Device and method for cleaning wells

Abstract

FIELD: oil and gas production industry.SUBSTANCE: group of inventions relates can be used for cleaning wells. The device comprises a drilling unit, a ball check valve, a container for contaminants, a shut-off valve with a stem, a circulation valve with a knock-down element connected to a column of tubing. A flap valve and a container for large contaminants are installed above the drilling unit, a ball check valve is installed between the container for large contaminants and the container for contaminants. The shut-off valve is located above the contaminant container and includes a cylindrical body in which a rod configured for axial movement is installed; radial holes are made in the lower part of the rod. The drilling unit comprises a cylindrical guide, configured for rotation around its axis, and a spring-loaded movable housing configured for rotation around its axis and axial movement. The cylindrical guide of the drilling unit is made with a through axial channel having a flow section comparable in size to the flow section of the pump-compressor pipes, equipped with teeth at the lower end and a curved closed groove on the outer surface. The spring-loaded movable body of the drilling unit is made with teeth on the lower end and a projection on the inner surface that engages with a closed curvilinear groove.EFFECT: efficiency of well cleaning.3 cl, 6 dwg

Description

[0001] The group of inventions relates to the oil and gas production industry and can be used to clean wells from large, undrillable contaminants or fragments located in the thickness of sand and proppant plugs.

[0002] In addition to sand and proppant plugs, wells may contain large, undrillable debris, such as metal cable clamps, pieces of packer rubber, packer anchors, and large, compacted fragments of downhole cuttings, which impede the drilling of proppant and sand plugs. The presence of undrillable debris during wellbore cleanout requires the use of specialized gripping and holding units or additional tripping operations to remove these large fragments.

[0003] A combined drilling attachment is known, according to the Russian Federation patent for utility model No. 190261, E21B 37 / 00, 2019, including a housing, external and internal cutters, a coupling movably inserted into the attachment housing, a nut with an external cutter fixed to it, a screw rotating in the housing, with an internal cutter at the end, a spring, expanding the coupling and nut by the value of the full working stroke.

[0004] The disadvantages of the analog include low drilling efficiency due to the alternating rotation of the cutters in forward and reverse directions during the up and down movements of the device, respectively. However, the working drilling motion of the cutter is only forward rotation during the down movement of the device. Furthermore, the narrow passages of the nozzle located between the outer and inner cutters are not designed to accommodate metal objects, lost parts of downhole equipment, and other large fragments. There is also a high risk of jamming the threaded assembly of the nozzle, consisting of a nut and screw, when exposed to abrasive sand or proppant particles.

[0005] A well depression cleaning device is known according to the Russian Federation patent for utility model No. 174629, E21B 37 / 00, 2017, which includes a drilling device connected in series from the bottom up at the end of the tubing string, a container for sludge formed by the tubing pipes with a check valve in its lower part and a bypass valve in the upper part, above which a knock-down valve is located, between the drilling device and the container check valve there is a filter for collecting a large fraction of sludge, consisting of coaxially installed pipes, the inner pipe of which has slotted holes and forms an inter-pipe receiving chamber with the outer pipe, while between the bypass and knock-down valves there is a direct-acting liquid flow regulator.

[0006] A disadvantage of the known device is its low efficiency in cleaning wells from large contaminants. This is due to the fact that once the tubing cavity is filled with fluid, the upward flow through the device ceases, and the large contaminants in the filter fall out. There is no structural element underneath the filter to retain the contaminants, unlike the fine contaminants, which are retained by a check valve. Furthermore, as the filter fills, the velocity of the upward flow of fluid will decrease, reducing the effectiveness of well cleaning.

[0007] A horizontal well cleaning system is known under Russian Federation Patent for Utility Model No. 193376, E21B 37 / 00, 2019, which was selected as the closest analogue for both the first and second inventions of this group of inventions. The horizontal well cleaning system comprises a knock-down valve, a throttling coupling, an adjustable hydraulic spring bailer, ball check valves, and a combination nozzle with outer and inner hollow cutters mounted on the process tubing. The outer and inner cutters are spring-loaded relative to each other by a power spring, and the internal cavity of the cleaning system is sealed by a system of ball check valves.The method for cleaning horizontal wells using a known complex consists of installing the complex on the tubing, lowering it to the surface of the plug formation, drilling out the plug while simultaneously providing a hydraulic connection between the cavity of the complex and the annular space and filling a container made of tubing with fragments of the plug due to the difference in the hydrostatic column of liquid in the annular space of the well and in the cavity of the complex and the tubing.

[0008] The disadvantages of the closest analogue include, firstly, the inability to temporarily lock the bailer rod, which leads to its activation upon the first unloading onto the plug without the possibility of preliminary drilling out. Consequently, the empty tubing begins to fill with wellbore fluid immediately, reducing the device's useful capacity in terms of volume and suction time, and consequently, the effectiveness of wellbore cleaning. Secondly, the installation of ball check valves directly above the combined nozzle, characterized by a narrowed flow area at the ball seat, further reduces the effectiveness of wellbore cleaning due to clogging / blocking of this narrowed flow area by large fragments or lost parts of downhole equipment, cable clamps, etc. Furthermore, when unloading the drilling tool onto the plug, its narrow cavities become filled with plastic contaminants, blocking the access of wellbore fluid.These factors make it impossible to continue using the device without inspecting and cleaning it in a workshop.

[0009] The technical result is to increase the efficiency of well cleaning.

[0010] The technical result is firstly achieved in that in a device for cleaning wells, comprising a drilling unit, a ball check valve, a container for contaminants, a shut-off valve with a rod, a circulation valve with a knock-down element connected to a tubing string, according to the first invention, a flap valve and a container for large contaminants are installed above the drilling unit, a ball check valve is installed between the container for large contaminants and the container for contaminants, the shut-off valve is located above the container for contaminants and includes a cylindrical body connected to the container for contaminants, the rod is installed with the possibility of axial movement inside the cylindrical body of the shut-off valve, radial holes are made in the lower part of the rod, the shut-off valve is provided with at least one destructible element for fixing the rod, the drilling unit contains a cylindrical guide,mounted with the possibility of rotation around its axis, and a spring-loaded movable body mounted with the possibility of rotation around its axis and the possibility of axial movement, wherein the cylindrical guide of the drilling unit is made with a through axial channel having a flow section comparable in size with the flow section of the tubing, the cylindrical guide is provided with teeth at the lower end and a curved closed groove on the outer surface, the spring-loaded movable body of the drilling unit is made with teeth at the lower end, is provided on the inner surface with a protrusion that engages with a closed curved groove on the outer surface of the cylindrical guide.

[0011] In addition, a lateral through hole can be made in the device at the lower end of the cylindrical guide of the drilling unit.

[0012] The technical result, secondly, is achieved by the fact that in the method of cleaning wells, including lowering a device for cleaning wells to the surface of contaminants on a column of tubing, opening a shut-off valve by extending its stem, drilling out contaminants with a drilling unit, opening a ball check valve, moving fragments of contaminants through a ball valve into a container for contaminants with a flow of well fluid, opening a circulation valve, draining the fluid, extracting from the well, according to the second invention, the internal cavities of the device are sealed by fixing the stem in the body of the shut-off valve with at least one destructible element, the device is lowered to the surface of contaminants with hermetically sealed internal cavities of the tubing and the device above the shut-off valve, preliminary drilling out of contaminants with a drilling unit is carried out,by rotating the cylindrical guide and the movable body of the drilling unit in one direction due to the movement of the protrusion on the inner surface of the movable body of the drilling unit along the curved closed groove of the cylindrical guide of the drilling unit, the shut-off valve is opened by cutting off the destructible element, drilling out contaminants with an upward flow of well fluid, with an upward flow of well fluid, moving contaminants through the axial channel of the guide of the drilling unit, opening the flap valve, filling the container for large contaminants with large fragments, opening the ball check valve, filling the container for contaminants with small fragments of contaminants.

[0013] The technical result according to the first and second inventions of the group of inventions is achieved due to the presence in the shut-off valve of the well cleaning device of a destructible element that temporarily fixes the rod from extending, eliminating the hydraulic connection of the internal cavity of the device above the shut-off valve and the tubing and the annular space, which allows for preliminary drilling of a solid surface of contaminants, for example, in the form of a proppant plug, without sucking in contaminants and filling the tubing, saving the useful volume of the device during preliminary drilling, thereby prolonging the useful action of the device and increasing the penetration into the depth of the plug body during well cleaning, and therefore increasing the efficiency of well cleaning.The drilling unit's efficiency is enhanced by a closed curved groove located on the outer surface of the guide and a projection located on the inner surface of the sliding body, which engages with the closed curved groove. This ensures that the guide teeth and the teeth of the drilling unit's sliding body rotate in only one direction without backfiring, thereby improving and accelerating the drilling of contaminants. Furthermore, the increased flow area of ​​the drilling unit's cylindrical guide, compared to similar models, improves the throughput of the device, and consequently increases the efficiency of cleaning the well of large contaminant fragments. This cross-section is similar in size to the flow area of ​​the tubing, allowing the upward flow of well fluid to move large contaminant particles into the cavity of the drilling unit.A flap valve, with a larger flow area than a ball check valve, located directly below the large waste container, allows the container to be filled with large particles, lost well equipment parts, etc. Smaller, lighter particles are carried upward by the upward flow into the waste container, which is located above the large waste container. A ball check valve, located directly below the waste container, allows fine particles to pass through a narrow flow channel and accumulate in the upper container, without overloading the lower container with fine particles.The presence of a through side hole at the lower end of the cylindrical guide of the drilling unit allows, in the event of impassable clogging of the through channel of the cylindrical guide with a plastic fragment of bottomhole cuttings, to redirect the flow of sucked well fluid, due to which the plastic fragment is washed away into smaller fragments, which are freely transferred to containers for large and small contaminants, which increases the efficiency of well cleaning.

[0014] Fig. 1 shows a device for cleaning wells in longitudinal section during the process of preliminary drilling of the hard surface of contaminants.

[0015] Fig. 2 shows a longitudinal section of the well cleaning device during the process of activating the shut-off valve, destroying contaminants and sucking contaminant fragments into containers.

[0016] Fig. 3 shows a drilling unit of a well cleaning device in longitudinal section.

[0017] Fig. 4 shows a cylindrical guide of a drilling unit with a closed groove on its outer surface.

[0018] Fig. 5 shows the development of a closed groove of a cylindrical guide and the direction of movement of the projection of the movable body of the drilling unit along the closed groove.

[0019] Fig. 6 shows a longitudinal section of the circulation valve of the well cleaning device.

[0020] The device includes a drilling unit 1 from the bottom up, a flap valve 2, a container 4 for large contaminants, a ball check valve 3, a container 5 for contaminants, a shut-off valve 6, a circulation valve 7. The device is connected to the tubing 37 and, together with the cavity 38 of the tubing 37, forms a single hollow sealed space inside, limited from below by the shut-off valve 6.

[0021] The flap valve 2, installed directly above the drilling unit 1, includes a flap 8. The ball check valve 3, installed directly below the container 5 for contaminants, includes a ball 9. The ball check valve 3 contains a restrictor 10 that prevents the ball 9 from exiting the valve in the presence of an upward flow of liquid through the device.

[0022] The shut-off valve 6 divides the device into an upper sealed cavity and a lower cavity communicating with the well. The shut-off valve 6 includes a cylindrical body 11, a rod 12 mounted in the body 11 with the possibility of axial movement, a destructible element 13 in the form of at least one shear pin, temporarily fixing the rod 12 from axial movement during lowering of the device and during preliminary drilling, a nut 14 limiting the rod 12 from completely exiting upward from the body 11, compensation holes 15 that discharge liquid from the body 11 into the annular space when the rod 12 moves downward and admit liquid into the body 11 when the rod 12 moves upward, radial holes 16 made in the lower part of the rod 12 for communicating the annular space with the cavity of the device and the cavity 38 of the tubing 37 through the drilling unit 1 (Fig. 2) when the rod 12 moves downward, and closed by the body 11 when the rod 12 is in the upper position.The shut-off valve 6 can be provided with an axial throttling channel 17 passing inside the rod 12, limiting the upward flow of liquid when filling the cavity of the device and the cavity 38 of the tubing 37 with well fluid.

[0023] Circulation valve 7 includes a housing 18, a hollow destructible element 19 installed in the housing 18, the cavity of which communicates with the annulus. After element 19 is destructed by the discharge element 32, circulation opening 33 opens.

[0024] The drilling unit 1 comprises a cylindrical guide 20, which is provided with teeth 22 at its lower end and has a side opening 23 at its lower end for washing out a blockage / clogging, a bearing unit 26, which ensures rotation of the cylindrical guide 20 around its axis relative to the device and the tubing 37, an upper sub 24 with a nut 25, a movable body 28 with teeth 29 at the lower end, installed outside the guide 20 on the same axis with it, a bearing unit 27, which ensures rotation of the movable body 28 around its axis relative to the device and the tubing 37, a return spring 31, which ensures axial movement of the movable body 28 along the guide 20.On the outer surface of the cylindrical guide 20, a curvilinear closed groove 21 is made, and on the inner surface of the movable body 28, a cylindrical projection 30 is made, which engages with the closed groove 21, which ensures rotation of the cylindrical guide 20 and the movable body 28 only in one direction relative to the device and the tubing 37. The engagement of the projection 30 of the movable body 28 and the curvilinear closed shape of the groove 21 of the cylindrical guide 20 ensure rotation of the guide 20 and the movable body 28 in one direction relative to the device and the tubing 37 during axial movement of the movable body 28 along the guide 20.For example, the optimal shape of the curved closed groove 21 may have upper 40 and lower 41 dead centers located in plan at 180 degrees relative to each other on diametrically opposite sides of the cylindrical guide 20 and connected to each other by a right-handed helical section 42 on one side and a left-handed helical section 43 on the other side, wherein the right-handed helical section 42 is located lower in the axial direction than the left-handed helical section 43 by an amount not less than the width of the groove 21 for the sequential redirection of the cylindrical projection 30 along the groove in only one direction (Fig. 5). The cylindrical guide 20 is made with a through axial channel 34 of large cross-section, close in size to the flow cross-section of the tubing 37.For example, the following tubing sizes are widely used in well cleaning operations: NKT60 tubing with a 50 mm flow area is used for wells with casing diameters of 102-114 mm; NKT73 tubing with a 62 mm flow area is used for wells with casing diameters of 127-178 mm. Preferably, the flow area diameter of the cylindrical guide 20 of the drilling unit 1 is at least 0.8 times the diameter of the tubing used. Accordingly, for NKT60, the flow area of ​​the guide 20 can be ~40 mm, and for NKT73, ~50 mm.

[0025] The method is as follows.

[0026] The device, consisting of (from bottom to top) a drilling unit 1, a flap valve 2, a container for large contaminants 4, a ball check valve 3, a container for contaminants 5, a shut-off valve 6, a circulation valve 7, is lowered into the well on tubing 37.

[0027] When lowering the device, shut-off valve 6 is in the transport, i.e., closed, position, with rod 12 temporarily secured in the upper position by breakable element 13, and openings 16 closed. In this position, the internal cavity of the device is hermetically sealed from the annulus, allowing the device to be lowered into the well without filling with fluid, keeping its cavity and the cavity 38 of tubing 37 empty.

[0028] Upon reaching the surface of contamination, for example, a proppant plug, a preliminary drilling out of the upper hard crust is performed with the shut-off valve 6 closed. For this purpose, the device with the tubing 37 is cyclically raised and lowered up and down with a force not exceeding the shear force of the element 13 being destroyed. The force is controlled by an electronic weight indicator installed on the lifting mechanism - a standard device with which all well workover hoists are equipped. The teeth 22 of the cylindrical guide 20 of the drilling unit 1 deepen into the plug, and the movable body 28 of the drilling unit 1 moves relative to the guide 20 upward, remaining above the plug and compressing the return spring 31, while the cylindrical protrusion 30 of the movable body 28 moves along the closed groove 21 of the guide 20 (Fig.5), which causes the movable body 28 to rotate with the cylindrical guide 20 in only one direction, without idle movement in the opposite direction, drilling out the plug. When the tubing 37 moves upward, the return spring 31 moves the movable body 28 downward relative to the guide 20, and the movable body 28 again rotates relative to the guide 20 in the same direction during further movement of the projection 30 along the groove 21.

[0029] Then, the shut-off valve 6 is activated as follows:

[0030] One or more pins of the destructible elements 13 are cut off, depending on their number in the shut-off valve 6. For this purpose, the device and the tubing 37 act on the proppant plug with cyclic up-and-down movements with a force greater than the shear force of one or more destructible elements 13. The plug continues to be divided into fragments using the drilling unit 1. In this case, the elements 13 are cut off, as a result of which the stem 12 of the shut-off valve moves downward, extending from the body 11. In this case, the holes 16 are opened, providing a hydraulic connection between the internal cavity of the device and the tubing with the annular space. The well fluid is sucked in and enters the well cleaning device in an upward flow through the through axial channel 34 of the drilling unit 1 (Fig. 2).

[0031] At a well depth of 2500 m, the difference in liquid level in the tubing and annulus, taking into account the length of containers 4 and 5, can be up to 2000 m, the pressure difference between the tubing and annulus when activating the shut-off valve 6 will be 20 MPa (200 atm), when lowering the device into the well on an empty tubing with a diameter of 73 mm, the volume of liquid sucked in when filling will be up to 4.5 m 3 taking into account the decrease in the liquid level in the annular space.

[0032] Liquid 35, sucked in due to the pressure difference, passes through the through axial channel 34 of the drilling unit 1, through the flapper valve 2, lifting the flapper 8 with an upward flow, moves upward and through the openings 16 fills the empty cavity 36 of the device. The ascending flow of liquid 35, moving upward as a result of the pressure difference, captures fragments of the proppant plug, due to the large cross-sectional area of ​​​​channel 34 and the flapper valve 2, transfers the large fraction in the form of large pieces of plug, lost parts of the well equipment, clamps, etc., into the container 4, and the small fraction, sand, proppant, into the container 5.In the event of a non-passable blockage of the through channel 34 of the drilling unit 1 by a plastic fragment 39 of the bottomhole cuttings, the sucked-in well fluid 35 is naturally redirected to the side opening 23 in the guide 20, due to which the plastic fragment 39 is washed away by a powerful jet under pressure of up to 20 MPa (200 atm) into smaller fragments, which pass unhindered into containers 4 and 5 (Fig. 3, 4).

[0033] After finishing cleaning the bottom of the well, element 32 is dropped into cavity 38 of tubing 37, knocking down hollow destructible element 19 of circulation valve 7, while opening circulation hole 33 in circulation valve 7, ensuring communication between cavity 38 of tubing 37 and the annular space for draining liquid when lifting the device.

[0034] Then the device is raised to the surface and the contaminants are disposed of.

[0035] Thus, the claimed group of inventions makes it possible to increase the efficiency of cleaning oil and gas producing wells, including from large contaminants and sand-proppant plugs.

Claims

1. A device for cleaning wells, comprising a drilling unit, a ball check valve, a container for contaminants, a shut-off valve with a rod, a circulation valve with a knock-down element connected to a tubing string, characterized in that a flap valve and a container for large contaminants are installed above the drilling unit, a ball check valve is installed between the container for large contaminants and the container for contaminants, the shut-off valve is located above the container for contaminants and includes a cylindrical body connected to the container for contaminants, the rod is mounted with the possibility of axial movement inside the cylindrical body of the shut-off valve, radial holes are made in the lower part of the rod, the shut-off valve is provided with at least one destructible element for fixing the rod, the drilling unit contains a cylindrical guide installed with the possibility of rotation about its axis, and a spring-loaded movable body,mounted with the possibility of rotation around its axis and the possibility of axial movement, wherein the cylindrical guide of the drilling unit is made with a through axial channel having a flow section comparable in size to the flow section of the pump-compressor pipes, the cylindrical guide is provided with teeth at the lower end and a curved closed groove on the outer surface, the spring-loaded movable body of the drilling unit is made with teeth at the lower end, provided on the inner surface with a projection that engages with a closed curved groove on the outer surface of the cylindrical guide.

2. The device according to paragraph 1, characterized in that a lateral through hole is made at the lower end of the cylindrical guide of the drilling unit.

3. A method for cleaning wells, which includes lowering a well cleaning device according to paragraph 1 on a tubing string to the surface of the contaminants, opening a shut-off valve by extending its stem, drilling out the contaminants with a drilling unit, opening a ball check valve, moving fragments of contaminants through the ball valve into a container for contaminants with a flow of well fluid, opening a circulation valve, draining the fluid, removing from the well, characterized in that the internal cavities of the device are sealed by fixing the stem in the body of the shut-off valve with at least one destructible element, lowering the device to the surface of the contaminants with hermetically sealed internal cavities of the tubing and the device above the shut-off valve, preliminary drilling out of the contaminants with a drilling unit,by rotating the cylindrical guide and the movable body of the drilling unit in one direction due to the movement of the protrusion on the inner surface of the movable body of the drilling unit along the curved closed groove of the cylindrical guide of the drilling unit, the shut-off valve is opened by cutting off the destructible element, drilling out contaminants with an ascending flow of well fluid, with an ascending flow of well fluid, moving contaminants through the axial channel of the guide of the drilling unit, opening the flap valve, filling the container for large contaminants with large fragments, opening the ball check valve, filling the container for contaminants with small fragments of contaminants.

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