The invention relates to the technical field of oil and gas
well drilling and completion, in particular to a
pressure control method for well cementation operation, a sealing device and application of the sealing device, and the
pressure control method comprises the steps that in the well cementation operation process, whether overflow occurs or not is judged; if yes, the shut-in casing pressure is calculated; the equivalent mud density or the equivalent completion
fluid density for balancing the formation pressure is calculated according to the shut-in casing pressure, and the needed equivalent
wellhead return pressure is calculated; annular sealing of the
wellhead is kept, and the equivalent
wellhead return pressure obtained through calculation in the above step is maintained at the wellhead by controlling the opening degree of a throttling valve; and the
slurry density or the well completion
fluid density is gradually increased, the opening degree of the throttling valve is correspondingly controlled, and the well cementation operation process continues. By means of the
pressure control method, the sealing device and the application of the pressure control method, the sealing device and the sealing device, the annulus pressure profile of a shaft can be controlled in the well cementation operation, manual intervention on downhole pressure abnormity in multiple links such as casing running and well cementation can be achieved, the
well control risk of the well cementation operation is greatly improved, and the well cementation operation quality is improved.