to be sealed, wherein said helical coil opening provides access to said annular space external to an outermost casing;
b) deploying a heat resistant ceramic base plug below said section;
c) deploying a solid bismuth alloy and a thermite heater to said section to form molten alloy;
d) squeezing said molten alloy to force it to flow out said helical coil openings while filling said section of annular space;
e) allowing said molten alloy to solidify thereby sealing said section of annular space; and
f) optionally repeating steps a)-d) at one or more different depths.
2. The method of claim 1 , wherein said cutting tool is a laser or an abrasive cutter.
3. The method of claim 1 , wherein in a further step g) said base plug is drilled out.
4. The method of claim 1 , wherein an inner tubing string is cut or removed at said section before said outermost casing is cut.
5. The method of claim 4 , wherein a mill or a laser is used to remove said inner tubing string.
6. The method of claim 1 , further comprising deploying a plugging material to said section to fill a space interior to said annular space, thereby plugging said well.
7. The method of claim 6 , wherein said plugging material is cement or resin or a bismuth alloy or combinations thereof.
8. The method of claim 6 , wherein said cutting tool is a laser or an abrasive cutter.
9. The method of claim 6 , wherein an inner tubing string is cut or removed at said section before said outermost casing is cut.
10. The method of claim 9 , wherein a mill or a laser is used to remove said inner tubing string.