METHOD FOR TROUBLESOME WELL ZONE ISOLATION AND PACKER Russian patent published in 2005 - IPC

FIELD: oil and gas industry, particularly for cementing and plugging holes, crevices, or the like.

SUBSTANCE: method involves lowering grout pipes provided with device for isolating annular space between casing pipe and grout pipes and with milling tool located in lover grout pipe parts; ejecting pressurized oil-based cement grout through grout pipes; forcing cement grout into troublesome zone by stepped rising cement grout pressure up to value increasing formation pressure and by following stepped pressure reduction, wherein above pressure increase and reduction operations are repeated with different rates of pressure change; drilling the cement bridge formed in well bore and packer with the use of grout pipes and milling tool, wherein packer includes docking unit to connect thereof with pipe string and connection pipe detachably attached with docking unit. Connection pipe has at least one overflow orifice. Seat for free fall member is formed in lower part of connection pipe under overflow orifice. Attached to connection pipe are split dies secured to the connection pipe by cup closing overflow orifice from connection pipe outside. The cup, lower dies and connection pipe define cavity hydraulically communicating with connection pipe interior through overflow orifice. Connection pipe has upper dies. Upper and lower wedges cooperate with corresponding dies. Sealing member is arranged on connection pipe between the wedges so that sealing member may be deformed in transversal direction when docking unit cooperates with upper dies. Upper dies may be split up under the action of force exceeding deforming force of sealing member installed in its operative position and during device securing inside the well. Docking unit has ring cutter.

EFFECT: increased efficiency of isolation method and improved operational reliability of the device.

6 cl, 1 dwg