A downhole composite impact tool

Abstract

The application provides a downhole composite impact tool, which comprises a shell, a power spindle provided with a first central flow channel, a helical spline groove arranged on the inner wall of the power spindle, an output spindle provided with a second central flow channel, a helical spline arranged on the outer wall of the output spindle, and a cam mechanism comprising a cam fixedly sleeved on the output spindle and a follower at the upper end of the cam, wherein the upper end of the cam is configured as a continuous cam surface, the lower end of the follower is configured as a plane and provided with a plurality of circumferentially distributed rollers, and the rollers are in adaptive contact with the cam surface; wherein the power spindle can drive the output spindle to rotate, the follower can reciprocate along the axial direction under the action of the cam, and the upper drill string connected with the shell can be lifted, so that the upper drill string and the output spindle can form axial and circumferential composite impacts on the helical spline through the helical spline groove after moving to the highest point under the action of the drilling pressure, and the impacts are transmitted to the drill bit.

Description

Technical Field

[0001] This invention belongs to the field of oil and gas drilling engineering technology, and specifically relates to a downhole composite impact tool. Background Technology

[0002] With the development of oil exploration and development, the proportion of complex wells such as deep wells and horizontal wells is gradually increasing, posing new challenges to drilling speed improvement. Drilling speed improvement technology is an important topic in oil and gas well engineering. Existing drilling methods mainly achieve rock breaking through shearing and impact by the rotation of the drill bit. When the drill bit encounters hard formations, it is prone to stalling and jumping, requiring low rotation speed and low drilling pressure, which severely restricts the mechanical drilling rate. Existing PDC drill bits mainly break formations through cutting, shearing, and extrusion. During drilling, insufficient rock-breaking energy and stick-slip vibration are important reasons for the low mechanical drilling rate. When the PDC drill bit encounters hard formations, or when the drill bit penetrates too deeply, insufficient rock-breaking energy can cause the drill bit to stop rotating momentarily, leading to periodic stick-slip vibration, which damages the drill bit's life and seriously affects the mechanical drilling rate.

[0003] To effectively increase the mechanical rotational speed of PDC drill bits while suppressing stick-slip vibration, a common approach in existing technologies is to employ composite impact drilling tools. These tools consist of an axial impact unit and a torsional impact unit. In the axial impact unit, the axial hammer transfers impact energy to the PDC drill bit after completing its forward stroke, increasing the drilling depth. However, existing composite impact drilling tools tend to cause longitudinal vibration at the bottom of the drill string when the axial hammer enters its reverse stroke. This leads to low mechanical drilling efficiency and short tool life, limiting the speed-up effect in difficult-to-drill, hard formations. Furthermore, existing drilling speed-up tools have a high failure rate, short service life, and poor reliability. Summary of the Invention

[0004] To address the technical problems described above, this invention aims to provide a downhole composite impact tool that can generate axial and circumferential composite impact forces on the drill bit and can generate pressure pulses to act on the drill bit to form a further axial impact. In addition, the downhole composite impact tool can automatically adjust to the downhole working conditions to reduce the soil penetration depth when the drill bit torque is too high, thereby effectively preventing the downhole motor from sluggish.

[0005] Therefore, according to the present invention, a downhole composite impact tool is provided, comprising: a cylindrical housing; a power spindle for connecting a downhole power motor, the power spindle being concentrically arranged within the housing and rotatable relative to the housing, the power spindle having a first central flow channel and a helical spline groove extending axially on the inner wall surface of the power spindle; an output spindle for connecting a drill bit, the output spindle having a second central flow channel and a helical spline on the outer wall surface of the output spindle adapted to the helical spline groove; and a cam mechanism, comprising a cam fixedly mounted on the output spindle. The system comprises a cam and a follower located at the upper end of the cam. The upper end of the cam is constructed as a continuous cam surface, and the lower end of the follower is constructed as a plane and provided with multiple circumferentially distributed rollers. The rollers are adapted to contact the cam surface. The power spindle can drive the output spindle to rotate, and the follower can reciprocate axially under the action of the cam, and lift the upper drill string connected to the housing. After the upper drill string and the output spindle move to the highest point of their stroke, under the action of drilling pressure, they can form an axial and circumferential compound impact on the helical spline through the helical spline groove and transmit it to the drill bit.

[0006] In one embodiment, a downward-facing limiting step is formed on the inner wall of the housing, and the upper end face of the follower can lift the upper drill string connected to the housing through the limiting step.

[0007] In one embodiment, the pitch of the helical spline is set to be in the range of 100-800 mm, and the helix angle of the helix formed by the helical extension of the helical spline is in the range of 5-85 degrees.

[0008] In one embodiment, the width of the helical spline is set to be in the range of 40-200 mm, and the depth is set to be in the range of 5-20 mm.

[0009] In one embodiment, a first eccentric hole communicating with the first central channel is provided in the power spindle. The first eccentric hole is located at the axial inner end of the spiral spline groove. A second eccentric hole communicating with the second central flow channel is provided at the upper end of the output spindle. When the first eccentric hole and the second eccentric through hole overlap, a throttling effect can be formed, thereby generating a pressure pulse.

[0010] In one embodiment, the outer axial end of the first eccentric hole is formed as a first axial impact surface, and the upper end face of the output spindle is formed as a second axial impact surface. The maximum distance D between the first axial impact surface and the second axial impact surface is less than the axial movement stroke H of the follower.

[0011] In one embodiment, an annular limiting groove is provided on the outer surface of the output spindle, and a through hole is provided on the side wall of the power spindle. An anti-dropping pin block is installed in the through hole, and the axial inner end of the anti-dropping pin block extends into the annular limiting groove.

[0012] The axial width of the annular limiting groove is greater than the width of the anti-dropping pin block.

[0013] In one embodiment, the housing is configured to include an upper outer shell, a middle connector, and a lower outer shell that are fixedly connected from top to bottom.

[0014] In one embodiment, a bearing string is sleeved on the power spindle, the bearing string is located between the upper housing and the power spindle, and a first upper straightening and anti-wear component and a second upper straightening and anti-wear component are respectively provided at both ends of the bearing string.

[0015] In one embodiment, a limiting cylinder is fixedly connected to the lower end of the lower housing, and a lower straightening and anti-wear component is provided between the limiting cylinder and the output spindle.

[0016] Compared with the prior art, the advantages of this application are:

[0017] The downhole composite impact tool of the present invention can drive the power spindle through a cam mechanism to move the upper drill string axially, and generate axial and circumferential composite impacts on the drill bit through the helical spline groove, thereby generating axial and circumferential composite impact forces on the drill bit. Furthermore, the downhole composite impact tool can generate pressure pulses that act on the output spindle, further enhancing the axial impact on the drill bit. This is highly beneficial for increasing the drill bit's impact force and improving drilling performance. In addition, when the drill bit torque is too high, the output spindle can automatically adjust to the downhole conditions. Under the cooperation of the helical spline and the helical spline groove, it can rotate upwards relative to the power spindle to reduce the drill bit's soil penetration depth and thus reduce the drill bit torque. This effectively prevents the downhole motor from sluggish. All of these features greatly improve the downhole performance of the composite impact tool, significantly increasing drilling efficiency and enhancing drilling effectiveness. Moreover, this downhole composite impact tool is easy to operate, automatically adjusting to the actual downhole conditions during operation, and is highly adaptable. Attached Figure Description

[0018] The invention will now be described with reference to the accompanying drawings.

[0019] Figure 1 The structure of the downhole composite impact tool according to the present invention is shown.

[0020] Figure 2 The structure of the spiral spline on the output spindle is schematically shown.

[0021] Figure 3 The structure of the helical spline groove on the power spindle is schematically shown.

[0022] Figure 4 The schematic diagram shows the distribution structure of the first eccentric hole on the power spindle and the second eccentric hole on the output spindle.

[0023] Figure 5 The structure of the cam is shown schematically.

[0024] Figure 6 schematically shown Figure 5 The unfolded structure of the cam surface of the cam shown.

[0025] Figure 7 The structure of the follower is shown schematically.

[0026] In this application, all drawings are schematic and are used only to illustrate the principles of the invention, and are not drawn to scale. Detailed Implementation

[0027] The invention will now be described with reference to the accompanying drawings.

[0028] In this application, it should be noted that the end of the downhole composite impact tool according to the present invention that is lowered into the wellbore near the wellhead is defined as the upper end or a similar term, and the end that is farther from the wellhead is defined as the lower end or a similar term.

[0029] It should also be noted that the directional terms or qualifiers such as "up" and "down" used in this application are all specific to the referenced appendix. Figure 1 In other words, they are not used to define the absolute position of the components involved, but can vary depending on the specific circumstances.

[0030] Figure 1 The structure of a downhole composite impact tool 100 according to the present invention is shown. Figure 1 As shown, the downhole composite impact tool 100 includes a housing 1, a power spindle 2 concentrically arranged within the housing 1, and an output spindle 4 for connecting the drill bit. The power spindle 2 is concentrically arranged inside the housing 1, and has a first central flow channel 21 extending axially within it for flowing drilling fluid. A bearing string 3 is fitted onto the power spindle 2, forming a rotatable connection between the power spindle 2 and the housing 1. The output spindle 4 is concentrically arranged within the housing 1 and is located at the lower end of the power spindle 2. The output spindle 4 has a second central flow channel 41 extending axially.

[0031] According to the present invention, such as Figure 1As shown, a helical spline groove 22 extending axially is provided on the inner wall surface of the power spindle 2. Simultaneously, a helical spline 42, which mates with the helical spline groove 22, is provided on the outer wall surface of the output spindle 4. The power spindle 2 and the driven spindle 4 can form a mating connection through the engagement of the helical spline groove 22 and the helical spline 42, allowing the driven spindle 4 to screw into or out relative to the power spindle 2, thereby achieving relative axial movement and relative rotation between the two. Thus, on the one hand, the power spindle 2 and the output spindle 4 can transmit torque through the helical spline 42 and the helical spline groove 22; on the other hand, the output spindle 4 can move upward or downward relative to the power spindle 2 under the action of the helical spline 42 and the helical spline groove 22.

[0032] like Figure 1 As shown, a cam mechanism 5 is mounted on the output spindle 4. The cam mechanism 5 includes a cam 51 fixedly mounted on the output spindle 4 and a follower 52 located at the upper end of the cam 51. The upper end of the cam 51 is constructed as a continuous cam surface 511, and the lower end of the follower 52 is constructed as a plane. A plurality of rollers 53 are provided at the lower end of the follower 52, which are evenly distributed in the circumferential direction. The rollers 53 are adapted to contact the cam surface 511.

[0033] In practical applications, the downhole composite impact tool 100 is mounted at the lower end of the downhole power motor (not shown). During operation, the downhole power motor drives the power spindle 2 to rotate. The power spindle 2 is configured to drive the output spindle 4 to rotate, thereby transmitting the power of the downhole power motor to the drill bit. Since the cam 51 is fixedly mounted on the output spindle 4, the output spindle 4 drives the cam 51 to rotate during rotation. The follower 52 can reciprocate axially under the action of the roller 53 and the cam surface 511 of the cam 51, and push up the upper drill string (not shown) connected to the housing 1. Thus, after the upper drill string and the output spindle 4 have moved past the highest point, they can form an axial and circumferential composite impact on the helical spline 42 through the helical spline groove 22 under the action of drilling pressure, and transmit the composite impact force to the drill bit.

[0034] In this embodiment, when the drill bit torque is too high, the output spindle 4 can also be rotated upward relative to the power spindle 2 under the cooperation of the spiral spline groove 22 and the spiral spline 42 to absorb a certain torque, thereby causing the output spindle 4 to move upward relative to the power spindle 2, reducing the drill bit's soil-digging depth. This can effectively prevent the downhole motor from lag.

[0035] According to the present invention, such as Figure 1As shown, the housing 1 is constructed to include an upper outer shell 11, a middle connector 12, and a lower outer shell 13, which are fixedly connected from top to bottom. The power spindle 2 is located within the upper outer shell 11 and the middle connector 12, and the output spindle 4 is located within the lower outer shell 13. The middle connector 12 can be a centralizer (a spiral centralizer or a straight-edged centralizer), which enables the middle connector 12 to centralize the downhole composite impact tool 100, greatly enhancing the performance of the downhole composite impact tool 100.

[0036] In one embodiment, the upper housing 11, the middle connector 12, and the lower housing 13 are all fixedly connected by positive and negative tapered connectors. This connection method is convenient and quick to install, and can effectively ensure the stability of the connection.

[0037] like Figure 1 As shown, the bearing string 3 is disposed between the power spindle 2 and the upper housing 11. Preferably, the bearing string 3 is a TC bearing string, such as a cemented carbide bearing or a tungsten carbide bearing, where TC refers to tungsten carbide, which is the main raw material for producing cemented carbide. The inner ring of the bearing string 3 is fixedly connected to the power spindle 2 by an interference fit, and the outer ring of the bearing string 3 is fixedly connected to the inner wall of the upper housing 11. Thus, the power spindle 2 and the housing 1 are rotatably connected through the bearing string 3.

[0038] According to the present invention, a first upper straightening and anti-wear component 31 and a second upper straightening and anti-wear component 32 are respectively provided at the upper and lower ends of the bearing string 3. Figure 1 As shown, the first upper anti-wear assembly 31 is located radially between the power spindle 2 and the upper housing 11. The first upper anti-wear assembly 31 includes a first anti-wear stationary ring 311 and a first anti-wear moving ring 312. The first anti-wear stationary ring 311 is fixedly connected to the inner wall of the upper housing 11, and its lower end face abuts against the upper end face of the outer ring of the bearing string 3. In one embodiment, the inner wall of the upper housing 11 has a two-stage step with its end face facing downwards, and the outer wall of the first anti-wear stationary ring 311 has a two-stage step with its end face facing upwards. The first anti-wear stationary ring 311 and the upper housing 11 are axially limited by the two-stage step. The first anti-wear moving ring 312 is fixedly connected to the power spindle 2, and its lower end face abuts against the upper end face of the inner ring of the bearing string 3. The first upper anti-wear assembly 31 effectively prevents wear between the power spindle 2 and the upper housing 11.

[0039] like Figure 1As shown, a tightening nut 9 is provided at the upper end of the first upper centering and anti-wear component 31, and the tightening nut 9 is fastened to the power spindle 2 by threads. The tightening nut 9 is used to lock the first anti-wear moving ring 312 of the first upper centering and anti-wear component 31 onto the power spindle 2, so that the first anti-wear moving ring 312 is relatively stationary with respect to the power spindle 2, thereby achieving a fixed connection between the first anti-wear moving ring 312 and the power spindle 2, thereby enhancing the stability of the downhole composite impact tool 100.

[0040] Additionally, an adjusting shim can be installed on the upper end of the tightening nut 9 as an adjustment component during installation to facilitate installation.

[0041] like Figure 1 As shown, the second upper anti-wear assembly 32 is located radially inner to the central connector 12. The second upper anti-wear assembly 32 includes a second anti-wear stationary ring 321 and a second anti-wear moving ring 322. The second anti-wear stationary ring 321 is fixedly connected to the inner wall of the central connector 12, and its upper end face abuts against the lower end face of the outer ring of the bearing string 3. In one embodiment, the inner wall of the central connector 12 has an upward-facing step, and the lower end face of the second anti-wear stationary ring 321 abuts against this step to form an axial limit. The second anti-wear moving ring 322 is fixedly connected to the power spindle 2, and its upper end face abuts against the lower end face of the inner ring of the bearing string 3. The second upper anti-wear assembly 32 effectively prevents wear between the power spindle 2 and the central connector 12.

[0042] During operation, the first upper centering and anti-wear assembly 31 and the second upper centering and anti-wear assembly 32 can withstand the eccentric movement of the rotor in the downhole motor, as well as the radial force generated by the oscillation of the universal joint shaft and the fixed-axis rotation of the power spindle 2 itself. This improves the guiding capability of the downhole composite impact tool 100 and the transmission performance of the power spindle 2.

[0043] According to the present invention, a clamping component may also be provided between the bearing string 3 and the second upper straightening and anti-wear component 32. For example... Figure 1 As shown, the clamping assembly is disposed axially between the bearing string 3 and the second upper straightening and anti-wear assembly 32. The clamping assembly includes an outer clamping sleeve 33 and an inner clamping sleeve 34. The outer clamping sleeve 33 is used to clamp the lower end face of the outer ring of the bearing string 3, and the inner clamping sleeve 34 is used to clamp the lower end face of the inner ring of the bearing string 3. In one embodiment, the inner clamping sleeve 34 is provided with an internal thread, which forms a fixed connection with the power spindle 2 through the internal thread, thereby clamping the inner ring of the bearing string 3 and thus axially limiting the bearing string 3.

[0044] According to one embodiment of the present invention, taking a 7” drill bit as an example, the pitch of the helical spline 42 on the output spindle 4 is set to be in the range of 100-800mm, and the helix angle of the helix formed by the helical extension of the helical spline 42 is set to be in the range of 5-85 degrees. The width of the helical spline 42 is set to be in the range of 40-200mm, and the depth is set to be in the range of 5-20mm. Correspondingly, the helical spline groove 22 on the power spindle 2 is adapted to the helical spline 42. In order to facilitate the mating of the helical spline 42 and the helical spline groove 22, the width and depth of the helical spline groove 22 are both set to be slightly larger than the width and depth of the helical spline 42.

[0045] According to the present invention, such as Figures 1 to 4 As shown, a first eccentric hole 211 communicating with the first central channel 21 is provided inside the power spindle 2, and the first eccentric hole 211 is located at the axial inner end of the helical spline groove 22. Simultaneously, a second eccentric hole 411 communicating with the second central flow channel 41 is provided at the upper end of the output spindle 4. The axial outer end of the first eccentric hole 211 forms a first axial impact surface 212, and the upper end surface of the output spindle 4 forms a second axial impact surface 412. During the axial reciprocating motion of the power spindle 2, the distance between the first axial impact surface 212 and the second axial impact surface 412 changes accordingly.

[0046] During operation, before the output spindle 4 rotates upward relative to the power spindle 2 to its highest point, the first central channel 21 connects to the second central flow channel 41 through the first eccentric hole 211 and the second eccentric hole 411. At this time, there is a certain distance between the axial end face of the first eccentric hole 211 and the axial end face of the second eccentric hole 411, and the first eccentric hole 211 is fully open. When the output spindle 4 moves upward to its highest point, the first axial impact surface 212 of the power spindle 2 contacts and overlaps with the second axial impact surface 412 of the output spindle 4, making the first eccentric hole 211 and the second eccentric hole 411 overlap and minimize the conducting area. At this time, the first central channel 21 connects to the second central flow channel 41 through the overlapping area of ​​the first eccentric hole 211 and the second eccentric hole 411. Due to the reduced area of ​​the overlapping region, throttling is formed, thereby generating a pressure pulse. The generated pulse pressure can act on the upper end face of the output spindle 4 and then be transmitted to the drill bit. This allows the output spindle 4 to exert a further axial impact on the drill bit under the action of the pulse pressure, which is very beneficial to enhance the impact force of the drill bit and improve the drilling operation.

[0047] To ensure that the first axial impact surface 212 of the power spindle 2 and the second axial impact surface 412 of the output spindle 4 can contact and overlap, the maximum distance D between the first axial impact surface 212 and the second axial impact surface 412 is set to be less than the axial movement stroke H of the driven member 52 (see...). Figure 6 ).

[0048] like Figures 1 to 3 As shown, an annular limiting groove 43 is provided on the outer surface of the output spindle 4, and a through hole 23 is provided on the side wall of the power spindle 2. An anti-drop pin block 6 is installed in the through hole 23, and the axial inner end of the anti-drop pin block 6 extends into the annular limiting groove 43. During the well entry process of the downhole composite impact tool 100, the anti-drop pin block 6 can play a good anti-drop role, effectively preventing the output spindle 4 from falling off. During installation, the anti-drop pin block 6 passes through the through hole 23 from the outside to the inside and is inserted into the annular limiting groove 43. To prevent the anti-drop pin block 6 from falling out during operation, a sleeve (not shown) is fitted on the power spindle 2 at the position corresponding to the through hole 23.

[0049] In this embodiment, the axial width of the annular limiting groove 43 is greater than the axial width of the anti-dropping pin block 6. Furthermore, the value of the width of the annular limiting groove 43 minus the axial width of the anti-dropping pin block 6 is greater than the maximum stroke of the output spindle 4 that can move axially relative to the power spindle 2, so as to ensure that when the output spindle 4 moves upward to the highest point, the axial end face position of the first eccentric hole 211 can coincide with the axial end face position of the second eccentric hole 411.

[0050] According to the present invention, the output spindle 4 is concentrically arranged inside the lower housing 13, and the cam mechanism 5 is fixedly mounted on the output spindle 4. Figure 5 As shown, the cam 51 in the cam mechanism 5 is constructed in a cylindrical shape, and the upper end surface of the cam 51 is formed as a continuous cam surface 511. Figure 6 The unfolded structure of cam 51 is shown. Figure 5 and Figure 6 In the illustrated embodiment, the upper end face of the cam 51 is provided with three cam working surfaces. The stroke of the follower 52 driven by the cam 51 to move axially is H, which is the distance between the highest and lowest working surfaces of the cam 51.

[0051] In one embodiment, the inner wall of the cam 51 is provided with an internal thread, and the outer wall of the output spindle 4 is provided with an external thread. The cam 51 is fixedly mounted on the output spindle 4 by a threaded connection. Thus, the cam 51 can rotate synchronously with the output spindle 4.

[0052] like Figure 7 As shown, the driven member 52 is generally cylindrical, with its inner diameter larger than the outer diameter of the output shaft 4. This allows for a clearance fit between the driven member 52 and the output shaft 4, enabling the driven member 52 to move axially along the output shaft 4. The lower end face of the driven member 52 is flat. Multiple rollers 53 are circumferentially distributed on the lower end face of the driven member 52, with the axial direction of the rollers 53 along the diametrical direction of the driven member 52. Figure 7In the illustrated embodiment, three rollers 53 are provided on the lower end face of the follower 52. To facilitate the installation of the rollers 53, the lower end face of the follower 52 can be constructed as a stepped surface, and the rollers 53 are mounted on the stepped surface. The follower 52 is adapted to contact the cam surface 511 at the upper end of the cam 51 through the rollers 53. Thus, when the cam 51 rotates with the output spindle 4, the follower 52 can reciprocate axially under the action of the rollers 53 and the cam surface 511.

[0053] In an embodiment not shown, roller 53 may also be replaced by balls.

[0054] According to the present invention, a limiting step 55 with its end face facing downward is formed on the inner wall of the housing 1, and the upper end face of the follower 52 can be pushed up by the limiting step 55 to lift the upper drill string connected to the housing 1. In one embodiment, the lower end of the middle housing 12 extends into the lower housing 13, and the lower end face of the middle housing 12 is formed as the limiting step 55.

[0055] like Figure 1 As shown, a limiting cylinder 7 is fixed to the lower end of the lower housing 13. In one embodiment, the limiting cylinder 7 is fixedly connected to the lower housing 13 by threads. A lower straightening and anti-wear assembly 8 is provided between the limiting cylinder 7 and the output spindle 4. The lower straightening and anti-wear assembly 8 includes a straightening and anti-wear moving ring and a straightening and anti-wear stationary ring formed on the inner wall of the limiting cylinder 7. The straightening and anti-wear moving ring is fixedly connected to the output spindle 4, for example, by threads. Thus, the lower straightening and anti-wear assembly 8 effectively prevents wear between the output spindle 4 and the lower housing 13.

[0056] The working process of the downhole composite impact tool 100 according to the present invention is briefly described below. First, the downhole composite impact tool 100 is connected to the lower end of the downhole motor. After assembly, it is lowered into the wellbore. During the lowering process, the output spindle 4 is effectively prevented from falling off by the anti-falling pin block 6 and the limiting cylinder 7. When the downhole composite impact tool 100 is lowered to the predetermined position in the well, the drilling tool is started.

[0057] Under normal operating conditions, the downhole power motor drives the power spindle 2 to rotate. The power spindle 2, through the interaction of the helical spline 42 and the helical spline groove 22, drives the output spindle 4 to rotate, thereby transmitting the power of the downhole power motor to the drill bit. Simultaneously, the output spindle 4, during its rotation, drives the cam 51 to rotate. This causes the follower 52 to reciprocate axially under the interaction of the roller 53 and the cam surface 511 of the cam 51. During its upward movement, it lifts the upper drill string connected to the housing 1 until it reaches its highest point (stroke H). After surpassing the highest point, the helical spline 42 tends to disengage. At this point, the output spindle 41 experiences a momentary deceleration due to the disengagement of the helical spline 42. Furthermore, under the influence of drilling pressure, the upper drill string and the output spindle 4, through the helical spline groove 22, generate a combined axial and circumferential impact on the helical spline 42, transmitting this combined impact force to the drill bit. Thus, a combined axial and circumferential impact is generated on the drill bit.

[0058] On the other hand, during the reciprocating axial motion of the power spindle 2, the distance between the first axial impact surface 212 of the power spindle 2 and the second axial impact surface 412 of the output spindle 4 changes periodically, causing the first eccentric hole 211 and the second eccentric hole 411 to periodically overlap and form a throttling effect, thereby generating pressure pulses. The generated pulse pressure acts on the upper end face of the output spindle 4 and is then transmitted to the drill bit, thereby causing the output spindle 4 to exert a further axial impact on the drill bit under the action of the pulse pressure. This is very beneficial for enhancing the impact force of the drill bit and improving the drilling operation.

[0059] When the drill bit torque is too high, the output spindle 4 can automatically adjust to the downhole working conditions. With the cooperation of the spiral spline groove 22 and the spiral spline 42, it can rotate upward relative to the power spindle 2 to absorb a certain amount of torque, thereby causing the output spindle 4 to move upward relative to the power spindle 2, reducing the drill bit's soil penetration depth and reducing the drill bit torque. This can effectively prevent the downhole motor from lag, which is very beneficial to improving the downhole working performance of the downhole composite impact tool 100, greatly improving drilling efficiency and significantly enhancing drilling effect.

[0060] The downhole composite impact tool 100 according to the present invention can drive the power spindle 2 to move the upper drill string axially through the cam mechanism 5, and form an axial and circumferential composite impact on the helical spline 42 through the helical spline groove 22, thereby generating an axial and circumferential composite impact force on the drill bit. Furthermore, the downhole composite impact tool 100 can generate pressure pulses and act on the output spindle 4, thereby forming a further axial impact on the drill bit, which is very beneficial for enhancing the drill bit impact force and improving drilling operations. In addition, when the drill bit torque is too high, the output spindle 4 can automatically adjust to the downhole working conditions. Under the cooperation of the helical spline groove 22 and the helical spline 42, it can rotate upward relative to the power spindle 2 to reduce the drill bit's soil penetration depth and reduce the drill bit torque, which can effectively prevent the downhole motor from laging. All of these are very beneficial for improving the downhole working performance of the downhole composite impact tool 100, greatly improving drilling efficiency, and significantly enhancing drilling results. In addition, the downhole composite impact tool 100 is easy to operate and can automatically adjust itself to the actual working conditions in the well during operation, making it highly adaptable.

[0061] In the description of this invention, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0062] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0063] In the description of this specification, references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0064] Finally, it should be noted that the above description is merely a preferred embodiment of the present invention and does not constitute any limitation on the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A downhole composite impact tool, comprising: The shell is constructed in a cylindrical shape (1); A power spindle (2) for connecting a downhole power motor is provided. The power spindle is concentrically arranged in the housing and can rotate relative to the housing. The power spindle is provided with a first central flow channel (21) and a spiral spline groove (22) extending axially is provided on the inner wall surface of the power spindle. An output spindle (4) for connecting drill bits, the output spindle having a second central flow channel (41), and a spiral spline (42) on the outer wall of the output spindle that can be adapted to the spiral spline groove; and The cam mechanism (5) includes a cam (51) fixedly mounted on the output spindle and a follower (52) located at the upper end of the cam. The upper end of the cam is constructed as a continuous cam surface (511), and the lower end of the follower is constructed as a plane and provided with a plurality of circumferentially distributed rollers (53). The rollers are adapted to contact the cam surface. A limiting step (55) with the end face facing downward is formed on the inner wall of the housing. The upper end face of the follower can lift the upper drill string connected to the housing through the limiting step. The power spindle can drive the output spindle to rotate, and the driven member can reciprocate along the axis under the action of the cam, and lift the upper drill string connected to the housing. After the upper drill string and the output spindle move to the highest point of the stroke, they can form an axial and circumferential compound impact on the helical spline through the helical spline groove under the action of drilling pressure, and transmit it to the drill bit.

2. The downhole composite impact tool according to claim 1, characterized in that, The pitch of the spiral spline is set to be in the range of 100-800mm, and the helix angle of the spiral line formed by the spiral extension of the spiral spline is in the range of 5-85 degrees.

3. The downhole composite impact tool according to claim 1 or 2, characterized in that, The width of the spiral spline is set to be in the range of 40-200mm, and the depth is set to be in the range of 5-20mm.

4. The downhole composite impact tool according to claim 1, characterized in that, The power spindle is provided with a first eccentric hole (211) that communicates with the first central channel. The first eccentric hole is located at the axial inner end of the spiral spline groove. The upper end of the output spindle is provided with a second eccentric hole (411) that communicates with the second central flow channel. When the first eccentric hole and the second eccentric hole overlap, they can form a throttling effect, thereby generating a pressure pulse.

5. The downhole composite impact tool according to claim 4, characterized in that, The outer axial end of the first eccentric hole is formed as a first axial impact surface (212), and the upper end face of the output spindle is formed as a second axial impact surface (412). The maximum distance D between the first axial impact surface and the second axial impact surface is less than the axial movement stroke H of the follower.

6. The downhole composite impact tool according to claim 1, characterized in that, An annular limiting groove (43) is provided on the outer surface of the output spindle, and a through hole (23) is provided on the side wall of the power spindle. An anti-dropping pin block (6) is installed in the through hole, and the axial inner end of the anti-dropping pin block extends into the annular limiting groove. The axial width of the annular limiting groove is greater than the width of the anti-dropping pin block.

7. The downhole composite impact tool according to claim 1, characterized in that, The housing is configured to include an upper outer shell (11), a middle connector (12), and a lower outer shell (13) that are fixedly connected from top to bottom.

8. The downhole composite impact tool according to claim 7, characterized in that, A bearing string (3) is sleeved on the power spindle. The bearing string is located between the upper housing and the power spindle. A first upper straightening and anti-wear component (31) and a second upper straightening and anti-wear component (32) are respectively provided at both ends of the bearing string.

9. The downhole composite impact tool according to claim 7, characterized in that, A limiting cylinder (7) is fixedly connected to the lower end of the lower housing, and a lower straightening and anti-wear component (8) is provided between the limiting cylinder and the output spindle.

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