Downhole tool fixation device and frac plug

Abstract

The present application provides a downhole tool fixing device and a fracturing plug with excellent installation property and water pressure resistance, and good breaking property. The downhole tool fixing device (slips 106a, 106b) of the fracturing plug (100) of one scheme of the present application is provided with a button (602) containing a powder metallurgy material, the compressive elastic modulus of which is at least 13.5 GPa, and the toughness of which is 0.23 GJ / m 3 and 1.0 GJ / m 3 below.

Description

TECHNICAL FIELD

[0001] The present application relates to a downhole tool fixing device and a fracturing plug. BACKGROUND

[0002] In order to efficiently recover oil and gas resources such as shale oil and natural gas, it is known to stimulate production of these hydrocarbon resources by a hydraulic fracturing method. The hydraulic fracturing method is a method of efficiently recovering oil and gas resources by a fluid pressure such as water pressure to cause a narrow hole and a crack (fracture) in a production layer. A hole for forming a borehole called a borehole is provided between the ground surface and the production layer. In the borehole, a vertical hole is excavated from the ground surface, and then the hole is bent to form a horizontal hole in the production layer located several kilometers underground.

[0003] When the hydraulic fracturing method is applied to such a borehole, a downhole tool for blocking the borehole hole at the time of hydraulic fracturing is provided in the borehole. At the time of provision, first, the downhole tool is sent to a prescribed position in the borehole. Then, the downhole tool is made to work to be fixed to the wall of the borehole, and an elastic member provided in the downhole tool is deformed to block the borehole. Thereafter, water is pressure-fed from the ground surface into the borehole, and water pressure is applied to a region closer to the ground surface than the position blocked previously. At the production layer, a narrow hole is further formed using explosives or the like, and water pressure is further applied, whereby a fracture is generated by perforation.

[0004] The downhole tool is called a fracturing plug or the like, and is composed of at least one mandrel and various members fitted to the outer periphery of the mandrel. In order to ensure close fixation to the wall of the borehole, a sealing member formed of an elastic material and a fixing device called a slip are provided on the outer periphery of the mandrel.

[0005] Further, since the downhole tool is used for temporary blocking of the borehole, it is necessary to remove the downhole tool after use, and development of a downhole tool having disassembly property is also being made in order to make removal easy.

[0006] In Patent Literature 1, a scheme is disclosed in which a cylindrical pad or button called a gripping element provided on the surface of the slip is used to fix the downhole tool to the borehole. It is disclosed that the gripping element is composed of a powder metallurgical material in consideration of disassembly property, and is subjected to a surface hardening treatment, and the surface layer has a Rockwell hardness of 55 to 62 HRC (or 40 to 80 HRC), and the core has a Rockwell hardness of 75 (converted to HRC, about 30) or 70 to 97 (converted to HRC, about 21 to more than 68) in terms of 15N.

[0007] Further, in Patent Literature 2, a configuration is disclosed in which a pad (button) is provided on the surface of a segment of a slip. It is disclosed that the pad is configured of a powder metallurgical material, is engaged with a housing, and has strength and hardness sufficient to secure a tool.

[0008] Further, in Patent Literature 3, a configuration is disclosed in which a pad is provided on the surface of a slip, the pad having a hardness of 50 to 60 Rc, and a powder metallurgical material can be used.

[0009] Further, in Patent Literature 4, a slip using a powder metallurgical material having a Rockwell C hardness of 55 to 60 is disclosed.

[0010] Prior Art Documents

[0011] Patent Literature

[0012] Patent Literature 1: US Patent No. 2018 / 0128073 Specification

[0013] Patent Literature 2: US Patent No. 2014 / 0224477 Specification

[0014] Patent Literature 3: US Patent No. 2015 / 0368994 Specification

[0015] Patent Literature 4: US Patent No. 2017 / 0044859 Specification SUMMARY

[0016] Problems to be Solved by the Invention

[0017] The button fitted to the slip needs to have strength to withstand high water pressure of, for example, 70 MPa in a state in which it is secured to a wall of a borehole (or a housing provided to the wall). On the other hand, after cracks are generated in a production layer, if the downhole tool is disassembled as described above, the button also needs to have fracturing properties.

[0018] Therefore, an object of one aspect of the present application is to realize a downhole tool securing device and a fracturing plug having excellent securing properties, pressure resistance, and fracturing properties.

[0019] Technical Solution

[0020] To solve the above problems, a downhole tool securing device of one aspect of the present application is a downhole tool securing device for securing a downhole tool to a housing in a borehole, the downhole tool securing device including: a main body portion; and a button fitted to the main body portion in a manner protruding from the surface of the main body portion, the button including a molded body of a powder metallurgical material, the button having a compressive elastic modulus of at least 13.5 GPa and a toughness of 0.23 GJ / m 3 and 1.0 GJ / m 3 or more.

[0021] To solve the above problems, a fracturing plug according to an aspect of the present application is provided with the downhole tool fixing device described above.

[0022] Advantages

[0023] According to an aspect of the present application, a downhole tool fixing device and a fracturing plug having excellent fixing properties, pressure resistance, and fracturing properties can be achieved. BRIEF DESCRIPTION OF DRAWINGS

[0024] Figure 1 is a side view of a fracturing plug according to an embodiment of the present application, provided with a downhole tool fixing device.

[0025] Figure 2 is a partial cross-sectional view of the fracturing plug of Figure 1

[0026] Figure 3 is a partial enlarged cross-sectional view of Figure 1 , and is a cross-sectional view showing the configuration of the downhole tool fixing device according to an embodiment of the present application.

[0027] Figure 4 is a partial perspective view of a slip base of a slip as the downhole tool fixing device according to an embodiment of the present application.

[0028] Figure 5 is a perspective view of a button as the downhole tool fixing device according to an embodiment of the present application. DETAILED DESCRIPTION

[0029] Hereinafter, an embodiment of the downhole tool fixing device and the fracturing plug according to the present application will be described with reference to Figures 1 to 3

[0030] Figure 1 is a side view of a fracturing plug according to an embodiment of the present application, provided with a downhole tool fixing device. Figure 2 is a cross-sectional view for explaining the mechanism of the fracturing plug of Figure 1 Figure 3 is a partial cross-sectional view of the frame portion B shown in Figure 2 Figure 4 is a partial perspective view of a slip base of a slip as the downhole tool fixing device according to an embodiment of the present application. Figure 5 is a perspective view of a button as the downhole tool fixing device according to an embodiment of the present application.

[0031] 〔Fracturing plug〕

[0032] As shown in Figure 1 ​​​​As shown, the fracturing plug 100 (downhole tool) of this embodiment includes: a mandrel 101; an elastic member 102; a retaining member 103 disposed adjacent to the elastic member 102 on one side; cones 104 and 105 disposed to clamp the elastic member 102 and the retaining member 103; a pair of slips 106a and 106b (downhole tool fixing devices); and a pair of ring members 107a and 107b.

[0033] like Figure 2 As shown in (a), the fracturing plug 100 is disposed within a housing 200 located inside a pit borehole (not shown). When the fracturing plug 100 is disposed within the housing 200, the mandrel 101 is moved along... Figure 2 The axial movement shown by P in (a) shortens the axial distance between the mandrels of the pair of ring members 107a and 107b. As a result, the slips 106a and 106b rise along the upper surface of the inclined surfaces of the cones 104 and 105, moving outwards orthogonal to the axial direction of the mandrel 101, and abut against the inner wall of the pit bore (the inner wall of the housing 200). Thus, the fracturing plug 100 is positioned at a predetermined location in the pit bore. Among the slips 106a and 106b, as described later, the button 602 protrudes outwards orthogonal to the axial direction of the mandrel 101. Thus, with the slips 106a and 106b abutting against the inner wall of the pit bore (the inner wall of the housing 200), a portion of the button 602 is recessed into the inner wall of the housing 200. This securely fixes the fracturing plug 100 to the inner wall of the pit bore.

[0034] It should be noted that as the mandrel 101 moves axially and the gap between the cone 105 and the retaining member 103 narrows, the elastic member 102 deforms and extends outward toward the outer periphery of the mandrel 101. Then the elastic member 102 abuts against the housing 200, thereby blocking the gap between the fracturing plug 100 and the housing 200.

[0035] After the fracturing plug 100 is positioned at a predetermined location in the pit hole as described above, a ball or the like (not shown) is installed in the axial hollow portion of the mandrel 101, thereby blocking the pit hole. Then, with the pit hole blocked, when fluid is introduced from the cone 104 side into the blocked area under high pressure, hydraulic fracturing that causes cracks in the production layer can be achieved.

[0036] Regarding the fracturing plug 100, it is removed from the well when hydraulic fracturing is completed. The fracturing plug 100 of this embodiment is a decomposable fracturing plug formed from decomposable material decomposed by fluid in the well. This is achieved by fluid exposed to the well (in the axial direction of the mandrel, i.e., in...). Figure 2The plug 100 is removed from the wellbore by the action of the fluid flowing in the direction of the arrow F1 or F2 in (b) for a prescribed time, and the plug 100 is disintegrated, dissolved, and removed from the portion in contact with the fluid, and the blocked flow path is restored. In order to achieve this process, the respective components of the plug 100 are preferably formed of a disintegrating resin or a disintegrating metal, respectively. Thus, after the wellbore treatment using the plug 100, the removal of the plug 100 becomes easy.

[0037] Note that, in the present specification, the "disintegrating resin or disintegrating metal" means a resin or a metal that is dissolved in water or hydrocarbons in the wellbore by biodegradation or hydrolysis, and is further disintegrated or embrittled by a certain chemical method to simply disintegrate. As the disintegrating resin, for example, a hydroxy carboxylic acid-based aliphatic polyester such as polylactic acid (PLA) and polyglycolic acid (PGA); a lactone-based aliphatic polyester such as polycaprolactone (PCL); a diol / dicarboxylic acid-based aliphatic polyester such as polyethylene succinate and polybutylene succinate; a copolymer thereof such as a glycolic acid / lactic acid copolymer and a mixture thereof; an aliphatic polyester using an aromatic component such as polyhexamethylene glycol terephthalate; and the like can be listed. In addition, a water-soluble resin can also be used as the disintegrating resin. As the water-soluble resin, polyvinyl alcohol, polyvinyl butyral, polyvinyl formal, polyacrylamide (N,N-substituted can also be used), polyacrylic acid, polymethacrylic acid, and the like can be listed, and further, a copolymer of monomers forming these resins, such as ethylene / vinyl alcohol copolymer (EVOH) and acrylamide / acrylic acid / methacrylic acid interpolymer, and the like can be listed. As the disintegrating metal, an alloy using magnesium, aluminum, calcium, and the like as a main component can be listed.

[0038] 〔Slips 106a, 106b (downhole tool fixing device)〕

[0039] Figure 3 is Figure 2 is an enlarged view of the frame portion B shown in (b), and shows the configuration of the slip 106b. Note that the slip 106a has the same configuration as the slip 106b shown in Figure 3 , and thus only the slip 106b will be described here.

[0040] As shown in Figure 3 , the slip 106b has a slip base 601 (main body portion) and a button 602 fitted to the slip base 601 in a manner protruding from the surface of the slip base 601.

[0041] • Slip base 601 (main body portion)

[0042] The slip base 601 is the main portion of the slip 106b, and slides on the inclined surface of the cone 105.

[0043] A recess 601b is provided on the outer peripheral surface 601a of the base 601 for inserting a button 602. Multiple buttons 602 are provided, and the recesses 601b are formed on the outer peripheral surface 601a in a manner that matches the number of buttons 602.

[0044] use Figure 4 One embodiment of the slip base 601 is described, wherein the slip base 601 comprises a plurality of slip segments 612, which are divided by a slit 611 terminating midway along the axial direction from one end toward the other. Each slip segment 612 has a plurality of buttons 602 on its surface 601a abutting against the housing 200. It should be noted that the embodiment of the slip base 601 is not limited to this embodiment. Figure 4 The scheme shown.

[0045] As described above, the locator base 601 can be a decomposable resin or a decomposable metal, preferably a reactive metal that dissolves in the pit using a prescribed solvent.

[0046] Reactive metals are metallic elements that readily bond with oxygen to form extremely stable oxides, react with water to generate diatomic hydrogen, and / or readily absorb oxygen, hydrogen, nitrogen, or other non-metallic elements, becoming embrittled and thus decomposing. More specifically, reactive metals refer to monomeric metallic elements or alloys with that metallic element as the main component that can decompose under specified conditions (e.g., temperature, pressure, etc.; contact with fluids such as aqueous fluids (preferably acidic fluids)) in the pit environment (hereinafter sometimes referred to as the "downhole environment") where downhole tools are used, and readily lose the shape of the initial downhole tool or downhole tool components.

[0047] The specified solvent refers to fluids such as fracturing fluids (i.e., well treatment fluids used for fracturing). In addition to water, it can also include various additives such as channeling agents, gelling agents, scale inhibitors, acids used to dissolve rocks, and friction-reducing materials.

[0048] Those skilled in the art can appropriately select the range of reactive metals based on the assumed pit environment and other specified conditions. In most cases, alkali metals or alkaline earth metals belonging to Group I or Group II of the periodic table, aluminum, etc., can be listed, with alloys with magnesium as the main component being preferred.

[0049] Button 602

[0050] like Figure 3 As shown, button 602 is mounted on the surface 601a of the locking base 601 that abuts against the housing 200. It should be noted that... Figure 4In the present embodiment, a configuration in which one of the slips 612 is provided with four buttons 602 is shown, but the number of buttons 602 is not limited thereto. Further, the number of buttons 602 provided with respect to the entire chuck base 601 is not particularly limited.

[0051] As described above, the buttons 602 are cylindrical. The buttons 602 are fitted to the chuck base 601 in a manner in which the central axis of the buttons 602 is inclined with respect to the axial direction of the mandrel 101. Figure 5 Figure 1 , Figure 2 As a method of fitting, there is no particular limitation, and a conventional method of fitting the buttons to the chuck base can be employed.

[0052] As the inclination angle of the central axis of the buttons 602 with respect to the axial direction of the mandrel 101, for example, 85° or less is considered from the viewpoint of the mountability to the steel pipe, and 80° or less is preferable. Further, from the viewpoint of the durability of the fixing device, the inclination angle is 45° or more, and 60° or more is preferable. In the case of the buttons 602, the edge (rim) of the cylindrical shape can also be chamfered.

[0053] As the dimensions of the buttons 602, appropriate dimensions can be set, and as one example, the outer diameter can be set to 9 mm, and the thickness (height) can be set to 5.9 mm, as in the following embodiment.

[0054] The buttons 602 include a molded body of a powder metallurgical material, and the compressive elastic modulus is at least 13.5 GPa, and the toughness is 0.23 GJ / m 3 or more and 1.0 GJ / m 3 or less. The buttons 602, by including a molded body of a powder metallurgical material, and the compressive elastic modulus being at least 13.5 GPa, do not deform when sinking into the housing 200 Figure 1 , Figure 2 , and show excellent mountability (fixing property).

[0055] Further, as described above, the buttons 602 include a molded body of a powder metallurgical material, and the toughness is 0.23 GJ / m 3 or more and 1.0 GJ / m 3 or less. By having the toughness be 0.23 GJ / m 3 or more, the strength against high water pressure (for example, water pressure of up to 70 MPa) when hydraulic fracturing is performed on the production layer is obtained. On the other hand, by having the toughness be 1.0 GJ / m 3 or less, good fracturing property is obtained. Thus, when the fracturing plug 100 Figure 1 is removed from the well, the buttons 602 can be easily removed. In this way, since removal is easy, when removed from the well, the buttons 602 do not remain in the well and become an obstacle (production obstacle) for the next process.

[0056] ​It is preferable that the button 602 is composed of a molded body of a powder metallurgical material, and the apparent density is 6.7 g / cm 3 and 7.2 g / cm 3 The button 602 can be composed of a molded body of a powder metallurgical material of iron, for example. Thereby, the apparent density is less than the specific gravity of iron, 7.8, and is easily broken. Therefore, it is not likely to become a cause of production trouble.

[0057] Further, the button 602 is composed of a surface and a core, and the Rockwell hardness (HRC) of the surface and the core is 20 or more and 45 or less, respectively. Here, the surface of the button 602 means a portion corresponding to the surface of a cylindrical shape. Further, a portion closer to the center portion than the surface is a portion corresponding to the core. Therefore, the surface and the core mentioned herein do not mean separate bodies from each other, but indicate a relative positional relationship in one molded body.

[0058] The HRC of the surface and the HRC of the core in the button 602 can be the same or different. Further, with respect to the HRC of the core, the HRC of the surface side and the center portion of the button 602 (the center portion of the cylindrical body) can be different. For example, it can be a constitution in which the HRC continuously differs from the surface side toward the center portion in the core. In the case where the HRC continuously differs in the core, the "HRC of the core" in the present specification means a value obtained by measuring the center portion of the core.

[0059] Further, from the viewpoint of the mountability and the water pressure resistance, the HRC of the surface and the HRC of the core of the button 602 are preferably 30 or more, respectively.

[0060] As described above, the button 602 of the present embodiment mounted to the slips 106a and 106b is excellent in the mountability (fixing property) and the water pressure resistance, and has a good breakability. Therefore, when the frac plug 100 is removed from the wellbore, it can be easily removed without causing production trouble. Figure 1 ) can be easily removed without causing production trouble.

[0061] (Modified example)

[0062] As another embodiment of the frac plug of the present application, a frac plug can be provided which has a mandrel and an elastic member, and further has one slip each and a corresponding cone and ring member.

[0063] The present application is not limited to the above-described embodiments, and various modifications can be made within the scope shown in the claims, which are also included in the technical scope of the present application.

[0064] Further, the downhole tool fixing device (the slips 106a and 106b of the present embodiment) of the present application can be applied to downhole tools other than the frac plug 100, which are also included in the scope of the present application.

[0065] [Summary]

[0066] The downhole tool fixing device (slips 106a, 106b) of the present application according to the aspect 1 is used to fix a downhole tool to a housing in a well, and has: a main body (a slip base 601); and a button 602 fitted to the main body in a manner protruding from a surface 601a of the main body, the button 602 including a molded body of a powder metallurgical material, the button 602 having a compressive elastic modulus of at least 13.5 GPa and a toughness of 0.23 GJ / m 3 and 1.0 GJ / m 3 or more.

[0067] According to the aspect 1, a downhole tool fixing device having excellent fixation, pressure resistance, and fracturing properties can be achieved.

[0068] The downhole tool fixing device (slips 106a, 106b) of the present application according to the aspect 2 is the aspect 1, preferably, the apparent density of the button 602 is 6.7 g / cm 3 and 7.2 g / cm 3 or more.

[0069] According to the aspect 2, a downhole tool fixing device having excellent fracturing properties can be achieved.

[0070] The downhole tool fixing device (slips 106a, 106b) of the present application according to the aspect 3 is the aspect 1 or 2, preferably, the button 602 is composed of a surface and a core, and the Rockwell hardness (HRC) of the surface and the core is 20 or more and 45 or less, respectively.

[0071] According to the aspect 3, when the button is sunk into the inner wall of the well (the inner wall of the housing), deformation is suppressed, and excellent fixation is exhibited.

[0072] The downhole tool fixing device (slips 106a, 106b) of the present application according to the aspect 4 is the aspect 1 to 3, preferably, the main body is composed of a reactive metal dissolved by a prescribed solvent, and the button includes a molded body of a powder metallurgical material of iron.

[0073] The fracturing plug 100 of the present application according to the aspect 5 has the above-described downhole tool fixing device (slips 106a, 106b).

[0074] According to the aspect 5, a fracturing plug having a downhole tool fixing device having excellent fixation, pressure resistance, and fracturing properties can be achieved.

[0075] Examples

[0076] The button attached to the chuck according to the present embodiment will be described using examples below.

[0077] [Manufacturing method of button]

[0078] (Example 1)

[0079] The button 602 shown in FIG. 6 was manufactured as follows: A powder metallurgical material (1) having the composition shown in Table 1 was used, the material charge and the compression amount were adjusted to set the density to a prescribed value, and surface hardening was performed by heat treatment. Figure 5

[0080] (Example 2)

[0081] The button 602 shown in FIG. 6 was manufactured as follows: A powder metallurgical material (2) having the composition shown in Table 1 was used, the material charge and the compression amount were adjusted to set the density to a prescribed value, Figure 5

[0082] surface hardening was performed by heat treatment.

[0083] [Table 1]

[0084] Composition [%]

[0085] Material Fe C Cu Mn Mo Ni Cr Others Example 1 Powder metallurgical material (1) remainder 0.1～0.5 1～3 0.05～0.45 0.2～0.6 - - less than 1 Example 2 Powder metallurgical material (2) remainder 0.2～0.6 1～3 - 0.2～0.7 3～5 - less than 1

[0086] (Comparative Examples 1, 2)

[0087] As comparative examples, an extruded material of tool steel (SKD11) was machined into the shape of a button, and heat treatment was performed to manufacture a button.

[0088] (Comparative Example 3)

[0089] An extruded material of structural alloy steel (SCM415) was used instead of the extruded material of tool steel (SKD11), the heat treatment conditions were set to conditions in which surface hardening occurs, and otherwise, the button was manufactured in the same manner as in Comparative Examples 1 and 2.

[0090] The composition of the buttons of Comparative Examples 1 to 3 is summarized in Table 2.

[0091]

[0092] (Comparative Examples 4, 5)

[0093] As comparative examples, a powder metallurgical material (3) having the composition shown in Table 3 was used, the material charge and the compression amount were adjusted to set the density to a prescribed value, and surface hardening was performed by heat treatment to manufacture a button.

[0094] [Table 3]

[0095] Composition [%]​​​

[0096] Material Fe C Cu Mn Mo Ni Cr Others Comparative examples 4, 5 Powder metallurgical material (3) remainder 0.2～0.8 1～2 - 0.2～0.7 3～5 - less than 1

[0097] (Comparative Example 6)

[0098] As a comparative example, a molded body of yttria-based zirconia (1) was used as a button.

[0099] (Comparative Example 7)

[0100] As a comparative example, a molded body of magnesium oxide-based zirconia was used as a button.

[0101] (Comparative Example 8)

[0102] As a comparative example, a molded body of yttria-based zirconia (2) was used as a button.

[0103] The compositions of the buttons of Comparative Examples 6 to 8 are summarized in Table 4.

[0104]

[0105] (2) Measurement method of each property

[0106] Each property of the buttons manufactured by the above-mentioned manufacturing method was measured as described below.

[0107] <Hardness measurement>

[0108] The hardness of the surface of the button was measured as described below. After polishing the upper surface of the cylindrical button to be smooth, the indenter of a micro Vickers hardness tester (Vickers hardness tester HV-114 manufactured by Mitutoyo Corporation) was pushed against the surface at room temperature with a load of 50 kgf, and the hardness was calculated from the diagonal length of the indentation and the test load. As for the hardness of the core layer, the button was cut in the vertical direction with respect to the axial direction of the cylindrical button, and after polishing the cut surface to be smooth, the hardness of the central portion of the cut surface was measured by the same method as the surface hardness described above. As for the Rockwell hardness (HRC), the Vickers hardness obtained by the above-mentioned method was converted according to ASTM E 140 Table 2.

[0109] <Density measurement (apparent density)>

[0110] The weight of the button in air at 23°C and the weight of the button in ion-exchange water were measured, and from the obtained weights and the density of the ion-exchange water, the apparent density was calculated according to the Archimedes principle.

[0111] <Compression test>

[0112] Two tungsten carbide plates were clamped together with the bottom and top surfaces of a cylindrical button in contact. Uniaxial compression was performed on the button at a compression rate of 2 mm / min at room temperature, yielding a strain-stress curve. The compressive modulus was calculated within the range where stress changes linearly with respect to strain. As the button cracked under compression, the point showing the maximum value was taken as the compressive strength. The toughness was calculated by integrating the strain-stress curve over the range up to the strain at which cracking occurred.

[0113] Compositional Analysis (Ceramics)

[0114] The elemental composition of the ceramic button was determined by X-ray fluorescence (XRF) analysis. The fundamental parameter (FP) method was used to convert the XRF peak intensities of each element into concentration ratios based on the measurement results.

[0115] Installation test (installation capability test)

[0116] Fracturing plug 100 equipped with Kassard 106a and 106b was prepared. Figure 1 The mandrel 101 uses polyglycolic acid (PGA). The elastic member 102 uses polyurethane. The retaining member 103 uses PGA. The cone 104 uses PGA, the cone 105 uses magnesium alloy, and in a pair of slips 106a and 106b, the slip base 601 ( Figure 3 Magnesium alloy was used, and button 602 used the button described in "(1) Method of manufacturing button" above. A pair of ring members 107a, 107b used PGA.

[0117] After the fracturing plug is placed inside the housing (steel pipe), a compressive load of 150 kN is applied to the components, including slips 106a and 106b, located on the side of the mandrel 101, so that the components including slips 106a and 106b come into contact with the housing (steel pipe). The evaluation is "0" if the fracturing plug is fixed to the steel pipe, and "×" if the fracturing plug is detached.

[0118] <Water pressure resistance test (test for water pressure resistance)>

[0119] In the method described in the above <installation test>, after fixing the fracturing plug to the steel pipe, the steel pipe is heated to a temperature of 200 deg F while water is enclosed in the steel pipe. After the enclosure, the fracturing plug is subjected to a water pressure of 10,000 psi (about 70 MPa) by a pump, and whether the fracturing plug can maintain the water pressure for 30 minutes or more is investigated. If the fracturing plug maintains the water pressure for 30 minutes or more, it is evaluated as "O", in the case where the position of the member including the slips 106a, 106b at the time of installation to the steel pipe moves 10 mm or more after the water pressure application in addition to maintaining the water pressure for 30 minutes or more, it is evaluated as "Δ", and in the case where the fixing member is broken and cannot maintain the water pressure for 30 minutes or more, it is evaluated as "X".

[0120] [Properties of the button]

[0121] The respective properties of the buttons and the fracturing plugs of the above-described Examples 1 to 3 and Comparative Examples 1 to 8 are summarized in Table 5.

[0122]

[0123] As shown in Table 5, the buttons of Example 1 and Example 2 showed good installation property and water pressure resistance. On the other hand, Comparative Examples 4 to 8 all showed insufficient installation property or water pressure resistance.

[0124] In addition, the buttons of Example 1 and Example 2 are powder metallurgy materials in the range of 0.23 GJ / m 3 or more and 1.0 GJ / m 3 or less in toughness, and 6.7 g / cm 3 or more and 7.2 g / cm 3 or less in apparent density. The buttons of Example 1 and Example 2 showed good destructiveness of the buttons after the hydraulic fracturing.

[0125] On the other hand, the toughness of Comparative Examples 1 to 3 exceeds 1.0 GJ / m 3 , and thus showed insufficient fracturing property.

[0126] Symbol explanation

[0127] 101: mandrel;

[0128] 100: fracturing plug (downhole tool);

[0129] 102: elastic member;

[0130] 103: retaining member;

[0131] 104, 105: cone;

[0132] 106a, 106b: slip (downhole tool fixing device);

[0133] 200: housing

[0134] 601: chuck base (main body portion)

[0135] 601a: outer peripheral surface (surface of main body portion)

[0136] 601b: recess

[0137] 602: button

Claims

1. A downhole tool fixing device, the downhole tool fixing device being used to fix a downhole tool to a housing inside a pit. The downhole tool fixing device includes: Main body; and The button is mounted on the main body in a manner that protrudes from the surface of the main body. The button comprises a molded body of powder metallurgy material. The button has a compressive modulus of at least 13.5 GPa and a toughness of 0.23 GJ / m. 3 Above 1.0 GJ / m 3 the following.

2. The downhole tool fixing device according to claim 1, wherein, The apparent density of the button is 6.7 g / cm³. 3 Above and 7.2g / cm 3 the following.

3. The downhole tool fixing device according to claim 1, wherein, The button consists of a surface and a core. The Rockwell hardness (HRC) of the surface and the core are both above 20 and below 45.

4. The downhole tool fixing device according to claim 1, wherein, The main body is composed of a reactive metal that can be dissolved in a specified solvent. The button comprises a molded body of iron powder metallurgy material.

5. A fracturing plug, the fracturing plug comprising the downhole tool securing device as described in claim 1.

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