A downhole ball-dropping reaming tool

Abstract

The present invention discloses a downhole ball-dropping reaming tool, comprising a reamer subsection and a ball-receiving subsection connected above the reamer subsection; the ball-receiving subsection comprises an outer shell, a limiting cylinder, a ball claw, an activating ball, a spring seat, and a first elastic member; the spring seat is located below the ball claw, and the bottom of the ball claw is divided into petals; the limiting cylinder comprises a small-diameter portion and a large-diameter portion distributed in an upper and lower manner, and a plurality of flow grooves for connecting the inside of the small-diameter portion and the large-diameter portion; the inner diameter of the small-diameter portion is smaller than the outer diameter of the ball claw in a natural state, and the inner diameter of the large-diameter portion is greater than or equal to the outer diameter of the ball claw in a natural state. The present invention is used to solve the problem in the prior art that ball-dropping reaming tools cannot be installed close to the drill bit due to the influence of existing channels in the drill string, and to achieve the purpose of enabling ball-dropping reaming tools to be installed close to the drill bit, thereby reducing the length of the section at the bottom of the well that cannot be reamed and reducing the number of drilling trips.

Description

Technical Field

[0001] The invention relates to the field of drilling and completion operations, and in particular to a downhole ball-dropping excitation reaming tool. Background Art

[0002] In the drilling and completion operations of oil and gas development projects, a commonly used technology for reaming tools is to release a ball from the drill table to hold down pressure and shear pins, triggering the extension of the blades of the hydraulic reaming tool. This technology has advantages such as reliable structure, stable operation, and a clear activation signal. However, the ball-dropping structure of the existing technology is affected by existing channels within the drill string, such as screw drills, rotary steerable drills, logging instruments such as MWD and LWD, trays within the drill string, and internal blowout preventers. The activation ball cannot pass through these tools, resulting in the reaming tool being unable to be installed below these tools or instruments in the bottomhole assembly (BHA). For example, it cannot be used in a drill string assembly consisting of a "drill bit-reamer-screw-drill pipe". This further limits the use of the reaming tool and prevents it from being installed close to the drill bit for operation. This results in a long section of the wellbore where reaming operations cannot be completed, which is not conducive to the smooth placement of subsequent casing / screens or completion strings.

[0003] In order to reduce the length of the section at the bottom of the well that cannot be expanded in the existing technology, it is generally necessary to circulate the well until the wellbore is stable and unobstructed after the drilling operation is completed, and then pull out the drill to replace the special bottom drill assembly without power (without screw drilling tools or rotary steerable drilling tools) and without downhole logging instruments. This will inevitably lead to a large number of trips and drills, which has an adverse impact on saving construction time and ensuring underground safety. Summary of the Invention

[0004] The present invention provides a downhole ball-actuated reaming tool to solve the problem in the prior art that the ball-actuated reaming tool cannot be installed close to the drill bit due to the influence of existing channels in the drill string. The ball-actuated reaming tool can also be installed close to the drill bit, thereby reducing the length of the section at the bottom of the well that cannot be reamed and reducing the number of drilling trips.

[0005] The present invention is achieved through the following technical solutions:

[0006] A downhole ball-dropping reaming tool includes a reamer sub and a ball-receiving sub connected above the reamer sub; the ball-receiving sub includes a housing, a retaining cylinder fixedly connected to the interior of the housing, a ball claw axially slidingly engaged with the retaining cylinder, an activating ball placed in the ball claw, a spring seat axially slidingly engaged with the housing, and a first elastic member abutting below the spring seat.

[0007] The spring seat is located below the ball claw, the bottom of the ball claw is divided into petals, and the side of the ball claw is provided with an upper bypass hole and a lower bypass hole;

[0008] The limiting cylinder includes a small diameter portion and a large diameter portion distributed in the upper and lower parts, and a plurality of flow grooves for connecting the small diameter portion and the large diameter portion; the inner diameter of the small diameter portion is smaller than the outer diameter of the ball claw in the natural state, and the inner diameter of the large diameter portion is greater than or equal to the outer diameter of the ball claw in the natural state;

[0009] When the bottom of the ball claw is located in the small-diameter portion, the inner diameter of the bottom of the ball claw is smaller than the diameter of the excitation ball, and the two ends of the flow groove are connected to the upper bypass hole and the lower bypass hole respectively;

[0010] When the bottom of the ball claw is located in the large-diameter portion, the inner diameter of the bottom of the ball claw is greater than the diameter of the excitation ball.

[0011] In order to solve the problem in the prior art that the ball-activated reaming tool cannot be installed close to the drill bit due to the influence of the existing channels in the drill string, the present invention proposes a downhole ball-activated reaming tool, wherein the reamer short section can be implemented by the ball-activated reamer short section in the prior art. The present application realizes the downhole ball-dropping function by using a ball-containing short section, and a limiting cylinder is provided in the outer shell of the ball-containing short section. A ball claw is slidably fitted in the limiting cylinder, and the activating ball is placed in the ball claw in advance. In addition, considering that the present application belongs to a reaming tool while drilling, it is necessary to ensure the normal flow of drilling and completion fluid in the tubing string. Therefore, upper bypass holes and lower bypass holes distributed in the upper and lower sides of the ball claw are also provided, and a flow groove is provided in the limiting cylinder.

[0012] In the normal state when the pump is not running, the elastic force of the first elastic member pushes the spring seat upward, causing the top of the spring seat to abut the bottom of the ball claw. At this time, the bottom of the ball claw is located within the small diameter portion of the retaining cylinder. The split ball claw cannot open, and the trigger ball is trapped inside the ball claw and cannot be released downward. At this time, the drilling and completion fluid enters the upper bypass hole, the flow trough, and the lower bypass hole in sequence, achieving normal downward flow.

[0013] During normal pump drilling or circulation, the mud pump displacement is lower than the set displacement (i.e., the lowest displacement at which the excitation ball can be released). The ball claw drives the excitation ball to compress the spring seat and move downward a certain distance together. The spring seat appropriately compresses the first elastic member, but at this time the ball claw still does not reach the large diameter part of the limit cylinder. Limited by the inner hole of the small diameter part of the limit cylinder, the petal-type ball claw still cannot open and the excitation ball still cannot be released.

[0014] When it is necessary to throw a ball to stimulate the short section of the reamer below, the mud pump is controlled from the drilling platform to provide a short-term large displacement that exceeds the aforementioned set displacement. Under the action of this short-term large displacement, the ball claw drives the excitation ball to continue to push the spring seat downward, and the spring seat compresses the first elastic member to a shorter state, so that the ball claw moves downward with a larger stroke until the bottom of the ball claw reaches the large diameter part. At this time, the petal structure at the bottom of the ball claw gets rid of the size restriction of the small diameter part, the bottom of the ball claw naturally opens outward, and the excitation ball is automatically released, thus completing the downhole ball throwing function.

[0015] It can be seen that when the present application is used in practice, it is only necessary to preset the preload force of the first elastic member in advance so that the set displacement required for ball throwing is significantly higher than the displacement during normal operation. The present application abandons the idea of ​​prior art that ball throwing needs to be performed at the wellhead, and adopts an automatic ball throwing operation method downhole. The entire ball throwing process is not affected by existing channels in the drill string such as screw drill tools, rotary guide drill tools, MWD, LWD, and internal blowout preventers, thereby solving the problem that the ball-throwing-activated reaming tool in the prior art cannot be installed close to the drill bit, and realizes the installation of the ball-throwing-activated reaming tool close to the drill bit, thereby reducing the length of the bottom hole section that cannot be reamed, and can realize reaming while drilling the bottom hole area, reduce the number of drilling trips, improve engineering efficiency, and ensure downhole safety.

[0016] It should be noted that the petal structure at the bottom of the ball claw in this application has an outer diameter that is at least larger than the inner diameter of the small diameter portion in its natural state, thereby ensuring that the bottom of the ball claw is always in an inwardly compressed state when it is located in the small diameter portion, and can automatically open when the bottom of the ball claw enters the large diameter portion.

[0017] Those skilled in the art should understand that the terms "up" and "down" in this application refer to the direction toward the bottom of the well after the reaming tool enters the well as the direction toward the wellhead as down, and the direction toward the wellhead as up.

[0018] Furthermore, the small diameter portion includes a plurality of ridges uniformly distributed along the circumference of the inner wall of the limiting cylinder, and a flow groove is formed between two adjacent ridges; and a transition portion with a gradually decreasing thickness is provided at the bottom of the ridges.

[0019] When installing the ball claw, each petal on the bottom of this solution faces at least one ridge, allowing the ball claw to be squeezed into place by the reduced diameter of the ridge. Furthermore, the transition section can be formed into a sloped structure to facilitate smooth opening and resetting of the ball claw, reducing the risk of jamming and ensuring stability during pitching.

[0020] Furthermore, the shell includes an upper shell of the ball-containing short joint and a lower shell of the ball-containing short joint connected at the upper and lower parts; the ball claw is slidably fitted in the upper shell of the ball-containing short joint, and a step surface is provided in the lower shell of the ball-containing short joint, and the bottom end of the first elastic member abuts against the step surface.

[0021] In this solution, the housing of the ball sub is designed as a two-stage structure, making it easy to open the sub to install the trigger ball and initialize the ball claw before the tool is placed in the well. A stepped surface within the lower housing prevents the first elastic member from extending downward, thereby ensuring a stable upward thrust on the spring seat and ball claw.

[0022] Furthermore, the reamer sub includes a reamer housing, blades connected to the reamer housing, a ball seat located inside the reamer housing and axially slidably connected, and a driving mechanism for driving the blades to open; the ball seat matches the excitation ball.

[0023] Those skilled in the art should understand that after the excitation ball self-contained short section is dropped, it moves downward to the ball seat under the action of gravity and drilling fluid, the excitation ball blocks the ball seat and moves downward with the ball seat, and the internal pressure of the tool is used to start the drive mechanism and realize the opening of the blade.

[0024] Furthermore, an upper end cover and a lower end cover are fixedly connected to the interior of the reamer housing;

[0025] The driving mechanism includes a spindle slidably connected to the inside of the reamer housing in the axial direction, a rack portion located on the spindle, and a gear portion located on the blade, wherein the gear portion is engaged with the rack portion; the driving mechanism also includes a second elastic member acting between the spindle and the reamer housing, and the second elastic member is used to apply an axial upward thrust to the spindle.

[0026] In this solution, the upper end cover is used to provide a limit for the spindle at the upper end. When the excitation ball blocks the ball seat and moves downward with the ball seat, due to the pressure drop of the drilling fluid inside the tool, the pressure difference between the upper and lower ends of the spindle is used to drive the spindle to compress the second elastic member and move downward, and then the gear portion on the blade is driven to rotate through the rack portion on the spindle, so that the blade rotates synchronously and the blade resting on the surface of the reamer shell is turned outward to open the blade. In addition, as long as the pump is kept on, there will always be a pressure difference between the upper and lower ends of the spindle, so that the blade can be kept in an open state; until the pump is stopped, the pressure difference between the upper and lower ends of the spindle disappears, and the spindle moves upward under the action of the second elastic member and resets to abut against the upper end cover. In this process, the blade is retracted by the gear rack structure.

[0027] The gear section in this solution can be a complete or incomplete gear structure, as long as it cooperates with the rack section to enable the blades to be opened and retracted. As can be seen, the underreamer sub provided in this solution can retract the blades after the pump is stopped, and can be forcibly retracted during upward drilling, significantly reducing the difficulty of drilling and the number of trips, thereby further ensuring the safety of drilling and completion operations.

[0028] Furthermore, a shear pin is connected between the ball seat and the lower end cover, and the ball seat has an axial downward stroke; it also includes a guide seat fixedly connected to the inside of the reamer housing, and the guide seat is used to limit the axial downward movement of the ball seat; when the ball seat moves to the bottom end of the stroke, the ball seat and the guide seat are axially abutted.

[0029] When the excitation ball reaches the ball seat, it blocks the fluid channel inside the ball seat, and the pressure inside the tool begins to build up until the shear pin is cut off. The ball seat and the excitation ball move downward together until the ball seat abuts against the guide seat, and the fluid channel is re-established.

[0030] Furthermore, a ball seat bypass hole is opened on the side of the ball seat, and an expanded diameter portion is arranged inside the guide seat; when the ball seat moves to the bottom end of the stroke, the ball seat bypass hole is connected to the expanded diameter portion.

[0031] In this solution, the ball seat moves to the bottom of the stroke and abuts against the guide seat. At this time, the bypass hole of the ball seat is connected to the expanded diameter part. The drilling and completion fluid can enter the expanded diameter part through the bypass hole of the ball seat and flow downward through the guide seat to re-establish the fluid channel.

[0032] Furthermore, a diversion hole is provided on the side of the lower end cover, a diversion channel is provided on the side of the reamer shell, and a nozzle is installed in the diversion channel; the spray direction of the nozzle is toward the area after the blade is opened.

[0033] In the prior art, when the reamer blades are operating, they can only be cleaned and cooled by drilling and completion fluid returning from the annulus. However, the flow of drilling fluid returning from the annulus is relatively stable and contains a large amount of rock debris, resulting in limited flushing effect and a high risk of mud packing on the blades. In this application, since the blades have the ability to retract, mud packing will seriously interfere with the blade retraction function. To overcome this problem, this solution provides a diversion hole on the side of the lower end cover, a diversion channel on the side of the reamer housing, and a nozzle. When the mandrel is in the initial state, the diversion hole is blocked by the mandrel; when the mandrel moves downward to the end of the stroke, the diversion hole is opened, and part of the drilling and completion fluid enters the diversion hole and is ejected outward through the nozzle of the diversion channel. The ejected drilling and completion fluid flushes and cools the blade; because the ejected drilling and completion fluid is still in a state of not being contaminated by the formation, it has a better ability to disperse and dissolve the rock cuttings attached to the blade, which is beneficial to reducing the risk of mud packing on the blade; and the ejected drilling and completion fluid and the drilling and completion fluid normally returned from the annulus mix with each other at the blade to form a complex turbulence, which can further improve the heat dissipation and cleaning effect of the blade, and is more conducive to ensuring the stable recovery of the blade of this application. In addition, a significant pressure drop will be formed at the diversion hole inside the tool, making the pressure difference between the upper and lower ends of the mandrel larger, which is more conducive to ensuring that the mandrel can stably compress the second elastomer and ensure the stability of the open state of the blade.

[0034] Furthermore, the diversion hole and the diversion channel are both located below the blade; the diversion channel is gradually inclined upward from the inside to the outside along the radial direction; and the nozzle is detachably connected in the diversion channel.

[0035] By defining the position and direction of the diversion channel in this solution, the fluid ejected from the nozzle also has an initial upward motion within the annulus, which facilitates flushing of the blades and allows for rapid mixing with the drilling and completion fluid returning from the annulus, thus avoiding unnecessary energy loss and allowing more of the fluid's kinetic energy to act on the blades. The nozzles in this solution can be replaced according to specific operating conditions, further facilitating flexible adaptation to the required pressure drop of the mandrel.

[0036] Furthermore, it also includes a pressure drop matching short section connected below the reamer short section, and a throttle nozzle is detachably connected to the pressure drop matching short section.

[0037] In the prior art, when using a reaming while drilling tool, it is necessary to match the nozzle of the reaming tool with the nozzle of the drill bit according to the displacement and density of the drilling fluid, so that the throttling pressure drop reaches the pressure drop at which the blades of the reaming tool can extend normally. In order to meet the required pressure drop, it is often necessary to replace the drill bit nozzle (usually replacing a smaller nozzle or blocking part of the nozzle). Since the drill bit nozzle standards used by different companies are not unified (the nozzle threads are different), and some drill bits even use dead nozzles that cannot be replaced, it is very difficult to match the pressure drop on site, or even fail to meet the matching requirements.

[0038] To overcome these drawbacks, this solution incorporates a pressure-drop matching nipple below the reamer. By incorporating a throttle nozzle into the nipple, this replaces the traditional drill nozzle replacement method, achieving a throttling effect equivalent to that of replacing the drill nozzle. This avoids the difficulty or even inability to replace the drill nozzle. Furthermore, the throttle nozzle in this solution maintains a stable pressure differential between the upper and lower ends of the mandrel, thereby ensuring stable maneuverability.

[0039] The specific model and type of the throttle in this solution can be selected by calculating the pressure drop matching based on the displacement of normal drilling or reaming operations before the tool is put into the well. The throttle can be flexibly replaced according to different working conditions to achieve matching with different pressure drop requirements.

[0040] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0041] 1. The present invention discloses a downhole ball-dropping reaming tool, which abandons the conventional method of dropping balls at the wellhead and adopts an automatic downhole ball-dropping operation method. The entire ball-dropping process is not affected by existing channels in the drill string, such as screw drills, rotary steerable drills, MWDs, LWDs, and internal blowout preventers. This solves the problem in the prior art that ball-dropping reaming tools cannot be installed close to the drill bit, and enables the ball-dropping reaming tool to be installed close to the drill bit, thereby reducing the length of the bottom hole section where reaming is not possible. In addition, the downhole reaming can be achieved while drilling in the bottom hole area, reducing the number of trips, improving engineering efficiency, and ensuring downhole safety.

[0042] 2. The present invention provides a downhole ball-dropping reaming tool. The reamer sub provided can recycle the blades after the pump is stopped, thereby reducing the difficulty of drilling and the number of drilling trips, and is more conducive to ensuring the safety of drilling and completion projects.

[0043] 3. The downhole ball-dropping reaming tool of the present invention is beneficial to reducing the risk of blade mud packing, improving the heat dissipation and cleaning effect of the blade, and is more conducive to ensuring the stable recovery of the blade.

[0044] 4. The present invention provides a downhole ball-dropping reaming tool, which replaces the traditional method of replacing the drill bit nozzle by setting a throttle nozzle in a pressure drop matching short section, thereby achieving a throttling effect equivalent to replacing the drill bit nozzle, thereby overcoming the problem that the drill bit nozzle is difficult or even impossible to replace. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] The drawings described herein are used to provide a further understanding of the embodiments of the present invention, constitute a part of this application, and do not constitute a limitation of the embodiments of the present invention. In the drawings:

[0046] Figure 1 This is a schematic diagram of the initial state of a specific embodiment of the present invention;

[0047] Figure 2 A quarter-section axonometric view of the limiting cylinder in a specific embodiment of the present invention;

[0048] Figure 3 for Figure 1 A partial enlarged view of point A in the middle;

[0049] Figure 4 Schematic diagram of the pitching process in the ball-containing short section in a specific embodiment of the present invention;

[0050] Figure 5 for Figure 1 A partial enlarged view of point B in the middle;

[0051] Figure 6 for Figure 1 A partial enlarged view of point C in the middle;

[0052] Figure 7 This is a schematic diagram of the eye expansion state after being activated according to a specific embodiment of the present invention;

[0053] Figure 8 for Figure 7 A partial enlarged view of point D in the middle;

[0054] Figure 9 This is a schematic diagram of a specific embodiment of the present invention after the pump is stopped by pitching.

[0055] Markings and corresponding parts names in the accompanying drawings:

[0056] 111- upper shell of ball-containing short joint, 112- ball claw, 1121- upper bypass hole, 1122- lower bypass hole, 113- excitation ball, 114- limiting cylinder, 1141- transition part, 1142- large diameter part, 1143- small diameter part, 115- spring seat, 116- first elastic member, 117- lower shell of ball-containing short joint, 118- reamer shell, 119- upper end cover, 120- spindle sealing ring, 121- second elastic member, 122- spindle, 1231- rack part, 1232- gear part, 124- pin shaft, 125 -blade, 126-lower end cover sealing ring I, 127-lower end cover sealing ring II, 128-nozzle, 129-ball seat diverter hole sealing ring, 130-lower end cover sealing ring III, 131-lower end cover, 132-ball seat, 133-shear pin, 134-set screw, 135-guide seat, 1351-expanded diameter part, 136-guide seat sealing ring, 137-hole retaining ring, 138-throttle nozzle sealing ring, 139-throttle nozzle, 140-pressure drop matching short section, 311-flow groove, 312-diverter hole, 313-ball seat bypass hole. DETAILED DESCRIPTION

[0057] In order to make the objects, technical solutions and advantages of the present invention more clear, the present invention is further described in detail below in conjunction with the examples and drawings. The schematic embodiments of the present invention and their description are only used to explain the present invention and are not intended to limit the present invention. In the description of this application, it should be understood that the orientations or positional relationships indicated by terms such as "front", "back", "left", "right", "up", "down", "vertical", "horizontal", "high", "low", "inside", "outside", etc. are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the scope of protection of this application.

[0058] Example 1:

[0059] like Figures 1 to 4The downhole ball-dropping reaming tool shown includes a reamer sub and a ball-receiving sub connected above the reamer sub; the ball-receiving sub includes an outer shell, a retaining cylinder 114 fixedly connected to the interior of the outer shell, a ball claw 112 axially slidingly engaged with the retaining cylinder 114, an activating ball 113 placed in the ball claw 112, a spring seat 115 axially slidingly engaged with the outer shell, and a first elastic member 116 abutting against below the spring seat 115; the first elastic member 116 is preferably a spring.

[0060] The spring seat 115 is located below the ball claw 112. The bottom of the ball claw 112 is divided into petals. An upper bypass hole 1121 and a lower bypass hole 1122 are formed on the side of the ball claw 112.

[0061] The limiting cylinder 114 includes a small-diameter portion 1143 and a large-diameter portion 1142, which are distributed in the upper and lower parts, and a plurality of flow grooves 311 for connecting the small-diameter portion 1143 and the large-diameter portion 1142. The inner diameter of the small-diameter portion 1143 is smaller than the outer diameter of the ball claw 112 in its natural state, and the inner diameter of the large-diameter portion 1142 is greater than or equal to the outer diameter of the ball claw 112 in its natural state.

[0062] When the bottom of the ball claw 112 is located in the small-diameter portion 1143 , the inner diameter of the bottom of the ball claw 112 is smaller than the diameter of the excitation ball 113 , and the two ends of the flow groove 311 are connected to the upper bypass hole 1121 and the lower bypass hole 1122 respectively;

[0063] When the bottom of the ball claw 112 is located in the large-diameter portion 1142 , the inner diameter of the bottom of the ball claw 112 is greater than the diameter of the excitation ball 113 .

[0064] The structure of the limiting cylinder 114 in this embodiment is as follows Figure 2 As shown, the small diameter portion 1143 includes a plurality of ridges uniformly distributed along the circumference of the inner wall of the limiting cylinder 114, and a flow groove 311 is formed between two adjacent ridges; a transition portion 1141 with a gradually decreasing thickness is provided at the bottom of the ridges.

[0065] like Figure 3 and Figure 4 As shown, the shell includes an upper shell 111 and a lower shell 117 of the ball-containing short joint that are connected at the upper and lower parts; the ball claw 112 is slidably fitted in the upper shell 111 of the ball-containing short joint, and a step surface is provided in the lower shell 117 of the ball-containing short joint, and the bottom end of the first elastic member 116 abuts against the step surface.

[0066] Those skilled in the art should understand that Figure 3 and Figure 4 The directions of the arrows in the diagram represent the flow directions of the drilling and completion fluid in the tool.

[0067] Example 2:

[0068] A downhole ball-casting reaming tool. Based on Example 1, this example improves and optimizes the reamer sub. Figures 1 to 9 As shown, the reamer sub includes a reamer housing 118, blades 125 connected to the reamer housing 118, a ball seat 132 located inside the reamer housing 118 and axially slidably connected thereto, and a driving mechanism for driving the blades 125 to open; the ball seat 132 matches the excitation ball 113.

[0069] The reamer housing 118 is fixedly connected to an upper end cover 119 and a lower end cover 131;

[0070] The driving mechanism includes a spindle 122 axially connected to the inside of the reamer housing 118, a rack portion 1231 located on the spindle 122, and a gear portion 1232 located on the blade 125, wherein the gear portion 1232 is engaged with the rack portion 1231; the driving mechanism also includes a second elastic member 121 acting between the spindle 122 and the reamer housing 118, and the second elastic member 121 is used to apply an axial upward thrust to the spindle 122; the second elastic member 121 is preferably a spring.

[0071] A shear pin 133 is connected between the ball seat 132 and the lower end cap 131. In its initial state, the ball seat 132 has an axially downward stroke. The ball seat 132 also includes a guide seat 135 fixedly connected to the interior of the reamer housing 118. The guide seat 135 is used to limit the axial downward movement of the ball seat 132. When the ball seat 132 reaches the bottom of its stroke, it axially abuts against the guide seat 135, preventing it from further downward movement.

[0072] A ball seat bypass hole 313 is provided on the side of the ball seat 132 , and an expanded diameter portion 1351 is provided inside the guide seat 135 ; when the ball seat 132 moves to the bottom end of the stroke, the ball seat bypass hole 313 is communicated with the expanded diameter portion 1351 .

[0073] A diversion hole 312 is provided on the side of the lower end cover 131 , and a diversion channel is provided on the side of the reamer housing 118 . A nozzle 128 is installed in the diversion channel. The spray direction of the nozzle 128 is toward the area after the blade 125 is opened.

[0074] The diversion hole 312 and the diversion channel are both located below the blade 125; the diversion channel is gradually inclined upward from the inside to the outside along the radial direction; and the nozzle 128 is detachably connected to the diversion channel.

[0075] The apparatus further comprises a pressure drop matching subsection 140 connected below the reamer subsection, wherein a throttle nozzle 139 is detachably connected to the pressure drop matching subsection 140 .

[0076] In this embodiment, a notch is formed on the surface of the reamer housing 118 for mounting the blade 125 . The blade 125 is hinged in the notch via a pin 124 , and the radially inward side of the notch is closed by a spindle 122 to prevent fluid leakage.

[0077] In this embodiment, a groove for mounting the second elastic member 121 is defined on the inner side wall of the reamer housing 118 . The top end of the spindle 122 has a stepped surface matching the groove, and the second elastic member 121 abuts against the stepped surface.

[0078] In a more preferred embodiment, in a cross section perpendicular to the axis of the tool, the surface area of ​​the upper end of the mandrel is larger than the surface area of ​​the lower end of the mandrel. This arrangement can make the pressure difference between the upper and lower ends of the mandrel 122 larger, which is more conducive to the automatic downward movement of the mandrel after the pressure drop occurs.

[0079] In a more preferred embodiment, the spindle 122 and the reamer housing 118 are sealed by a spindle sealing ring 120; the lower end cover 131 above the diverter channel and the reamer housing 118 are sealed by a lower end cover sealing ring I 126; the lower end cover 131 below the diverter channel and the reamer housing 118 are sealed by a lower end cover sealing ring III 130; the lower end cover 131 and the spindle 122 are sealed by a lower end cover sealing ring II 127; the ball seats 132 at the upper and lower ends of the diverter hole 312 and the lower end cover 131 are sealed by ball seat diverter hole sealing rings 129; the ball seat 132 and the guide seat 135 are sealed by a guide seat sealing ring 136; and the throttle nozzle 139 and the pressure drop matching short section 140 are sealed by a throttle nozzle sealing ring 138.

[0080] In a more preferred embodiment, the bottom end of the throttle nozzle 139 abuts against a dedicated step surface inside the pressure drop matching short section 140 , and the top end of the throttle nozzle 139 is installed in the hole inside the pressure drop matching short section 140 and is limited by a retaining ring 137 .

[0081] Example 3:

[0082] A method for stimulating a hole reaming tool by dropping a ball downhole is used to stimulate Figures 1 to 9 The reaming tools shown include:

[0083] In the initial state, the tool structure is as follows Figure 1 、 Figure 3 、 Figure 5 and Figure 6As shown: under the action of the first elastic member 116, the top of the spring seat 115 abuts against the bottom of the ball claw 112, and the top of the ball claw 112 abuts against the step surface corresponding to the inner wall of the upper shell 111 of the ball-containing short joint. The bottom of the ball claw 112 is located in the said small-diameter portion 1143, and the excitation ball 113 is located in the ball claw 112. The drilling and completion fluid enters the flow groove 311 and the lower bypass hole 1122 in sequence from the upper bypass hole 1121, and then continues to flow downward; under the action of the second elastic member 121, the core shaft 122 is located at the top of the stroke, and the blade 125 is in a retracted state; the ball seat 132 and the lower end cover 131 are kept in a connected state by the shear pin 133. At this time, the diverter hole 312 is blocked by the ball seat 132.

[0084] When the pump is turned on for normal drilling, reaming, circulation, and other operations, the mud pump displacement is lower than the set displacement, which is the minimum displacement at which the excitation ball can be released. At this time, the ball claw 112 drives the excitation ball 113 to compress the spring seat 115, and the spring seat 115 appropriately compresses the first elastic member 116. The ball claw 112 moves downward for a certain distance, but is limited by the small diameter portion 1143 of the limiting cylinder 114. The ball claw 112 cannot expand and the excitation ball 113 cannot be released. At this time, the central channel inside the ball-containing short section is still blocked by the excitation ball 113, and the fluid still needs to enter the flow groove 311 and the lower bypass hole 1122 from the upper bypass hole 1121 in sequence before continuing to flow downward.

[0085] When the ball is needed to excite, the mud pump is controlled to give an instantaneous large displacement exceeding the above-mentioned set displacement. After exceeding the set displacement, the ball claw 112 drives the excitation ball 113 to compress the spring seat 115. The spring seat 115 continues to compress the first elastic member 116, and the ball claw 112 moves downward with a larger stroke until the bottom of the ball claw 112 moves into the large diameter portion 1142 of the limit cylinder 114. The ball claw 112 automatically opens in this area, and the excitation ball 113 is released. Figure 4 As shown, the downhole ball throwing function is completed.

[0086] The excitation ball 113 continues to move downward until it lands on the ball seat 132. The central channel inside the ball seat 132 is blocked by the excitation ball 113. The pressure inside the tool rises rapidly, cutting off the shear pin 133. The ball seat 132 moves downward until it is limited by the guide seat 135. The diversion hole 312 of the lower end cover is opened. At this time, the state is as follows: Figure 7 and Figure 8As shown, a portion of the fluid enters the nozzle 128 through the diverter hole 312 and is ejected from the nozzle 128, while another portion of the fluid 403 enters the expanded diameter portion 1351 through the ball seat bypass hole 313 and continues to flow downward. After the diverter hole 312 is opened, the mandrel 122 moves axially downward under the action of the pressure differential, compressing the second elastic member 121. The linear motion of the rack portion 1231 drives the gear portion 1232 to rotate, converting the downward axial motion of the mandrel 122 into rotational motion of the blade 125 about the pin 124. Finally, the blade 125 is fully extended and is stopped by the corresponding step on the outer surface of the reamer housing 118, completing the activation of the reaming tool. At this point, the mud pump displacement can be reduced to the normal operating displacement, and normal reaming operations can be carried out.

[0087] When the reaming operation is completed, or the blade 125 needs to be retracted: the pump is stopped, the pressure difference at both ends of the spindle 122 disappears, the second elastic member 121 is reset, the spindle 122 is driven to move upward, the linear motion of the rack portion 1231 drives the gear portion 1232 to rotate, and the upward axial motion of the spindle 122 is converted into a rotational motion of the blade 125 around the pin 124. Finally, the blade 125 is completely retracted. At this time, the state is as follows Figure 9 shown.

[0088] The specific implementation methods described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific implementation method of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

[0089] It should be noted that, in this document, relational terms such as first and second, etc., are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "include", "comprises", or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, article, or device comprising a series of elements includes not only those elements, but also other elements not explicitly listed, or elements inherent to such process, method, article, or device. In addition, the term "connected" as used in this document, unless otherwise specified, may refer to a direct connection or an indirect connection via other components.

Claims

1. A downhole ball-dropping reaming tool, comprising a reamer sub, characterized in that: The invention also includes a ball-containing short section connected above the reamer short section; the ball-containing short section includes a housing, a limiting cylinder (114) fixedly connected to the interior of the housing, a ball claw (112) axially slidingly fitted in the limiting cylinder (114), an excitation ball (113) placed in the ball claw (112), a spring seat (115) axially slidingly fitted in the housing, and a first elastic member (116) abutting against the bottom of the spring seat (115); The spring seat (115) is located below the ball claw (112), the bottom of the ball claw (112) is divided into petals, and an upper bypass hole (1121) and a lower bypass hole (1122) are provided on the side of the ball claw (112); The limiting cylinder (114) includes a small-diameter portion (1143) and a large-diameter portion (1142) distributed in an upper and lower manner, and a plurality of flow grooves (311) for connecting the inside of the small-diameter portion (1143) and the large-diameter portion (1142); the inner diameter of the small-diameter portion (1143) is smaller than the outer diameter of the ball claw (112) in a natural state, and the inner diameter of the large-diameter portion (1142) is greater than or equal to the outer diameter of the ball claw (112) in a natural state; When the bottom of the ball claw (112) is located in the small-diameter portion (1143), the inner diameter of the bottom of the ball claw (112) is smaller than the diameter of the excitation ball (113), and the two ends of the flow groove (311) are respectively connected to the upper bypass hole (1121) and the lower bypass hole (1122); When the bottom of the ball claw (112) is located in the large diameter portion (1142), the inner diameter of the bottom of the ball claw (112) is greater than the diameter of the excitation ball (113).

2. A downhole ball-dropping reaming tool according to claim 1, characterized in that: The small diameter portion (1143) includes a plurality of ridges uniformly distributed along the circumference of the inner wall of the limiting cylinder (114), and a flow groove (311) is formed between two adjacent ridges; a transition portion (1141) with a gradually decreasing thickness is provided at the bottom of the ridges.

3. A downhole ball-dropping reaming tool according to claim 1, characterized in that: The housing comprises an upper ball-containing short joint shell (111) and a lower ball-containing short joint shell (117) connected to each other; the ball claw (112) is slidably fitted in the upper ball-containing short joint shell (111); a step surface is provided in the lower ball-containing short joint shell (117); and the bottom end of the first elastic member (116) abuts against the step surface.

4. A downhole ball-dropping reaming tool according to claim 1, characterized in that: The reamer sub comprises a reamer housing (118), blades (125) connected to the reamer housing (118), a ball seat (132) located inside the reamer housing (118) and connected in an axial sliding manner, and a driving mechanism for driving the blades (125) to open; the ball seat (132) matches the excitation ball (113).

5. A downhole ball-dropping reaming tool according to claim 4, characterized in that: An upper end cover (119) and a lower end cover (131) are fixedly connected inside the reamer housing (118); The driving mechanism comprises a spindle (122) axially slidably connected to the interior of the reamer housing (118), a rack portion (1231) located on the spindle (122), and a gear portion (1232) located on the blade (125), wherein the gear portion (1232) meshes with the rack portion (1231); the driving mechanism further comprises a second elastic member (121) acting between the spindle (122) and the reamer housing (118), wherein the second elastic member (121) is used to apply an axial upward thrust to the spindle (122).

6. A downhole ball-dropping reaming tool according to claim 5, characterized in that: A shear pin (133) is connected between the ball seat (132) and the lower end cover (131), and the ball seat (132) has an axially downward stroke; the ball seat (132) also includes a flow guide seat (135) fixedly connected to the inside of the reamer housing (118), and the flow guide seat (135) is used to limit the axial downward movement of the ball seat (132); when the ball seat (132) moves to the bottom of the stroke, the ball seat (132) and the flow guide seat (135) abut axially.

7. A downhole ball-dropping reaming tool according to claim 6, characterized in that: A ball seat bypass hole (313) is provided on the side of the ball seat (132), and an expanded diameter portion (1351) is provided inside the guide seat (135); when the ball seat (132) moves to the bottom end of the stroke, the ball seat bypass hole (313) is communicated with the expanded diameter portion (1351).

8. The downhole ball-dropping reaming tool according to claim 5, characterized in that: A diversion hole (312) is provided on the side of the lower end cover (131), and a diversion channel is provided on the side of the reamer housing (118). A nozzle (128) is installed in the diversion channel; the spraying direction of the nozzle (128) is toward the area after the blade (125) is opened.

9. A downhole ball-dropping reaming tool according to claim 8, characterized in that: The diversion hole (312) and the diversion channel are both located below the blade (125); the diversion channel is gradually inclined upward from the inside to the outside along the radial direction; and the nozzle (128) is detachably connected in the diversion channel.

10. A downhole ball-dropping reaming tool according to claim 5, characterized in that: The invention also comprises a pressure drop matching short section (140) connected below the reamer short section, wherein a throttle nozzle (139) is detachably connected to the pressure drop matching short section (140).

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