Backflow preventing device for well cementation

Abstract

The invention relates to a well cementation tool for petroleum drilling, in particular to a backflow preventing device for well cementation. A suspension body is fixedly connected to a step in the body of the device; the upper ends of a plurality of connecting bars are connected with the suspension body, and the lower ends of the connecting bars are connected with a limit seat and fixing nuts; the middle of the limit seat is connected with the outer side at the lower end of a limit body; a valve body is arranged in the limit body and is sleeved with a return spring; the lower end of the return spring is propped against a step in the limit body, and the upper end of the return spring is propped against a step of the valve body; the spherical surface at the upper end of the valve body is matched with the lower cambered surface of the suspension body to form a sealed state. The backflow preventing device realizes safe well cementation, can prevent cement paste from flowing back, has the characteristics of high backflow preventing pressure, backflow preventing reliability, simple structure and convenience in use, and overcomes the defects that in the prior art, cement paste flows back after well cementation bumping, a cement plug exists in a pipe and cement outside the pipe flows back at a velocity.

Description

Technical field: [0001] The invention relates to an oil drilling cementing tool, in particular to a cementing anti-backflow device. Background technique: [0002] In well cementing, since the density of the cement slurry is greater than that of the drilling fluid, after the cement slurry replaces the casing, if there is no anti-backflow device, the phenomenon of cement backflow will occur, the cement outside the pipe will return low, and the cement plug will remain inside the pipe. Cause engineering accidents, affect quality, and cause large economic losses. Invention content: [0003] The technical problem to be solved by the present invention is to provide a cementing anti-backflow device, which realizes safe cementing to prevent cement slurry backflow, high anti-backflow pressure, reliable backflow prevention, simple structure and convenient use. It overcomes the disadvantages of the cement back-up after bumping in the existing well cementing, cement plugs inside the p...

AI Technical Summary

Problems solved by technology

[0002] In well cementing, since the density of the cement slurry is greater than that of the drilling fluid, after the cement slurry replaces the casing, if there is no anti-backflow device, the phenomenon of cement backflow will occur, the cement outside the pipe will return low, and the cement plug will remain inside the pipe. Cause engineering accidents, affect quality, and cause large economic losses

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