Packer and method for fixation thereof in a well

Abstract

The invention relates to the oil industry and can be used for increasing well productivity by increasing the oil flowrate, for a well workover and isolation of a water-encroached bench. The inventive packer (1) comprises a body (4) provided with a scaling ring (5) which is collapsible in a radial direction and fitted with a drive. Said drive is embodied in the form of a chamber (6) containing a working medium in an such initial aggregative state in which it occupies a minimum volume, and comprises an element transferring the working medium from the initial state to another state. In order to fix the packer (1) in the well, the working medium of the drive of the sealing ring is transferred from the initial aggregative state to another state, where the working medium occupies a greater volume.

Description

FIELD OF THE ART

[0001] The contemplated invention relates to the oil-producing industry and is intended for raising the producing ability of wells by intensifying oil influxes, and also for overhauling wells, for shutting-off water-bearing strata, etc.

PRIOR ART

[0002] Known in the art is a packer, disclosed in Inventor's Certificate of the USSR, No. 304345, Cl. E21B33/12, published in Bulletin of Inventions No. 17, 1971, comprising a body with radial ducts, sealing members with sockets, a housing, and a fixing unit with spring-loaded slips interacting with pushers and with the toothed surface of the connecting pipe. Arranged concentrically between the body and the housing is a piston rigidly connected to the pushers, and the space under the piston is communicated with the casing pipe space.

[0003] A disadvantage of the known packer is its low operation reliability because of possible clogging of ducts “a” and “b” and spaces “A” and “B” with particles found in the well fluid. Furthermore, the cross-section of the central duct of the packer is sharply reduced because of the concentrically arranged body, annular piston and housing.

[0004] Also known in the art is a packer, disclosed in Inventor's Certificate of the USSR, No. 1099047, Cl. E21B33/12, published in Bulletin of Inventions No. 23, 1984, comprising a hollow body with radial ducts, on which a packing element with a space for its drive is mounted, disposed in the body with a possibility of its axial travel, and a hollow shaft, blanked-off in its lower portion, associated with a string and provided with two rows of radial ducts for the communication of the in-string space with the annulus above the packer and with the space of the drive of the sealing element, respectively. The packer is provided with a housing with radial ducts, installed above the sealing element, constituting together with the sealing element as chamber, in which a spring-loaded connecting-pipe sleeve is installed, the communication of the space above the packer with the in-pipe space being effected via the duct of the connecting-pipe sleeve.

[0005] A disadvantage of this prior-art packer is complexity of its construction and, as a result, a low reliability of the packer operation, since particles present in the well fluid may clog the duct “A” and the openings communicating its inner space with the upper one, as well as the upper and lower chambers.

[0006] The most relevant prior art in terms of the essential features is a load-bearing element according to Inventor's Certificate of the USSR, No. 1240121, Cl. E21C37/07, published in Bulletin of Inventions No. 23, 1987, comprising expandable cheeks with bevels on their inner surfaces, trapezoidal inserts installed between the expandable cheeks and adjoining with their inclined faces the beveled surfaces of the expandable cheeks, an elastic tubular chamber arranged longitudinally between the expandable cheeks and the major bases of the inserts, cylindrical locking end flanges with a connecting pipe for feeding a working agent to the tubular chamber. The load-bearing element is provided with annular resilient seals installed coaxially on the tubular chamber in clearances between the faces of the locking flanges and the expandable cheeks. The locking flanges are installed between the expandable cheeks, and on their outer cylindrical surfaces and on the inner surfaces of the expandable cheeks grooves and mating projections are made.

[0007] The known load-bearing element is used for breaking rocks and other monolithic objects into blocks. It cannot be used directly as a packer, because it is intended for disintegrating adjacent rocks rather than for being fixed to the well walls and for sealing the well space, due to the presence of a clearance between the expandable cheeks and the inserts, which precludes sealing along their conjugated peripheral surfaces and the well surface. Furthermore, for disintegrating rocks a concentrated force is required, which should be transmitted to the rocks, therefore the peripheral surfaces do not adjoin the rocks over the entire circumference, their contact area must be small. These properties are not required for a packer.

[0008] A method of fixing a packer in a well is known, which is effected for a packer whose construction is disclosed in Inventor's Certificate of the USSR, No. 252244, Cl. E21B, published in Bulletin of Inventions No. 29, 1969. This method consists in that the sealing elements of the packer are wedged out by shifting one part thereof with respect to the other, the packer elements being shifted having conical surfaces (in a longitudinal section two neighboring elements have an inclined surface, and each element is made as a triangle, the base of one of the neighboring elements facing the wall of the well and the base of the other of the neighboring elements facing the longitudinal axis of the well). For extracting the packer, it is pulled upwards, the pins are cut off, and the packer cross-section is thereby reduced.

[0009] This method is disadvantageous in view of the difficulties involved in extracting the packer of such a construction because of its large diameter, since conical sections pushed one upon the other are employed, this making the packer cross-section larger. With wedging-out, the cross-section of the packer cannot be appreciably reduced for reliable extraction from the well.

[0010] Also known in the art is a method of fixing a packer in a well, which is effected for a hydraulic packer whose construction is disclosed in Inventor's Certificate of the USSR, No. 571581, Cl. E2133/12, published in Bulletin of Inventions No. 33, 1977. This method consists in that an elastic cup is deformed in a radial direction by supplying a drilling fluid under pressure to the interior of the elastic cup. The pressure is created by means of a piston and a hydraulic pump. When extracting the packer, the pressure is cut off and by moving the piston to the upper position the elastic cup is returned to its initial position by springs specially provided for this purpose.

[0011] The described method is disadvantageous in view of the necessity to use two drives for fixing the packer to the walls of the well and for disconnecting it, this making the construction of the packer and its control more complicated.

[0012] A method of fixing a packer is known, which is effected in a packing device according to Inventor's Certificate of the USSR, No. 898043, Cl. E21B33/12, published in Bulletin of Inventions No. 2, 1982. This method consists in varying the radial size of the sealing element of the packing device by subjecting it to a mechanical axial effect, this effect being carried out in two steps, namely: first, the lower portion of the packing device is abutted against the well bottom by shifting one of the parts of the device with respect to the other in an axial direction; then a compression is provided by means of a hydraulic head.

[0013] This known method is disadvantageous in that the packing device cannot be installed high from the well bottom, because the device is controlled by the force which originates during the interaction with the face of the well. Besides, using two drives for fixing and disconnecting involves complexities in the construction and control of the packing device.

[0014] The most relevant prior art in terms of the technical essence and the achieved result is a method of fixing a packer in a well, which is effected for a packer described in Inventor's Certificate of the USSR, No. 304345, Cl. E21B33/12, published in Bulletin of Inventions No. 17, 1971. The method consists in a radial deformation of the sealing annular element of the packer owing to axial compression of this element by the hydraulic pressure of a fluid pumped into the well.

[0015] A disadvantage of this known method is that it does not provide reliable operation of the packer, since it is necessary to supply constantly well fluid under pressure, which, ultimately, leads to clogging the working chamber of the packer, which transmits hydraulic pressure of the fluid via the moving piston to the sealing elements of the packer.

[0016] The technical problem solved by the contemplated invention is to increase the reliability of fixing the packer in a well owing to the effect produced by the pressure of the working medium of the packer drive on a comparatively large area of contact of the packer with the walls of the well, and also owing to simplifying the construction of the packer and the technology of installing it in a well at any distance from the well bottom.

[0017] Said problem is solved owing to the fact that in a packer comprising a body with a seal cup expandable in a radial direction, with a drive, according to the proposed technical solution, the drive of the seal cup is made in the form of a chamber with a working medium in such initial aggregate state that it occupies a minimum volume and an element which brings the working medium from the initial aggregate state to another.

[0018] Such design of the packer minimizes its radial size when installing it into a well and extracting it therefrom, simplifies these operations and predetermines simplification of the packer construction. This is achieved due to the possibility of changing the aggregate state of the working medium, whereby its volume changes from the minimum to maximum one, and the working medium acts on the seal cup, deforming and expanding it in a radial direction.

[0019] It is expedient to divide the chamber of the drive of the seal cup into a preparatory chamber for accommodating therein the working medium in the initial aggregate state and the element bringing the working medium from its initial aggregate state to another, and at least one working part, in which the working medium acts on the seal cup, the parts of the chamber being interconnected by at least one duct.

[0020] Such construction of the packer makes it possible to dispose the chamber along the longitudinal axis of the packer, this contributing to a reduction of its radial size and at the same time to increase the area of contact of the seal cup with the walls of the chamber, whereby the reliability of fixing the packer in a well is increased.

[0021] It is possible to use a liquid as the working medium and a thermoheater as the element bringing the working medium from its initial aggregate state to another.

[0022] Such construction of the packer makes it possible to bring in the simplest manner the working medium in the form of a liquid (the initial aggregate state) into steam (another, gaseous, aggregate state). The volume occupied by the working medium increases by as much as hundreds of times, or with the volume remaining the same, the pressure of gases formed on bringing the working medium from the initial aggregate state to another increases in the same proportion, this making it possible to fix the packer reliably to the walls of the well.

[0023] It is also possible to use a cooler as the element bringing the working medium from its initial aggregate state to another. In this case it is possible, using, e.g., water, to convert it into ice. At the temperature of −4° C. the ice will have maximum volume and ensure reliable fixing of the packer to the walls of the well. In the case of using a gas, it is necessary to convert the latter into a liquid and then to cool it down, converting it into ice with a temperature predetermining it maximum volume.

[0024] It is possible to use a liquid as the working medium and electrodes with a source of current, constituting an electric circuit with the working medium, as the element bringing the working medium from its initial aggregate state to another.

[0025] Such construction of the packer makes it possible to decompose the liquid by electrolysis into gaseous components (for instance, to decompose water into oxygen and hydrogen), which will provide an increase in the volume of the working medium and, consequently, an increase of pressure in the working part of the chamber, which will expand the seal cup in a radial direction, providing thereby reliable fixing of the packer to the walls of the well.

[0026] It is also expedient to use a combustible substance with oxygen as the working medium and a fuse as the element bringing the working medium from its initial aggregate state to another. Such construction of the packer makes it possible to use a solid or liquid substance as the working medium, thus rendering the construction universal.

[0027] It is expedient to use a heated resistance element as the fuse. Such a packer has the simplest construction and is universal, because with this resistance element it is possible both to heat the working medium if it is a liquid and to ignite it if it is combustible.

[0028] It is also expedient to use an electric spark as the fuse.

[0029] Such a packer is noted for a simplest construction and easy servicing.

[0030] It is expedient to use gunpowder as the combustible substance. This substance is widely spread, and, having a minimum volume, is convenient in service and provides the desired effect.

[0031] A combustible liquid, for instance, gasoline, may be used as the combustible substance. It is available at any well site, and therefore such a packer is convenient in service.

[0032] It is also possible to have the seal cup comprised of an element interacting with the working part of the chamber and several elements encompassing said element, all said elements being arranged coaxially.

[0033] With such construction of the packer, the seal cup can be made elastic enough for radial deformation owing to the elasticity of the element interacting with the working part of the chamber, and rigid for increasing the wear-resistance of the elements encompassing the first said element.

[0034] It is expedient to provide the chamber of the drive of the seal cup with a remote-controlled valve for discharging the working medium in the gaseous aggregate state from said chamber. Thereby fixing of the packer can be controlled (if necessary, the gas pressure in the chamber of the drive may be reduced and the packer may be extracted from the well).

[0035] In a method of fixing a packer in a well, comprising lowering a packer into a well to a required depth, increasing the diameter size of the packer and deforming its seal cup in a radial direction, according to the proposed technical solution, a working medium of the seal cup drive brings the working medium from its initial aggregate state, in which the working medium occupies minimum volume, into another aggregate state, in which the working medium occupies a larger volume. Such a combination of operations increases the reliability of fixing the packer in the well due to the action of the working medium on a comparatively large area of contact of the packer with the walls of the well, creates a radial seal and a force fixing the packer in the well at any distance from the well bottom. This simplifies the technology of mounting and dismantling the packer in the well, since the radial deformation of the seal cup can be controlled from the surface.

[0036] It is expedient to effect bringing the working medium to another aggregate state by cooling the working medium in the form of a liquid to a temperature not higher than its boiling point. At present such an operation is the easiest to perform with the provision of the required effect.

[0037] It is also expedient to effect bringing the working medium to another aggregate state by the electrolysis of the working medium in the form of a liquid (e.g., water). Such an operation will also provide an increase in the volume occupied by the working medium and, consequently, will permit carrying out radial deformation of the seal cup, that is, it will provide fixing the packer to the walls of the well and tightness over the surface of fixing.

[0038] It is expedient to effect bringing the working medium to another aggregate state by burning the working medium in the form of a combustible substance with oxygen. Such an operation is simple to perform, and it will provide, on the one hand, minimization of the initial volume of the working medium when lowering the packer into the well, so that the radial size of the packer will be minimum, this simplifying lowering the packer into the well and extracting it therefrom, while, on the other hand, when burning the working medium, this operation will provide maximum pressure of the formed gas on the seal cup, that is, reliability of fixing the packer to the well.

BRIEF DESCRIPTION OF THE DRAWINGS

[0039] In the accompanying drawings

[0040] FIG. 1 illustrates the operation of mounting a packer in a well (in a casing pipe);

[0041] FIG. 2 illustrates the operation of bringing a working medium from its initial aggregate state to another, whereby there occurs radial deformation of a seal cup with the formation of a closed system (a packer with a thermocouple);

[0042] FIG. 3 shows a packer with a thermocouple, a thermoheater and a remote-controlled electric valve, e.g., an electromagnetic one (an open packer system);

[0043] FIG. 4 shows a packer with several working parts of a drive chamber, arranged along the longitudinal axis of the well;

[0044] FIG. 5 shows a packer with coaxial elements of a seal cup and electrodes.

DESCRIPTION OF THE BEST EMBODIMENTS OF THE INVENTION

[0045] The proposed packer and a method of fixing thereof are embodied in the following manner.

[0046] Packer 1 (FIG. 1) secured to a suspension means (a wire rope or pipe 2) is mounted into a well (into a casing pipe not shown in the Figure) 3. The packer 1 comprises a body 4 with a seal cup 5 and its drive which expands the seal cup 5 in a radial direction. The drive may have a single chamber 6 (FIGS. 1-3) or the chamber may consist of parts 7 and 8 (FIGS. 4, 5), (the part 7 being a preparatory one, and the part(s) 8 being working one(s)), interconnected by at least one duct 9. In the first case the chamber 6 (FIGS. 1-3) serves for accommodating therein a working medium in a solid or liquid initial aggregate state and is a preparatory and working chamber simultaneously, i.e., in the same chamber the working medium passes into another aggregate state and acts on the seal cup 5. In the same chamber 6 or beyond it (the latter is not shown in the Figure) elements are disposed, which bring the working medium from its initial aggregate state to another. For example, when converting a liquid into a solid (ice), a thermocouple 10 is required (FIGS. 1-3); when converting a liquid into a gas, a thermoheater 11 is required (FIGS. 3, 4) or electrodes 12, 13 with a source of current (not shown in FIG. 5) are required for decomposing water into gaseous components (oxygen and hydrogen); when converting a solid into a gas it is necessary to produce a spark igniting the solid (oxygen for burning the solid may be in a free state in the chamber 6 or in the part 7 or be in the bound state in the solid itself), for which purpose the electrodes 12 and 13 spaced apart to a distance for a spark (breakdown) to originate therebetween, with a source of current may be used. In the case of using the chamber consisting of several parts 7, 8, one of said parts 7 (preparatory one) serves for accommodating the working medium in its initial aggregate state, in which it occupies a minimum volume (in the form of a liquid or a solid), and the other part 8, the working one (FIG. 4), may be arranged along the seal cup 5 on the inside thereof, and the working medium in the gaseous state comes to said part 8, ensuring radial deformation of the seal cup 5. The chamber 6 or the working part 8 of the chamber may be made as one part extending under the seal 5 (FIGS. 1-3, 5) or the chamber may have several working parts 8, whose number corresponds to the number of contiguous surfaces of the seal cup 5 (FIGS. 4, 5). The preparatory and working parts 7, 8 of the chamber are arranged along the longitudinal axis of the packer 1 (FIGS. 4, 5). The seal cup 5 may have one part contiguous with the walls of the well 3 (FIGS. 1-3) or several parts 14-16 (FIG. 4) contacting the walls of the well 3 and arranged in succession along the longitudinal axis. An embodiment is possible (FIG. 5), wherein the seal cup 5, being of a combination-type, consists of one element 17 interacting with the working part 8 of the chamber, and of several elements 14-16 encompassing the element 17 and being coaxial thereto. The seal cup 5 is secured on the body 4 by ring springs or yokes 18 (they may be round (FIGS. 1, 2, 5) or flat (FIGS. 3, 4) in cross-section. The ring springs 18 may be secured at the ends of the seal cup 5 (FIGS. 1-3, 5) or in the middle of it (FIG. 4). In the latter case their transverse size must, on the one hand, ensure the deformation of the seal cup 5 and, on the other hand, the ends of the seal cup 5 must ensure after the deformation the tightness of the working part 8 of the chamber. The position of the seal cup 5 with several elements 14-16 contacting the walls of the well 3 after the deformation is shown with a dotted line in FIG. 4. One of possible constructions of the combination-type seal cup 5, ensuring the fulfillment of these conditions, is shown in FIG. 5.

[0047] The packer 1 may comprise a closed system (FIGS. 1, 2, 4) in which the working medium is not discharged to the atmosphere through the well 3. In this case the preparatory part 7 of the chamber is hermetically closed with a plug 19. If the packer comprises an open system (FIGS. 3, 5), then a remote-controlled valve 20 is provided (it is most expedient to use an electromagnetic valve), which, when necessary, discharges the working medium, that is in the gaseous state, into the well 3 and thence to the atmosphere. Shown at 21 (FIGS. 1-4) is a cable along which electric power is supplied to the thermocouple 10; shown at 22 (FIGS. 3, 4) is a cable along which electric power is supplied to the thermoheater 11; shown at 23 (FIGS. 3, 5) is a cable via which the electromagnetic valve 20 is controlled; shown at 24, 25 (FIG. 5) are cables connecting the electrodes 12, 13 to a source of current.

[0048] The principle of the packer operation and fixing thereof in a well is as follows.

[0049] The packer 1 is lowered on the wire rope (pipe) 2 into the well (casing pipe) 3 (FIGS. 1-5) to a depth at which the packer has to be fixed. Taking into account that the temperature of the well fluid increases with depth, a working medium is selected such that at the temperature at the site of mounting the packer 1 in the well 3 the volume of the working medium in its initial aggregate state should be minimum. The working medium in its initial aggregate state occupies minimum volume, when it is in the solid or liquid aggregate state; therefore, the size of the chamber 6 and of the part 7 of the chamber (FIGS. 1-5) in which the working medium is disposed may be reduced. Then the working medium is brought from its initial aggregate state to another. If a liquid was used as the working medium, then it must be either converted into a solid (ice), or into a gas. As is known, if pure water is used, then ice has minimum volume at the temperature of −4° C., so that ice can be used in a closed volume for acting upon the walls surrounding it, and, consequently, on the seal cup 5 as well. For converting a liquid into ice, it is necessary to use the thermocouple 10 which brings the temperature of the liquid down below its freezing point (FIG. 1). The ice will expand the seal cup 5, fixing the packer 1 to the walls of the well 3 (FIG. 2). It is expedient to use special liquids which ensure attaining maximum volume at minimum power consumption. In view of the above-stated, at present it is more rational to bring a liquid to the gaseous state. In this case it is possible to use the thermoheater 11 (FIGS. 3, 4) which will heat the liquid to a temperature not lower than its boiling point and convert it into a gas. The temperature in the well 3 at the level of mounting the packer 1 will promote the heating. The heating may be continued. In this case the gas pressure in the chamber 6, in the parts 7, 8 of the chamber will be increased, and this will lead to the deformation of the seal cup 5, and, consequently, to reliable fixing of the packer 1 to the walls of the well 3.

[0050] Conversion of a liquid into a gas can also be accomplished by decomposing the liquid into hydrogen and oxygen (if the liquid employed is water). For this to be done, it is necessary to have electrodes 12, 13 (FIG. 5) with a source of current (not shown in the Figure).

[0051] In the case of using a solid substance, for instance, a gunpowder as the working medium, for bringing it to the gaseous aggregate state the gunpowder must be ignited. For this purpose it is possible either to use the same electrodes 12, 13, by spacing them apart from each other to a distance required for an electric charge breakdown to occur (FIG. 5) and supplying electric power to them, or to heat the thermoheater 11.

[0052] A particular use of any of the methods of bringing the working medium from its initial aggregate state to another will depend on the economic expedience and the degree of its development under particular conditions. For example, a solid working medium occupies minimum volume, which provides for minimizing the size of the packer 1, simplifying its mounting into the well 3, especially into a small-diameter casing pipe. The use of a liquid working medium, e.g., of water, is easier to carry out and safer in servicing, because water is not explosion-hazardous and is available in any well 3. If the packer 1 is embodied with a single chamber 6 (FIGS. 1-3), then the action of the working medium on the seal cup 5 occurs in also in the chamber 6, this being more simple structurally. If the chamber consists of several parts: a preparatory part 7 and working parts 8 (FIGS. 4, 5), then in one of them, in the part 7, the working medium is brought from one aggregate state to another, and the other part(s) 8 serve as the working one(s), that is, the action of the working medium on the seal cup 5 occurs therein. If the chamber has several parts 7, 8, there is a possibility of increasing the area of contacting the seal cup 5 by extending the latter along the longitudinal axis of the packer 1. Another effect is a reduction of the diameter size of the packer 1, since the chamber 7 may be arranged along the longitudinal axis of the parts 8 of the chamber. The interaction of the seal cup 5 with the wall of the well 3 may be either direct (FIGS. 1-4) or through the elements 14-16 which may be made more wear-resistant. In the latter case the element of the seal cup 5, interacting with the working part 8 of the chamber, may be made elastic, while the elements encompassing said element may be made rigid, i.e., more wear-resistant.

[0053] For extracting the packer 1 from the well 3, it is necessary to restore the initial radial size of the seal cup 5. If the construction is provided with electromagnetic valve 20, it can be opened remotely for bleeding the gaseous working medium into the well 3. In the parts 7, 8 of the chamber the gas pressure will drop, and the seal cup 5 under the effect of its elastic forces will restore its initial radial size. After that the packer 1 can be extracted from the well 3.

[0054] If the packer 1 comprises a closed system, that is, has plug 19 (FIGS. 1, 2, 4) which provides for the tightness of the chamber 6 or of the parts 7, 8 of the chamber, in this case it is necessary to cool the gaseous working medium down in order to lower its pressure therein. This may be effected by natural cooling by way of the heat transfer through the walls of the chamber 6 and of the parts 7, 8 of the chamber of the packer 1, such a process being time-consuming. This process can be accelerated by cooling the working medium artificially with the help of the thermocouple 10 (FIGS. 1-3).

[0055] It is expedient to provide both thermoheater 11 and thermocouple 10 in the construction of the packer 1 (FIGS. 3, 4). This will provide a better system of controlling the packer operation.

Claims

1. A packer comprising a body with a seal cup expandable in a radial direction, provided with a drive, characterized in that the drive of the seal cup is made as a chamber with a working medium in such initial aggregate state that it occupies a minimum volume, and an element that brings the working medium from the initial aggregate state to another.

2. The packer of claim 1, characterized in that the chamber of the drive of the seal cup is divided into a preparatory part for accommodating a working medium in its initial aggregate state and the element that brings the working medium from its initial aggregate state to another, and at least one working part in which the working medium acts on the seal cup, the parts of the chamber being interconnected by at least one duct.

3. The packer of claims 1 or 2, characterized in that a liquid is used as the working medium and a heater or a cooler is used as the element bringing the working medium from its initial aggregate state to another.

4. The packer of any one of claims 1 to 3, characterized in that the seal cup comprises a member interacting with the working part of the chamber and several other members encompassing said interacting member, all said members being arranged coaxially.

5. A method of fixing a packer in a well comprising lowering the packer into the well to a required depth, increasing the diameter of the packer, and deforming its seal cup in a radial direction, characterized in that the working medium of the drive of the seal cup is brought from its initial aggregate state, in which the working medium occupies a minimum volume, to another aggregate state, in which the working medium occupies a larger volume.

6. A method of claim 5 characterized in that bringing the working medium to another aggregate state is effected by heating the working medium in the form of a liquid to a temperature not lower than the boiling point thereof.

7. A method of claim 13, characterized in that bringing the working medium to another aggregate state is effected by cooling the working medium in the form of a liquid to a temperature not higher than the freezing point thereof.