RU2209921C2 - Casing centralizer - Google Patents

Abstract

FIELD: hole clearance cementation, casing string centering in hole. SUBSTANCE: casing centralizer has cylinder, plug in shear communicating space of cylinder with space inside string, piston, centering members. Cylinder is made fast to casing string, lower part of piston is conical. Centering members come in the form of tabs of conical bushing that has annular groove around edges on outside. Cylindrical part of conical bushing is made fast to casing string. Lower conical part of piston interacts with split tabs of conical bushing. EFFECT: simplified design and raised operational reliability of casing centralizer. 1 cl, 3 dwg

Description

 The present invention relates to the field of cementing annular spaces, casing, namely, centering the casing in the well.

 A known centralizer (RF patent 2034128, class E 21 B 17/10 dated 04/30/1995) containing a working cylinder with a working piston mounted on the casing with the possibility of interaction with one of the ends of the centering elements pivotally connected to the other end of the casing , on the inner surface of which destructible plugs are installed, and the opposite end of the working piston (hydraulically) interacts with the tapered shank of the locking piston, which mates with a spring split ring rigidly connected to the casing. The centering elements are presented in the form of levers made wedge-shaped for interaction with the wedge-shaped surfaces of the working piston. The working cylinder is mounted with the possibility of axial movement and has a ledge at the lower end that interacts with the protrusion of the locking piston, and at the upper end there are "P" -shaped grooves for fixing the centering elements.

 The disadvantage of this centralizer is the complexity of the design and, as a consequence of this, the unreliability of its operation.

 In the process of lowering the casing string into the well, its transverse-oscillatory, rotational and reciprocal movements additionally occur. In this case, there is a danger of destruction of the spring split ring on the protrusions of the walls of the borehole, axial displacement of the working cylinder and, as a consequence, spontaneous opening of the centering elements. The hinged fastening of the centering elements to the column with their upper ends when the lower ends come into contact with the walls of the well causes a positive moment for the centering elements to open, which leads to their jamming and prevents the possibility of further lowering of the column or to the destruction of the centering elements.

 In the transport position of the centralizer, a piston with wedge-shaped protrusions for rotation with levers can freely rotate relative to the casing. Due to the rotational movement of the casing string during its descent into the well, it is possible to rotate the piston relative to the centering elements and to exit the interaction of the wedge-shaped surfaces with levers. When you try to bring the centralizer into working position, the centering elements in this case will not open. The presence of a locking piston with a protrusion and a tapered shank and a working cylinder having a protrusion at one end and U-shaped grooves on the other complicates the design and reduces the reliability of the device, because it becomes possible to form additional channels for downhole fluid flow between the inner surface of the working cylinder and the outer surface of the lock piston and between the inner surface of the lock piston and the outer surface of the casing.

 After lowering the casing to the design depth and breaking the destructible plug with a cementing plug, the annular liquid enters the cavity of the working cylinder. Formed additional channels will pass this fluid. As a result, the fluid pressure in the cavity of the working cylinder will be insignificant for the centering elements to open and the casing to be centered relative to the well.

 The aim of the invention is to simplify the design and increase the reliability of the casing centralizer. This is achieved by the fact that from the design of the casing centralizer, including a cylinder located on the casing, a shear plug communicating the cylinder cavity with the casing, piston, centering elements, shoes and a lock piston, which are complex in configuration, are excluded. The working cylinder, made without a ledge and U-shaped grooves, is rigidly fastened with its upper end to the casing. The execution of the cylinder is continuous more technologically advanced in its manufacture. The working cylinder, rigidly connected with the upper end to the casing, eliminates the flow of fluid between the cylinder cavity and annular space, which contributes to a more reliable operation of the centralizer. The execution of the lower end of the piston conical to interact with the centering elements does not affect the operation of the device when it is rotated.

 The implementation of the centering elements in the form of petals of a conical sleeve simplifies the design and eliminates the possibility of spontaneous opening of the centering elements.

 The implementation of the piston with a longitudinal slot improves assembly technology.

 Figure 1 shows the centralizer in the transport position.

 Figure 2-3 shows the piston 4 with a longitudinal slot and holes.

 The centralizer consists of a casing 1, cylinder 2, rigidly connected (connected) with the casing, a shear plug 3, which communicates the cavity of the cylinder with the column space, a piston 4, which interacts with its lower conical part with centering elements made in the form of split petals of the conical sleeve 5, having a groove from the outside on the perimeter. The cylindrical part of the sleeve 5 is rigidly connected with the casing 1.

 For assembly, the piston 4 (see FIGS. 2-3) has a longitudinal slot along the entire length.

 The centralizer works as follows.

 After the casing 1 is lowered into the well, along with the centralizers installed under it, the squeeze plug moves from top to bottom under pressure of the cement slurry, which, passing through the casing 1 of the centralizer, breaks the plug 3. After that, the entry of the column fluid into the cavity of the cylinder 2 is opened. the differential pressure of the annular and intra-annular liquids on the end face of the working piston 4, the latter begins to move down. In this case, the lower conical surface of the piston 4 acts on the petal of the conical sleeve 5, which, overcoming the elasticity of the material in the groove zone located on the outside of the sleeve, are moved apart in the radial direction and abut against the borehole wall, setting the casing axially axially to its axis.

Claims (2)

 1. The casing centralizer, including a cylinder located on the casing, a shear plug communicating the cylinder cavity with the casing, a piston, centering elements, characterized in that the cylinder is rigidly connected to the casing, the piston in the lower part is made conical, and the centering elements are made in in the form of split petals of a conical sleeve having a groove from the outside along the perimeter, while the cylindrical part of the conical sleeve is rigidly connected to the casing, and the lower conical part of the piston is installed Lena with the possibility of interaction with split petals of the conical sleeve.  2. The centralizer according to claim 1, characterized in that the piston is made with a longitudinal slot.

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