Grading Hoops

Abstract

The invention provides a classifying hoop for sealing multistage oil wells. The classifying hoop comprises a roughly cylindrical body, a first sliding sleeve, a first plug holder and a first sealing plug, a circulation port and a first groove are formed in the side wall of the body, the first plug holder can drive the first sliding sleeve to axially slide relative to the body under the action of the first sealing plug to open the circulation port, the first sliding sleeve is connected with the first plug holder by the aid of a first clamp pin, and the first clamp pin at least partially slides into the first groove when the first sliding sleeve axially slides relative to the body, so that connection between the first sliding sleeve and the first plug holder is removed. Compared with the prior art, the classifying hoop is lower in manufacturing cost, has better operation reliability, and can adapt to wider operation conditions.

Description

technical field [0001] The invention relates to the field of oil well sealing, in particular to a grading hoop used for grading oil well sealing. Background technique [0002] At present, the shallow layers of most oilfields have been explored and developed. In order to obtain more oil and gas reserves and development production, only medium-deep wells, deep wells and ultra-deep wells can be deployed for exploration and production. In medium-deep wells, deep wells and ultra-deep wells, due to the large upper and lower intervals of oil and gas layers, gas and formation water corrosion on casings, etc., it is necessary to implement sealing technology for the entire well. Earlier, the cementing of the whole well usually adopted the conventional cement one-time upward cementing process. In this process, leakage often occurred, ranging from insufficient cement return height to serious quality accidents of unsealed upper oil layers. Using low-density high-strength cement to carr...

AI Technical Summary

Problems solved by technology

However, due to the possible defects of the material used to make the pins and the constraints of the cementing operation, it is easy to happen that the pins cannot be cut as required, such as not cut off or cut off in advance, resulting in operation failure

At the same time, the sheared pin part is easy to fall into the gap between the grading hoop assembly and the assembly is stuck and unable to move, resulting in operation failure

[0006] Therefore, although the grading hoops in the prior art can realize drilling-free grading cementing operations, they have many defects such as high manufacturing costs and poor reliability, which seriously affect the smooth progress of cementing operations.

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