Ball seat milling and re-fracturing method

摘要

A well that has a plurality of sliding sleeves used to originally fracture multiple zones with balls of increasing size dropped on balls seats to sequentially open ports for fracturing in a direction toward the well surface is refractured. The method involves using a bottom hole assembly (BHA) that has a fluid motor driven mill that mills out ball seats and has with it a ported sub and a resettable packer. Once the lowermost ball seat is milled out a ball is dropped into the BHA to isolate the fluid motor and open a ported sub below a resettable packer. The dropped ball also enables a collet to latch an open sleeve to give a surface signal that the BHA is located properly for packer deployment so that the refracturing can begin through the coiled tubing string that can support the BHA or in a surrounding annular space.

主权项

1. A re-fracturing method for a subterranean location having a plurality of valves adjacent ports in a tubular string that were opened for earlier fracturing at the subterranean location by an object delivered to a seat thereon, comprising:running in a string to at least one of said valves;
removing at least one seat associated with said valves with said string when said one of said valves is in an open position with respect to said port adjacent to said valve and removing cuttings from the subterranean location in an uphole direction toward a borehole entrance to the subterranean location; isolating said at least one open port in said tubular string with said string from at least one other said port in said tubular string; refracturing through said at least one open isolated port using said string; performing said removing, isolating and refracturing in a single trip with said string to the subterranean location.