Method for performing downhole remedial cementing operations

Abstract

The invention relates to a method for performing downhole remedial cementing operations. A module with hydraulic cylinders is installed at a wellhead and then lowered into the wellbore, said module being mounted on a tubing string and being connected to a plug-packer having a fixed mandrel and movable parts. When a given depth is reached, excess pressure is generated in the tubing, causing the hydraulic cylinders to move downwards in relation to the fixed mandrel and to apply a force to the movable parts of the plug-packer. Next, a module with hydraulic cylinders and a cementing retainer-packer having a fixed mandrel and movable parts is lowered on the tubing. When a given depth is reached, excess pressure is generated in the tubing, causing the hydraulic cylinders to move downwards in relation to the fixed mandrel and to apply a force to the movable parts of the cementing retainer-packer. Next, via the installed cementing retainer-packer, a sealing material in the form of a cement composition is introduced under pressure with the guaranteed penetration thereof into holes made by a perforator. The result is an increase in the efficiency, versatility and safety with which downhole remedial cementing operations are performed.

Description

[0001] METHOD OF CARRYING OUT REPAIR AND ISOLATION WORKS IN A WELL

[0002] Field of technology to which the invention relates

[0003] The present invention relates to the field of oil and gas production industry, in particular to devices for oil production, and can be used in the development of oil fields to restore the integrity of cement stone, eliminate leaks in production columns, and restore the sealing composition of the inter-column space of a well.

[0004] State of the art

[0005] The patent for invention RU2414586C1 “Method for carrying out insulation work in a well and packer equipment” is known.

[0006] The invention relates to oil production, in particular to downhole operations during major and routine repairs of wells, and can be used in operations to carry out repair and insulation work in order to restore the integrity of the annular cement stone.

[0007] The method consists of lowering a pipe string with a packer drilled on a hydraulic installation tool, installing it in a given interval of the well and pumping the required volume of material into the space under and above the packer. After which the hydraulic installation tool is removed from the packer and the overlying interval is treated under pressure or the production string is pressure tested for leaks without waiting for the previously pumped material to harden. The packer has upper and lower dividers. The packer locking mechanism contains dogs, on the inner surface of which there are teeth for interaction with the threaded cut of the outer surface of the packer barrel.Between the upper cone and the sealing element of the packer, a support sleeve is installed with double-sided saw-toothed projections and depressions that enter the corresponding grooves of the upper cone and the sealing element, the lower end of which also has saw-toothed projections that enter the corresponding grooves of the lower cone.

[0008] The disadvantages of this method are:

[0009] 1 Requirement to use different sizes of packer plug installer (for 102mm-120mm columns one size, for 140mm-178mm columns another size of installation mechanism).

[0010] 2) the need to differentiate between blind packer plugs for isolating part of the wellbore and retainers used for pouring a solution into the inter-packer space for insulation work and restoration of cement stone.

[0011] 3) the use of packer plugs to eliminate leaks in production columns is complicated by the need to ensure penetration of the insulating solution into the behind-the-casing zone.

[0012] These shortcomings do not allow for high efficiency of repair and insulation work in wells, universality of insulation of well intervals of various sizes and creation of special openings.

[0013] Disclosure of the essence of the invention

[0014] The proposed invention solves the problem of creating a universal, safe and effective method for carrying out repair and insulation work in a well, ensuring the isolation of well intervals of various sizes, ensuring a reduction in time and labor costs, and also possessing a wide range of technological potential.

[0015] The technical result of the claimed invention consists in increasing the efficiency, versatility and safety of repair and insulation work in wells, allowing for the insulation of well intervals of various sizes and the creation of the necessary openings, reducing time and labor costs, and expanding technological potential.

[0016] The technical result of the claimed invention is achieved due to the fact that the method for carrying out repair and isolation work in a well includes the following stages: - an assembly is installed at the wellhead, containing an installation module with hydraulic cylinders, mounted on a tubing string and connected to a packer-plug, including a fixed barrel and moving parts;

[0017] - the specified arrangement on a column of pump and compressor pipes is lowered into the well;

[0018] - when the specified depth is reached, a ball is dropped into the tubing string and excess pressure is created in the tubing pipes, as a result of which, under the action of hydraulic pressure, the hydraulic cylinders of the installation module move downwards relative to the fixed wellbore and exert a force on the moving parts of the packer plug, ensuring its installation in the well and isolating the required interval;

[0019] - above the location of the packer plug installation, if the hydraulic connection between the well and the casing stone is insufficient, an intermediate descent of a piercing perforator is carried out on the tubing pipe to create a puncture in the production casing, wash out the cement stone and ensure the above-mentioned hydraulic connection for successful penetration of the insulating material.

[0020] - when the interval required for restoring the cement stone with a hydraulic perforator is reached, fluid is pumped into the tubing, creating pressure to activate the perforator’s piercing knives.

[0021] - lowering of the assembly containing the installation module with hydraulic cylinders, mounted on the tubing string and connected to the filling packer - retainer, including a fixed barrel and moving parts;

[0022] - when the specified depth is reached, a ball is dropped into the tubing string and excess pressure is created in the tubing, as a result of which, under the action of hydraulic pressure, the hydraulic cylinders of the installation module move downwards relative to the fixed wellbore and exert a force on the moving parts of the filling packer-retainer, ensuring its installation in the well and isolating the required interval;

[0023] - through the installed filling packer-plug retainer under pressure, the cement composition is poured with guaranteed penetration of the active substance through the holes made by the hydraulic perforator. Brief description of the drawings

[0024] The details, features, and advantages of the present invention follow from the following description of the implementation of the claimed technical solution and drawings,

[0025] 5 of which are shown:

[0026] Fig. 1 shows a diagram of a hydraulic packer-plug installer;

[0027] Fig. 2 shows a diagram of an additional section with a hydraulic cylinder;

[0028] Fig. 3 shows two types of packer plugs (blind packer plug, filling packer plug);

[0029] 10 Fig. 4 shows a hydraulic perforator.

[0030] Implementation of the invention

[0031] The claimed method includes the following steps.

[0032] A) an assembly is installed at the wellhead, containing an installation module with hydraulic cylinders, mounted on a column of pump and compressor pipes and connected to a packer-plug, including a fixed barrel and moving parts;

[0033] B) the specified arrangement on a column of pump and compressor pipes is lowered into the well;

[0034] 20 B) when the specified depth is reached, a ball is dropped into the tubing string and excess pressure is created in the tubing, as a result of which, under the action of hydraulic pressure, the hydraulic cylinders of the installation module move downwards relative to the fixed wellbore and exert a force on the moving parts of the packer plug, ensuring its installation in the well and isolating the required interval;

[0035] D) above the place of installation of the packer-plug, if the hydraulic connection between the wellbore and the casing stone is insufficient, an intermediate descent of the piercing perforator is carried out on the tubing pipe to create a puncture in the production casing, wash out the cement stone and provide a hydraulic connection for successful penetration of the insulating material. For this purpose, when the interval required for restoration of the cement stone is reached, the hydraulic perforator pumps fluid into the tubing to create the activation pressure of the piercing knives of the perforator. D) the final stage is the descent of the assembly containing the installation module with hydraulic cylinders mounted on the tubing column and connected to the filling packer-retainer, including a fixed barrel and moving parts.

[0036] When the specified depth is reached, a ball is dropped into the tubing string and excess pressure is created in the tubing, as a result of which, under the action of hydraulic pressure, the hydraulic cylinders of the installation module move downwards relative to the fixed wellbore and exert a force on the moving parts of the filling packer-retainer, ensuring its installation in the well and isolating the required interval.

[0037] E) if the hydraulic connection is insufficient, the cement composition is poured under pressure through the installed filling packer-retainer plug, with guaranteed penetration of the active substance through special holes made by a hydraulic perforator;

[0038] The use of a perforator may not always be required - but for a guaranteed effect with a high degree of probability it is necessary to use it, since the reason for the leakage of the casing and its deformation is never known.

[0039] These stages of the method increase the efficiency, versatility and safety of repair and insulation work in wells, allowing for the insulation of well intervals of various sizes and the creation of the necessary openings, as well as reducing time and labor costs.

[0040] The device for installing packer plugs contains the following main units sequentially mounted on the tubing string from top to bottom (Fig. 1, 2): upper barrel 1, upper sleeve 2, nut body 3, split nut 4, outer collar 5, inner collar 6, cover 8, rod 9, barrel 10, lower sleeve 11, sleeve 12, cylinder 13, lower piston 14, upper piston 15, adapter 16, nipple 17, shear pin 18, lock screw 19, ring 22, ring 23, ball 24, hydraulic cylinder assembly 25.

[0041] The packer is connected to the installation module via an adapter. Then this assembly on the tubing string is lowered into the well. When the specified depth is reached, a ball included in the delivery set is dropped into the tubing, creating excess pressure in the tubing. Under the action of hydraulic pressure, the cylinders of the installation module move downwards relative to the fixed wellbore and exert a force on the moving parts of the packer, ensuring its installation in the well. By adding two additional hydraulic cylinders to the installation design, it is possible to create the required hydraulic force to activate all sizes of packer plugs.

[0042] The packer in general form (Fig. 3) consists of a barrel 26, on which a lower anchor, a sealing cuff 27, an upper anchor, a split nut 28, and an upper nut 29 are installed.

[0043] The lower anchor is formed from grips 30 with inserts 31 and cone 32. The grips are connected to the cone by means of shear screws M8 (or M10), in the amount of 6 pieces. The grips of the lower anchor enter from below into the grooves of shoe 33, which is screwed onto barrel 26 by thread.

[0044] A clip 34 with 6 shear pins 35 is installed in shoe 33. The clip with the pins inserted into it is clamped between shoe 33 and barrel 26. To prevent shoe 33 from spontaneously unscrewing, a locking screw 36 is screwed into it. Sealing ring 37 is designed to ensure tightness between barrel 26 and shoe 33.

[0045] The upper anchor, like the lower one, is formed from a cone 32, grips 30 with inserts 31. From above, the grips enter the grooves of the upper nut 29. The upper nut 29 is connected to the barrel through a split nut 28, which is screwed onto the barrel along a special stop thread. The split nut 28, elastically expanding, is capable of jumping along the barrel thread under external axial action, exclusively in one direction - downwards. Movement of the split nut upwards is excluded.

[0046] The upper nut 29 is fixed relative to the barrel 26 by means of 8 M8 shear pins, which protect the packer from premature activation during lowering and lifting operations.

[0047] The packer with a check valve differs in that instead of shoe 33, a plate check valve is screwed onto the lower part of the barrel, allowing the solution to be pumped under the packer.

[0048] The check valve is formed from a valve body 38, a rotary plate 39 and a cap 40. The valve plate is movably mounted on an axis fixed to the valve body. The plate is moved to the closed position by a torsion spring 41.

[0049] To ensure tightness between the adapter and the packer, a cuff 42 is used. The packers are installed in the well using a hydraulic installation module (Fig. 1). The packer is connected to the installation module using an adapter (9).

[0050] The perforator (Fig. 4) is a mechanism that converts the reciprocating axial movement of the power unit into the radial-reciprocating movement of the perforator cutters. Additional sections are installed if necessary.

[0051] The power unit consists of two cylinders 43,44 and a housing 45, connected to each other by a threaded connection; two pistons 46,47 and a rod 48, connected to each other by a threaded connection. On the rod there is a seat for a ball 49 and holes, which are covered by a movable sleeve 50. When the perforator is triggered, the sleeve shifts and the holes open, thereby opening a channel for carrying out hydromonitor processing. At the end of the rod there is a seat for a safety ring 51, which serves to protect against premature triggering of the perforator during descent.

[0052] A stop 52 is installed on the cylinder 43, which is secured in the cylinder with shear screws 53. The housing of the return mechanism 54 is screwed onto the stop 52, which ends with a thread NKT-73 GOST 633-80 for connection to the tubing column. Inside the housing 54, a piston 55 is installed, which is connected by a threaded connection to the piston 46. In the housing 54, there are holes 56 for bleeding air during assembly. After assembly, the holes are sealed with a plug.

[0053] The body of the perforator 57 is screwed into the lower part of the body 45 of the power unit, into which the wedge 58 is inserted, which, in turn, is screwed into the cavity of the additional rod (10)48. A safety ring 51 is installed in the body 57, the ring 51 is fixed with a nut 59.

[0054] Cutters 60 are inserted into the grooves of wedge 58. Two plates 62 are attached to body 57, at the level of the position of the cutters, from the inside using screws 61, which fix the cutters 60 in the axial direction relative to body 57. The lower edge of the cutters 60 rests against stop 63.

[0055] Sealing of gaps between cylinders, pistons and rods is ensured by sealing rings.

[0056] The perforator is connected to the tubing and lowered into the well to a specified depth. During lowering, the tubing column is filled with well fluid. The device operates as follows.

[0057] The device for installing packer plugs is mounted on the wellhead, connected to the tubing string and attaching the packer plug. The tool is lowered to the desired interval, a ball is dropped into the internal cavity of the tubing and pressure is created with liquid. By means of the hydraulic cylinders, movement of the cylinders is created, by means of which the packer plug is compressed, isolating this interval. Considering that it is necessary to create pressure for this period of time to carry out the work, two types of installer are used: small outer diameter 75 mm and large diameter 112 mm. To simplify the work and reduce the costs of manufacturing and delivery of two types of equipment, an installer with a diameter of 75 mm with the ability to install large packer plugs (with a diameter of 102 mm and above) has been developed. For this purpose, the device is equipped with two additional hydraulic cylinders, which allows creating the necessary hydraulic pressure for successful work with large diameter packer plugs.

[0058] The packer plug (Fig. 3) in addition to the standard sizes is divided into types: blind and filling. The difference is based on the design of the packer plug itself: the blind one is represented by a shoe, the retainer is represented by a through shoe with a valve. As part of the operations on repair and insulation works and elimination of leaks in the production columns, a blind packer plug (Fig. 3) is lowered into the well, a filling plug, through the inner body of which the solution for insulation is poured. The solution for insufficient hydraulic connection between the well and the casing stone is solved by intermediate lowering of a piercing perforator on the tubing pipe (Fig. 4) to create a puncture in the production column, wash out the cement stone and provide a hydraulic connection for successful penetration of the insulating material.

[0059] The claimed method allows to increase the efficiency and safety of carrying out repair and insulation works in wells to reduce water inflow into the well, eliminate leaks in production columns, and also reduce time and labor costs.

Claims

Invention formula A method for carrying out repair and insulation work in a well, characterized by the fact that it includes the following stages: - a configuration is installed at the wellhead, containing an installation module with hydraulic cylinders, mounted on a tubing string and connected to a packer plug, including a fixed barrel and moving parts; - the specified arrangement on a column of pump and compressor pipes is lowered into the well; - when the specified depth is reached, a ball is dropped into the tubing string and excess pressure is created in the tubing pipes, as a result of which, under the action of hydraulic pressure, the hydraulic cylinders of the installation module move downwards relative to the fixed wellbore and exert a force on the moving parts of the packer plug, ensuring its installation in the well and isolating the required interval; - if the hydraulic connection between the well and the casing stone is insufficient, above the location where the packer plug is installed, an intermediate descent of a piercing perforator is carried out on the tubing pipe to create a puncture in the production casing, wash out the cement stone and ensure the above-mentioned hydraulic connection for the successful penetration of the insulating material. - lowering of the assembly containing the installation module with hydraulic cylinders, mounted on the tubing string and connected to the filling packer - retainer, including a fixed barrel and moving parts; - when the specified depth is reached, a ball is dropped into the tubing string and excess pressure is created in the tubing, as a result of which, under the action of hydraulic pressure, the hydraulic cylinders of the installation module move downwards relative to the fixed wellbore and exert a force on the moving parts of the filling packer-retainer, ensuring its installation in the well and isolating the required interval; - if the hydraulic connection between the well and the casing stone is insufficient, the cement composition is poured under pressure through the installed filling packer-plug - retainer, with guaranteed penetration of the active substance through the holes made by the hydraulic perforator.

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