A downhole composite impact tool

Abstract

The application provides a downhole composite impact tool, which comprises a housing, a power spindle provided with a first central flow channel and a helical spline groove formed on the inner wall of the power spindle, an output spindle provided with a second central flow channel and a helical spline formed on the outer wall of the output spindle, and a cam mechanism comprising a cam fixedly sleeved on the output spindle and a follower, wherein the upper end surface of the cam is configured as a continuous first cam surface, the lower end surface of the follower is configured as a second cam surface capable of being matched with the first cam surface, and a plurality of circumferentially distributed rollers are arranged on the second cam surface; 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 lift an upper drill string connected with the housing, so that the upper drill string and the output spindle move to the highest point of stroke, and then under the action of the drilling pressure, the helical spline groove forms axial and circumferential composite impacts on the helical spline and transmits the impacts to a drill bit.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of oil and gas drilling engineering, and particularly relates to a downhole composite impact tool. BACKGROUND

[0002] With the development of oil exploration and development, the proportion of complex wells such as deep wells and horizontal wells gradually increases, and drilling speedup is facing new challenges. Drilling speedup technology is an important topic in oil and gas well engineering. The existing drilling method mainly realizes rock breaking through rock shearing and impact of a drill bit. The drill bit is prone to jump drilling when drilling through hard formations, and thus low rotation speed and low drilling pressure drilling is required, which seriously restricts the mechanical drilling speed. The existing PDC drill bit mainly breaks the formation in a cutting, shearing and extruding manner. In the drilling process, insufficient rock breaking energy and stick-slip vibration are important reasons for low mechanical drilling speed. When the PDC drill bit drills through hard formations, or the drill bit eats too much depth, the drill bit will stop rotating instantaneously due to insufficient rock breaking energy, and thus periodic stick-slip vibration of the drill bit will occur, thereby damaging the service life of the drill bit and seriously affecting the mechanical drilling speed.

[0003] To effectively improve the mechanical rotation speed of the PDC drill bit and inhibit the stick-slip vibration of the drill bit, a common method in the prior art is to use a composite impact drilling tool. The tool is composed of an axial impact unit and a torsional impact unit. The axial impact hammer in the axial impact unit transmits impact energy to the PDC drill bit to increase the cutting depth after completing the forward stroke. However, the impact work generated when the axial impact hammer enters the reverse stroke of the existing composite impact drilling tool easily causes longitudinal vibration of the bottom of the drilling tool, thereby causing problems such as low mechanical drilling efficiency, low service life of the tool, and limited speedup effect in hard and hard formations. In addition, the existing drilling speedup tool has a high failure rate, a short service life and poor reliability. SUMMARY

[0004] In view of the above technical problems, the present application aims to provide a downhole composite impact tool which can generate axial and circumferential composite impact forces on the drill bit and can generate pressure pulses acting on the drill bit to form further axial impact on the drill bit. In addition, the downhole composite impact tool can adapt to downhole working conditions and automatically adjust to reduce the soil depth when the torque of the drill bit is too large, thereby effectively preventing the downhole motor from producing the stalling phenomenon.

[0005] To this end, the application provides a downhole composite impact tool, comprising: a housing configured in a cylindrical shape; a power spindle for connecting a downhole power motor, the power spindle being concentrically arranged in the housing and rotatable relative to the housing, the power spindle being provided with a first central flow channel and a helical spline groove on an inner wall surface of the power spindle; an output spindle for connecting a drill bit, the output spindle being provided with a second central flow channel and a helical spline on an outer wall surface of the output spindle, the helical spline being adapted to the helical spline groove; and a cam mechanism comprising a cam fixedly sleeved on the output spindle and a follower at an upper end of the cam, an upper end surface of the cam being configured as a continuous first cam surface, a lower end surface of the follower being configured as a second cam surface adapted to the first cam surface, and a plurality of circumferentially distributed rollers being provided on the second cam surface; wherein the power spindle can drive the output spindle to rotate, the follower can reciprocate along an axial direction under the action of the cam, and a top drill string connected with the housing can be lifted by the follower, so that the top drill string and the output spindle can form axial and circumferential composite impacts on the helical spline through the helical spline groove under the action of a drilling pressure after moving to a highest point of stroke, and the impacts are transmitted to the drill bit.

[0006] In one embodiment, the axis direction of the roller is arranged along a diameter direction of the follower.

[0007] In one embodiment, a limit step with a downward end surface is formed on an inner wall of the housing, and an upper end surface of the follower can lift the top drill string connected with the housing through the limit step.

[0008] In one embodiment, a pitch of the helical spline is arranged in a range of 100-800 mm, and a helix angle of a helix line formed by helical extension of the helical spline is arranged in a range of 5-85 degrees.

[0009] In one embodiment, a width of the helical spline is arranged in a range of 40-200 mm, and a depth is arranged in a range of 5-20 mm.

[0010] In one embodiment, a first eccentric hole communicating with the first central channel is arranged in the power spindle, the first eccentric hole being at an axial inner end of the helical spline groove, a second eccentric hole communicating with the second central flow channel is arranged at an upper end of the output spindle, and the first eccentric hole and the second eccentric hole can form throttling when overlapping, thereby generating pressure pulses.

[0011] In one embodiment, an axial outer end of the first eccentric hole is formed as a first axial impact surface, an upper end surface of the output spindle is formed as a second axial impact surface, and a maximum distance D between the first axial impact surface and the second axial impact surface is less than an axial movement stroke H of the follower.

[0012] In one embodiment, an annular limiting groove is arranged on an outer surface of the output spindle, a through hole is arranged on a side wall of the power spindle, a limiting block is mounted in the through hole, an axial inner end of the limiting block extends into the annular limiting groove,

[0013] An axial width of the annular limiting groove is greater than a width of the limiting block.

[0014] In one embodiment, a bearing string is sleeved on the power spindle, the bearing string is between the housing and the power spindle, and a first upper centralizing anti-wear assembly and a second upper centralizing anti-wear assembly are arranged at two ends of the bearing string, respectively.

[0015] In one embodiment, a limiting cylinder is fixed to a lower end of the housing, and a lower centralizing anti-wear assembly is arranged between the limiting cylinder and the output spindle.

[0016] Compared with the prior art, the application has the following advantages:

[0017] The downhole composite impact tool can drive the power spindle to move the upper drill string axially through the cam mechanism, and can form axial and circumferential composite impacts on the helical spline through the helical spline groove, so as to generate axial and circumferential composite impact forces on the drill bit. Moreover, the downhole composite impact tool can generate pressure pulses and act on the output spindle, so as to further form axial impacts on the drill bit, which is very beneficial to enhancing the impact force of the drill bit and improving the drilling construction. In addition, when the torque of the drill bit is too large, the output spindle can automatically adjust according to the downhole working condition, and it can be rotated upward relative to the power spindle under the cooperation of the helical spline and the helical spline groove, so as to reduce the soil depth of the drill bit and reduce the torque of the drill bit, which can effectively prevent the downhole motor from generating a drag phenomenon. These are very beneficial to improving the downhole working performance of the downhole composite impact tool, greatly improving the drilling construction efficiency, and significantly enhancing the drilling construction effect. In addition, the downhole composite impact tool is easy to operate, and can automatically adjust according to the actual downhole working condition during the working process, so it has strong adaptability. BRIEF DESCRIPTION OF DRAWINGS

[0018] The application will be described below with reference to the drawings.

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

[0020] Figure 2The 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 The structure of the follower is shown schematically.

[0025] Figure 7 The schematic diagram shows the unfolded structure of the mating contact between the cam and the follower.

[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. (See diagram below.) 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 located at the lower end of the power spindle 2, and has a second central flow channel 41 extending axially.

[0031] According to the present invention, such as Figure 1As shown, the inner wall surface of the power spindle 2 is provided with a helical spline groove 22 extending along the axial direction. Meanwhile, the outer wall surface of the output spindle 4 is provided with a helical spline 42 capable of being matched with the helical spline groove 22. The power spindle 2 and the driven spindle 4 can be matched and connected through the helical spline groove 22 and the helical spline 42, and the driven spindle 4 can be screwed into or out of the power spindle 2, so as to realize the relative axial movement and rotation of the two. Thus, on the one hand, the output spindle 4 can transmit torque through the helical spline 42 and the helical spline groove 22, and on the other hand, the output spindle 4 can move up or down relative to the power spindle 2 under the action of the helical spline 42 and the helical spline groove 22.

[0032] As shown in the drawings, Figure 1 The output spindle 4 is sleeved with a cam mechanism 5. The cam mechanism 5 includes a cam 51 fixedly sleeved on the output spindle 4 and a follower 52 at the upper end of the cam 51. The upper end of the cam 51 is configured as a continuous first cam surface 511. Meanwhile, the lower end surface of the follower 52 is configured as a continuous second cam surface 521, and a plurality of rollers 53 are uniformly distributed on the second cam surface 521 of the follower 52, which are in matched contact with the first cam surface 511.

[0033] In actual application, the downhole composite impact tool 100 is installed at the lower end of a downhole power motor (not shown). In operation, the downhole power motor drives the power spindle 2 to rotate, which is configured to drive the output spindle 4 to rotate to transmit the power of the downhole power motor to the drill bit. Since the cam 51 is fixedly sleeved on the output spindle 4, the output spindle 4 drives the cam 51 to rotate in the process of rotation, and the follower 52 can reciprocate along the axial direction under the action of the rollers 53 and the first cam surface 511 of the cam 51, and lift the upper drill string (not shown) connected with the housing 1, so that the upper drill string and the output spindle 4 can form axial and circumferential composite impact on the helical spline 22 through the helical spline 42 after moving beyond the highest point under the action of the weight on bit, and transmit the composite impact force to the drill bit.

[0034] In this embodiment, when the torque of the drill bit is too large, the output spindle 4 can also be screwed into the power spindle 2 under the action of the helical spline 22 and the helical spline 42 to absorb a certain torque, so as to move the output spindle 4 upward relative to the power spindle 2, and reduce the bit balling depth, which can effectively prevent the downhole motor from producing the phenomenon of stalling.

[0035] According to the present application, as Figure 1As shown, the housing 1 is configured to include an upper housing 11, a middle joint 12 and a lower housing 13 fixedly connected in sequence from top to bottom. The power main shaft 2 is correspondingly located in the upper housing 11 and the middle joint 12, and the output main shaft 4 is correspondingly located in the lower housing 13. The middle joint 12 can be a centralizer (a spiral centralizer or a straight edge centralizer), so that the middle joint 12 can form centralization to the downhole composite impact tool 100, which is very beneficial to enhance the performance of the downhole composite impact tool 100.

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

[0037] As shown in the figure, Figure 1 The bearing string 3 is arranged between the power main shaft 2 and the upper housing 11. Preferably, the bearing string 3 is a TC bearing string, which can be a hard alloy bearing or a tungsten carbide bearing, where TC refers to tungsten carbide, which is the main raw material for producing hard alloy. The inner ring of the bearing string 3 is fixedly connected with the power main shaft 2 by interference fit, and the outer ring of the bearing string 3 is fixedly connected with the inner wall of the upper housing 11. In this way, the power main shaft 2 is rotationally connected with the housing 1 through the bearing string 3.

[0038] According to the present application, a first upper centralizing anti-wear assembly 31 and a second upper centralizing anti-wear assembly 32 are respectively arranged at the upper and lower ends of the bearing string 3. As shown in the figure, Figure 1 The first upper centralizing anti-wear assembly 31 is located between the power main shaft 2 and the upper housing 11 in the radial direction. The first upper centralizing anti-wear assembly 31 includes a first anti-wear static ring 311 and a first anti-wear dynamic ring 312. The first anti-wear static ring 311 is fixedly connected with the inner wall of the upper housing 11, and the lower end surface of the first anti-wear static ring 311 abuts and presses the upper end surface of the outer ring of the bearing string 3. In one embodiment, the inner wall of the upper housing 11 is provided with a two-stage step with the end surface facing downward, and the outer wall of the first anti-wear static ring 311 is provided with a two-stage step with the end surface facing upward, and the first anti-wear static ring 311 is axially limited by the two-stage step and installed in the upper housing 11. The first anti-wear dynamic ring 312 is fixedly connected with the power main shaft 2, and the lower end surface of the first anti-wear dynamic ring 312 abuts and presses the upper end surface of the inner ring of the bearing string 3. The first upper centralizing anti-wear assembly 31 can effectively prevent wear between the power main shaft 2 and the upper housing 11.

[0039] As shown in the figure, 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 application, taking the 7" drilling tool as an example, the pitch of the helical spline 42 on the output spindle 4 is set to be in the range of 100-800 mm, and the helix angle of the helix line 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 40-200 mm, and the depth is set to be in the range of 5-20 mm. Correspondingly, the helical spline groove 22 on the power spindle 2 is adapted to the helical spline 42. In order to facilitate the cooperation of the helical spline 42 and the helical spline groove 22, the width and depth of the helical spline groove 22 are set to be slightly larger than the width and depth of the helical spline 42.

[0045] According to the present application, as shown in the drawings, a first eccentric hole 211 in communication with the first central passage 21 is arranged in the power spindle 2, and the first eccentric hole 211 is located at the axial inner end of the helical spline groove 22. At the same time, a second eccentric hole 411 in communication with the second central flow passage 41 is arranged at the upper end of the output spindle 4. The axial outer end of the first eccentric hole 211 is formed as a first axial impact surface 212, and the upper end surface of the output spindle 4 is formed as a second axial impact surface 412. During the circumferential reciprocating movement of the power spindle 2, the distance between the first axial impact surface 212 and the second axial impact surface 412 changes accordingly. Figure 1

[0046] During the operation of the downhole composite impact tool 100, before the output spindle 4 is rotated upward relative to the power spindle 2 to reach the highest point, the first central passage 21 is sequentially communicated with the first eccentric hole 211, the second eccentric hole 411 and the second central flow passage 41. At this time, there is a certain distance between the axial end surface position provided with the first eccentric hole 211 and the axial end surface position provided with the second eccentric hole 411, and the first eccentric hole 211 is in a fully open state. When the output spindle 4 moves upward to the highest point, the first axial impact surface 212 of the power spindle 2 and the second axial impact surface 412 of the output spindle 4 are in contact and coincide, so that the first eccentric hole 211 and the second eccentric hole 411 overlap and the communication area is minimized. At this time, the first central passage 21 is communicated with the second central flow passage 41 through the overlapping area of the first eccentric hole 211 and the second eccentric hole 411, and a throttle is formed due to the reduction of the overlapping area, thereby generating a pressure pulse. The generated pulse pressure can act on the upper end surface of the output spindle 4, and then be transmitted to the drill bit, so that the output spindle 4 can form further axial impact on the drill bit under the action of the pulse pressure, which is very helpful to enhance the impact force of the drill bit and improve the drilling construction of the drill bit.

[0047] In order 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 be in contact and coincide, 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 follower 52 (see​Figures 1 to 4 )。

[0048] As shown in Figure 7 , an annular limiting groove 43 is arranged on the outer surface of the output spindle 4, a through hole 23 is arranged on the side wall of the power spindle 2, and a drop prevention pin block 6 is mounted in the through hole 23. The axial inner end of the drop prevention pin block 6 extends into the annular limiting groove 43. During the process of entering the well, the drop prevention pin block 6 can play a good anti-drop role, effectively preventing the output spindle 4 from falling off. During installation, the drop prevention pin block 6 passes through the through hole 23 from the outside to the inside and is inserted into the annular limiting groove 43. In order to avoid the drop prevention pin block 6 from falling out during work, a sleeve (not shown) is arranged at the position corresponding to the through hole 23 of the power spindle 2.

[0049] In this embodiment, the axial width of the annular limiting groove 43 is greater than the axial width of the drop prevention pin block 6. Moreover, the value obtained by subtracting the axial width of the drop prevention pin block 6 from the width of the annular limiting groove 43 is greater than the maximum value of the stroke of the axial movement of the output spindle 4 relative to the power spindle 2, so as to ensure that when the output spindle 4 moves upward to the highest point, the position of the axial end face provided with the first eccentric hole 211 can coincide with the position of the axial end face provided with the second eccentric hole 411.

[0050] According to the present application, the output spindle 4 is arranged concentrically inside the lower housing 13, and the cam mechanism 5 is fixedly sleeved on the output spindle 4. As shown in Figures 1 to 3 , the cam 51 in the cam mechanism 5 is configured in a cylindrical shape, and the upper end face of the cam 51 is formed as a continuous first cam face 511. In Figure 5 the embodiment shown, three sections of cam working faces are arranged on the upper end face of the cam 51. Figure 5 The unfolded structure of the cam 51 is shown. The stroke of the axial movement of the driven part 52 driven by the cam 51 is H, that is, the distance between the highest working face and the lowest working face of the cam 51.

[0051] In one embodiment, the inner wall of the cam 51 is provided with an internal thread, and one section of external thread is arranged on the outer wall of the output spindle 4. The cam 51 is fixedly installed on the output spindle 4 in a threaded connection manner. In this way, the cam 51 can rotate synchronously with the output spindle 4.

[0052] As shown in Figure 6 , the driven part 52 is configured in a substantially cylindrical shape, and the inner diameter of the driven part 52 is set to be greater than the outer diameter of the output spindle 4, so that the driven part 52 is in clearance fit with the output spindle 4 and can move along the axial direction of the output spindle 4. The lower end face of the driven part 52 is configured as a continuous second cam face 521. In Figure 6In the shown embodiment, three cam working surfaces are provided on the upper end surface of the follower 52. A plurality of rollers 53 are circumferentially distributed on the lower end surface of the follower 52, and the axis direction of the rollers 53 is along the diameter direction of the follower 52. In the shown embodiment, the first cam surface 511 of the cam 51 is provided with nine rollers 53, which are evenly spaced in the circumferential direction. The follower 52 is in adaptive contact with the first cam surface 511 of 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 in the axial direction under the action of the second cam surface 521, the rollers 53 and the first cam surface 511. Figure 6 In the shown embodiment, nine rollers 53 are provided on the lower end surface of the follower 52, which are evenly spaced in the circumferential direction. The follower 52 is in adaptive contact with the first cam surface 511 of 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 in the axial direction under the action of the second cam surface 521, the rollers 53 and the first cam surface 511.

[0053] In an embodiment not shown, a plurality of circumferentially distributed rollers can also be provided on the first cam surface 511 of the cam 51, so that the upper end surface structure of the cam 51 is the same as the lower end surface structure of the follower 52. Thus, the contact and cooperation between the cam 51 and the follower 52 is formed by two sets of the same cam surface and roller structure. This is more conducive to the transmission between the cam 51 and the follower 52.

[0054] Figure 7 The expanded structure of the adaptive contact between the first cam surface 511 of the cam 51 and the second cam surface 521 of the follower 52 is schematically shown. As shown in the figure, Figure 7 As shown, the axial movement stroke H of the follower 52 is the distance between the highest point and the lowest point of the first cam surface 511 plus the distance between the highest point and the lowest point of the second cam surface 521.

[0055] According to the present application, a limit step 55 with a downward end surface is formed on the inner wall of the housing 1, and the upper end surface of the follower 52 can be lifted by the limit step 55 to connect with the upper drill string of the housing 1. In an embodiment, the lower end of the middle housing 12 extends into the lower housing 13, and the lower end surface of the middle housing 12 is formed as the limit step 55.

[0056] As shown in the figure, Figure 7 Figure 1 As shown in the figure, a limit cylinder 7 is fixed to the lower end of the lower housing 13. In an embodiment, the limit cylinder 7 is fixedly connected to the lower housing 13 by threads. A lower centralizing and anti-wear assembly 8 is provided between the limit cylinder 7 and the output spindle 4. The lower centralizing and anti-wear assembly 8 includes a centralizing and anti-wear dynamic ring and a centralizing and anti-wear static ring formed on the inner wall of the limit cylinder 7. The centralizing and anti-wear dynamic ring is fixedly connected to the output spindle 4, for example by threads. Thus, the wear between the output spindle 4 and the lower housing 13 is effectively prevented by the lower centralizing and anti-wear assembly 8.

[0057] The working process of the downhole composite percussion tool 100 according to the present application is briefly described as follows. First, the downhole composite percussion tool 100 is connected to the lower end of the downhole motor, and after assembly, it is lowered into the wellbore. During the process of being lowered into the wellbore, the drop prevention block 6 and the limiting cylinder 7 can effectively prevent the output spindle 4 from falling off. When the downhole composite percussion tool 100 is lowered to the predetermined position in the well, the drilling tool is started.

[0058] In the normal working state, the downhole power motor drives the power spindle 2 to rotate, and the power spindle 2 drives the output spindle 4 to rotate through the cooperation of the helical spline 42 and the helical spline groove 22, so as to transmit the power of the downhole power motor to the drill bit. At the same time, on the one hand, the output spindle 4 drives the cam 51 to rotate in the rotating process, which makes the follower 52 reciprocate along the axial direction under the cooperation of the second cam surface 521 and the first cam surface 511 of the cam 51, and when moving upward, the upper drill string connected with the housing 1 is lifted until the upward movement H (stroke) reaches the highest point. After passing the highest point, the helical spline 42 tends to disengage, and at this time, the output spindle 41 will have a momentary speed reduction due to the disengagement of the helical spline 42. Further, the upper drill string and the output spindle 4 form axial and circumferential composite impacts on the helical spline 22 through the helical spline groove 42, and transmit the composite impact force to the drill bit. Thus, the drill bit is subjected to axial and circumferential composite impacts.

[0059] On the other hand, during the reciprocating axial movement 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 periodically changes, so that the first eccentric hole 211 and the second eccentric hole 411 periodically overlap to form a throttle, thereby generating a pressure pulse. The generated pulse pressure acts on the upper end surface of the output spindle 4, and then is transmitted to the drill bit, so that the output spindle 4 forms further axial impact on the drill bit under the action of the pulse pressure, which is very helpful to enhance the impact force of the drill bit and improve the drilling construction.

[0060] When the torque of the drill bit is too large, the output spindle 4 can automatically adjust to the downhole working condition, and under the cooperation of the helical spline 22 and the helical spline groove 42, it can be rotated upward relative to the power spindle 2 to absorb a certain torque, so that the output spindle 4 moves upward relative to the power spindle 2, reduces the soil depth of the drill bit, and reduces the torque of the drill bit, which can effectively prevent the downhole motor from producing a lag phenomenon, and is very helpful to improve the downhole working performance of the downhole composite percussion tool 100, greatly improves the drilling construction efficiency, and significantly enhances the drilling construction effect.

[0061] The downhole composite impact tool 100 according to the present application can drive the upper drill string to move axially by the cam mechanism 5, and can form axial and circumferential composite impacts on the screw spline 22 by the helical spline groove 42, so as to generate axial and circumferential composite impact forces on the drill bit. Moreover, the downhole composite impact tool 100 can generate pressure pulses and act on the output main shaft 4, so as to form further axial impacts on the drill bit, which is very beneficial to enhance the impact force of the drill bit and improve the drilling construction. In addition, when the torque of the drill bit is too large, the output main shaft 4 can be automatically adjusted according to the downhole working condition, which can be rotated upward relative to the power main shaft 2 under the cooperation of the screw spline 22 and the helical spline groove 42, so as to reduce the soil depth of the drill bit and reduce the torque of the drill bit, which can effectively prevent the downhole motor from generating the phenomenon of stalling. These are very beneficial to improve the downhole working performance of the downhole composite impact tool 100, greatly improve the drilling construction efficiency, and significantly enhance the drilling construction effect. In addition, the downhole composite impact tool 100 is easy to operate, and can automatically adjust according to the actual downhole working condition during the working process, so it has strong adaptability.

[0062] In the description of the present application, the terms "first", "second" are only used for the purpose of description, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first", "second" can explicitly or implicitly include one or more of the features. In the description of the present application, the meaning of "a plurality of" is two or more, unless otherwise specifically limited.

[0063] In the present application, unless otherwise specifically defined and limited, the terms "mounting", "connection", "connection", "fixing" and the like should be understood in a broad sense, for example, it can be fixedly connected, or it can be detachably connected, or it can be integrally connected; it can be mechanically connected, or it can be electrically connected; it can be directly connected, or it can be indirectly connected through an intermediate medium; it can be the communication inside two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0064] In the description of the present application, the description of the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present application. In the present application, the illustrative description of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0065] Finally, it should be noted that the above only describes the preferred embodiments of the present application and does not constitute any limitation on the present application. Although the present application is described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions recorded in the foregoing embodiments or make equivalent replacements to some technical features thereof. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A downhole composite impact tool, comprising: a housing (1) configured in a cylindrical shape; a power spindle (2) for connecting a downhole power motor, the power spindle being arranged concentrically within the housing and rotatable relative to the housing, the power spindle being provided with a first central flow passage (21) extending in an axial direction, and a helical spline groove (22) being provided on an inner wall surface of the power spindle; an output spindle (4) for connecting a drill bit, the output spindle being provided with a second central flow passage (41) extending in an axial direction, and a helical spline (42) being provided on an outer wall surface of the output spindle and being adapted to the helical spline groove; a cam mechanism (5) comprising a cam (51) fixedly sleeved on the output spindle and a follower (52) at an upper end of the cam, an upper end surface of the cam being configured as a continuous first cam surface (511), a lower end surface of the follower being configured as a second cam surface (521) adapted to the first cam surface, and a plurality of circumferentially distributed rollers (53) being provided on the second cam surface, and a limit step (55) with a downward end surface being formed on an inner wall of the housing, and an upper end surface of the follower being able to be lifted by the limit step to connect with an upper drill string of the housing; wherein the power spindle is able to rotate the output spindle, the follower is able to reciprocate in an axial direction under the action of the cam, and lift the upper drill string connected with the housing, so that the upper drill string is able to form axial and circumferential composite impacts on the helical spline through the helical spline groove after the output spindle moves to the highest point of stroke under the action of the weight on bit, and transmit to the drill bit.

2. The downhole composite impact tool of claim 1, wherein, The axial direction of the rollers is arranged along the diameter direction of the follower.

3. The downhole composite impact tool of claim 1, wherein, The helical pitch of the helical spline is arranged in a range of 100-800 mm, and the helix angle of a helix line formed by the helical extension of the helical spline is arranged in a range of 5-85 degrees.

4. The downhole composite impact tool of claim 1 or 3, wherein, The width of the helical spline is arranged in a range of 40-200 mm, and the depth is arranged in a range of 5-20 mm.

5. The downhole composite impact tool of claim 1, wherein, A first eccentric hole (211) in communication with the first central passage is provided in the power spindle, the first eccentric hole being at an axial inner end of the helical spline groove, a second eccentric hole (411) in communication with the second central flow passage is provided at an upper end of the output spindle, and the first eccentric hole and the second eccentric hole are able to form a throttle when they overlap, thereby generating a pressure pulse.

6. The downhole compound impact tool of claim 5, wherein, The axial outer end of the first eccentric hole is formed as a first axial impact surface, the upper end surface of the output spindle is formed as a second axial impact surface, and 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.

7. The downhole composite impact tool of claim 1, wherein, An annular limit groove (43) is provided on the outer surface of the output spindle, a through hole (23) is provided on the side wall of the power spindle, a limit block (6) is installed in the through hole, and the axial inner end of the limit block extends into the annular limit groove. The axial width of the annular limit groove is greater than the width of the limit block.

8. The downhole composite impact tool of claim 1, wherein, A bearing string (3) is sleeved on the power spindle, the bearing string is between the shell and the power spindle, and first and second upper centralizing anti-wear assemblies (31 and 32) are arranged at two ends of the bearing string respectively.

9. The downhole compound impact tool of claim 8, wherein, A limiting cylinder (7) is fixed to the lower end of the shell, and a lower centralizing anti-wear assembly (8) is arranged between the limiting cylinder and the output spindle.

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