METHOD OF SIDETRACKING IN CASED WELL WITH EXTRACTION OF PART OF PRODUCTION CASING Russian patent published in 2017 - IPC E21B29/00 

FIELD: petroleum industry.

SUBSTANCE: invention refers to the construction of oil and gas wells mainly for reconstruction of idle wells. The method includes a descend of cutting tools, the sidetracking of a site of the production casing in the sidetracking area. Whereupon, the production casing in the area of sidetracking is cut, lifted, and cemented; and a cemented bridge is installed on the open part of the hole; the lateral hole is drilled from this bridge. In the case of cement rock in the bore-hole annulus, firstly, cement rock integrity is destructed between the conductor string and the production casing to the depth of at least 50 m below the conductor shoe by the special device, the burning shoe with the "left" taper tap. In the case of cement rock on the site of more than 50-100 m from the conductor shoe in the bore-hole annulus, between the conductor and the production casing, after production of works for extraction of the production casing and further impossibility of the extraction of the production casing, the whipstock is installed below the conductor shoe, and the cutting-out of a "window" above the conductor shoe with the diameter larger than the diameter of prospective boring cutter and sidetracking of the lateral hole with the normal diameter of drilling tools are performed.

EFFECT: time expenditures are reduced, process capabilities for reconstruction of the "old" well inventory are expanded.

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