RU2376446C2 - Anchor-centraliser of stepanov hydro-mechanical structure - Google Patents

Abstract

FIELD: oil-and-gas production.

SUBSTANCE: invention related to casing string hole clearance cementing , particularly cementing casing string in a well. Hydro-mechanical anchor centraliser, includes cylinder connected to string, inside which installed 3 barrels, executed as half barrels, connected in pair with each other via seals, working piston, installed under barrels and executed as half barrels, stiff fixed in a conical part, centralising arms, roller fixed with string, lockers, executed as a T-shaped channels on the barrels bottom, interacting with T-shaped pins, stiff fixed with centralising arms top ends, destroyable plug, installed in radial hole with thread, connecting internal cavities of cylinder with string, stepped executed along its external working surface, slide barrel with conical external surface on its top part for interaction with cylinder internal conical surface and radial hole, located under conical surface, installed over barrels and on bigger diametre of the string inside cylinder internal cavity with possibility of radial hole closing with it after anchor centraliser actuation and executed along external diametre, less tha cylinder internal diametre, and actuation, fixed relatively to cylinder working barrel, and on the bottom part of working barrel along generating line radial pins executed in gaps between centralising arms.

EFFECT: anchor centraliser reliability increase.

4 dwg

Description

The invention relates to the field of cementing the annulus of a string, namely, cementing a casing in a well.

A well-known centralizer is a hydromechanical casing string, including a casing connected to the barrel, in the cavity of which there are 3 pieces of bushings made in the form of half bushes, interconnected in pairs with dowels, a working piston mounted under the bushings and made in the form of a half-piston, rigidly fastened in the conical part , centering levers, lower ends pivotally connected to the barrel, locking devices made in the form of T-grooves on the bottom of the working piston, interacting with the T-shaped pin and, rigidly fastened to the upper ends of the centering levers, a destructible plug screwed into a radial hole with a thread connecting the internal cavities of the cylinder and the barrel, stepwise along the length of the external working surface, a spool sleeve with an external conical surface on its upper part for interaction with the internal conical the surface of the cylinder and a radial hole located below the conical surface mounted above the bushings and on the larger diameter of the barrel in the inner cavity of the cylinder to overlap the radial opening it in the barrel after firing centralizer and formed on the outer diameter smaller than the inner diameter of the cylinder, and a torque pin, fixed relative to the cylinder working piston (Pat. RU No. 2275489, class ЕВВ 17/10, publ. in bull. April 12 - April 27, 2006).

The main disadvantage of this device is the unreliability of its operation.

In the process of cementing a casing equipped with hydromechanical centralizers, and when the latter are activated, the hydraulic resistance increases due to a decrease in the bore in the annular space between the hydromechanical centralizer and the borehole walls at the locations of the centering levers of the hydromechanical centralizers.

The increase in hydraulic resistance worsens the condition for the centralizer to operate.

After cementing the column, the excess internal pressure inside it at the wellhead is released to atmospheric pressure. In this case, the cement mortar, passing through the channels formed between the two half-pistons of the working piston of the hydromechanical centralizer, shifts the bushings and the spool sleeve to its original position. This increases the likelihood of the working piston returning to its original position, since the working piston is held in working position due to friction between the centering arms and the working piston.

A hydromechanical centralizer-anchor is proposed, including a cylinder connected to the barrel, in the cavity of which there are 3 pieces of bushings made in the form of half-sleeves interconnected in pairs by dowels, a working piston mounted above the bushings and made in the form of a half-piston, rigidly fastened in the conical part , centering levers, lower ends pivotally connected to the barrel, locking devices made in the form of T-grooves on the bottom of the working piston interacting with T-shaped pins, rigidly with replicated with the upper ends of the centering levers, a destructible plug screwed into a radial hole with a thread connecting the internal cavities of the cylinder and the barrel, stepwise along the length of the outer working surface, a spool sleeve with an outer conical surface on its upper part for interaction with the inner conical surface of the cylinder and a radial hole located below the conical surface mounted above the bushings and on the larger diameter of the barrel in the inner cavity of the cylinder with by locking the radial hole in the barrel after the centralizer-anchor is triggered and having an outer diameter smaller than the inner diameter of the cylinder, and a calibrated pin fixed to the cylinder working piston, and the lower part of the working piston has grooves made along the generatrix of the working piston in the gaps between the centering levers .

The present invention solves the following tasks.

The implementation of the radial grooves in the gaps between the centering levers on the lower part of the working piston along the generatrix increases the area of the bore in the annular space between the anchor centralizer and the borehole walls and creates additional friction between the barrel and the working piston due to the violation of the integrity of the cross section around the circumference of the working piston in places interacting between the centering levers of the latter with the working piston when the centralizer-armature is triggered.

An increase in the cross-sectional area in the annular space between the anchor centralizer and the borehole walls reduces hydraulic resistance during cementing of the casing with anchor centralizers installed on it, which improves the condition for the latter to operate and increases the reliability of the anchor centralizers.

The creation of additional friction force between the working piston and the barrel when the centralizer-armature is triggered increases the likelihood of eliminating the return of the working piston to its original position, which helps to increase the reliability of the centralizer-armature.

Figure 1 shows the centralizer-anchor hydromechanical, axial section; figure 2 shows a section aa, figure 3 - section bb, figure 4 - section bb.

The hydromechanical centralizer-anchor (Fig. 1) consists of a barrel 1 with a cylinder 2 screwed on it. Inside the cylinder 2, a spool sleeve 3, half-bush 4, coupled between the keys 5, protective rings 6, rubber o-rings 7 and a working piston 8 are installed, made in the form of a half-piston, rigidly interconnected along a conical surface. On the lower part of the working piston 8, T-grooves 9 are made, interacting with the T-shaped pins 10. The pins 10 are rigidly fixed to the upper ends of the centering levers 11. The lower ends of the centering levers 11 are pivotally mounted in the lock nut 12. On the barrel 1 there is a radial a threaded hole 13 into which a destructible plug 14 is screwed. A radial hole 15 located below the conical surface is made on the spool sleeve 3. The working piston 8 is fixed relative to the cylinder 2 by a calibrated pin 16, and on the lower part of the working piston 8 along the generatrix in the gaps between the centering levers 11 there are radial grooves 17. And an extension 18 with a coupling 19 is screwed to the upper end of the barrel 2.

The central anchor hydromechanical works as follows.

After lowering the casing with centralizers-anchors installed into the well, under the influence of the pressure drop of the squeezing fluid, the cementing plug moves from top to bottom, which, passing through the hydromechanical centralizer-anchor, destroys the destructible plug 14 screwed into the radial hole 13 with a thread. After that, through the radial hole 13, the intra-column fluid is opened into the cavity of the cylinder 2. Under the action of the differential pressure of the annular and intra-column fluids, the spool sleeve 3, half-bush 4 connected by dowels 5, protective rings 6, rubber o-rings 7 and the working piston 8 will move down by cutting off the calibrated pin 16. While moving down the working piston 8, the centering levers 11 move in the radial direction. Upon reaching the upper ends of the centering levers 11 of the borehole walls, the casing in the places where the anchor centralizers are installed is centered relative to the borehole.

In the process of cementing the casing and when the centralizers-anchors are triggered, the made radial grooves 17 on the lower part of the working piston 8 along its generatrix in the gaps between the centering levers 11 contribute to a decrease in the hydraulic resistance in the annular space between the borehole walls and the centralizer-anchor in the places of installation of the latter casing string. This improves the triggering condition of the anchor centralizers mounted on the casing.

After the casing string is cemented, the internal overpressure in the string at the wellhead is vented to atmospheric pressure.

In this case, under the action of pressure, due to the difference in the densities of the annular and annular liquids, the latter, acting through the channels in the working piston 8, made in the form of a half-piston, rigidly fastened together on a conical surface, acts on the ends of the half-sleeves 4 connected by dowels 5. B As a result of this, half-sleeves 4, safety rings 6, rubber o-rings 7 and spool sleeve 3 move upward at high speed. At the moment of reaching the barrel 1 with half-sleeves 4, the last and safety rings 6 and rubber o-rings 7 stop, and the spool sleeve 3 continues to move further by inertia until it is fixed with the conical surface of the cylinder 2. At the same time, the radial hole 15 made on spool sleeve 3, allows to increase the fixation of the latter.

The implementation of the radial grooves 17 on the lower part of the working piston 8 along its generatrix in the gaps between the centering levers 11 reduces the hydraulic resistance in the cementing process and creates an additional friction force between the barrel 1 and the working piston 8, which improves the condition for the centralizer-armature to work hydromechanical and helps to eliminate the return of the latter to its original position at the time of dumping the internal overpressure in the column at the wellhead.

The proposed technical solution significantly increases the reliability of the centralizer-anchor due to the grooves on the bottom of the working piston along its generators in the gaps between the centering levers.

Claims (1)

A hydromechanical centralizer-anchor, including a cylinder connected to the barrel, in the cavity of which there are 3 pieces of bushings made in the form of half bushes, interconnected in pairs with dowels, a working piston installed under the bushings and made in the form of a half-piston, rigidly fastened in the conical part, centering levers, lower ends pivotally connected to the barrel, locking devices made in the form of T-grooves on the bottom of the working piston, interacting with T-shaped pins, rigidly fastened and with the upper ends of the centering levers, a destructible plug screwed into a radial hole with a thread connecting the internal cavities of the cylinder and the barrel made in steps along the length of the outer working surface, the spool sleeve with the outer conical surface on its upper part for interaction with the inner conical surface of the cylinder and a radial hole located below the conical surface mounted above the bushings and on the larger diameter of the barrel in the inner cavity of the cylinder with the possibility of transition digging a radial hole in the barrel after the centralizer-anchor is triggered and having an outer diameter smaller than the inner diameter of the cylinder, and a calibrated pin fixed to the cylinder working piston, characterized in that on the lower part of the working piston along the generatrix radial grooves are made in the gaps between the centering levers .

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