RU2282705C1 - Casing pipe centrator - Google Patents

Abstract

FIELD: mining industry, particularly casing pipe cementing inside well.

SUBSTANCE: device comprises casing pipe, working cylinder with annular piston installed outside the casing pipe. Inner cavities of working cylinder and casing pipe are communicated with each other by means of through channels closed with breakable plugs. Main and additional centering members are made as levers having cross-sections defining tubular billet sectors. The first ends of main cementing members are pivotally connected with clutch. The first ends of additional cementing members are fastened to lower piston end. Free ends of main and additional cementing members are pivotally connected with each other in pairs. Angle between each cementing member axis and casing pipe axis exceeds 90° in working position.

EFFECT: increased reliability of opened cementing member fixation during casing pipe cementing.

3 dwg

Description

The invention relates to the mining industry and can be used for cementing casing strings during the construction of wells.

Known casing centralizer containing a working cylinder mounted on the casing with a piston having the ability to interact with one of the ends of the centering elements pivotally connected to the other end of the casing. Destructible plugs are installed on the inner surface of the casing. The piston can interact with the tapered shank of the locking piston, which is mated to a split spring ring rigidly connected to the casing. The centering elements are made in the form of wedge-shaped levers that interact with the counter surface of the piston of the working cylinder [1].

A disadvantage of the known centralizer is the design complexity and unreliability in operation.

Also known is a casing centralizer comprising a working cylinder with an annular piston located on the casing, adapted to interact with one of the ends of the centering elements pivotally connected to the casing by the other end, a spring split ring and collapsible plugs. The slave cylinder with its upper end is rigidly connected to the casing. The lower end of the annular piston is made conical and can interact with the centering elements, and the spring ring is installed in the radial grooves of the centering elements. The latter are made in the form of levers with thickenings of circular cross-section at the ends opposite the annular piston. In cross section, the levers are sectors of a tube stock. Their round thickenings form hinges with the casing, which provide the possibility of radial deflection of the levers relative to the casing [2]. The specified known centralizer can be adopted as a prototype.

The disadvantages of the known centralizer include the impossibility of fixing the centering elements after bleeding off the excess pressure from the inner cavity of the casing string. As a rule, overpressure in the inner cavity of the casing is etched off during the period of the bcc so that the casing does not experience radial deformations that adversely affect its adhesion to the cement stone.

The objective of the present invention is to increase the reliability of the device by ensuring reliable fixation of the centering elements in the open position when cementing the casing.

The problem is achieved in the proposed technical solution due to the fact that the device consisting of a working cylinder located on the outer surface of the casing string, the upper end of which is rigidly connected to it, the main centering elements made in the form of levers, the cross section of which is a sector of the pipe billet, pivotally connected at one end to the casing and installed with the possibility of radial deviation relative to it, an annular piston placed inside the working cylinder ra, and destructible plugs installed on the inside in the radial channels of the casing, is equipped with additional centering elements, which at one end are pivotally connected to the lower end of the annular piston. The free ends of the main and additional centering elements are connected in pairs by means of articulated joints. The angle formed by the axis of each of the main centering elements with the axis of the casing may be more than 90 °.

The design of the casing centralizer is illustrated by drawings, in which Fig. 1 shows a general view of the device in the transport position, Fig. 2 is a general view of the device at the time of alignment of the centering elements in a radial position, Fig. 3 is a combination of sections AA in Fig. 1 and BB in FIG. 2.

The proposed device consists of a casing 1 with made through it radial channels 2. On the inside, the radial channels 2 are closed installed in them destructible plugs 3.

At the ends of the casing 1, couplings 4 and 5 are installed. The upper end of the working cylinder 6 is rigidly connected to the coupling 4. An annular piston 7 is placed inside the working cylinder 6.

The main 8 and additional 9 centering elements at one end are pivotally connected respectively to the coupling 5 and to the lower part of the piston 7. The free ends of the main 8 and additional 9 centering elements are paired together using a swivel 10. The distance from the center of the hinge 10 to the axis of the casing 1 is greater than the corresponding distance to the last from the rest of the hinges, thereby eliminating the possibility of jamming of the centering elements during operation of the device. The main 8 and additional 9 centering elements have the ability to radially deviate relative to the casing, and the angle (α) between the axis of each of the main centering elements 8 with the axis of the casing 1 can be more than 90 °. The main 8 and an additional 9 centering elements are made in the form of levers, the cross section of which is a sector of a pipe billet, at the ends of which articulated joints are installed.

The centralizer works as follows.

After the casing is lowered into the borehole with centralizers installed on it in the calculated places, the cementing process begins. When the squeeze plug passes through the casing 1, the plugs 3 are destroyed. Through the radial passages 2 in the casing 1, the squeeze fluid enters the inner cavity of the working cylinder 6. Under the action of the excess pressure of the fluid, the piston 7 begins to move axially relative to the casing 1. this piston 7 moves the additional centering elements 9. The latter through the hinge 10 transmit the generated force to the associated main centering elements 8. The main 8 and additional 9 the centering elements are moved apart in the radial direction and abut against the walls of the borehole, thereby ensuring the alignment of the casing. The deviation of the main centering elements 8 at an angle of more than 90 ° makes it impossible to return to their original position, i.e. arbitrary "closure" of the centralizer.

After the cement grouting process has been completed, the overpressure inside the casing for the period of the SCC can be completely relieved.

Information sources

1. RF patent No. 2034128, Е 21 В 17/10, 1995.

2. RF patent №2176719, Е 21 В 17/10, 2001.

Claims (1)

The casing centralizer, including the working cylinder located on the outer surface of the casing, the upper end of which is rigidly connected to the casing, the main centering elements in the form of levers, the cross section of which is a sector of the pipe billet pivotally connected at one end to the casing and having the possibility of radial deviations relative to it, an annular piston placed inside the working cylinder and destructible plugs installed on the inside in radial channels casing string, characterized in that it is equipped with additional centering elements, one end pivotally connected to the lower end of the annular piston, and the free ends of the main and additional centering elements are paired with each other using swivel joints, while the angle between the axis of each of the main centering elements with the axis of the casing in the working position is more than 90 °.

Images