WELL CASING METHOD IN COMPLICATED CONDITIONS AND DEVICE FOR ITS IMPLEMENTATION Russian patent published in 2022 - IPC E21B33/14 E21B28/00 

FIELD: wells fixing.

SUBSTANCE: method for fixing a well in complicated conditions and a device for its implementation. The method includes wellbore preparation. The method also includes lowering the casing string to the bottomhole, tying the wellhead with an inlet line for pumping cement slurry into the casing string. The method also includes piping with an inlet line for pumping buffer and squeezing fluid into the casing string, piping with a preventer for sealing the annular space of the casing string, piping with an output line of process fluids with the possibility of their throttling. The method also includes flushing the well, preparing process fluids at the wellhead, and cementing the well in a straight line with excess pressure at the wellhead. Also, the method includes the preparation of a cement slurry according to the recipe of a specific well with a certain volume evenly closed and pumped into the casing string through an averaging tank, a manifold block and a cementing head. The method also includes squeezing the cement slurry with a squeezing fluid into the annulus with hydraulic impulse action on the wellhead, replacing the drilling fluid with the cement slurry with removal of the clay cake from the well wall, waiting for the cement to harden and continuing the hydraulic impulse action on the cement slurry until the end of its setting in the annulus. The cement slurry volume uniformly closed at the wellhead is divided into 5-10 equal portions, which are sequentially pumped into the casing string with increasing activation by means of their ultrasonic treatment. In each pumped portion of the solution, the power of the ultrasonic impact on them is proportionally increased to create in the annulus a sequential setting of the indicated portions of the cement slurry column ahead from the bottom to the mouth. Hydropulse action on the mouth is carried out simultaneously in the low-frequency and high-frequency ranges using two throttling elements. The plugging of the cement slurry into the annulus is carried out with an accelerated replacement of the removed clay cake with a cement cake, which is intensively built up on the well wall from an additional pack of water-cement slurry pressed in front of the cement slurry in the mode of simultaneous high-frequency and low-frequency hydropulse action. At the end of the squeezing of the cement slurry into the annulus, it is switched to the surface circulation of the squeezing fluid and the hydropulse action is continued both inside and outside the casing string.

EFFECT: improving the quality of cementing casing strings while reducing the accident rate, simplifying the device and increasing the reliability of its operation.

2 cl, 4 dwg