RU2445442C1 - Method to repair casing string without reduction of throughput diameter - Google Patents

Abstract

FIELD: mining.

SUBSTANCE: method includes lowering, installation and expansion of a metal plaster in the repair interval. At the same time the plaster prior to lowering is equipped with an anchor, at the bottom - with a block having a check valve made of easily drilled material, after lowering into the installation interval, the anchor is fixed relative to the casing string by development of an excessive internal pressure, the metal plaster is expanded to the diameter equal tot he inner diameter of the casing string together with the casing string and with cement compaction behind the string, afterwards the block is broken.

EFFECT: higher quality and reliability of casing strings repair by metal plasters, reduced costs due to reduction of lowering and lifting operations.

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Description

The invention relates to the oil and gas industry, namely to the overhaul of casing strings using metal adhesives.

A known method of repairing a casing string (RF patent No. 2,336,408, IPC ЕВВ 29/10, published in Bull. No. 29 of 10/20/2008), including milling the inner surface of the casing string and calibration to form an annular sample for a metal patch in the repair interval and subsequent installation in it with a regulated tightness of the metal patch, and before installing the metal patch in the upper and lower parts of the annular selection on the casing perform annular grooves.

The disadvantages of this method are:

- reducing the thickness and integrity of the casing string during milling and especially when performing annular grooves, which may affect its strength and durability in future operation;

- additional tripping operations for milling and grooving the casing string before installing the metal patch.

The closest in technical essence to the claimed is a method of repairing a casing string (A.S. SU No. 1616216, IPC Е21В 29/10, 05.05.88), including milling the inner surface of the casing string in the repair interval and subsequent installation in it with a regulated a tight fit of a metal patch, and in order to increase the reliability of repair of casing strings with different internal diameters due to the possibility of standardizing the sizes of metal plasters, the repair interval after milling is calibrated to Sample under a metal patch.

The main disadvantages of this method are:

- a decrease in the thickness and integrity of the casing string during milling, which may affect its strength and durability in future operation;

- additional tripping operations for milling the casing string before installing the metal patch.

The technical objectives of the invention are to improve the quality and reliability of repair of casing strings with metal adhesives by maintaining the integrity of the body of the string, excluding milling and boring operations, as well as reducing costs by reducing tripping operations.

The technical problem is solved by a method including descent, installation and expansion in the repair interval of a metal patch.

It is new that the patch is equipped with an anchor before the descent, the boot with the check valve made of easily drilled material from the bottom, after the descent into the installation interval, the anchor is fixed relative to the casing by creating excessive internal pressure, the metal patch is expanded to a diameter equal to the inner diameter of the casing together with the casing and with cement compaction behind the string, after which the shoe is destroyed.

In Fig.1 shows the descent of the metal patch in the interval of violation of the casing, Fig.2 - the installation process of the patch in the casing.

The method is carried out in the following sequence.

Before carrying out repair work in the well, geophysical studies are performed to establish the interval of violation 1 (Fig. 1) of the casing string 2. Then, at a specified interval on the drill pipe string 3, a metal patch 4 of the required length is equipped, equipped below with an anchor in the form of a longitudinally corrugated pipe 5 rigidly (for example, by welding) connected to the patch 4, from the bottom to a shoe 6 with a check valve 7 made of easily drilled material (for example, textolite).

In the upper part of the patch 4 is hermetically separable with the possibility of disconnecting, for example, using a straight thread 8, a flare 9 is installed, connected to the drill string 3 from above and from the bottom to destroy the shoe in the form of an end mill 10.

Moreover, thanks to the check valve 7 of the shoe 6, the internal cavity of the patch 4 is filled with well fluid. After that, the longitudinally corrugated pipe 5 with the help of a pump (not shown) through the drill pipe 3 and the passage channel 11 of the flare 9 is straightened by hydraulic pressure until it is pressed against the walls of the casing 2 (Fig. 2), fixing the patch 4 in the installation interval 1.

Then, the drill pipe string 3 is rotationally driven and the flare tool 9 is disconnected by thread 8 from the plaster 4. Continuing to rotate the drill pipe 3, they are moved downward, while the flare tool 9, thanks to rollers 12 with wide gauge surfaces, expands the plaster 4 to a diameter equal to the inner diameter the diameter of the casing string 2 together with the casing string 2 and with a cement seal 13 behind the string 2.

It has been experimentally proved that, for example, a casing string with a diameter of 168 mm and a wall thickness of 7 mm, expanding together with cement stone using a roller flare, increases by 10 mm in inner diameter, making it possible to install a repair patch 5 mm in thickness without loss of passage diameter.

When the shoe 6 is reached, the flare 9 thanks to the end mill 10 destroys it and extends the patch 4 together with the nozzle 5. After removing the flare 9 with the cutter 10 from the well, casing 2 is patterned and crimped.

Thus, the use of the invention improves the quality and reliability of repair of casing strings with metal adhesives without reducing the bore of the casing strings due to their local expansion, excluding milling and boring operations, and also reduces costs by reducing tripping operations.

Claims (1)

A method of repairing a casing string without reducing the bore diameter, including launching, installing and expanding a metal patch in the repair interval, characterized in that the patch is equipped with an anchor before lowering, a shoe with a check valve made of easily drilled material from below, and the anchor is fixed after lowering into the installation interval relative to the casing string by creating excessive internal pressure, the expansion of the metal patch is carried out to a diameter equal to the inner diameter of the casing string together but with the casing and cement to seal the annulus, whereupon the destruction shoe.

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