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.