RU2305744C1 - Downhole casing pipe vibrator - Google Patents

Abstract

FIELD: well construction, particularly casing pipe cementing equipment.

SUBSTANCE: vibrator comprises hollow body with connection threads, piston-valve spring-loaded upwards and installed inside body and bypass channel. Body is connected to pipe string to be lowered in casing pipe and has upper, lower and central rows of radial orifices. Orifice rows are connected with each other from outside through bypass channel. Central radial orifice row may be sealed in initial position with piston-valve. Bypass channel between upper and central radial orifice rows is provided with valve, which permits fluid flow only in bottom-top direction.

EFFECT: simplified structure and increased operational reliability and possibility of vibrator interior cleaning of residual cement mortar.

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Description

The invention relates to the construction of wells, and in particular to devices for cementing casing strings.

Known vibratory shoe cemented columns (patent RU No. 2061841, IPC 7 ЕВВ 33/16, published on 06/10/1996), including a hollow body with side holes, connecting thread and safety valve, a cylinder made of easily drilled material with a cavity, an inlet channel, communicating a body cavity with a cylinder cavity, and an output axial channel communicating a cylinder cavity with external space, a gear wheel made of easily drilled material on an easily drilled shaft, placed in the cavity, a nozzle of easily drilled material, bent in the inlet channel and oriented in the region of the pitch diameter of the gear wheel and the guide plug, the cylinder being made with a pocket and a cavity in the form of a cylindrical cavity, which is covered by a disk having a pocket and an eccentric hole, and the gear shaft is made with an unbalance in the form of a sleeve with an eccentric plate circle and mounted along the axis of the cylindrical cavity in the pockets of the cylinder and the disk with the possibility of opening and closing a plate circle of the eccentric hole, while the input channel is made tangential with respect to the cylindrical cavity, and the side opening of the housing is made from the disk side along the axis of the cylindrical cavity.

The closest in technical essence to the proposed one is the casing shoe (copyright certificate SU No. 1661372, IPC 7 ЕВВ 33/14, published in Bulletin No. 25 dated 07/07/1991), which includes a hollow body with an upper and lower pass through and a piston-valve located inside the housing with protrusions on the outer surface in the upper part, spring-loaded relative to the upper sub, and a rod passing inside the piston-valve and connected by the lower end to the lower sub, while the piston-valve is made with two internal cavities, section lennymi annular shoulder forming the axial bore and has a member for closing this channel, wherein the member overlaps the axial bore in the upper position of the piston valve and opening the latter in lowered position.

Both analog and prototype have common disadvantages:

firstly, the complexity of the design, due to the large number of nodes and parts;

secondly, the complexity of manufacturing and assembly, due to the large number of technologically complex parts, and failure to meet stringent requirements in the manufacture and assembly reduces the reliability of the device;

thirdly, in the internal cavities of the vibratory shoe, at the end of pumping, a cement mortar remains, which, solidifying, clogs the passage channels, which before reuse requires disassembly, cleaning and assembly of the device.

An object of the invention is to simplify the design of the device and increase the reliability, as well as the ability to rinse the internal cavity of the device from the remnants of the cement after completion of its injection.

The technical task is solved by the proposed casing borehole vibrator, including a hollow body with connecting threads, a spring-loaded piston-valve and an overflow channel installed in the body cavity.

What is new is that the casing is connected to a string of pipes lowered into the casing and is provided with upper, middle and lower rows of radial holes that are connected externally by a bypass channel, the middle row of radial holes being configured to overlap with the piston-valve in the initial position, and the bypass channel between the upper and middle rows of the radial holes is equipped with a valve that allows upward flow.

The drawing shows the proposed device before cementing the casing in longitudinal section.

The downhole vibrator for the casing string includes a hollow body 1 with connecting threads 2 and 3, spring-loaded upward by means of a spring 4, and a piston valve 5 and a bypass channel 6 installed in the cavity of the body 1. The body 1 is connected to the pipe string 7 from above (for example, a pump string -compressor pipes) lowered into the casing 8.

The housing 1 is equipped with upper 9, middle 10, lower 11 rows of radial holes that are connected externally bypass channel 6. The middle row of radial holes 10 is made with the possibility of overlapping piston-valve 5 in the initial position. The bypass channel 6 between the upper 9 and middle 10 rows of radial holes is equipped with a valve 12, passing from the bottom up.

The layout of the lower part of the casing string 8 and the layout attached to the bottom of the casing 1 of the downhole vibrator for the casing string may be different.

As an example, consider one of the layout options, which is presented in the drawing. A nozzle 13 is screwed onto the lower end of the housing 1, which is plugged from below by a plug 14. In the nozzle 13 above the plug 14 there are made radial holes 15 that hydraulically communicate the internal spaces of the pipe string 7 and casing string 8.

The plug 14 by means of a shear element 16 is connected to a non-return valve 17 made in the form of a hollow cylinder muffled from below, having an outer cylindrical sample 18, in which a retaining ring 19 is placed, which can interact with the cylindrical sample 20 of the seat 21. The saddle 21 is hermetically installed in the casing columns 8 above the central back pressure valve (CKOD) 22 and is connected to the latter via an adapter 23.

A shoe pipe 24 is screwed onto the lower end of TsKOD 22 with through holes 25 hydraulically connecting the inner space of the casing 8 to its outer space.

The device operates as follows.

In the casing 8, arranged and lowered into the well, is assembled and downhole vibrator for the casing is lowered at the end of the pipe string 7, while the lower end of the pipe string 7 is screwed into the connecting thread 3, and the pipe 13 is screwed into the connecting thread 2 of the housing 1 valve 17 at the end. The pipe string 7 is gradually increased and the device is lowered into the casing 8 until the check valve 17 reaches TsKOD 22, while the layout elements are calculated so that the lower end of the housing 1 is 5-10 meters above the seat 21.

The casing string 8 is cemented, and cement slurry is pumped into the pipe string 7 from the wellhead, which, having reached the borehole vibrator for the casing string, first passes through the upper row of radial holes 9 into the bypass channel 6, filling it above valve 12, since the latter is hermetically sealed divides the upper 9 and middle 10 rows of radial holes in the bypass channel 6 and passes only from bottom to top.

After filling the bypass channel 6 above the valve 12, the injection pressure acts on the piston-valve 5 from above, as a result, the last, compressing the spring 4, drops down until the middle row of radial holes 10 is opened, which was blocked by the piston-valve 5 in the initial position.

The cement mortar is continued to be injected, as a result of which the last of the pipe string 7, through the middle row of radial holes 10 of the housing 1, which opened under the pressure of injection, passes through the bypass channel 6 below the valve 12 through the lower row of radial holes 11 into the housing 1 and then into the pipe 13, while the pressure above the piston-valve 5 drops and the latter due to the return force of the spring 4 is returned back, blocking the middle row of radial holes 9.

The injection of cement mortar continues, while the pressure above the piston-valve 5 again increases and the latter again drops down, compressing the spring 4 and opening the middle row of radial holes 9, and again the cement flows into the nozzle 13.

Subsequently, the cycle repeats, a pulsating injection of cement takes place through the radial holes 15 of the pipe 13, the inner space of the casing 8 is lower than the seat 21, through the adapter 23 and TsKOD 22, and also through the holes 25 of the shoe 24 into the outer space of the casing 8, cementing the last one.

At the end of cementing the casing string 8, the injection of cement into the pipe string 7 is stopped. TsKOD 22 closes under pressure of a column of cement behind the casing 8. The pipe string 7 is lifted up until the check valve 17 hermetically interacts with the seat 21. After that, an additional load of about 40-50 kN is applied to the pipe string 7 from the wellhead until the shear elements 16 are destroyed. After failure shear elements 16 the pipe string 7 is raised another 2-3 meters, while the check valve 17 circlip 19 located in its outer cylindrical sample 18, is fixed in the cylindrical sample 20 of the saddle 21.

Then, backwash (supply of flushing fluid to the casing 8) removes excess cement from the pipe string 7 and the borehole vibrator for the casing.

The flushing fluid pumped into the casing 8 through the radial holes 15 rises up the nozzle 13 and then, falling into the housing 1 through the lower row of radial holes 11, flows from below into the bypass channel 6, where, rising and filling the latter, acts on the valve 12 from below. The valve 12, passing from the bottom up, rises up, squeezing cement from the bypass channel 6 above the valve 12 and passing the flushing liquid through itself, since the middle row of radial holes 10 of the housing 1 is hermetically closed from the inside by the piston-valve 5. The flushing liquid, bypassing the valve 12, through the bypass channel 6, through the upper row of radial holes 9 enters the housing 1 and further along the pipe string 7 up at the wellhead.

Thus, the internal cavities of the casing borehole vibrator are flushed.

The proposed borehole vibrator for the casing string consists of technologically simple parts, which allows to reduce material costs for manufacturing and assembly, and the increase in the reliability of its operation is associated with a simplification of the design and the possibility of washing the internal cavities of the device from the cement slurry residues at the end of its injection.

Claims (1)

A downhole vibrator for a casing string, comprising a hollow body with connecting threads, a piston-valve, spring-loaded upward and installed in the body cavity, and a bypass channel, characterized in that the body is connected to a string of pipes lowered into the casing and is provided with upper, middle and lower rows of radial holes that are connected externally bypass channel, and the middle row of radial holes is configured to overlap the piston-valve in the initial position, and the bypass channel between the upper and In the same rows of radial holes is equipped with a valve that passes from the bottom up.