SU898037A1 - Device for centering pipes in borehole - Google Patents

Description

(54) WELL CENTER TUBE

one

The invention relates to the drilling of oil and gas wells, namely to centering the casing string in the wellbore during the cementing process, the quality of which depends on the proper centering of the tubing string in the wellbore.

A casing centralizer is known that includes two couplings connected by spring arcs 1.

The disadvantage of this centralizer is that it requires precise installation on the pipe string, since a centralizer displacement in the axial direction can take it out of operation.

Closest to the invention is a pipe centralizer in a borehole, comprising a body, an elastic sleeve with stiffening ribs mounted on its outer surface, forming a cavity with the body, connected by radial channels to the cavity of body 2.

However, the known centralizer does not provide sufficient reliability of the centering of the casing and, moreover, the elastic element will completely block the annular space, which is unacceptable during cementing.

The purpose of the invention is to improve the reliability of casing centering during the cementing process.

This goal is achieved in that the centralizer is provided with a split elastic sleeve, located above the radial channels of the housing, the latter, at the location of the radial channels, has an annular groove under the split elastic sleeve, and the stiffeners at the ends are rigidly connected to the housing. 10 The drawing shows the proposed pipe centralizer in the well.

On the outer surface of the housing 1 there is an elastic elastic element 2 fixed by means of stop sleeves 3, 5 rigidly connected to the housing 1. Inside the latter there is an annular groove 4 with radial channels 5 in the wall of the housing. The annular groove 4 is the same size as the cylinder elastic sleeve 6, which in the cut and compressed state is located in the housing 1 above the annular groove.

Along the elastic elastic element 2 are located, and rigidly fixed steel ribs 7 on the ends on the resistant couplings 3.

A centralizer is installed on the casing in the right places. After the casing is lowered, a buffer fluid, a cement slurry is pumped into the well, and a squeeze plug is lowered. When moving through the pipes, the squeeze plug slides the cylinder sleeve 6 into the annular groove 4. Sleeve 6 expands and closes the opening 5.

The expansion plug thus closes all centralizers in the column. When cement mortar is pushed through the pipes, fluid pressure arises, which activates the resilient elastic element 2. Between the ribs 7, the element 7 expands, abuts against the borehole wall, and centers the column. The cement slurry continues to move at the locations of the hard ribs 7.

The elastic element of the centralizers is molded with cement mortar, which is locked with a cylinder bushing under pressure.

The proposed design is effective for centering the column in directional and curved wells with abrupt changes in azimuth and in wells with a small annular gap between the well and the pipes.

The outer diameter of the centralizer to the equal diameter of the casing coupling. During the descent of the column, it is possible to conduct flushing, turning, lifting pipes. The length of the centralizers may be different. Getting into the cavernous part of the centralizer will also center the column,, contributing to a more complete displacement of the washing solution from the cavity.

Technical and economic efficiency is to improve the quality of cementing wells, especially in directional or deviated wells with a sharp change in azimuth.

Claims (2)

1. USSR author's certificate number 368386, cl. E 21 B 177lO, 1971. 2. USSR author's certificate No. 344101, cl. E 21 B 17/10, 1970 (prototype).