METHOD OF PLACING CEMENT PLUG IN CASED WELL AND DEVICE THEREFOR Russian patent published in 2016 - IPC E21B33/13 E21B33/12 

FIELD: oil industry.

SUBSTANCE: invention relates to oil and gas industry and can be used during testing and repair of oil and gas wells with installation of a cement bridge. Method comprises lowering into a well on a working string a device consisting of shoe assembly, shank and packer-anchor. Then well is washed, followed by successive pumping of first buffer liquid, grouting mortar, a second buffer fluid and displacement fluid. Cement plug is passed between backfill solution and second buffer liquid. Shoe assembly is located in lower interval of placing cement plug, and in upper interval of placing cement plug is placed packer-anchor, consisting of packer assembly and anchor unit, fixed by a shear pin. Packer-anchor also includes a check valve. When cement plug passes through packer assembly separating plug removes hollow pin and opens delivery channel to communicate hydraulic chamber with intra-string space. After placing cement plug in shoe unit, anchor unit is actuated by raising pressure, as a result of which packer-anchor is fixed in casing string and detached from working string. Cement plug is fixed in shoe assembly. Grouting mortar is placed in range of placing cement plug in annular space between casing and shank, as well as above packer-anchor at its margin for replacement of volume, released after lifting shank with shoe assembly from interval of installing cement bridge. Second buffer fluid and displacement liquid are placed inside shank and working string. Then working string with shank is lifted to interval of arrangement of packer-anchor. When shoe assembly exits packer-anchor, closure of closing check valve is provided, covering central channel of packer-anchor. Further, using spring-loaded cams through shoe assembly of working string, axial load is generated on upper part of packer-anchor and packing is performed. By further increase of pressure in working string in shoe assembly, circulation holes are opened and second buffer fluid is used to wash out excess grouting mortar from interval above installation of packer-anchor. Then working string with shank and shoe assembly is lifted to surface.

EFFECT: technical result is higher reliability, safety, reduced volume of technological operations and preservation of mineral resources during installation of cement plug.

2 cl, 3 dwg