METHOD FOR CEMENTING THE CASING STRING OF A BOREHOLE Russian patent published in 2022 - IPC E21B33/14 

FIELD: petroleum industry.

SUBSTANCE: invention relates to the field of drilling petroleum and gas boreholes and can be used in cementing casing strings in the steady-state mode. Casing strings are cemented with a shut-in wellhead in the steady-state mode. Before tempering the cement, the annular preventer (PUG) is closed, the hydraulic valve in the working flow line is opened, a cementing unit is connected to the valve block in order to control the volume of the solution exiting the borehole. The back pressure required to ensure the steady-state mode is created in the behind-the-casing space at the wellhead by means of a throttle valve. The back pressure value depending on the position of the lower boundary of the cement solution in the borehole is determined by calculation, with account for the depth of descent of the casing string and the distance from the wellhead to the moving lower interface between the cement solution and the drilling mud in the casing string, respectively, the height of the cement solution column in the casing string at the end of pumping, corresponding to the volume required to cement the casing string; for the injection pressure and back pressure at the wellhead, respectively; the densities of the cement solution and the drilling mud, respectively; the coefficients of hydraulic resistances in the movement of the cement solution and the drilling mud in the casing string and the drilling mud and the cement solution in the annular behind-the-casing space; the speed of the cement solution or drilling mud in the casing string; the diameters of the borehole, the outer and inner casing string.

EFFECT: increase in the quality of cementing and increase in the effectiveness thereof due to the reduction in the borehole construction cost caused by preventing the occurrence of complications and the cost of elimination thereof.

1 cl, 2 dwg