METHOD FOR MULTI-STAGE CUFF CEMENTING OF WELLS Russian patent published in 2021 - IPC E21B33/14 

FIELD: oil industry.

SUBSTANCE: invention can be applied for the collar stage cementing of casing strings in oil and gas wells. The method is characterized in that a collar cementing packer is installed above the filter part, consisting of a sleeve part designed to close the annulus of the well, and a collar part designed to fill the annular space above the packer with cement slurry of the first stage of cementing. At a predetermined depth, a cementing sleeve is installed to fill the annulus with cement slurry of the second stage of cementing. The sealing element of the packer is inflated until it contacts the borehole wall. The cementing holes in the packer sleeve portion open for performing the collar cementing. The first volume of cement slurry is pumped in and the first squeeze plug is placed. Drilling fluid is pumped over the plug and the plug is pushed, while simultaneously displacing the cement slurry from the pipe space into the annular space. A second squeeze plug is placed in the pipe space and two plugs are simultaneously pushed at a predetermined distance from each other until the first squeeze plug fits into the saddle located in the collar cementing packer. After the first displacement plug has been seated, the cementing windows are closed. The technological windows located in the cementing sleeve are opened, to provide communication between the pipe and annular spaces, and the second cementing plug is pushed through until it fits into the landing seat of the cementing sleeve. Excessive pressure is created over the second displacement plug and the cementing holes in the cementing sleeve are opened to receive the second stage cement slurry. After the cement slurry of the first stage has set, a second volume of cement slurry is pumped into the pipe and a third squeeze plug is placed. It is pushed through until it fits into the saddle located in the cementing sleeve, while the cement slurry of the second stage is squeezed out into the annulus. After the third plug is seated in the landing seat, overpressure is created and the cementing holes in the cementing sleeve are closed.

EFFECT: increased reliability and simplified method of collar step cementing of wells without cementing the filter section in the zone of the productive formation.

1 cl, 1 dwg