RU2478771C1 - Check valve for casing string - Google Patents

Abstract

FIELD: oil and gas industry.

SUBSTANCE: device includes a housing, a mounting seat for interaction with a shutoff element in the form of a ball that is arranged in a cylindrical container, one end face of which is rigidly attached to the mounting seat, the other end face is provided with an axial channel and a mounting ball movement restrictor, and its side surface has holes and is closed with an elastic bushing on external surface. Length of cylindrical container is 1.5-3 of the ball diameter. A gap between outer diameter of cylindrical container and inner diameter of the housing in the arrangement place of the mounting seat, as well as elastic bushing, are chosen so that interaction of the latter with internal wall of the housing is provided during the process of well washing, pumping and cementing slurry squeezing to the space after the housing and casing string of the well at deformation of elastic bushing, which does not exceed maximum allowable value.

EFFECT: improving operating reliability of the valve; improving mounting reliability of a shutoff element on a mounting seat in working position of the device.

3 cl, 1 dwg

Description

The invention relates to the field of oil and gas wells and, specifically, to the arrangement of the lower part of the casing string.

A non-return valve for a casing string is known, including a housing, a set of steel split washers, a rubber diaphragm, restrictive rings and a locking element in the form of a ball (see Bulatov A.I. et al. Handbook of a Drilling Engineer, Moscow, Nedra, 1995, vol. 3, p. 130-132).

A disadvantage of the known device is the complexity of drilling steel split washers, the likelihood of foreign objects getting into the valve, as well as the unreliable operation of the valve when the column is in a horizontal position (in a horizontal well).

The technical result of the invention is to increase the reliability of the valve in various conditions and different wells, including horizontal, by increasing the reliability of landing of the locking element on the seat seat in the working position of the device.

The required technical result is achieved by the fact that the check valve for the casing string of the well includes a housing, a seating seat for interacting with a locking element in the form of a ball, which is placed in a cylindrical container, one end of which is rigidly connected to the landing seat, the other end is made with an axial channel and a landing a ball limiter, and its lateral surface has openings and is blocked by an elastic sleeve on the outer surface, while the length of the cylindrical container is 1.5-3 diameters w RA, and the gap between the outer diameter of the cylindrical container and the inner diameter of the body at the location of the seat, and the elastic sleeve are selected so that they interact with the inner wall of the body during the flushing of the well, pumping and forcing the grout into the space behind the body and the casing the casing hole during deformation of the elastic sleeve, not exceeding the maximum permissible value.

Besides:

the landing seat for interacting with the locking element is provided with a sealing elastic element, which is fixed on the landing seat with a cylindrical container;

the locking element is made of a material with a density close to or equal to the density of the grouting material.

The essence of the invention is to increase the reliability of the check valve due to the fact that it provides for the possibility of creating better conditions for landing the locking element-ball on the seat. This is ensured by the implementation of a cylindrical container of a certain length - 1.5-3 ball diameter. When selling the last portions of cement slurry, periodic stops are foreseen for multiple actuation of the check valve. With the selected length of the cylindrical container, it is possible to sufficiently disperse the ball before landing on the landing seat. With mini-high-speed, multiple ball landings on the seat saddle, multiple microshocks are created that provide mechanical destruction of the sediments, crusts on the walls of solutions and hydrodynamic cleaning of both the landing seat itself and the adjacent zone from the destroyed sediments. The elastic sleeve on the outer surface of the cylindrical container, as a unit with a different inertia of operation, provides water hammer less rigid - smoothed and less dangerous for the destruction of the landing seat. For this twin system, with a cylindrical container less than 1.5 times the diameter of the ball, the magnitude of the impact is not sufficient to destroy the sediment on the landing saddle. When the length of the cylindrical container is more than 3 ball diameters, the magnitude of the water hammer is dangerous for the destruction of the landing seat. For unforeseen cases, when the ball in any case remains on the landing stop (in the lowest position, since, for example, it can be locked by precipitation), the elastic sleeve also acts as an understudy for the locking element. During repeated exposure, the elastic sleeve experiences alternating loads. To reduce their destructive effect, the elastic sleeve during operation should always have support either on the outer surface of the cylindrical container, or on the inner surface of the housing. Empirically select the material of the elastic sleeve, its thickness and the gap between the outer surface of the cylindrical container and the inner surface of the body from the condition of deformation (fatigue) of the elastic cuff, not exceeding the maximum permissible value. In the case of using rubber, its Shore hardness is selected.

The figure 1 shows a General view of the check valve.

The check valve for the casing string of the well includes a housing 1, a landing seat 2 for interacting with a locking element in the form of a ball 3, which is placed in a cylindrical container 4, one end of which is rigidly connected to the landing seat 2, the other end is made with an axial channel 5 and a landing limiter movement 6 for the ball 3. The lateral surface of the cylindrical container 4 has openings 7 and is blocked externally by an elastic sleeve 8. The length of the cylindrical container 4 is 1.5-3 times the diameter of the ball 3. The gap between the outer diameter of the cylinder dricheskogo container 4 and the inner diameter of the housing 1 at the location of the landing seat 2, as well as the elastic sleeve 8 are selected such that they interact with the inner wall of the housing during the washing of the well, injection and selling cement slurry into the space behind the casing string during elastic deformation cuff 8, not exceeding its maximum permissible value.

The landing seat 2 for interacting with the locking element-ball 3 is equipped with a sealing elastic element 9, which is fixed (preloaded) on the landing seat with a cylindrical container 4. This container is mounted on the landing seat with a thread 10 and secured from the lap by the locking screws 11. Elastic sleeve 8 made with an inner annular collar 12, which is placed in the annular groove 13, made on the outer surface of the cylindrical container 4. The tightness of the device is provided by the sealing rings 14. To prevent clogging of the device above the landing seat 2 in the housing 1 can be installed a filter unit 15.

The check valve for the casing operates as follows.

When injecting drilling or grouting fluids, the ball 3 overlaps the axial channel 5 of the cylindrical container 4. As a result, the solution through the holes 7 of the cylindrical container 4, inflating the elastic sleeve 8, through the shoe of the casing string (in the figure, the shoe and casing string associated with the housing are not shown) enters the space behind the casing and the housing 1.

At the final stage of well plugging, periodic shutdowns are carried out during the course of grouting grouting into the space behind the casing string. This forces the non-return valve to operate several times with the implementation of micro-impacts and work on cleaning the landing seat from precipitation and creating conditions for reliable final operation. After completion of the plugging process and relieving pressure in the casing string and casing 1, the elastic sleeve 8 returns to its original position, blocking the openings 7 of the cylindrical container 4. In this case, the ball 3 flows with the cement slurry coming from the space behind the casing and casing 1 through the axial channel 5 of the cylindrical container 4, is pressed against the landing seat 2.

In order to increase the reliability of operation of the check valve under certain conditions, its shut-off element-ball can be made with a specific gravity close to the specific gravity of the injected grout, for example, from caprolon or based on bakelite.

The claimed device (as shown by tests) is reliable in operation, easy to manufacture, and is essentially doubled with a small length.

Claims (3)

1. The check valve for the casing string, borehole, comprising a housing, a seat seat for interacting with a locking element in the form of a ball, which is placed in a cylindrical container, one end of which is rigidly connected to the seat seat, the other highlander is made with an axial channel and a seat limiter to move the ball and its lateral surface has holes and is overlapped on the outer surface by an elastic sleeve, while the length of the cylindrical container is 1.5-3 the diameter of the ball, and the gap between the outer diameter is cylindrical of the container and the inner diameter of the body at the location of the landing seat, as well as the elastic cuff, are selected so that they interact with the inner wall of the body during washing the well, injecting and selling grouting mortar into the space behind the body and the casing of the well when the elastic cuff is deformed, not exceeding the maximum permissible value. 2. The non-return valve according to claim 1, characterized in that the seat seat for interacting with the locking element is provided with a sealing elastic element, which is fixed on the seat seat with a cylindrical container. 3. The check valve according to claim 1, characterized in that the shut-off element is made of material with a density close to or equal to the density of the cement slurry.