CN110924892A

CN110924892A - Well choke device and method for temporarily choking a well

Info

Publication number: CN110924892A
Application number: CN201911271240.4A
Authority: CN
Inventors: 吉田博明; 小林卓磨
Original assignee: Kureha Corp
Current assignee: Kureha Corp
Priority date: 2017-04-28
Filing date: 2018-04-17
Publication date: 2020-03-27
Also published as: WO2018198881A1; RU2717466C1; GB2584023B; US20200149368A1; CN110168190A; GB202009313D0; RU2020109744A3; CA3050226C; GB2584023A; CA3050226A1; RU2020109744A; GB201910253D0; GB2575557B; GB2575557A

Abstract

The invention aims to provide a well blocking device which can reduce the cost of well excavation and shorten the process, and a temporary well blocking method using the well blocking device. The well choke device of the present invention comprises: a downhole plug; a setting tool (2) for activating and setting a downhole packer; and an obstacle for blocking a flow path of the downhole plug, wherein the obstacle is enclosed within the setting tool (2), and thus the flow path of the downhole plug can be reliably blocked in a short time after the downhole plug is disposed in the well and the setting tool (2) is removed. Further, by using the well shut-off device of the present invention, temporary shut-off of the well can be reliably performed in a short time.

Description

Well choke device and method for temporarily choking a well

The invention is a divisional application of patent applications with the application number of 2018800060422, the application date of 2018, 4 and 17, and the invention name of 'a well blocking device and a well temporary blocking method'.

Technical Field

The present invention relates to a well plugging device used in an Enhanced Oil Recovery method (Enhanced Oil Recovery) of a well for producing Oil and gas resources such as Oil and gas, and a method for temporarily plugging a well using the same.

Background

The "fracturing method" or the "hydraulic fracturing method" is one of the methods for enhanced recovery of oil and gas resources, and is a method for generating cracks (fissures) in a highly deep underground productive formation (a formation which produces oil such as shale oil or oil and gas resources such as natural gas such as shale gas) by the hydraulic pressure of a fracturing fluid. With this method, a predetermined region is partially blocked in order from the tip of a well bore (well) dug in a formation of several kilometers underground, and a fracturing fluid is fed into the blocked region at high pressure to fracture a producing formation. Next, the next predetermined area (usually, the area immediately before the existing area, i.e., the area on the upper ground side) is blocked and fractured. This procedure is repeated below until the necessary plugging and fracturing are completed.

As a method of sequentially blocking a borehole from a distal end portion of the borehole, various methods are known, and examples thereof include a method using a downhole tool called a downhole packer (also referred to as a "frac plug", "bridge plug", a "packer", or the like). As the downhole plug, for example, patent documents 1 to 4 disclose a downhole plug capable of plugging and fixing a borehole.

Patent document 1 discloses a downhole plug for pit excavation (hereinafter, may be simply referred to as "plug"), specifically, a plug comprising: the mandrel is provided with a mandrel (main body) having a hollow portion in the axial direction, and a ring or annular member (annular member), a first conical member (conical member) and a slip (slip), a malleable element (malleablelement) formed of an elastic body, rubber or the like, a second conical member and a slip, and an anti-rotation mechanism (anti-rotation feature) are provided along the axial direction on the outer circumferential surface orthogonal to the axial direction of the mandrel. The closing of the borehole by the downhole packer for borehole excavation is as follows.

That is, the clearance between the ring or the annular member and the rotation preventing mechanism is reduced by moving the spindle in the axial direction thereof. Accordingly, the slips come into contact with the inclined surface of the conical member and advance along the conical member, and the slips radially expand outward and come into contact with the inner wall of the borehole, thereby being fixed to the borehole. The malleable element expands and deforms to come into contact with the inner wall of the borehole to close the borehole, thereby closing the borehole. The mandrel has an axial hollow portion, and the hollow portion is provided with a ball or the like, whereby the borehole can be closed.

As described above, as a material for forming the plug, a metal material (aluminum, steel, stainless steel, or the like), a fiber, wood, a composite material, a plastic, or the like is widely exemplified, and a composite material containing a reinforcing material such as a carbon fiber, particularly a composite material containing a polymer such as an epoxy resin or a phenol resin, is preferable, and the mandrel is formed of aluminum or a composite material. On the other hand, according to the description, the ball and the like can be decomposed by temperature, pressure, pH (acid, alkali) and the like, in addition to the materials described above.

Patent document 2 discloses a packer assembly (assembly) for excavation in a well, in which each packer is separably connected to an adjacent packer.

Patent document 3 describes a packer as follows: the present invention relates to a packer including a mandrel having a hollow portion in an axial direction, and including slips, a sliding wedge (slip wedge), an elastic packer element (resilient packer element), an extrusion limiter (extrusion limiter), and the like along the axial direction on an outer circumferential surface perpendicular to the axial direction of the mandrel.

Patent document 3 discloses a disposable downhole tool (a so-called downhole plug or the like) or a member thereof containing a decomposable material which decomposes when exposed to the environment in a well, and discloses a decomposable polymer such as an aliphatic polyester such as polylactic acid as a biodegradable material. Patent document 3 describes a combination of: a cylindrical body member (tubular body element) having a flow hole (flow hole) in an axial direction; a packer element assembly (packer element assembly) formed by an upper seal element, a center seal element, and a lower seal element along an axial direction on an outer peripheral surface orthogonal to the axial direction of the cylindrical body member; and a mechanical slip body (mechanical slip body). Further, it is disclosed that by providing a ball in the flow hole of the cylindrical body member, the fluid is allowed to flow only in one direction.

Patent document 4 discloses a downhole packer comprising: the setting stem comprises a fracturing plug, a mandrel which exists in the axial direction of the fracturing plug and is provided with a hollow part, and a setting stem which penetrates through the hollow part of the mandrel. The setting rod disclosed in patent document 4 is attached to the front end of the downhole plug.

Generally, the downhole packer has an opening in the center and uses a structure having a seat (seat) to block the obstacle. In particular, when a ball is used as an obstacle, in the case of plugging a borehole using a downhole plug having a ball seat (ball seat), the downhole plug is set at a predetermined position using a setting tool and activated. Then, the obstruction is supplied to and arranged in a seat of the downhole packer to block an opening of the seat, thereby completing the blocking of the borehole (for example, patent document 5).

However, when using balls as an obstacle, for example, it takes a certain amount of time to convey the balls by a high-pressure water flow in order to supply the balls of a predetermined size from the ground and to arrange the balls to a ball seat of an underground plug installed in the ground having a depth of 1000 to 5000 m. In this case, since a high-pressure water flow is used, the ball may be deformed or broken such as by colliding with the well wall during conveyance, or the sealing performance may be impaired by a crack or a notch.

In contrast, patent document 6 discloses a mandrel existing in the axial direction of a fracture plug; and a cylindrical metal sleeve provided inside the metal sleeve, and a downhole packer including a ball in the metal sleeve is described.

Further, the downhole plug is sequentially disposed in the well before completion of the well, but these need to be removed at the stage of starting recovery of the oil and gas resources. The plug is not generally designed to be recovered after use, and therefore, it is removed by fracturing, perforating, or other methods by breaking or chipping the plug, but fracturing, perforating, and the like require a lot of expenditure and time. Further, although there are also plugs (retrievable plugs) which are specially designed to be recovered after use, since the plugs are placed in the ground at a high depth, a lot of expenses and time are required to recover them all.

Further, it is required to provide a well choke apparatus and a method of temporarily shutting down a well, which can reliably perform the seating of an obstacle on a seat of a downhole choke in a short time, thereby reducing the cost of well excavation and shortening the process, in addition to the more severe and various excavation conditions such as the deepening of the well.

Documents of the prior art

Patent document

Patent document 1: U.S. patent application publication No. 2011/0277989 specification

Patent document 2: U.S. patent application publication No. 2003/0183391 specification

Patent document 3: U.S. patent application publication No. 2005/0205266 specification

Patent document 4: U.S. patent application publication No. 2011/0277987 specification

Patent document 5: U.S. patent application publication No. 2015/0252643 specification

Patent document 6: U.S. patent application publication No. 2002/0189822 specification

Disclosure of Invention

Problems to be solved by the invention

The present invention has been made in an effort to provide a well shut-down device capable of reliably supplying an obstacle for shutting down a flow path of a downhole shut-down device in a short time while the mining conditions such as the increase in depth and the like are becoming more severe and varied, and a temporary shut-down method for a well using the well shut-down device.

Technical scheme

As a result of intensive studies to solve the above problems, the present inventors have found that the problems can be solved by providing a setting tool for installing a downhole packer with an obstacle for blocking a flow path of the downhole packer and supplying the obstacle to the downhole packer in a state in which breakage is suppressed in a short time without throwing the obstacle from the ground, and have completed the present invention.

That is, according to the present invention, there is provided a well choke device for choking a well, comprising: a downhole plug; the setting tool is configured at the rear end side of the underground plug and starts and sets the underground plug; and one or more obstructions blocking a flow path of the downhole plug, the downhole plug comprising a hollow mandrel open at least at a back end, the setting tool comprising: a setting rod directly or indirectly connected with the front end side of the mandrel; and a setting sleeve configured to cover a part or all of the setting rod and at least a part of the downhole packer, the setting rod being inserted into a hollow portion of the mandrel from an opening portion at a rear end of the mandrel, the barrier including a space within the setting tool.

It is noted that the setting tool itself or a part thereof of the present invention is sometimes referred to as a kit comprising a setting stem and a setting sleeve.

Here, the "front end" and the "rear end" in the present specification refer to front and rear ends of the downhole packer in a direction in which the downhole packer advances from an entrance of the well into the well. The "front end side" and the "rear end side" refer to the front and rear of the midpoint of the longitudinal length.

Further, there is provided a method of temporarily blocking a well using a well blocking device, the well blocking device comprising: a downhole plug; the setting tool is configured at the rear end side of the underground plug and starts and sets the underground plug; and one or more obstructions blocking a flow path of the downhole plug, in which method the downhole plug comprises a hollow mandrel open at least at a rear end, the setting tool comprising: a setting rod directly or indirectly connected with the front end side of the mandrel; and a setting sleeve having a shape covering a part or all of the setting rod and at least a part of the downhole packer, wherein the setting tool is inserted into the hollow portion of the mandrel from an opening portion at the rear end of the mandrel, and the well is temporarily blocked by using a well blocking device that includes the obstacle in a space in the setting tool through the following steps a) to d):

a) moving the well choke device to any position of the well, and starting and setting the downhole choke;

b) releasing the connection between the setting tool and the underground blanking plug, and pulling out the setting rod;

c) moving an obstacle in the setting tool to block a flow path of the hollow part of the mandrel;

d) after a predetermined time has elapsed, the obstacle is removed and the flow path is restored.

Advantageous effects

According to the present invention, in a well plugging device including a setting tool and a downhole packer, by including an obstacle that blocks a flow path of the downhole packer in the setting tool close to the downhole packer, it is possible to provide a well plugging device that can supply an obstacle to the downhole packer in a short time and reliably, in addition to the fact that mining conditions such as a higher depth have become more and more severe and various. Further, a method of temporarily blocking a well using the well blocking device can be provided.

Drawings

Fig. 1 is a diagram showing one specific example of the well choke device of the present invention.

Fig. 2 is a schematic front cross-sectional view showing one specific example of the well choke device of the present invention.

Fig. 3 is a diagram showing the appearance of a frac plug as one specific example of a downhole packer included with the well choke apparatus of the present invention.

Fig. 4 (a) is a schematic front cross-sectional view showing a frac plug as a specific example of a downhole packer included in the well plugging device according to the present invention, and fig. 4 (B) is a schematic front cross-sectional view showing a state in which the downhole packer of fig. 4 (a) is installed and fixed in a well bore.

Fig. 5 (a) is a view showing a circumferential cross section obtained by cutting a part of the setting stem of fig. 2 straight, fig. 5 (B) is a view showing a circumferential cross section obtained by cutting a part of the setting stem of fig. 2 curved, and fig. 5 (C) and 5 (C') are views showing a circumferential cross section obtained by cutting a part of the setting stem of fig. 2 square.

Fig. 6 (a) is a view showing a circumferential cross section of the curved groove formed in the inner surface of the setting sleeve of fig. 2, and fig. 6 (B) and 6 (C) are views showing a circumferential cross section of the square groove formed in the inner surface of the setting sleeve of fig. 2.

Detailed Description

The present invention relates to a well choke device and a temporary well choke method using the same, the well choke device comprising: a downhole plug; a setting tool for setting a downhole plug; and an obstruction for blocking a flow path of the downhole plug. An embodiment of a well plugging device and a plugging method according to the present invention will be described below.

1. Well choke device

The well choke device according to the present embodiment will be described with reference to the drawings. The well choke device of the present embodiment comprises a downhole choke 1, a setting tool 2 and an obstacle 3 for choking the flow path of the downhole choke. It should be noted that fig. 1 is a specific example of a solution to the problem of the present invention, and the scope of the present invention is not limited to the well choke device of the solution shown in fig. 1.

(1) Downhole blanking plug

A downhole plug is a device that is placed in a well bore in order to block a portion of the well, and is also known as a frac plug, bridge plug, or packer. The downhole packer has at least one mandrel and one or more members fitted on an outer peripheral surface orthogonal to an axial direction of the mandrel. As an example of a downhole packer, a frac plug 1 is illustrated in the solution shown in fig. 1. Fig. 3 shows the appearance of the fracture plug 1. As shown in fig. 3, the fracture plug 1 includes: a spindle 11 and a member fitted on an outer peripheral surface orthogonal to an axial direction of the spindle 11.

1) Mandrel

The mandrel 11 included in the frac plug 1 has a substantially circular cross section, and is a member having a length sufficiently long with respect to the diameter of the cross section to substantially ensure the strength of the frac plug 1. The diameter of the cross section of the mandrel 11 is suitably selected according to the size of the borehole. The diameter is slightly smaller than the inner diameter of the wellbore whereby the frac plug 1 can move within the wellbore. On the other hand, the diameter of the mandrel 11 and the inner diameter of the borehole have a difference in diameter to such an extent that the borehole can be blocked by expanding the annular rubber member 15 capable of expanding the diameter as described later. The length of the mandrel 11 is, for example, about 5 to 20 times the diameter of the cross section, but is not limited thereto. The diameter of the cross section of the mandrel 11 is usually in the range of about 5 to 30 cm.

The mandrel 11 may be solid, but from the viewpoints of securing a flow path at the initial stage of fracturing, reducing the weight of the mandrel, and the like, it is preferable that the mandrel 11 be a hollow mandrel having a hollow portion at least a part of which extends in the axial direction. That is, the hollow portion may or may not penetrate the spindle 11 in the axial direction. When the frac plug 1 is pushed and conveyed into a well by using a fluid, the mandrel 11 preferably has a hollow portion in the axial direction. When the mandrel 11 has a hollow portion in the axial direction, the cross-sectional shape of the mandrel 11 is an annular shape formed by two concentric circles that divide the diameter (outer diameter) of the mandrel 11 and the outer diameter (corresponding to the inner diameter of the mandrel 11) of the hollow portion. The ratio of the diameters of the two concentric circles, i.e., the ratio of the outer diameter of the hollow portion to the diameter of the spindle 11 is preferably 0.7 or less. Since the magnitude of the ratio is in inverse relation to the magnitude of the ratio of the wall thickness of the hollow shaft 11 to the diameter of the mandrel 11, the upper limit value defining the ratio can be equivalent to a preferable lower limit value defining the wall thickness of the hollow mandrel. If the wall thickness of the hollow mandrel is too thin, the strength (particularly tensile strength) of the hollow mandrel is insufficient when the frac plug 1 is placed in a well bore or when the well bore is clogged or fractured, and in some cases, the frac plug 1 may be damaged. Therefore, the ratio of the outer diameter of the hollow portion to the diameter of the mandrel 11 is more preferably 0.6 or less, and still more preferably 0.5 or less.

The diameter of the mandrel 11 and the outer diameter of the hollow portion may be uniform in the axial direction of the mandrel 11, but may also vary in the axial direction. That is, the outer diameter of the spindle 11 may be changed in the axial direction, so that the spindle 11 may have a convex portion, a stepped portion, a flange portion, a concave portion (groove portion) on the outer peripheral surface thereof, and further may have a bent portion such as a threaded portion (usually, a male screw structure) or a meshing portion of a ratchet mechanism described later. Further, the outer diameter of the hollow portion (the inner diameter of the hollow mandrel 11) may be changed in the axial direction, so that the inner circumferential surface of the mandrel 11 may have a convex portion, a step portion, a groove portion, and a bent portion such as a screw portion (male screw structure or female screw structure). Further, the meandering portion may have a tapered structure.

In the well plugging device according to the present embodiment, as described later, since the obstacle may be disposed in a space formed by the inner wall of the setting sleeve, the setting rod, and the rear end of the mandrel (hereinafter, this space may be referred to as "space in the setting tool"), the rear end of the mandrel may be cut so that the obstacle can be disposed. The shape of the notch is preferably substantially the same as the surface shape of the obstacle.

The convex portion, the stepped portion, the flange portion, and the concave portion (groove portion) which may be provided on the outer peripheral surface or the inner peripheral surface of the mandrel 11 can also be used as a support portion when the frac plug 1 is transported in a well, and can also be used as a portion for attaching or fixing other members to the outer peripheral surface or the inner peripheral surface of the mandrel 11. Further, even when the spindle 11 has a hollow portion, it can serve as a seat surface for holding an obstacle for blocking a flow path. The hollow portion of the mandrel 11 is opened when it is present at least at the rear end, but the opening is a seat having a shape capable of holding an obstacle, whereby the obstacle can be more reliably seated, and as a result, the flow path can be more reliably blocked. The seat may be formed not only in a shape of a seat for the opening of the spindle 11, but also in a seat member having a central opening for the spindle 11. For example, when a ball is used as an obstacle, the size of the opening of the seat (ball seat) of the downhole plug is appropriately selected, whereby the ball can be prevented from being broken and falling off, and the flow path can be blocked more reliably. Further, a plurality of engaging portions may be formed on the outer peripheral surface of the mandrel 11, and the engaging portions may be configured to form an annular ratchet mechanism orthogonal to the axial direction of the mandrel by allowing movement of a member in one direction along the axial direction of the mandrel and restricting movement in the opposite direction together with the inner peripheral surface of the member attached to the outer peripheral surface orthogonal to the axial direction of the mandrel 11.

[ Material for Forming the mandrel ]

The material for forming the mandrel 11 provided in the downhole plug is not particularly limited, and a material conventionally used as a material for forming a mandrel provided in a downhole plug can be used. Examples thereof include metal materials (aluminum, steel, stainless steel, etc.), fibers, wood, composite materials, and resins. Specifically, a composite material containing a reinforcing material such as carbon fiber, in particular, a composite material containing a polymer such as an epoxy resin or a phenol resin, and the like can be cited. The downhole plug of the present embodiment is a downhole plug that can reduce the cost of well drilling and shorten the process by facilitating removal of the downhole plug and securing of the flow path, and therefore, it is preferable that the mandrel 11 be formed of a decomposable material.

[ resolvable Material ]

In the downhole choke plug used in the present embodiment, when the mandrel 11 is formed of a decomposable material, the decomposable material having biodegradability or hydrolyzability may be used as the decomposable material, or a decomposable material that can be chemically decomposed by any other method may be used.

The physically decomposed material such as destruction and disintegration by applying a large mechanical force does not conform to the decomposable material forming the mandrel 11 provided in the downhole packer, like a metal material such as aluminum which has been conventionally used as a mandrel provided in the downhole packer. However, as seen from a composite material of a decomposable resin and a metal material or an inorganic substance, the strength of the resin originally decreases and becomes brittle due to a decrease in the degree of polymerization or the like, and as a result, the resin is easily disintegrated and deformed by applying a very small mechanical force, and such a material is suitable for the decomposable material. Specifically, a base material made of a decomposable material such as a decomposable resin typified by polyglycolic acid (hereinafter, also referred to as "PGA") is provided with a recess having a predetermined shape, a metal (metal sheet or the like) or an inorganic material having a shape conforming to the shape of the recess is embedded in the recess, and the metal or the inorganic material is fixed by an adhesive or a wire, a fiber, or the like is wound so that the metal or the inorganic material and the base material can be maintained in a fixed state.

In the downhole packer used in the present embodiment, when the mandrel 11 is formed of a decomposable material, a hydrolyzable material decomposed by water at a predetermined temperature or higher is preferable. The decomposable material is more preferably PGA as a main component, and polyglycolic acid having a weight average molecular weight of 15 ten thousand or more is preferable among PGA, and polyglycolic acid having a high molecular weight of 18 ten thousand or more is particularly preferable because it has high strength. That is, it is desirable that the mandrel 11 be a downhole packer formed from high molecular weight PGA. The decomposable material may contain a reinforcing material or other compounding ingredients. In addition, as the decomposable material forming the mandrel 11, a decomposable metal can also be used. As the decomposable metal used for the mandrel 11, a Mg alloy is preferable because of its high strength. 2) Member mounted on outer peripheral surface orthogonal to axial direction of spindle

The downhole plugging tool used in the present embodiment includes a mandrel and a member attached to an outer peripheral surface orthogonal to an axial direction of the mandrel. That is, in the downhole plug, various members are generally mounted on the outer peripheral surface of the mandrel in order to efficiently and reliably perform transportation and installation of the plug, plugging and fracturing of the pit hole, and further to improve operability and the like. The member attached to the outer circumferential surface perpendicular to the axial direction of the mandrel is not particularly limited as long as it is a member conventionally used in a downhole plug. In particular, as shown in fig. 3, the frac plug 1 preferably includes at least one selected from the group consisting of slips 12, wedges 13, a pair of annular fixing members 14, and an annular rubber member 15 capable of expanding a diameter. These members are referred to as members in the sense of including fitting members for fitting the respective members to the spindle.

[ Material for forming a member to be fitted to an outer peripheral surface orthogonal to an axial direction of the spindle ]

The material for forming the member to be attached to the outer peripheral surface of the mandrel used in the present embodiment is not particularly limited, and a material conventionally used as a material for forming the member provided in the downhole packer can be used. Examples of the resin include a resin, a fiber, a wood, a composite material, and a metal material (aluminum, steel, stainless steel, and the like), specifically, a composite material containing a reinforcing material such as a carbon fiber, and particularly, a composite material containing a polymer such as an epoxy resin and a phenol resin. In view of reducing the cost of excavation and shortening the process by facilitating the removal of the blockage and the securing of the flow path after use, it is preferable that at least one of the members is formed of a decomposable material, as described above for the spindle.

[ resolvable Material ]

In the downhole plug used in the present embodiment, as the decomposable material forming at least one of the members, as in the case of the mandrel described above, a decomposable material having biodegradability or hydrolyzability, a decomposable material that can be chemically decomposed by any other method, or a decomposable material that can be easily disintegrated by embrittlement can be used. In the case where the member is an annular rubber member capable of expanding the diameter, examples of the decomposable material include decomposable rubbers such as aliphatic polyester rubber, polyurethane rubber, natural rubber, polyisoprene, acrylic rubber, aliphatic polyester rubber, polyester thermoplastic elastomer, and polyamide thermoplastic elastomer.

3) Downhole packer activation, setting, and well bore plugging

The downhole packer used in the present embodiment is activated by a setting tool described later, and is set in the borehole. For example, in the frac plug 1, when a force is applied to reduce the axial distance between the pair of annular fixing members 14 in the mandrel direction, the slips 12 move outward perpendicular to the axial direction of the mandrel while jumping the upper surface of the inclined surface of the wedge 13. Then, the outermost circumferential surface perpendicular to the axial direction of the mandrel of the slip 12 abuts against the inner wall of the well bore, so that the plug can be set at a predetermined position in the well bore. The annular rubber member 15 capable of expanding the diameter is compressed in the axial direction of the mandrel, and the annular rubber member 15 capable of expanding the diameter expands in the direction orthogonal to the axial direction of the mandrel as the distance in the axial direction decreases (decreases in diameter). The annular rubber member 15 is expanded in diameter, and the outer side portion thereof in the direction orthogonal to the axial direction abuts against the inner wall of the well bore and the inner side portion thereof in the direction orthogonal to the axial direction abuts against the outer peripheral surface of the mandrel, whereby the space between the plug 1 and the well bore (the blockage of the well bore) can be blocked (sealed). Then, the fracturing can be performed in a state where the space between the plug and the well bore is blocked (sealed).

(2) Setting tool

The setting tool used by the well choke device of this embodiment is substantially cylindrical and includes a setting stem and a setting sleeve. The setting stem is generally rod-shaped and is disposed at the center of the cross section of the setting tool (the cross section parallel to the bottom surface of the substantially cylindrical column). I.e. the setting stem is inserted into the hollow of the setting tool. Further, the setting sleeve is cylindrical surrounding one end of the long axis of the setting rod.

The setting tool of this embodiment itself or a part thereof is sometimes also referred to as a kit comprising a setting stem and a setting sleeve.

The setting tool used in the present embodiment is disposed from the rear portion of the rear end of the downhole plug to the rear end side in the hollow portion, and the setting rod and the setting tool are respectively in contact with the downhole plug. That is, the setting stem is directly or indirectly connected to the mandrel, and the setting sleeve is disposed adjacent to a member fitted on an outer circumferential surface orthogonal to the axial direction of the mandrel. When the setting tool is activated, the setting sleeve restrains the member fitted on the outer circumferential surface of the mandrel from moving in the rear direction, and the setting rod moves in the rear direction and transmits a force in the rear direction to the mandrel, thereby pulling out the mandrel in the rear direction, and as described above, the downhole plug is activated. As an example, a setting tool comprising a setting sleeve and a setting rod activated by gas generated by an explosion can be cited.

1) Setting rod

In the well plugging device of the present embodiment, the setting rod is connected to the mandrel, but the setting rod is usually connected directly or indirectly to the mandrel at the end opposite to the end surrounded by the setting sleeve. Further, the setting stem is inserted into the hollow portion of the mandrel from an opening portion at the rear of the mandrel. The connection position of the mandrel to the setting stem may be the rear end side, the center side, or the front end side in the longitudinal direction of the mandrel, but when the mandrel is made of resin or the like and the compressive strength is insufficient, it is preferable to connect the mandrel to the front end side. In this case, the setting stem is connected from the rear end side of the mandrel to the front end side through the hollow. An example of connecting the setting stem to the front end of the mandrel will be described below with reference to fig. 2 and 3.

The setting stem 21 of fig. 2 is connected to the downhole packer 1 by a connection 23. Examples of the connecting method of the connecting portion 23 include a method of directly connecting and fixing the connecting portion to the tip of the spindle 11 and a method of indirectly connecting and fixing the connecting portion to the tip of the spindle 11 via a connecting member (not shown) provided in the spindle 11. Examples of a method of fixing the connection portion 23 to the downhole packer 1 include a method of fixing the connection portion 23 to the downhole packer 1 by a screw thread engraved on the outer periphery of the connection portion and a method of fixing the connection portion by a pin. Preferably, the threads and pins are broken by the application of force axially to the mandrel, releasing the connection of the downhole plug and setting tool.

As will be described later, the well choke device of this embodiment disposes an obstacle in the space formed by the inner wall of the setting sleeve, the setting rod, and the rear end of the mandrel or a member fitted to the rear end. Thus, the setting stem may also be deformed such that a portion of the rod shape is recessed, bent or cut in a fan shape in the axial direction, etc., so that the obstacle (ball) can be enclosed within the setting sleeve. That is, the setting stem may have a groove or notch structure with respect to the axial direction.

Specific examples of the deformation of the setting stem include linear cutting (fig. 5 a), curved cutting (fig. 5B), or square cutting (fig. 5C and C')) of a circular portion of the cross section of the setting stem.

The position and length of deformation over the entire length of the setting stem are not particularly limited as long as the function of the setting stem is not hindered, but the deformed portion shown in fig. 5 is preferably located on the front end side in the length from the tip (front end) on the side not connected to the downhole plug of the setting stem to the rear end of the downhole plug. Further, it is preferable that the length of the deformed portion is 10mm or more in the axial direction of the setting stem.

2) Setting sleeve

The setting sleeve 22 of the present embodiment is adjacently located on the rear end side of the member fitted on the outer peripheral surface of the mandrel 11, and has a function of suppressing the movement of the member on the outer peripheral surface of the mandrel to the rear side.

In addition, the setting sleeve may have a groove or notch structure on the inner wall so as to enclose the obstacle (ball) as in the setting rod. Specific examples of the grooves in the inner wall of the setting sleeve include a curved groove (fig. 6 (a)) or a square groove (fig. 6 (B) and (C)) in the cross-section of the setting sleeve.

The groove in the inner wall of the setting sleeve is not particularly limited as long as it is in a shape capable of enclosing an obstacle inside the setting sleeve, and the position, length, and depth are not particularly limited, but the groove shown in fig. 6 is preferably 10mm or more in length (axial direction of the setting sleeve), 5mm or more in width, and 1mm or more in depth.

[ Material for Forming setting tools ]

The material for forming the setting tool used in the present embodiment is not particularly limited, and conventionally used materials can be used.

(3) Obstruction for blocking a flow path of a downhole plug

The obstacle for blocking the flow path of the downhole plug used in the present embodiment is disposed in a space formed by the inner wall of the setting sleeve of the setting tool, the setting stem, and the rear end of the mandrel or a member attached to the rear end. The obstacle for blocking the flow path of the downhole packer has a function of blocking the flow path of the downhole packer after the downhole packer is set in the pit and the setting stem is removed. The shape of the obstacle is not particularly limited as long as it is a size and a shape of a space that can block the flow path of the downhole plug and can be accommodated in the setting tool, and examples thereof include: ball, dart, or disc. In particular, the ball is preferable because it can close the opening of the seat and reliably block the flow path regardless of the orientation of the ball.

[ Material for forming an obstacle for blocking the flow path of a downhole plug ]

The material for forming the obstacle used for the flow path of the downhole packer used in the present embodiment is not particularly limited, and a material conventionally used for forming the obstacle may be used. Examples of the resin include a resin, a wood, a composite material, and a fiber made of a metal material (aluminum, steel, stainless steel, or the like), and specifically include a composite material containing a reinforcing material such as a carbon fiber, and particularly a composite material containing a polymer such as an epoxy resin or a phenol resin. In view of reducing the cost of the well drilling and shortening the process by releasing the blockage after the use of the downhole plug and securing the flow path, it is preferable that at least a part of the obstacle is formed of a decomposable material, as described above with respect to the mandrel. As the decomposable material, PGA is more preferably used as a main component. When PGA is used as a main component, the weight average molecular weight of PGA is preferably large, for example, preferably 5 ten thousand or more, more preferably 10 ten thousand or more, and still more preferably 15 ten thousand or more, from the viewpoint of improving strength.

[ resolvable Material ]

As the decomposable material forming the obstacle for blocking the flow path of the downhole packer used in the present embodiment, as in the above description of the mandrel, a decomposable material having biodegradability or hydrolyzability, a decomposable material capable of chemical decomposition by any other method, or a decomposable material capable of being easily disintegrated by embrittlement can be used. In particular, a decomposable resin or a decomposable metal is easy to adjust the decomposition rate, and therefore, a decomposable material used as the obstacle is preferable. In particular, polyglycolic acid is preferable as the decomposable resin and Mg alloy is preferable as the decomposable metal because of its high strength.

According to the above-described well plugging device of the present embodiment, an obstacle that blocks the flow path of the downhole plug can be reliably supplied in a short time. Therefore, damage to the obstacle accompanying conveyance of the obstacle can be avoided, and the amount of fluid used to convey the obstacle can be saved. This reduces the cost of drilling the well and shortens the steps required for drilling the well.

2. Method for blocking a well

The well choke device of this embodiment can be used regardless of the depth of the well and whether it is a longitudinal hole or a lateral hole.

The method of plugging a well using the well plugging device of the present embodiment is as follows. First, the well choke device of the present embodiment is moved to an arbitrary position in the well using a fluid or the like (fig. 4 (a)). Then, when the setting tool is activated, the downhole plug is expanded and set by the annular rubber member and the slips and fixed to the inner wall of the borehole (fig. 4 (B)). Next, the setting tool and the downhole plug are disconnected and the setting stem is removed from the hollow of the mandrel. The obstruction enclosed by the setting sleeve is arranged at a position where the flow path of the downhole plug is blocked, and is supplied to, for example, a seat (seat) provided in the mandrel, thereby completing the blocking.

Here, when the obstacle is formed of a decomposable material having hydrolyzability, for example, the obstacle is decomposed by exposure to water for a predetermined time, and is disintegrated, dissolved, or separated from the opening of the seat (receiving portion), whereby the blocked flow path can be restored.

3. Summary of the invention

A well choke device for choking a well, comprising: a downhole plug; a setting tool disposed on a rear end side of the downhole plug, the setting tool activating the downhole plug and setting the downhole plug; and one or more obstructions blocking a flow path of the downhole plug, the downhole plug comprising a hollow mandrel open at least at a back end, the setting tool comprising: a setting rod directly or indirectly connected with the front end side of the mandrel; and a setting sleeve configured to cover at least a portion of the setting rod and at least a portion of the downhole plug, the setting rod being inserted into the hollow portion of the mandrel from an opening portion at the rear end of the mandrel, the barrier including a space within the setting tool.

Further, it is preferable that the mandrel contains a resin as a main component.

Further, it is preferable that the mandrel contains a decomposable metal as a main component.

Further, it is preferable that the mandrel contains a decomposable resin as a main component.

Further, it is preferred that the downhole packer comprises a seat (seat) to receive the obstruction.

Further, it is preferable that the obstacle is a ball, a dart, or a disc.

Further, it is preferable that at least a part of the obstacle contains a decomposable material.

Further, it is preferable that the decomposable material is a decomposable resin or a decomposable metal.

Further, it is preferred that the rear end of the mandrel has a notched configuration to allow an obstruction to be contained within the space within the setting tool.

Furthermore, it is preferred that at least one of the setting stem or the setting sleeve has a groove or notch configuration with respect to the axial direction in order to enable obstacles to be enclosed in the space within the setting tool.

Preferably, at least one of the setting stem or the setting sleeve has a fan-shaped notch configuration with respect to the axial direction in order to enable an obstacle to be enclosed in the space within the setting tool.

Furthermore, it is preferred that the setting stem has a groove or notch configuration with respect to the axial direction.

Furthermore, it is preferred that the setting sleeve has a groove on the inner surface.

A method of temporarily blocking a well using a well blocking device, the well blocking device comprising: a downhole plug; a setting tool disposed on a rear end side of the downhole plug, the setting tool activating the downhole plug and setting the downhole plug; and one or more obstructions blocking a flow path of the downhole plug, in which method the downhole plug comprises a hollow mandrel open at least at a rear end, the setting tool comprising: a setting rod directly or indirectly connected with the front end side of the mandrel; and a setting sleeve having a shape covering at least a part of the setting rod and at least a part of the downhole packer, wherein the setting rod is inserted into the hollow portion of the mandrel from an opening portion at the rear end of the mandrel, and the well is temporarily blocked by the following steps a) to d) using a well blocking device that includes a space in the setting tool for containing the obstacle:

a) moving the well choke device to any position of the well, and starting and setting the underground plug;

Industrial applicability of the invention

The present invention provides a well plugging device including a setting tool and a downhole packer, wherein an obstacle blocking a flow path of the downhole packer is included in the setting tool close to the downhole packer, thereby supplying the obstacle to the downhole packer safely in a short time, avoiding damage of the obstacle, and reducing the cost of well excavation and the number of processes, as represented by saving the amount of fluid used for transporting the obstacle, and therefore, the present invention has high industrial applicability. Further, a method for temporarily blocking a well using the well blocking device is provided, and thus, industrial applicability is high.

Description of the symbols

1: fracturing plug

2: setting tool

3: ball with ball-shaped section

12a, 12 b: slip

13a, 13 b: wedge

14a, 14 b: annular fixing member

15: annular rubber member capable of expanding diameter

21: setting rod

22: setting sleeve

23: connecting part of setting tool and fracturing plug

Inner wall of H-pit well

Claims

1. A well choke device for choking a well, comprising in the device:

a downhole plug;

the setting tool is configured at the rear end side of the underground plug and starts and sets the underground plug; and

one or more obstacles for blocking the flow path of the downhole packer,

the downhole packer has a hollow portion with at least a rear end open,

the setting tool comprises:

a setting stem connected directly or indirectly with the downhole plug; and

a tubular setting sleeve surrounding one end of the long shaft of the setting rod,

the setting rod is inserted into the hollow part of the downhole plug from the opening part at the rear end of the downhole plug,

the barrier is enclosed in a space enclosed by the inner wall of the setting sleeve, the setting rod and the downhole packer.

2. The well choke device of claim 1,

the downhole plug includes a seat to receive the obstruction.

3. The well choke device of claim 1,

the downhole plug is constructed from a plurality of components, at least 1 of which is formed from a degradable material.

4. A well choke device as claimed in any one of claims 1 to 3,

the barrier is formed of a decomposable material.

5. A method of temporarily plugging a well using a well plugging device comprising:

a downhole plug;

one or more obstacles for blocking the flow path of the downhole packer,

the downhole packer has a hollow portion with at least a rear end open,

the setting tool comprises:

a setting stem connected directly or indirectly with the downhole plug; and

the barrier is enclosed in a space enclosed by the inner wall of the setting sleeve, the setting rod and the downhole packer,

the method uses the well plugging device to temporarily plug a well by the following steps (a) to (c),

a step (a): moving the well choke device to any position of the well, and starting and setting the downhole choke;

a step (b): releasing the connection between the setting tool and the underground blanking plug, and pulling out the setting rod;

a step (c): moving an obstruction within the setting tool to block a flow path in a hollow of the downhole plug.

6. The method according to claim 5, further comprising a step (d) after the step (c),

step (d): after a predetermined time has elapsed, the obstacle is removed and the flow path is restored.