The grading hoop (grading cement injector) is a special tool used in two-stage cementing operations. The use of this tool can divide the section to be cemented into two stages from bottom to top for cementing, and can also realize any section of formation cementing operations.

The use of graded collars for graded cementing operations can reduce the hydrostatic column pressure in the annulus, which not only reduces the possibility of lost circulation during cementing operations, but also reduces construction pressure and cementing time, while preventing or reducing The oil and gas water channeling caused by the weight loss of the cement slurry is beneficial to improve the cementing quality.
The actual work situation on site: the outer pipe packer + grading hoop does not work before the first-level cementing and pressing the rubber plug, and the replacement rubber plug will start to work after passing through the outer pipe packer, and confirm the expansion and sealing - put in the shell to open the grading injection channel Hole (longer free fall time in the mud, 35 minutes required by the insurance manufacturer) - circulating the excess mud from the upper part - waiting for setting for 24 hours - secondary injection - closing the hole - waiting for setting for 48 hours - measuring sound amplitude.