SU709799A1 - Centering device for casing pipes - Google Patents

Description

one

The invention relates to a well casing technique and can be used in any branch of the national economy that produces cementing.

Spring centralizers are known, consisting of rings, with arched spring bars attached to them to center the casing in the wellbore fl.

However, centralizers of this design do not provide reliable centering of the column in an inclined or curved shaft of inclined wells.

During the casing's descent into the inclined shaft, which is often complicated by plaintive workings, under the action of large pressing forces and dynamic loads, the arches of the centralizer are deformed, and often destroyed, and the centralizer does not fulfill its functions.

The disadvantage of the used spring centralizers is their low strength due to pressing forces and dynamic loads and the impossibility

Strictly centering the casing in the wellbore.

It is known to include: a spring centralizer for centering casing strings, consisting of a set of fastened spring bars and a KYaenovogo unit for fixing the centralizer on the casing pipe, including bushings and

half-sleeves mating on conical surfaces 2.

The knot securing the centralizer does not directly interact with the well, and perceives axial loads from the interaction of the centralizer bars with the well, which are transmitted to the wedge pair.

Such a device is closest to the proposed technical essence and the achieved result.

Its disadvantage is that such fastening of the centralizer on the casing pipe cannot work in direct contact with the borehole wall, since one of the wedge pairs is

connects when the pipe moves in any direction; another when the pipe moves in the opposite direction.

The aim of the invention is to increase the reliability of fastening a rigid centralizer on the casing and to increase its reliability in operation in an inclined borehole.

This is achieved by the fact that the outer sleeve of the centralizer and the inner wedge half-sleeves of its center are aligned on a cylindrical surface at an angle to the axis of the casing, and the tops of the wedge-half-sleeves are directed in opposite directions. At the same time, in order to increase the reliability of the centralizer retention on the casing, the interfaced surfaces have corrugations.

FIG. 1 shows the proposed centralizer, the longitudinal section of FIG. 2, section A-A in FIG. one.,

The centralizer consists of an outer sleeve 1 with four outer grooves 2 and two wedge semi-sleeves 3.

The inner bore of the sleeve 1 is made with a diameter greater than the outer diameter of the casing 4 and is at an angle to the axis of the cylinder of the sleeve. As a result of this, when free-fitting the sleeve to the pipe, two oppositely directed conical spaces are formed between them. In these spaces, after screwing the pipe and moving the sleeve in the required spacing, the conical half of the sleeve is inserted. Since the surface S of the mating of half-sleeves with the casing is made corrugated, when the sleeve of the bore hole stops interacting with the borehole wall, the interface of the sleeve 4 of the sleeve and the half-sleeve seal. Self-consolidation is proportional to the bias force. The sleeve is held in place and moves with the casing.

The presence of two half-sleeves, working in reverse directions, ensures that the centralizer on the casing is held in the required place both during the descent and when the casing is raised.

The casing is launched using the proposed centralizer using conventional technology, without wasting time on the installation of centralizers,

as when using spring centralizers. Before screwing the next casing 4, the required number of sleeves 1 is put on it. Two half-sleeves 3 are lightly inserted into the sleeve from the bottom and from the top and the descent continues. In the future, all works are repeated depending on the number of pipes on which centralizers are required to be installed. . The circus / shci fluid in the annulus

This space is provided by the presence on the outer surface of the sleeve 1 of the longitudinal grooves 2.

Sleeve centralizers able to withstand high dynamic loads

when pulling the casing, especially in the inclined sections of the wells, provide improved casing cementing quality due to the guaranteed clearance between the wall

well and casing.

Claims (2)

1. A centralizer for casing, including an outer sleeve and two wedge half-sleeves, distinguished by the fact that, in order to increase the reliability of its mounting on the casing and in operation in an inclined wellbore, the outer sleeve and the inner wedge half-sleeves are coupled along a cylindrical surface at an angle to the axis of the casing, and the tops of the wedge x semi-sleeves directed in opposite directions. 2. A centralizer according to claim 1, characterized in that the mating surfaces of the wedge semi-sleeves with the casing pipe and the outer sleeve are made corrugated. Sources of information taken into account in the examination 1. US patent No. 2824613, CL „166/241, published. 1958. 2. USSR author's certificate No. 314880, class, Е 21 В 17/00, 197О. R