WO2015060246A1 - Plug for well drilling - Google Patents

Plug for well drilling Download PDF

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Publication number
WO2015060246A1
WO2015060246A1 PCT/JP2014/077831 JP2014077831W WO2015060246A1 WO 2015060246 A1 WO2015060246 A1 WO 2015060246A1 JP 2014077831 W JP2014077831 W JP 2014077831W WO 2015060246 A1 WO2015060246 A1 WO 2015060246A1
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WO
WIPO (PCT)
Prior art keywords
mandrel
plug
formed
peripheral surface
portion
Prior art date
Application number
PCT/JP2014/077831
Other languages
French (fr)
Japanese (ja)
Inventor
大倉正之
▲高▼橋健夫
Original Assignee
株式会社クレハ
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
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Publication date
Priority to JP2013220223 priority Critical
Priority to JP2013-220223 priority
Application filed by 株式会社クレハ filed Critical 株式会社クレハ
Publication of WO2015060246A1 publication Critical patent/WO2015060246A1/en

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    • EFIXED CONSTRUCTIONS
    • E21EARTH DRILLING; MINING
    • E21BEARTH DRILLING, e.g. DEEP DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
    • E21B33/00Sealing or packing boreholes or wells
    • E21B33/10Sealing or packing boreholes or wells in the borehole
    • E21B33/12Packers; Plugs
    • EFIXED CONSTRUCTIONS
    • E21EARTH DRILLING; MINING
    • E21BEARTH DRILLING, e.g. DEEP DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
    • E21B33/00Sealing or packing boreholes or wells
    • E21B33/10Sealing or packing boreholes or wells in the borehole
    • E21B33/12Packers; Plugs
    • E21B33/128Packers; Plugs with a member expanded radially by axial pressure
    • EFIXED CONSTRUCTIONS
    • E21EARTH DRILLING; MINING
    • E21BEARTH DRILLING, e.g. DEEP DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
    • E21B33/00Sealing or packing boreholes or wells
    • E21B33/10Sealing or packing boreholes or wells in the borehole
    • E21B33/12Packers; Plugs
    • E21B33/129Packers; Plugs with mechanical slips for hooking into the casing
    • E21B33/1291Packers; Plugs with mechanical slips for hooking into the casing anchor set by wedge or cam in combination with frictional effect, using so-called drag-blocks
    • EFIXED CONSTRUCTIONS
    • E21EARTH DRILLING; MINING
    • E21BEARTH DRILLING, e.g. DEEP DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
    • E21B43/00Methods or apparatus for obtaining oil, gas, water, soluble or meltable materials or a slurry of minerals from wells
    • E21B43/25Methods for stimulating production
    • E21B43/26Methods for stimulating production by forming crevices or fractures

Abstract

Provided is a plug for well drilling comprising a mandrel and a member attached to the outer circumferential face that intersects the mandrel in the axial direction, wherein at least one of the mandrel or the member is formed from a degradable material, preferably polyglycolic acid, and the radius of curvature for a bent portion is 0.5-50 mm. Also provided is a well digging method characterized in that all or a portion of the plug for well drilling degrades after the wellbore is sealed using the plug for well drilling.

Description

Well drilling for the plug

The present invention is well drilling plug for use in wellbore drilling performed to produce hydrocarbon resources, such as petroleum or natural gas, and to a well drilling method.

Hydrocarbon resources, such as petroleum or natural gas has been mined through wells having a subsurface layer of permeable porous (oil well or gas wells. Collectively may be referred to as "wellbore".) Produced. With the increase of energy consumption, the process goes high depth of the well, in the world there is also a record of drilling beyond the depth of 9000m, there is a high depth wells in excess of 6000m in Japan. In wellbore drilling is continued, subterranean and the permeability have been decreased over time, further from originally permeability is not sufficient subterranean, in order to mine efficiently hydrocarbon resources to continue the production layer done that were stimulated (stimulate), as the stimulation method, acid treatment and crushing methods are known (Patent Document 1). Acid treatment, the mixture was poured in hydrochloric acid or a strong acid such as hydrogen fluoride in the production layer, increasing the reaction components of the rock (carbonates, clay minerals, silicates, etc.) by dissolving, the permeability of the production layer is a method of, problems associated with the use of a strong acid has been pointed out, also increase the cost, including the various measures have been pointed out. Therefore, cracks in the production layer using a fluid pressure (fractures, fracture) (also referred to as "fracturing method" or "hydraulic fracturing".) The method of forming a has attracted attention.

Hydraulic fracturing, the water pressure or the like fluid pressure is a method of generating cracks in production layer by (hereinafter simply referred to as "water pressure".) In general, drilling a vertical hole, followed by a vertical holes the bending, after drilling a horizontal hole in the subterranean formation several thousand m, (meaning a hole provided to form the wellbore, is sometimes referred to as "downhole".) these wellbore in fed at a high pressure fracturing fluid, the hydraulically production layer of high deep underground (layers that produce hydrocarbon resources, such as petroleum or natural gas) cause cracks (fractures), collecting hydrocarbon resources through the fracture it is a method of stimulating production layer for. Hydraulic fracturing is called shale oil (oil aged in shale), also in the development of unconventional resources such as shale gas, and efficacy is noted.

Cracks formed by the fluid pressure of the hydraulic or the like (fractures) is thus closed by immediately formation pressure when no longer water pressure. To prevent blockage of the crack (fracture), fracturing fluid (i.e., well treatment fluid for use in fracturing) to contain a proppant (Proppant), fed into the wellbore, the proppant in cracks (fractures) placing is being performed. The proppant is contained in the fracturing fluid, an inorganic or organic material is used, as long as possible, in the environment of high deep underground high-temperature and high-pressure, since it is possible to prevent the clogging of the fracture, conventional, silica, alumina and other is the inorganic particles used, sand, such as 20/40 mesh sand are generally used.

The well treatment fluid such as a fracturing fluid, water-based, oil based, various types of emulsion used. The wellbore treatment fluid, proppant, so functions that may be transported to the place to cause fracture of Anaiananai is required, usually has a predetermined viscosity, together with dispersion of the proppant is good, after ease of processing, such as small environmental load is determined. In addition, the fracturing fluid is between proppant, shale oil, for the purpose of shale gas or the like to form a flow path can pass, also contain a Chaneranto (channelant). Thus, the well treatment fluid, in addition to the proppant, Chaneranto, gelling agents, scale inhibitors, acid to dissolve the rock or the like, friction reducing agents, various additives are used.

Use fracturing fluid, to produce a crack (fracture) hydraulically production layer of high deep underground (layers that produce hydrocarbon resources, such as natural gas and petroleum or shale gas, such as shale oil) is , usually, the following methods have been adopted. That is, for a wellbore that drilled into the subterranean formation several thousand m (downhole), sequentially from the tip of the wellbore, while the sealer, partially occlude the predetermined section, and the closed by entering fed at a high pressure fracturing fluid into the compartment, perform fracturing cause cracks in production layer. Then, (usually the preceding front of compartments, i.e. the ground side compartment) following predetermined compartments performing fracturing closes the. Below, it is repeated until the sealing and fracturing required this process is complete.

Well drilling of a new well, the already formed desired compartment of the wellbore may also be performed stimulation of production layer by fracturing again. Similarly this time, it is possible to repeat the operation for performing such obstruction and fracturing the wellbore. Further, in order to perform the finishing of the well, and blocking fluid from the lower closes the wellbore, after finishing the top, also to release the blockage.

Sequentially from the tip of the wellbore, as a method of performing such obstruction and fracturing of the wellbore are known various methods, for example, Patent Documents 2 to Patent Document 4, blockage of the wellbore and well drilling plug fixing can be performed ( "Flack plug", sometimes referred to as "bridge plug" or "packer" or the like.) is disclosed.

Patent Document 2, downhole plug for well drilling (hereinafter, simply referred to as "plug".) Is disclosed, in particular, a mandrel having a hollow portion in the axial direction (main body), on the outer surface perpendicular to the axial direction of the mandrel, along the axial direction, the ring or the annular member (annular member), a first conical member (conical member) and slip (slip), is formed from an elastomeric or rubber that malleable element (malleable element), the second conical member and the slip, and plug comprising a detent mechanism (anti-rotation feature) is disclosed. Blockade of the wellbore by a downhole plug for the well drilling is as follows. That is, by moving the mandrel in the axial direction, along with reducing the gap between the ring or the annular member and the detent mechanism, the slip is brought into contact with the inclined surface of the conical member, travels along the conical member it is, by expanding radially outwardly to the inner wall of the wellbore in contact with and fixed to the wellbore, and, in contact with malleable element diametrically enlarged deformed to the inner wall of the wellbore due to the fact that to seal the wellbore. The mandrel, with the hollow portion in the axial direction are present, this set of balls or the like, it is possible to seal the wellbore. As the material for forming the plug, metallic material (aluminum, steel, stainless steel, etc.), fibers, wood, is illustrated broadly include composites and plastics, preferably, a composite material containing reinforcing material such as carbon fiber, in particular, be a composite material containing a polymer such as epoxy resin, phenol resin, it is described that the mandrel is made of aluminum or composite material. On the other hand, balls or the like, in addition to the materials described above, the temperature, pressure, it is described that pH (acids, bases) that degrade material by the like can be used.

Patent Document 3, each packer, the adjacent packer, packer assembly for well drilling that is detachably connected (assembly) is disclosed. Patent Document 3, a mandrel having a hollow portion in the axial direction, on an outer peripheral surface perpendicular to the axial direction of the mandrel, along the axial direction, slip, slip wedge (slip active wedge), elastic packer element (resilient packer element) , and extrusion limiter packer comprising (extrusion limiter), etc. are described.

Downhole plug for well drilling, the wellbore is are arranged sequentially wellbore to completion, natural gas and petroleum or shale gas, such as shale oil (hereinafter, collectively, "oil and gas" or is sometimes referred to as "petroleum and / or natural gas".) in the stage where the production of such initiated, it is necessary to remove these. Plugs, usually because it is not designed to allow to recover releasing the closure after use, crushed, with perforations otherwise, or destroyed, but is removed by or are cut into small pieces, crushing and perforation, etc. had to spend a lot of money and time to. Moreover, essential there is also specially designed plug to be recovered (retrievable plug) after use, the plug because it was placed in a high deep underground, and a lot of expenses to recover all time Was.

Patent Document 4, and (to. Meaning downhole plugs) or a member is disclosed disposable downhole tools containing degrades degradable material when exposed to wellbore environment, raw as degradable material, such as aliphatic polyesters such as polylactic acid degradable polymers have been disclosed. Furthermore, Patent Document 4, a cylindrical body part which axially has a flow hole (flow bore) (tubular body element), on the outer peripheral surface perpendicular to the axial direction of the cylindrical body part, along the axial direction Te, upper sealing element, packer element assembly consisting of central sealing element and a lower sealing element and (packer element assembly), the combination of the slip and mechanical slip body (mechanical slip body) is described. Further, the flow holes of the cylindrical body part, by setting the ball, be adapted to permit flow only in one direction of the fluid is disclosed. However, Patent Document 4, for any of the downhole tool or a member, the disclosure of whether to use a material containing a degradable material is not observed.

Under increasing secure and requirements of environmental protection of energy resources, particularly in the mining of unconventional resources spreads, mining conditions and high depth of focus has become more and more severe and diverse. Well drilling plug (downhole tool, etc.), to a high deep underground to implement the fracturing using wire-like material and (string, stinger, sometimes referred to as cable or the like.), Being transferred, the mandrel Ya various members attached to the outer peripheral surface of the mandrel is relatively moved to close the wellbore, while performing fracturing that use high pressure fluid, against the pressure of the high pressure fluid wellbore it is necessary to maintain the blockage. That is, the downhole tool and the downhole tool member is a plug for well drilling, transport, sufficient resistance is required for the high load applied during maintenance of the closure in closed and fracturing the wellbore there. For example, when maintenance of the closure in the closed and fracturing of the wellbore is generally (corresponding to about 10,000 pounds.) 45 kN or more load is applied. Accordingly, the downhole tool and the downhole tool member is a plug for well drilling, for example, (corresponding to F to about 150 degrees.) Normal Temperature 66 ° C. is reached, in some cases, it can exceed the temperature 100 ° C. in an environment of a certain kind of downhole, to have the mechanical properties that does not cause damage in various operations associated with fracturing (tensile and / or compressive properties regarding strength and elongation, etc.) has been desired.

In particular, various members attached to the outer peripheral surface of the mandrel and the mandrel, i.e. a part of or all downhole tools or members are well drilling plug, in order to allow its removal by decomposing after fracturing completion , the degradable material, for example, when using a degradable resin material, until the various operations involved in the fracturing is complete, the plug well drilling, the fracture in an environment of wellbore it is necessary that those may have no required mechanical properties (tensile and / or compression characteristics).

In Moto high depth of such mining conditions has become more and more severe and diverse, to reduce the load of a large load applied to the bent portion, reliably transported in wellbores, occlusion and fracturing the wellbore It can be performed, and, well drilling plug can cost reduce and process shortening of well drilling by facilitating securing of its removal and flow path, and, required to provide a well drilling method It is to have.

Kohyo 2003-533619 JP (U.S. Patent Application Publication No. 2003/0060375 Pat corresponding) U.S. Patent Application Publication No. 2011/0277989 Pat U.S. Patent Application Publication No. 2003/0183391 Pat U.S. Patent Application Publication No. 2005/0205266 Pat

An object of the present invention, by Moto digging conditions such as high depth of has become more and more severe and diverse, to reduce the load of a large load applied to the bent portion, reliably transported in wellbores, wellbore It can be performed occlusion and fracturing of the hole, and is to provide a plug for well drilling that can cost reduce and process shortening of well drilling by facilitating securing of its removal and flow path. A further object of the present invention is to provide a well drilling method of using the plug 該坑 well drilling.

The present inventors have made intensive studies in order to solve the above problems, the mandrel and, the plug wells drilled and a member mounted on the outer peripheral surface orthogonal to the axial direction of the mandrel, transport in wellbores , when occlusion and fracturing the wellbore, the bent portion of the mandrel or the member, found that high stress concentration occurs as a result of further extensive research, by controlling the shape of the bent portion in the mandrel or the member , it found that it is possible to solve the problems and completed the present invention.

That is, according to the first aspect of the present invention, (1) the mandrel and, a plug for wells drilled and a member mounted on the outer peripheral surface orthogonal to the axial direction of the mandrel, the mandrel or the member at least one,
It formed from degradable material, and well drilling plug curvature radius of the bent portion characterized in that it is a 0.5 ~ 50 mm is provided.

Further, according to the first aspect of the present invention, a specific embodiment of the invention, the following (2) well drilling plug to (19) are provided.

(2) member mounted on the outer peripheral surface orthogonal to the axial direction of the mandrel, slips, wedge, a pair of ring-shaped fixing member, and at least one selected from the group consisting of expandable annular rubber member well drilling for the plug of the above (1) it is.
(3) a pair of ring-shaped fixing member, the one in which it is possible to fix the expandable annular rubber member attached to the outer circumferential surface perpendicular to the axial direction of the mandrel remains in the compressed state (2) well drilling for the plug.
(4) a combination of at least one slip and wedge, well drilling plug according to (2) or (3) to be placed between a pair of ring-shaped fixing member.
(5) member mounted on the outer peripheral surface orthogonal to the axial direction of the mandrel is formed from a degradable material, said formed by a composite material with a degradable material and a metal or inorganic material (1) to (4) one of the wells drilled for the plug.
(6) the mandrel is formed from degradable material, and any of the wells drilled plug of the curvature radius of the bent portion is 0.5 ~ 50mm (1) ~ (5).
(7) a mandrel formed from degradable material, well drilling plug according to (6) having a hollow portion along the axial direction.
(8) said that the mandrel is formed from a degradable material, and the member mounted on the outer peripheral surface orthogonal to the axial direction of the mandrel is formed from a degradable material are formed integrally (6) or (7) well drilling for the plug.
(9) well drilling plug of the which are integrally formed by integral molding (8).
(10) well drilling plug of the formed integrally by machining (8).
(11) bent portion, the convex portion, the stepped portion, the flange portion, the groove portions, at least is one wherein selected from the group consisting of threads and the thread root (1) for any of the wells drilled through (10) plug.
(12) bent portion further comprises a tapered portion, well drilling plug of the (11) the height of the tapered portion is 1mm or more.
(13) degradable material, wherein an aliphatic polyester (1) either wellbore drilling plug to (12).
(14) an aliphatic polyester, well drilling plug of the (13) is a polyglycolic acid.
(15) polyglycolic acid, weight average molecular weight of from 180,000 to 300,000 and a temperature of 270 ° C., well drilling plug of the melt viscosity measured at a shear rate of 122 sec -1 is 700 ~ 2000Pa · s (14) .
(16) degradable material, one of wells drilled plug of the containing reinforcing material (1) to (15).
(17) mandrel, said formed from polyglycolic acid (1) or wellbore drilling plug to (16).
(18) a mandrel formed from degradable material, comprising a mating portion of the ratchet mechanism on an outer peripheral surface, the radius of curvature of the engagement portion is 0.5 ~ 50 mm (1) ~ any of the (17) well drilling for the plug.
(19) a mandrel formed from degradable material, comprising an external thread structure on the outer peripheral surface, one of a pair of ring-shaped fixing member comprises a male screw structure facing the female thread structure on the inner peripheral surface thereof, and, wherein 1 is one of a pair of ring-shaped fixing member, one of wells drilled plug of the are fixed in a state that can not be slid in the axial direction of the mandrel (1) to (18).

Further, according to the second aspect of the present invention, (20) (1) by using one of the wells drilled plug to (19), after the sealing treatment of the wellbore, well drilling method, wherein a part or all of the well drilling plug is degraded is provided.

According to a first aspect of the present invention, mandrel, a plug for wells drilled and a member mounted on the outer peripheral surface orthogonal to the axial direction of the mandrel, at least one mandrel or the member, degradation formed from sexual material, and, by the curvature radius of the bent portion is well drilling plug, which is a 0.5 ~ 50 mm, is increasingly severe and diverse mining conditions such as high depth of in Moto has become a thing, to reduce the load of a large load applied to the bent portion, reliably transported in wellbores, it is possible to perform occlusion and fracturing the wellbore, and its removal and the flow path effect that well drilling plug which can cost reduce and process shortening of well drilling is provided by facilitating securing can be exhibited.

According to the second aspect of the present invention, by using the plug wellbore drilling, after the sealing treatment of the wellbore, some or all of the plug well drilling is decomposed by a well drilling method comprising Rukoto, mining conditions and high depth of system, under which become increasingly severe and diverse, to reduce the load of a large load applied to the bent portion, securely transported in wellbores, it is possible to perform occlusion and fracturing the wellbore and well drilling that can cost reduce and process shortening of well drilling by facilitating securing of its removal and the flow path effect is achieved in that the method is provided.

It is a front sectional view schematically showing a specific example of a wellbore drilling plug according to the present invention. Expandable annular rubber member of the well drilling plug of FIG. 1A is a front sectional view schematically showing a state where the diameter. It is a schematic front view of a mandrel having a flange portion.

The present invention includes a mandrel, a plug for wells drilled and a member mounted on the outer peripheral surface orthogonal to the axial direction of the mandrel, at least one mandrel or the member is formed of a degradable material, and relates to well drilling plug curvature radius of the bent portion characterized in that it is a 0.5 ~ 50 mm. It will be described below with reference to FIGS. 1A and 1B.

I. Well drilling for the plug 1. Mandrel wells drilled plug of the present invention, a mandrel and a plug for wells drilled and a member mounted on the outer peripheral surface orthogonal to the axial direction of the mandrel. Mandrel 1 provided in the wells drilled plug of the present invention, which is also commonly referred to as "core metal" cross-section with a substantially circular, is sufficiently large length relative to the diameter of the cross section, of the present invention the strength of the well drilling for the plug is a member that basically collateral. Mandrel 1 provided in wells drilled plug of the present invention, the diameter of the cross section, by slightly less than the inner diameter of the suitably selected (the wellbore in accordance with the size of the wellbore, the Anaiananai is movable, whereas, with a difference in diameter of the extent to which blockage of the wellbore is enabled by enlarged like the expandable annular rubber member 5 as will be described later.), the length of the cross section the diameter, for example, 5 to 20 times, but not limited thereto. Normally, the diameter of the cross section of the mandrel 1 is in the range of about 5 ~ 30 cm.

[Hollow]
Mandrel 1 provided in wells drilled plug of the present invention may be of solid but, fracturing the initial flow path ensuring, reduce the weight of the mandrel, from the viewpoint of control of the degradation rate of the mandrel, the mandrel 1 but is preferably a hollow mandrel having at least a portion of the hollow portion along the axial direction (i.e., the hollow portion may be through along the mandrel 1 in the axial direction, along the mandrel 1 in the axial direction it may be one that does not pass through Te.). Further, in the case of transferring pushing the well drilling plug wellbore with fluid, the mandrel 1 preferably has a hollow portion along the axial direction. If the mandrel 1 and has a hollow portion along the axial direction, the cross-sectional shape of the mandrel 1, the diameter of the mandrel 1 (outer diameter) and (corresponding to the inner diameter of the mandrel 1.) Outer diameter of the hollow portion defines an annular shape which is formed by two concentric circles. The ratio of the diameter of two concentric circles, namely, it is preferable ratio of the outer diameter of the hollow portion to the diameter of the mandrel 1 is 0.7 or less. The magnitude of this ratio, since the inverse relationship between the magnitude of the ratio of the wall thickness of the hollow mandrel 1 to the diameter of the mandrel 1, to define the upper limit of the ratio defines the preferred lower limit of the thickness of the hollow mandrel it can be said that in particular the corresponding. When the thickness of the hollow mandrel is too thin, or to place plug well drilling in the wellbore, when performing closed and fracturing the wellbore, the strength of the hollow mandrel (especially tensile strength) is insufficient Te, in an extreme case may plug well drilling damage. Accordingly, the ratio of the outer diameter of the hollow portion to the diameter of the mandrel 1, more preferably 0.6 or less, more preferably 0.5 or less.

The outer diameter of the diameter and / or the hollow portion of the mandrel 1 may be uniform along the axial direction of the mandrel 1 but may be one that varies along the axial direction. That is, the outer diameter of the mandrel 1 is changed along the axial direction, the convex portions on the outer peripheral surface of the mandrel 1, the stepped portion, the flange portion, the concave portion (groove), more threaded portion (normally a male screw structure. ) and may be as having a bent portion, such as engagement portion of the ratchet mechanism described later. Further, by the outer diameter of the hollow portion (inner diameter of the hollow mandrel 1) along the axial direction, the convex portion on the inner peripheral surface of the mandrel 1, the stepped portion, the groove portion, and further threaded section (male thread structure or internal thread structure) or as having a bent portion such as. Further, bent portions can also be made to have a tapered portion.

Protrusion having an outer peripheral surface and / or the inner circumferential surface of the mandrel 1, the stepped portion, the flange portion and the recess (groove) may also be used for plug well drilling as a bearing portion when transferring downhole, it is also possible to use the outer peripheral surface and / or the inner circumferential surface of the mandrel 1, as the site for or fixing or attaching a separate member. Also, when the mandrel 1 has a hollow portion may be a seat surface for holding the ball to be used to control the flow of fluid. Further, on the outer peripheral surface of the mandrel 1, in conjunction with the inner peripheral surface of the member attached to the outer circumferential surface perpendicular to the axial direction of the mandrel 1, allowing movement in one direction along the axial direction of the mandrel of the member and, forming a plurality of engagement portions for restricting the movement in the opposite direction may be a ring shaped ratchet mechanism that is orthogonal to the axial direction of the mandrel.

[Material forming the mandrel]
Material forming the mandrel 1 provided in wells drilled plug of the present invention is not particularly limited, conventionally, the use of materials that have been used as a material for forming the mandrel provided in the well drilling plug it can. For example, metallic materials (aluminum, steel, stainless steel, etc.), fibers, wood, and the like can be illustrated composites and resins, specifically, a composite material containing reinforcing material such as carbon fiber, in particular, epoxy resin and the like composites containing or polymer such as phenol resin. Borehole Drilling plug of the present invention, it after the fracturing is a well drilling plug which can cost reduce and process shortening of well drilling by facilitating securing of its removal and the flow path from it is preferable that the mandrel 1 is formed of a degradable material.

[Degradable material]
In plug wells drilling of the invention, when one in which the mandrel 1 is formed of a degradable material, the biodegradable material, the biodegradable, degradable material having hydrolyzable, by still some other methods it can be used degradable material that can be chemically degraded.

As in the metallic material such as aluminum, which is widely used as a mandrel provided with the conventional well drilling plug, by applying a large mechanical force, destruction and disintegration like physically degrades material, the present invention It does not correspond to the degradable material forming the mandrel 1 provided in the well drilling plug. However, as seen in the composite material of the decomposable resin and a metal material described later, the results of strength having the original resin by such as reduction of the degree of polymerization becomes brittle lowered, the addition of very small mechanical force easily disrupted by, the material, such as loss of shape, corresponding to the decomposition material.

In plug wells drilling of the invention, when one in which the mandrel 1 is formed of a degradable material, as described in detail later, is preferably a hydrolyzable material decomposes by a predetermined temperature or more water. Moreover, degradable material, more preferably aliphatic polyester, polyglycolic acid (hereinafter sometimes referred to as "PGA".) It is more preferably. That is, the mandrel 1 is intended well drilling plug formed from PGA is desirable. Moreover, the degradability material may be those containing reinforcing material may be one that contains the other ingredients.

[Radius of curvature of the bent portion]
In plug wells drilling of the invention, when one in which the mandrel 1 is formed of a degradable material, to reduce the load of a large load applied to the bent portion, reliably transported in wellbores, occlusion of the wellbore and from the viewpoint of performing the fracturing, the radius of curvature of the bent portion in the mandrel 1 can be assumed to be 0.5 ~ 50 mm. Borehole Drilling plug of the present invention, by the radius of curvature of the bent portion in the mandrel 1 is in the range described above, by Moto digging conditions such as high depth of has become more and more severe and diverse, bent to reduce the load of a large load applied to the portion, reliably transported in wellbores, it is possible to perform occlusion and fracturing the wellbore and wellbore by facilitating securing of its removal and the flow path cost reducing and shortening the process of drilling a well drilling plug that can. That is, a possibility that the radius of curvature of the bent portion in the mandrel 1 is formed of a degradable material is too small, curved folding portions, transfer the well bore, is damaged by high pressure acting on the closure and the fracturing of the wellbore there is. The radius of curvature of the bent portion in the mandrel 1 is formed of a degradable material is too large, the transition portion (portion where the outer diameter or the inner diameter of the mandrel 1 to form a bent portion changes gradually) is desired too long it may not be formed a bent portion of the shape and position.

2. Borehole Drilling plug attachment are members present invention on the outer peripheral surface orthogonal to the axial direction of the mandrel, the mandrel and, in the plug for wells drilled and a member mounted on the outer peripheral surface orthogonal to the axial direction of the mandrel is there. That is, in the plug well drilling, transport of the plug, in order to perform closure and fracturing the wellbore efficiently and reliably, and further, for purposes such as to improve the handling property, usually the outer peripheral surface of the mandrel various members are attached to the upper. They include various members, along member mounted on the outer peripheral surface orthogonal to the axial direction of the mandrel, member mounted on the outer peripheral surface along the axial direction of the mandrel, and, in the other direction with respect to the axial direction of the mandrel and the like member mounted on the outer peripheral surface. The present invention is a mandrel or a member mounted on the outer peripheral surface orthogonal to the axial direction of the mandrel (hereinafter sometimes referred to as "outer peripheral surface on the mounting member.") Of at least one, is formed from a degradable material, and can be the radius of curvature of the bent portion is assumed, which is a 0.5 ~ 50 mm.

Borehole Drilling plug of the present invention, by having the features described above for the outer peripheral surface on the mounting member, by Moto digging conditions such as high depth reduction is becoming increasingly severe and diverse, according to the bent portion to reduce the load of the heavy load, reliably transported in wellbores, it is possible to perform occlusion and fracturing the wellbore, and cost of well drilling by facilitating securing of its removal and the flow path reducing or shortening the process is a well drilling plug that can.

The outer peripheral surface on the mounting member, conventionally, is not particularly limited as long as members used in the plug well drilling, slip, wedge, a pair of ring-shaped fixing member, and, expandable annular rubber at least one selected from the group consisting of members can be mentioned preferably. As these members are those in its sense including a mounting member for mounting the respective members on the mandrel is referred to as a member.

[Slip and wedge]
The combination of slip 2a, 2b and the wedge 3a, combination of 3b (FIG. 1A, in FIG. 1B, the combination of the slip 2a and wedge 3a, and, as a combination of slip 2b and wedge 3b, and two slip and wedge are shown, to the combination of the slip and wedge provided in well drilling plug may be one, more in may.), as a means for performing fixing of the plug and the wellbore, the wellbore those known per se in drilling plug. That is, the metal, inorganic, slip 2a which is formed of a material such as resin, 2b are wedge 3a which is formed of a material such as resin composite, it is placed in slidable contact with the upper surface of the slope 3b, wedge 3a, 3b are, by moving applied axial force of the mandrel 1, slip 2a, 2b are moved outward perpendicular to the axial direction of the mandrel 1 rides on the upper surface of the inclined surface of the wedge 3a, 3b , the peripheral surface of the outermost perpendicular to the slip 2a, axial mandrel 1 2b abuts against the inner wall H of the wellbore, performing the fixing of the inner wall H of the plug and the wellbore. Slip 2a, the 2b, to occlude the space between the plug and the wellbore (the seal) and made more reliable, the contact portion between the inner wall H of the wellbore, one or more protrusions , stepped portions, grooves, bent portions, such as rough surfaces (jagged) may be provided. Slip 2a, 2b may be one that is divided into a predetermined number in the circumferential direction perpendicular to the axial direction of advance mandrel 1, as shown in FIG. 1, he is divided in advance into a predetermined number It not, or may have a cut end with a middle toward the other end from one end along the axial direction. In this case, the wedge 3a, and the axial force of the mandrel 1 is added to 3b, by wedge 3a, 3b enters the lower surface of the slip 2a, 2b, slip 2a, 2b are, the discontinuities and divided is divided along its extension, then although the split pieces are moved outwardly perpendicular to the axial direction of the mandrel 1, which itself is a well-known structure.

[A pair of ring-shaped fixing member]
Wedge 3a, so that it can move added axial force of the mandrel 1 to 3b, at least one slip 2a, 2b and the wedge 3a, combined with 3b are a pair of ring-shaped fixing member 4a, 4b of it is preferably placed between. That is, a pair of ring-shaped fixing member 4a, 4b is can slide along the axial direction of the mandrel 1 on the outer peripheral surface of the mandrel 1, it is configured to be able to change the mutual spacing , the end portion along the axial direction of the wedge 3a, 3b, by directly or indirectly abutting, and is configured to be able to apply an axial force of the mandrel 1 thereto. A pair of ring-shaped fixing member 4a, each of the shape and size of 4b, as long as capable of performing the functions described above is not particularly restricted, the wedge 3a, relative to 3b, and axial force of the mandrel 1 from the viewpoint of capable of effectively adding a pair of ring-shaped fixing member 4a, the wedge 3a of 4b, it is preferable that the planar end face of each of the side abutting the 3b. A pair of ring-shaped fixing member 4a, 4b each of the ring-shaped fixing member, but preferably has an annular completely surrounds an outer circumferential surface of the mandrel 1, or may have a cut or deformed point in the circumferential direction. Further, as a shape separating the ring in the circumferential direction, it may be obtained by so as to form a circular ring optionally. A pair of ring-shaped fixing member 4a, 4b each of the ring-shaped fixing member, by placing adjacent a plurality of rings in the axial direction, (a large axial length of the mandrel 1.) Wide ring It may be a fixed member.

A pair of ring-shaped fixing member 4a, 4b is, it may be one having the same or similar composition and shape and structure, composition and shape or structure may be different. For example, each of the ring-shaped fixing member, the length and the outer diameter of the axial mandrel 1 may be different. Further, for example, a pair of ring-shaped fixing member 4a, one of the ring-shaped fixing member 4b, which optionally can be configured to a state that can not slide relative to the mandrel 1. In this case, by a pair of ring-shaped fixing member 4a, the other ring-shaped fixing member 4b slides on the outer peripheral surface of the mandrel 1, a pair of ring-shaped fixing member 4a, 4b form each ring fixed members, respectively abut the end portion along the axial direction of the wedge 3a, 3b. A pair of ring-shaped fixing member 4a, one of the ring-shaped fixing member 4b, configured to state where it can not slide relative to the mandrel 1 if desired is not particularly limited. For example, i) a mandrel 1, a pair of ring-shaped fixing member 4a, and the one of the ring-shaped fixing member 4b is assumed to be formed integrally (in this case, the ring-shaped fixing member, a mandrel 1 it is impossible to slide at all times against.), ii) and those utilizing clutch structure and fitting structures such as dog clutch (in this case, be slid between a state in which slide with respect to the mandrel 1 it can be switched between a state where it can not.), a mandrel formed from iii) degradable material, comprising an external thread structure on the outer peripheral surface, one of a pair of ring-shaped fixing member, faces the male threaded female thread structure its inner provided on the peripheral surface, and while the said pair of ring-shaped fixing member, and is fixed in a state that can not be slid in the axial direction of the mandrel, a configuration such as Door can be. A mandrel 1, a pair of ring-shaped fixing member 4a, as the well drilling plug and one of the ring-shaped fixing member 4b is integrally formed, well drilling plug is formed by integral molding or, , well drilling plug formed by machining is provided.

Well drilling plug includes a pair of ring-shaped fixing member 4a, 4b may be one of the provided pairs. In this case, the slip 2a, 2b and the wedge 3a, combination of 3b, and / or capable enlarged detail later annular rubber member 5, each of the one or more separately or in combination, a plurality of pairs of it is also possible to be placed in position between the ring-shaped fixing member 4a, 4b.

[Expandable annular rubber member]
Well drilling plug is a on the outer peripheral surface perpendicular to the axial direction of the mandrel 1, a pair of ring-shaped fixing member 4a, at a position between the 4b, at least one expandable annular rubber member 5 it can be made with a. Preferably, those a pair of ring-shaped fixing member 4a discussed above, 4b secures the expandable annular rubber member 5 mounted on the outer peripheral surface orthogonal to the axial direction of the mandrel 1 remain in the compressed state it can be. That is, the rubber member 5 of expandable annular, the transfer pair of ring-shaped fixing member 4a, directly or indirectly coming into contact to 4b, and axial force of the mandrel 1 on the outer peripheral surface of the mandrel 1 is, as a result, is compressed in the axial direction of the mandrel 1, with the possible axial distance is reduced (reduced in diameter), the diameter increases in the direction perpendicular to the axial direction of the mandrel 1. The annular rubber member 5 is enlarged in diameter, with the outer portion in the direction perpendicular to the axial direction abuts against the inner wall H wellbore, inner portion in the direction perpendicular to the axial direction of the mandrel 1 the outer circumference by contacting the surface, in which the space between the plug and the wellbore to close (seal). Expandable annular rubber member 5 is maintained pair of ring-shaped fixing member 4a, is fixed while in the compressed state by 4b, while the fracturing is performed, the contact state with the inner wall H of the wellbore it can be, and has a function of maintaining the seal between the plug and the wellbore.

Rubber member 5 of expandable annular, as long as it has a function as described above, the material is not limited to the shapes and structures. For example, by a rubber member 5 annular circumferential direction of the cross section perpendicular to the axial direction of the mandrel 1 has the shape of an inverted U shape, with to the tip portion of the U-shape is compressed in the axial direction of the mandrel 1 it can be expanded to face the apex of the inverted U-shaped Te. Rubber member 5 of expandable annular abuts the inner wall H of wellbores when expanded with closing the space between the plug and the wellbore (seal), and the plug when not expanded since between the wellbore in which voids are present, the axial length of the mandrel 1, the length of the mandrel 1, preferably from 10 to 70%, more preferably 15 to 65% and in this manner, wells drilled plug of the present invention has a sufficient sealing function, after the seal can serve fixation assisting the wellbore and the plug.

Well drilling plug may comprise a plurality of rubber members 5 of expandable annular, thereby it can be closed at a plurality of positions of the space between the plug and the wellbore (seal), also it can serve the fixation assisting the wellbore and the plug more reliably. Well drilling plug is, when provided with a plurality of rubber members 5 of expandable annular, the composition of the rubber member 5 of a plurality of expandable annular, shape or structure, the position in the axial direction of the mandrel 1, a pair of ring fixing member 4a, the relative positional relationship between 4b can be appropriately selected.

Expandable annular rubber member 5 of the high temperature and high pressure environment of high deep underground, by contact with more of the high pressure and fracturing fluid with a fracturing, loss of sealing function is required not occur since, usually, heat is preferably excellent rubber material in oil and water resistance, for example, nitrile rubber, hydrogenated nitrile rubber, often acrylic rubber or the like is used. Further, the rubber member 5 of expandable annular, for example, may be a rubber structure formed from a plurality of rubber members such as laminated rubber, may be of structure formed by laminating another member. Furthermore, in order to make more reliable the fixing aid of the closing (sealing) and the wellbore and the plug of the space between the plug and the wellbore when the diameter of the inner wall H of the wellbore the contact portion, one or more protrusions, the step portion, the groove portion may be provided bent portions, such as rough surfaces (jagged).

[Material forming the member mounted on the outer peripheral surface orthogonal to the axial direction of the mandrel]
Material forming the outer peripheral surface on the mounting member provided in the wells drilled plug of the present invention is not particularly limited, conventionally, a material used as a material for forming the member provided in well drilling plug it can be used. For example, metallic materials (aluminum, steel, stainless steel, etc.), fibers, wood, and the like can be illustrated composites and resins, specifically, a composite material containing reinforcing material such as carbon fiber, in particular, epoxy resin and the like composites containing or polymer such as phenol resin. Borehole Drilling plug of the present invention, it after the fracturing is a well drilling plug which can cost reduce and process shortening of well drilling by facilitating securing of its removal and the flow path from the same manner as described for mandrel above, it is preferred that at least one of an outer peripheral surface on the mounting member but are those formed from degradable material.

[Degradable material]
In plug wells drilling of the invention, similarly to Examples of the decomposable material to form at least one of the outer peripheral surface on the mounting member, described mandrel above, degradable material having biodegradability, a hydrolyzable , it can be used degradable material that can be chemically degraded further by some other method.

[Radius of curvature of the bent portion]
In plug wells drilling of the invention, if at least one of an outer peripheral surface on the mounting member are those formed from degradable material, a large load applied to the bent portion of the outer peripheral surface on the mounting member is formed from a degradable material load reduces the securely transported in wellbores, from the viewpoint of performing occlusion and fracturing the wellbore, the radius of curvature of the bent portion in the outer peripheral surface on the mounting member is assumed to be 0.5 ~ 50 mm can. Borehole Drilling plug of the present invention, by the radius of curvature of the bent portion in the outer peripheral surface on the mounting member is in the range of above, Moto digging conditions such as high depth reduction is becoming increasingly severe and diverse in, to reduce the load of a large load applied to the bent portion, reliably transported in wellbores, it is possible to perform occlusion and fracturing the wellbore and to facilitate the securing of its removal and the flow path by a well drilling for the plug, which can cost reducing and shortening the process of well drilling. That is, the radius of curvature of the bent portion in the outer peripheral surface on the mounting member is formed from a degradable material is too small, curved folding portions, transfer the well bore, the high pressure acting on the closure and the fracturing of the wellbore there is a risk of damage. The radius of curvature of the bent portion in the outer peripheral surface on the mounting member is formed from a degradable material is too large, the transition portion (portion where the outer diameter of the outer peripheral surface on the mounting member to form the bent portion changes gradually) becomes long too and it may not be formed a bent portion of the desired shape and position.

3. And the mandrel of the degradable material present invention, plug for wells drilled and a on the outer peripheral surface mounting member, at least one mandrel or the outer peripheral surface on the mounting member is formed of a degradable material, and the curvature of the bent portion radius characterized in that it is a 0.5 ~ 50 mm. The degradable material will be described in detail below.

The degradable material that forms at least one of the mandrel or the outer peripheral surface on the mounting member of the present invention, for example, biodegradable fracturing fluid are decomposed by microorganisms in the soil to be used, or, fracturing fluid solvents, in particular, by the water, there are such further degradable materials having a decomposing hydrolyzable by optionally an acid or an alkali, a degradable material that can be further chemically degraded by some other method it may be. Preferably, a hydrolysable material decomposes by a predetermined temperature or more water. Incidentally, as described above, a metal material such as aluminum which are commonly used in conventional well drilling plug, destroyed by the addition of a large mechanical force, collapse or the like physically degrade materials, degradable Although not applicable to material, as seen in the composite material of the decomposable resin and a metal material described later, the intensity having the original resin by such as reduction of the degree of polymerization becomes brittle reduced result, very small mechanical easily disrupted by the addition of forces, the material to lose shape, corresponding to the decomposition material.

[Decomposable Resin
The degradable material that forms at least one of the mandrel or the outer peripheral surface on the mounting member of the present invention, at the same time having the desired strength at high temperature and pressure environment of high deep underground, it is demanded that is excellent in degradability from degradable resin. The degradable resin refers biodegradable as described above, hydrolyzable, the resin which can be chemically degraded by yet another method. The decomposable resin, for example, polylactic acid, polyglycolic acid, aliphatic and poly -ε- caprolactone polyester or polyvinyl alcohol (about saponification degree 80-95 mol% partially saponified polyvinyl alcohol, etc.) and the like but more preferably is an aliphatic polyester. That is, degradable material is preferably an aliphatic polyester. Decomposable resin may be used singly or two or more in combination by blending or the like. Also, if the outer peripheral surface on the mounting member is formed from a degradable material is a rubber member expandable annular as degradable material, for example, aliphatic polyester-based rubber, polyurethane rubber, natural rubber, polyisoprene , it can be used acrylic rubber, aliphatic polyester rubber, polyester thermoplastic elastomer, a biodegradable rubber and polyamide-based thermoplastic elastomer.

[Aliphatic polyester]
Aliphatic polyesters, for example, homopolymerization or copolymerization of oxycarboxylic acid and / or lactone, esterification reaction of an aliphatic dicarboxylic acid and an aliphatic diol, and aliphatic dicarboxylic acids, and aliphatic diols, hydroxycarboxylic acids and an / or aliphatic polyesters obtained by copolymerization of a lactone, which rapidly dissolved to a temperature 20 ~ 100 ° C. of about water.

The hydroxycarboxylic acid, glycolic acid, lactic acid, malic acid, hydroxypropionic acid, hydroxybutyric acid, hydroxy pentanoic acid, hydroxycaproic acid, hydroxyheptanoic acid, and aliphatic hydroxycarboxylic acids having 2-8 carbon atoms such as hydroxy octanoic acid and the like. The lactone, propiolactone, butyrolactone, valerolactone, lactone having 3 to 10 carbon atoms such as ε- caprolactone.

Examples of the aliphatic dicarboxylic acids, oxalic acid, malonic acid, succinic acid, glutaric acid, aliphatic saturated dicarboxylic acids having 2-8 carbon atoms such as adipic acid, maleic acid, having 4 aliphatic 1-8 carbon atoms, such as fumaric acid and unsaturated dicarboxylic acids. Examples of the aliphatic diols include ethylene glycol, propylene glycol, butanediol, alkylene glycols having 2 to 6 carbon atoms such as hexane diol, polyethylene glycol, polypropylene glycol, polyalkylene glycols having 2 to 4 carbon atoms and polybutylene glycol and the like and the like.

Components forming these polyesters can also be used either alone or in combination of two or more. Also, unless losing the properties as a biodegradable resin may be used in combination component forming the polyester is an aromatic such as terephthalic acid.

Particularly aliphatic polyester is a preferred decomposable resin, polylactic acid (hereinafter sometimes referred to as "PLA".) Or hydroxycarboxylic acid-based aliphatic polyesters, such as PGA; poly -ε- caprolactone (hereinafter, "PCL" . diol dicarboxylic acid such as polyethylene succinate and polybutylene succinate-based aliphatic polyesters; sometimes referred to) lactone aliphatic polyesters, such as those copolymers, for example, glycolic acid-lactic acid copolymer (hereinafter sometimes referred to as "PGLA");. and, mixtures thereof; and the like. Mention may also be made of aliphatic polyester used in combination aromatic components such as polyethylene adipate / terephthalate.

From strength and degradability aspect required for the mounting member on the mandrel or the outer peripheral surface, an aliphatic polyester, PGA, and most preferably at least one selected from the group consisting of PLA and PGLA, PGA is more preferable. As the PGA, in addition to the homopolymer of glycolic acid, a repeating glycolate units 50 wt% or more, preferably 75 wt% or more, more preferably 85 mass% or more, more preferably 90 wt% or more, particularly preferably includes 95 wt% or more, and most preferably at least 99 wt%, especially preferably a copolymer having more than 99.5 wt%. As the PLA, in addition to the L- lactic acid or D- lactic acid homopolymer, L- lactic acid or D- lactic acid repeating units of 50 mass% or more, preferably 75 wt% or more, more preferably 85 wt% or more, more preferably includes a copolymer having more than 90 wt%, it may also be a stereocomplex polylactic acid obtained by mixing polylactic -L- lactic acid and polylactic -D- acid. The PGLA, the ratio of the repeating units units and lactic repeated glycolic acid (weight ratio), 99: 1 to 1: 99, preferably 90:10 to 10:90, more preferably 80:20 to 20: is 80 it can be used a copolymer.

(Melt viscosity)
Aliphatic polyesters, preferably PGA, as PLA or PGLA the melt viscosity of usually 50 ~ 5000 Pa · s, can be preferably used 0.99 ~ 3000 Pa · s, those more preferably 300 ~ 1500Pa · s. The melt viscosity is to measure the temperature 240 ° C., at a shear rate 122 sec-1. If the melt viscosity is too small, the strength required for the mandrel provided in the well drilling plug is insufficient. If the melt viscosity is too high, for example, high melting temperature to produce a mandrel is required, it may aliphatic polyester or a risk of thermal degradation, or becomes insufficient degradable. The melt viscosity of the is a capillary (diameter 1 mm in diameter × length 10 mm) was attached to Capirograph using (Toyo Seiki Seisaku-Sho, Ltd. manufactured "Capirograph 1-C"), a predetermined temperature A sample of about 20 g (240 ° C.) after holding for 5 minutes Te, and performs measured at a shear rate of 122 sec -1.

Particularly PGA preferred aliphatic polyesters, for example, from the viewpoint of moldability such as hardly cracked when forming is carried out by solidification extrusion molding, the weight-average molecular weight of 180,000 to 300,000, and a temperature of 270 ° C., shear rate PGA melt viscosity measured at 122 sec -1 is 700 ~ 2000 Pa · s is more preferable. Particularly preferable PGA has a weight average molecular weight of 190000 to 240000 and a temperature of 270 ° C., melt viscosity measured at a shear rate of 122 sec -1 is PGA is 800 ~ 1200Pa · s. Melt viscosity according to the method described previously (measurement temperature is 270 ° C..) Is measured. Obtained was filtered with a - weight average molecular weight of above, a sample of PGA in 10 mg, sodium trifluoroacetate in hexafluoroisopropanol dissolved at a concentration of 5 mM (HFIP), after a 10mL dissolved, membrane filter use 10μl of sample solution, and measures by gel permeation chromatography (GPC) under the following conditions.
<GPC measurement conditions>
Apparatus: manufactured by Shimadzu Corporation of Shimazu LC-9A
Column: Showa Denko HFIP-806M 2 present Co., Ltd. (series connection) + precolumn: HFIP-LG 1 This column temperature: 40 ° C.
Eluent: sodium trifluoroacetate was dissolved at a concentration of 5 mM HFIP solution flow rate: 1 mL / min Detector: differential refractometer Molecular weight calibration: molecular weight different standard molecular weight of polymethyl methacrylate five (POLYMER LABORATORIES Ltd. Ltd. ) using the calibration curve data made by molecular weight using.

[Other Ingredients]
Degradable material, the preferably decomposable resin, more preferably an aliphatic polyester, more preferably PGA, within a range that does not impair the object of the present invention, further as other formulation ingredients, a resin material (degradable material degradable If a resin, other resins) or, stabilizers, decomposing accelerator or decomposition inhibitor, contain a variety of additives such as reinforcing materials, or may be blended. Degradable material, preferably contains reinforcement, in this case, the degradable material may be referred to the composite material. Degradable material, if it is degradable resin is a so-called reinforced resin. Mandrel or an outer peripheral surface on the mounting member is formed from a reinforced resin, preferably those formed from aliphatic polyesters containing reinforcement.

[Reinforcement]
The reinforcing material, conventionally, it is possible to use a material used as reinforcement in a resin material or the like for the purpose of improving the mechanical strength and heat resistance, and a fibrous reinforcing material, a granular or powdery reinforcement it can be used. Reinforcement against degradable material 100 parts by weight of such degradable resin, typically 150 parts by weight or less, preferably be contained in the range of 10 to 100 parts by weight.

Examples of the fibrous reinforcing material, glass fiber, carbon fiber, asbestos fiber, silica fiber, alumina fiber, zirconia fiber, boron nitride fiber, silicon nitride fiber, boron fiber, inorganic fibrous material such as potassium titanate fibers; stainless steel, aluminum , titanium, steel, metal fibrous materials such as brass, and the like; aramid fibers, kenaf fibers, polyamide, fluororesin, polyester resin, high-melting organic fibrous material such as acrylic resin. Examples of the fibrous reinforcing material, is 10mm or less in length, more preferably 1 ~ 6 mm, further short fibers preferably are preferably 1.5 ~ 4 mm, also inorganic fibrous material is preferably used, glass fibers are particularly preferable.

The granular or powdery reinforcement material, mica, silica, talc, alumina, kaolin, calcium sulfate, calcium carbonate, titanium oxide, ferrite, clay, glass powder, zinc oxide, nickel carbonate, iron oxide, quartz powder, magnesium carbonate, it can be used barium sulfate. Reinforcement may be used alone or in combination of two or more, respectively. Reinforcement, optionally, may be treated by a sizing agent or surface treatment agent.

[Composite]
The mandrel or the outer peripheral surface on the mounting member is formed of a degradable material, it can be assumed to be formed by the composite of the degradable material and a metal or an inorganic material. Specifically, a base material made of a degradable material such as biodegradable resin, including PGA, a recess of the recess or the like of a predetermined shape, a metal of shape matching that of the recess (metal piece or the like) or fit inorganic, or secure them with an adhesive, wire, those formed by or fixed by winding the fibers like as metal pieces or inorganic and the matrix can remain stationary.

4. And the mandrel radius of curvature present invention bent portion, plug wells drilled and a on the outer peripheral surface mounting member, at least one mandrel or the outer peripheral surface on the mounting member is formed of a degradable material, and bent portions thereof radius of curvature characterized in that it is a 0.5 ~ 50 mm. That is, the radius of curvature of the bent portion in the mandrel or the outer peripheral surface on the mounting member is formed of a degradable material is 0.5 ~ 50 mm. Described in detail below radius of curvature of at least one bent portion of the mandrel is formed of a degradable material or an outer peripheral surface on the mounting member.

As previously described, the mandrel provided in the well drilling plug or the outer peripheral surface on the mounting member, for example, slip, wedge, a pair of or a ring-shaped fixing member, such as the expandable annular rubber member sometimes protrusion, a stepped portion, the flange portion, is bent portions of Hitoshi Mizobe is provided. Furthermore, these bent portions, the inner peripheral surface of the outer peripheral surface and the outer peripheral surface on the mounting member of the mandrel, to permit movement in one direction along the axial direction of the mandrel of the member, for regulating the movement in the opposite direction forming a plurality of engagement portions may be formed so as to constitute a ring-shaped ratchet mechanism that is orthogonal to the axial direction of the mandrel. The outer peripheral surface on the mounting member, the mounting member or mandrel, for mounting the outer peripheral surface on the mounting member to the mandrel, may screw portion (male thread structure or internal thread structure) is provided, the threaded portion Needless to say, there is a bent portion of the thread and the thread root. Thus, wells drilled plug of the present invention, the convex portion of the mandrel or the outer peripheral surface on the mounting member is formed of a degradable material, the stepped portion, the flange portion, the groove portion, threads and the radius of curvature of the bent portion of the thread root, etc. There characterized in that it is 0.5 ~ 50 mm. Further, mandrel formed from degradable material, comprising a mating portion of the ratchet mechanism on an outer peripheral surface, the radius of curvature of the meshing portion can be assumed to be 0.5 ~ 50 mm.

That is, plug wells drilling comprising a mandrel of the present invention, and on the outer peripheral surface mounting member includes a on the mounting member mandrel and the outer peripheral surface is jointly occlude the wellbore, to enable fracturing. Thus, the mandrel and the outer peripheral surface on the mounting member provided in the well drilling plug, by Moto digging conditions such as high depth of has become more and more severe and varied, the load of a large load applied to the bent portion to reduce the reliably transported in wellbores, in order to be able to perform the occlusion and fracturing the wellbore, the required mechanical properties that does not cause damage in the environment of a wellbore (tensile and / or compression it is required are those that may have properties). For example, in the occlusion and fracturing the wellbore, pressure is applied of about several tons closed space, the outer peripheral surface on the mounting member, a tensile pressure and / or compression pressure is applied corresponding to the high pressure. In particular, the convex portion, the stepped portion, groove, thread and the thread root, the more bent portion of the engagement portion or the like of the flange portion and the ratchet mechanism, cause stress concentration, it takes greater tensile pressure and / or compression pressure.

Borehole Drilling plug of the present invention, after fracturing completion, in order to facilitate the securing of the removal and the flow path of the mandrel or the outer peripheral surface on the mounting member, at least a portion of the mandrel or the outer peripheral surface on the mounting member, It is formed from a degradable material. Degradable materials such as biodegradable resins such as aliphatic polyester, conventionally, when compared with metallic materials such as aluminum that has been used as a material for forming the plug well drilling, mechanical properties under the environment of wellbore If small is large. However, in the present invention, by the radius of curvature of the bent portion in the mandrel or the outer peripheral surface on the mounting member is formed of a degradable material is 0.5 ~ 50 mm, the required which does not cause damage in the environment of a wellbore It may have mechanical properties (tensile and / or compression characteristics). In the case the radius of curvature of the bent portion in the mandrel or the outer peripheral surface on the mounting member is formed of a degradable material, in which bent portions are composed of a radius of curvature of different curved surface, a minimum in the bent portion It refers to the radius of curvature.

By having the required mechanical properties that does not cause damage in the environment of the wellbore (the tensile and / or compression characteristics) ensured, to reduce the load of a large load applied to the bent portion, reliably transported in wellbores from the viewpoint of performing occlusion and fracturing the wellbore, the radius of curvature of the bent portion in the mandrel or the outer peripheral surface on the mounting member is formed of a degradable material, preferably 1 ~ 40 mm, more preferably 3 ~ 36 mm, further is preferably in the range of 5 ~ 32mm.

Note that in the plug wells drilling of the invention, when the outer peripheral surface on the mounting member formed from the mandrel or degradable material is formed from a degradable material and has a plurality of bent portions, all bent portion for, also good as the radius of curvature is 0.5 ~ 50 mm, the transfer in the well bore, in the closed and fracturing the wellbore, the more the radius of curvature of the bent portion where a large load is loaded in the range of the it may be some.

At least bent portion in the mandrel or the outer peripheral surface on the mounting member is formed of a degradable material, the convex portion, the stepped portion, the flange portion, the engaging portion of the ratchet mechanism, the groove is selected from the group consisting of threads and the thread root is one, bent portion, if further having a tapered portion, since the cases can reduce the load of the heavy load is, sometimes it is preferable that the height of the tapered portion is 1mm or more, more preferably 2 ~ 50 mm, more preferably in the range of 3 ~ 45 mm, particularly preferably from 5 ~ 40 mm. Here, the tapered portion means a length along the mandrel axis direction of a portion excluding the portion having a minimum radius of curvature at bent portions of the mandrel or the outer peripheral surface on the mounting member is formed of a degradable material.

Figure 2 is formed from a biodegradable resin PGA, the flange portion as bent portion [Thickness (A): is a schematic diagram of one embodiment of a mandrel having a 30 mm). In this example, it becomes the flange portion in the radial downward large round bar mandrel round rod (pipe-shaped) is the radius of curvature Rmm, and that is connected via a tapered portion of the height Tmm tapered portion shape ing. Securing the uppermost end of the upper portion of the round bar, the flange portion applying a load of 45 kN (corresponding to the tensile force caused by the pressure acting during fracturing.). The radius of curvature R (unit: mm) and the height T (unit: mm) of the tapered portion and by changing the tensile according to the flange portion Stress (Unit: MPa) The results of measurement are shown in Table 1.

Figure JPOXMLDOC01-appb-T000001

From Table 1, the radius of curvature of the bent portion is 0.5 ~ 50 mm No. 1 ~ No. Maximum stress is loaded on the flange portion 4 was less than 82 MPa. 45kN since stress of PGA at a temperature 66 ° C. (0.99 ° F) is about 90 MPa, a mandrel formed from PGA having a flange portion, in an environment of temperature 66 ° C., the flange portion of the plug well drilling be a load of the load was inferred to be one which does not lead to damage.

In particular, the radius of curvature of the bent portion is 10, 20 or 30 mm No. 2 ~ No. Maximum stress is loaded on the flange portion 4 is not more than 36 MPa, because it is less stress about 40MPa of PGA at a temperature 149 ° C., a mandrel having a flange portion, at a high temperature of environment of high depth, pit even at a pressure well drilling for the plug is subjected to was presumed to be those which do not lead to damage. Among them, a further 10 or 20mm height of the tapered portion No. 3 and No. Maximum stress is loaded on the flange portion 4 to be smaller than 31 MPa, the mandrel having the flange portion, even in higher temperature environment higher depth, the pressure reliably well drilling plug receives it it is capable against is inferred.

5. Borehole drilling plug well drilling plug the present invention includes a mandrel, a plug for wells drilled with an outer peripheral surface on the mounting member, at least one mandrel or the member is formed of a degradable material and a well drilling plug, wherein a curvature radius of the bent portion is 0.5 ~ 50 mm. Borehole Drilling plug of the present invention may further comprise other members which may be provided in the ordinary well drilling plug. For example, the mandrel, if having a hollow portion along the axial direction, is placed in the hollow portion, a ball for controlling the flow of fluid (metal, formed from a material such as a resin may be formed from a degradable material.) it can be provided with. Also, the mandrel of the plug well drilling, the outer peripheral surface on the mounting member, and further the other member of the, each or another member coupled to or released or members for, for example, a like rotation stopping member be able to. And the mandrel of the present invention, plug for wells drilled and a on the outer peripheral surface mounting member can also be assumed to be formed of all the degradable material.

[Blockage of the wellbore]
Borehole Drilling plug of the present invention, as described above, for example, by applying an axial force of the mandrel in a ring-shaped fixing member of the pair, expandable axis of the annular mandrel rubber member transmitting the force, resulting compressed into expandable axial direction of the rubber member is a mandrel of circular, as that distance in the axial direction is reduced (reduced in diameter), expandable annular rubber member, the diameter increases in a direction perpendicular to the axial direction of the mandrel. Said annular rubber member is diametrically enlarged, with the outer portion in the direction perpendicular to the axial direction is the inner wall and the abutment of the wellbore, the inner portion in the direction perpendicular to the axial direction on the outer peripheral surface of the mandrel those by contacting can the space between the plug and the wellbore to close (seal) (obstruction of the wellbore). Furthermore, the slip is moved outward perpendicular to the axial direction of the mandrel rides on the upper surface of the inclined surface of the wedge, the peripheral surface of the outermost perpendicular to the axial direction of the mandrel of the slip, the wellbore inner wall and those in contact, it is possible to secure the plug in position in the wellbore. Then, in a state of closing (sealing) the space between the plug and the wellbore, it is possible to perform the fracturing.

[Wellbore degradation of drilling plug]
Borehole Drilling plug of the present invention, after the fracturing of the predetermined various compartments has been completed, usually, wells are completed drilling of the well is completed, when starting the production of petroleum and natural gas the biodegradation, chemical degradation by hydrolysis or even in some other way, at least one of the mandrel or the outer peripheral surface on the mounting member is formed of a degradable material, formed from more decomposable material desired by the Rumandoreru, it is possible to remove easily decomposed, it is possible to perform the extraction of hydrocarbon resources efficiently. Therefore, according to the wellbore drilling plug according to the present invention, conventionally, after the well completion, remove a number of the plug wells drilling that has been left on the wellbore, or recovered, disrupted by drilling and other methods, destruction or, since many cost and time it takes to or shredding into is not required, it is cost reduce and process shortening of well drilling.

II. Borehole Drilling plug wells TECHNICAL FIELD The present invention drilling plug mandrel, a plug for wells drilled with an outer peripheral surface on the mounting member, at least one mandrel or the member, degradable material it is formed from, and, as long as the curvature radius of the bent portion can be produced plug well drilling, which is a 0.5 ~ 50 mm, the manufacturing method is not limited. For example, (., Including solidification extrusion) injection molding, extrusion molding, centrifugal molding, compression molding and other methods known molding, molding the respective members provided in well drilling plug, each member obtained, after machining such as cutting or drilling optionally in combination with per se known methods, it is possible to obtain a plug well drilling.

If wells drilled plug of the present invention, a mandrel formed of degradable material, and the outer peripheral surface on the mounting member is formed from a degradable material is well drilling plug are formed integrally injection molding, extrusion molding (including solidified extrusion.), by integral molding by a molding method such as a centrifugal molding, or by machining such as cutting, and the mandrel formed from degradable material, formed from a degradable material it is preferably formed integrally with the outer peripheral surface on the mounting member that.

III. Using the mandrel of well drilling method of the present invention, a plug for wells drilled and a on the outer peripheral surface mounting member, after the sealing treatment of the wellbore, some or all of the plug well drilling According to well drilling methods but being degraded, fracturing the predetermined various compartments is completed, or, wells are completed drilling of the well is completed, when starting the production of petroleum and natural gas , biodegradation, chemical degradation by hydrolysis or even in some other way, at least one of the outer peripheral surface on the mounting member, further a mandrel formed from degradable material, removed readily decomposed desired by it is possible, it is possible to perform the extraction of hydrocarbon resources efficiently. As a result, according to the wells drilling method of the present invention, conventionally, after the well completion, remove a number of the plug wells drilling that has been left on the wellbore, or recovered, disrupted by drilling and other methods, destruction or, since many cost and time it takes to or shredding into is not required, it is cost reduce and process shortening of well drilling.

The present invention includes a mandrel, a plug for wells drilled and a member mounted on the outer peripheral surface orthogonal to the axial direction of the mandrel, at least one mandrel or the member is formed of a degradable material, and by the radius of curvature of the bent portion is well drilling plug, which is a 0.5 ~ 50 mm, Moto digging conditions such as high depth reduction is becoming increasingly severe and diverse in, to reduce the load of a large load applied to the bent portion, reliably transported in wellbores, it is possible to perform occlusion and fracturing the wellbore and to facilitate the securing of its removal and the flow path it is possible to provide a well drilling plug can cost reduce and process shortening of well drilling by, has high industrial applicability.

Further, the present invention is anti to using the plug wellbore drilling, after the sealing treatment of the wellbore, some or all of the plug well drilling is characterized in that it is decomposed by a well drilling method, drilling conditions such as high depth of system, under which become increasingly severe and diverse, to reduce the load of a large load applied to the bent portion, reliably transported in wellbores, it can be performed occlusion and fracturing the wellbore, and can provide a well drilling method which can cost reduce and process shortening of well drilling by facilitating securing of its removal and the flow path since, there is a high availability of the industry.

1: mandrel 2a, 2b: slip 3a, 3b: wedge 4a, 4b: ring-shaped fixing member 5: expandable annular rubber member H: wellbore inner wall A: thickness of the flange portion R: radius of curvature T: the height of the tapered portion

Claims (20)

  1. And the mandrel, a plug for wells drilled and a member mounted on the outer peripheral surface orthogonal to the axial direction of the mandrel, at least one mandrel or the member,
    It formed from degradable material, and well drilling plug, wherein a curvature radius of the bent portion is 0.5 ~ 50 mm.
  2. Member mounted on the outer peripheral surface orthogonal to the axial direction of the mandrel, slips, wedge, a pair of ring-shaped fixing member, and, expandable billing annular at least one is selected from the group consisting of rubber member wells drilling plug of claim 1, wherein the.
  3. A pair of ring-shaped fixing member, is capable of fixing the expandable annular rubber member attached to the outer circumferential surface perpendicular to the axial direction of the mandrel remains in the compressed state according to claim 2, wherein the wellbore drilling plug.
  4. At least one combination of slip and wedge, pair ring fixed claim 2 or 3 wells drilling plug according placed between members.
  5. Member mounted on the outer peripheral surface orthogonal to the axial direction of the mandrel is formed from a degradable material, according to any one of claims 1 to 4 is formed by a composite of a degradable material and a metal or an inorganic material well drilling for the plug.
  6. Mandrel is formed from degradable material, and wells drilling plug according to any one of claims 1 to 5 the radius of curvature of the bent portion is 0.5 ~ 50 mm.
  7. Mandrel formed from degradable material, wells drilling plug of claim 6, further comprising a hollow portion along the axial direction.
  8. A mandrel formed from degradable material, for the member mounted on the outer peripheral surface perpendicular to the axial direction wells drilled according to claim 6 or 7, wherein are formed integrally of a mandrel formed from degradable material plug.
  9. Integral wells drilling plug according to claim 8, wherein are integrally formed by molding.
  10. Borehole drilling plug according to claim 8, characterized in that integrally formed by machining.
  11. Bent portion, the convex portion, the stepped portion, the flange portion, the groove portions, at least one in wells drilling plug according to any one of claims 1 to 10 is selected from the group consisting of threads, and the thread root.
  12. Bent portion further comprises a tapered portion, claim 11 wells drilling plug according the height of the tapered portion is 1mm or more.
  13. Degradable material, wells drilling plug according to any one of claims 1 to 12 aliphatic polyester.
  14. Aliphatic polyester, wells drilled plug of claim 13 wherein the polyglycolic acid.
  15. Polyglycolic acid, weight average molecular weight of 180,000 to 300,000 and a temperature of 270 ° C., wells drilled plug of claim 14, wherein the melt viscosity measured at a shear rate of 122 sec -1 is 700 ~ 2000Pa · s.
  16. Degradable material, wells drilling plug according to any one of claims 1 to 15 containing a reinforcing material.
  17. Mandrel, wells drilling plug according to any one of claims 1 to 16 formed from polyglycolic acid.
  18. Mandrel formed from degradable material, comprising a mating portion of the ratchet mechanism on an outer peripheral surface, according to any one of claims 1 to 17 the radius of curvature of the engagement portion is 0.5 ~ 50 mm wells drilling plug.
  19. Mandrel formed from degradable material, comprising an external thread structure on the outer peripheral surface, 1 one of the pair of ring-shaped fixing member, provided with a male screw structure facing the female thread structure on the inner peripheral surface thereof, and the pair one is, wells drilling plug according to any one of the axial direction 1 to claim is secured to a state that can not be slid to 18 of the mandrel of the ring-shaped fixing member.
  20. Use plug wells drilling according to any one of claims 1 to 19, after the sealing treatment of the wellbore, that some or all of the plug well drilling is degraded well drilling method according to claim.
PCT/JP2014/077831 2013-10-23 2014-10-20 Plug for well drilling WO2015060246A1 (en)

Priority Applications (2)

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JP2013-220223 2013-10-23

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US15/028,227 US20160237774A1 (en) 2013-10-23 2014-10-20 Plug for well drilling
JP2015543843A JP5955469B2 (en) 2013-10-23 2014-10-20 Well drilling for the plug
CA2927080A CA2927080C (en) 2013-10-23 2014-10-20 Plug for well drilling

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USRE46028E1 (en) 2003-05-15 2016-06-14 Kureha Corporation Method and apparatus for delayed flow or pressure change in wells
WO2017111159A1 (en) * 2015-12-25 2017-06-29 株式会社クレハ Shaped material for downhole tool member, downhole tool member, and downhole tool
US9708878B2 (en) 2003-05-15 2017-07-18 Kureha Corporation Applications of degradable polymer for delayed mechanical changes in wells

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JPS641892A (en) * 1987-04-13 1989-01-06 Drilex Syst Inc Packing aggregate
US20050205266A1 (en) * 2004-03-18 2005-09-22 Todd Bradley I Biodegradable downhole tools
US20110277989A1 (en) * 2009-04-21 2011-11-17 Frazier W Lynn Configurable bridge plugs and methods for using same

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US9500061B2 (en) * 2008-12-23 2016-11-22 Frazier Technologies, L.L.C. Downhole tools having non-toxic degradable elements and methods of using the same

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JPS641892A (en) * 1987-04-13 1989-01-06 Drilex Syst Inc Packing aggregate
US20050205266A1 (en) * 2004-03-18 2005-09-22 Todd Bradley I Biodegradable downhole tools
US20110277989A1 (en) * 2009-04-21 2011-11-17 Frazier W Lynn Configurable bridge plugs and methods for using same

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
USRE46028E1 (en) 2003-05-15 2016-06-14 Kureha Corporation Method and apparatus for delayed flow or pressure change in wells
US9708878B2 (en) 2003-05-15 2017-07-18 Kureha Corporation Applications of degradable polymer for delayed mechanical changes in wells
US10280703B2 (en) 2003-05-15 2019-05-07 Kureha Corporation Applications of degradable polymer for delayed mechanical changes in wells
WO2017111159A1 (en) * 2015-12-25 2017-06-29 株式会社クレハ Shaped material for downhole tool member, downhole tool member, and downhole tool
CN108368572A (en) * 2015-12-25 2018-08-03 株式会社吴羽 Shaped material for downhole tool member, downhole tool member, and downhole tool

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US20160237774A1 (en) 2016-08-18
CA2927080C (en) 2018-07-10
CA2927080A1 (en) 2015-04-30
JPWO2015060246A1 (en) 2017-03-09
JP5955469B2 (en) 2016-07-20

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