Underground variable-diameter limiting body blocking and isolating device in casing

Abstract

The invention relates to an underground variable-diameter limiting body blocking and isolating device in a casing, which mainly solves the problems that drilling fluid retention occurs in a water replacing casing in the prior art and the obstructed phenomenon due to delayed measurement of sound change easily occurs. The underground variable-diameter limiting body blocking and isolating device is characterized in that a first-stage pressing cover is in threaded connection with the front end of a center shaft, a first-stage limiting body, a first-stage positioning ring and a height adjustment ring are fixedly connected to the center shaft on the back part of the first-stage pressing cover in sequence, and a first-stage rubber body is sheathed on the outer part of the first-stage limiting body; a second-stage pressing cover is connected to the center shaft on the lower part of the height adjustment ring, and a second-stage limiting body, a second-stage positioning ring and a third-stage positioning ring are fixedly connected to the center shaft on the lower part of the second-stage pressing cover; a second-stage rubber body is sheathed on the outer part of the second-stage limiting body; a four-head trapezoidal fastening screw and a reducing motor are connected in an inner cavity in the back part of the center shaft, and the motor is connected with a controller. By using the underground variable-diameter limiting body blocking and isolating device in the casing, after the well cementing operation is completed, the casing is guaranteed to be filled with clean water, and the obstructed phenomenon due to delayed measurement of sound change is avoided.

Description

technical field [0001] The invention relates to an isolating device in the field of petroleum engineering well cementing, in particular to a blocking and isolating device of an in-pipe downhole variable-diameter limiting body. Background technique [0002] At present, in the cementing operation of petroleum engineering, the cementing displacement process adopts the clean water displacement technology. The technical scheme of cementing displacement fluid is as follows: clean water + drilling fluid is used for the first displacement, and clean water is used for the second displacement. During a displacement process, a section of clean water is first replaced (the design volume of clean water is from 80 meters above the tool to the inner volume of the casing of the floating hoop), and then the drilling fluid is replaced until it hits pressure. After the completion of a displacement operation, the liquid in the pipe is clean water and drilling fluid . The second displacement u...

AI Technical Summary

Problems solved by technology

[0003] The technical problem to be solved by the present invention is to overcome the problems in the background technology that the drilling fluid will be retained in the casing of the clear water displacement technology and the phenomenon of delayed sound measurement and variable resistance is easy to occur, and to provide a downhole variable diameter limit body resistance in the pipe. Cut-off isolation device, the downhole variable-diameter limiter blocking isolation device in the pipe, after the cementing operation is completed, ensure that the pipe is filled with clean water to avoid the occurrence of delayed sound change resistance

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