Negative pressure oscillation tool for drilling tools

Abstract

The application discloses a negative pressure oscillation tool for a drilling tool, comprising a negative pressure pulse generating unit, a power generating unit and a power output unit connected in sequence. The power generating unit comprises a hollow cylindrical stator shell and a screw rotor installed in the stator shell. The negative pressure pulse generating unit comprises a body with a central channel, which is installed in the stator shell and connected with the screw rotor. The body is configured to periodically change the flow of fluid flowing through the central channel into the stator shell, so that the screw rotor generates periodic pressure fluctuations, thereby forming a composite impact force of axial and torsional and transmitting to the power output unit.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of oil and gas drilling equipment, and particularly relates to a negative pressure oscillation tool for a drilling tool for realizing drilling speed-up in oil and gas exploration and development. BACKGROUND

[0002] With the continuous development of oil and gas exploration and development, the fields of deep well and ultra-deep well drilling, deepwater offshore drilling, shale oil / gas exploitation, hot dry rock geothermal resource development, energy development and scientific drilling are continuously broadened, the drilled strata are more ancient, the rock strength is large, the abrasiveness is high, and the drillability is poor. This will cause severe bouncing of the drilling tool, and eventually lead to slow drilling speed, long drilling cycle and gradually increasing drilling cost. Therefore, the demand for drilling speed-up in the field of drilling is increasingly strong.

[0003] Rotary percussion drilling technology is one of the existing methods for fast drilling. In this technology, various percussion drilling tools are used to generate high-frequency impact dynamic load by driving a hammer with drilling fluid, which can make the rock produce volume crushing, thereby improving the rock breaking efficiency. In addition, by combining the screw rod composite double-drive drilling technology with the impact rotary drilling technology, a composite impact drilling technology is formed, and the speed-up effect is also relatively obvious. In addition, a screw rod rotary table double-drive composite drilling technology is also proposed, which improves the rotary speed and cutting strength by optimizing a high-power screw rod. In the rotary percussion drilling process, the drilling pressure keeps the cutting teeth in close contact with the rock, and the impact load instantaneously increases the rock crushing specific work. At the crack formed by the impact, the rock is further crushed and rotary shearing broken under the high rotation speed of the screw rod, thereby improving the rock breaking efficiency.

[0004] However, when the rock breaking capacity of the drill bit is insufficient, the drill bit that bites into the rock will instantaneously stop rotating. In this case, the drill string remains rotating until the energy accumulated at the drill bit reaches the critical value of shearing the stratum. At this time, the drill bit instantaneously rotates at high speed and releases the drill string energy, and then the entire drill string enters a "stuck-slip" cycle. The occurrence of the "stuck-slip" phenomenon directly causes irregular vibration and exerts a much higher impact load on the teeth of the drill bit than usual, resulting in premature failure of the drill bit. At the same time, this "stuck-slip" phenomenon also shortens the service life of the bottom hole assembly, and eventually also affects the wellbore quality. The above rotary percussion drilling technology, composite impact drilling technology and screw rod rotary table double-drive composite drilling technology cannot well solve this "stuck-slip" phenomenon. SUMMARY

[0005] In view of the above technical problems, the applicant of the present application has found through research that by periodically applying a composite impact effect of both torsional impact and axial impact at the end of the drill bit, the rock breaking efficiency of the drill bit can be improved, and a series of problems caused by the "stuck-slip" phenomenon in the drilling process can be effectively alleviated.

[0006] Therefore, the application provides a negative pressure vibration tool for a drilling tool, which comprises a negative pressure pulse generating unit, a power generating unit and a power output unit connected in sequence. The power generating unit comprises a hollow cylindrical stator shell and a screw rotor installed in the stator shell. The negative pressure pulse generating unit comprises a body with a central passage, which is installed in the stator shell and connected with the screw rotor. The body is configured to periodically change the flow of fluid flowing into the stator shell through the central passage, so that the screw rotor generates periodic pressure fluctuations, thereby forming axial and torsional composite impact force and transmitting to the power output unit.

[0007] According to a preferred embodiment of the application, the body is provided with radially extending first through holes, and the stator shell is provided with radially extending second through holes. The body rotates under the driving of the screw rotor, causing the first through holes to periodically communicate or not communicate with the second through holes, so that part of the fluid flowing through the central passage is discharged into the annulus outside the stator shell through the first and second through holes.

[0008] According to a preferred embodiment of the application, the first through holes and / or the second through holes are configured to gradually increase in diameter towards the radial outside.

[0009] According to a preferred embodiment of the application, the diameter of the first through holes is smaller than the diameter of the second through holes.

[0010] According to a preferred embodiment of the application, an equal number of first through holes and second through holes are uniformly arranged circumferentially.

[0011] According to a preferred embodiment of the application, the body is connected with the screw rotor through a first universal shaft assembly.

[0012] According to a preferred embodiment of the application, the power generating unit is connected with the power output unit through a current collecting unit. The current collecting unit comprises a hollow cylindrical shell, a second universal shaft assembly and a current collecting piece installed in the cylindrical shell. The second universal shaft assembly is connected with the screw rotor, and the current collecting piece is connected with the power output spindle of the power output unit.

[0013] According to a preferred embodiment of the application, the current collecting piece comprises an upstream portion with a smaller diameter and a downstream portion with a larger diameter. The upstream portion and the downstream portion are connected with each other through a transition slope or arc surface.

[0014] According to a preferred embodiment of the present application, a plurality of flow converging holes are arranged in the upstream portion, and each of the flow converging holes is arranged in a manner that is inclined toward the downstream in a direction of the radial inward.

[0015] According to a preferred embodiment of the present application, the negative pressure oscillation tool further comprises a bypass valve arranged upstream of the negative pressure pulse generating unit. BRIEF DESCRIPTION OF DRAWINGS

[0016] The present application will be described in detail below with reference to the accompanying drawings, in which:

[0017] Figure 1 schematically shows the structure of a first portion of a negative pressure oscillation tool according to an embodiment of the present application;

[0018] Figure 2 schematically shows the structure of a second portion of a negative pressure oscillation tool according to an embodiment of the present application;

[0019] Figure 3 For Figure 1 schematically shows the structure of a flow converging member in a negative pressure oscillation tool according to an embodiment of the present application.

[0020] Figure 4 schematically shows the structure of a flow converging member in a negative pressure oscillation tool according to an embodiment of the present application.

[0021] In the drawings, the same components are designated by the same reference numerals. The drawings are not drawn to scale. DETAILED DESCRIPTION

[0022] The present application will be further described below with reference to the accompanying drawings. For the convenience of understanding, in the present specification, the directional terms "longitudinal" or "axial" refer to the direction along the length of the negative pressure oscillation tool, i.e. the left-right direction in Figure 1 and 2 the horizontal direction, the term "transverse" or "radial" refers to the direction perpendicular to the "longitudinal" or "axial" direction, i.e. the vertical direction in Figure 1 and 2 the vertical direction, the term "upstream" or "up" or similar terms refer to the direction close to the wellhead, i.e. the left end direction in Figure 1 and 2 the left end direction, and the term "downstream" or "down" or similar terms refer to the direction away from the wellhead, i.e. the right end direction in Figure 1 and 2 the right end direction.

[0023] Figure 1 and 2 collectively schematically shows a negative pressure oscillation tool 100 according to an embodiment of the present application, wherein Figure 1 shows a first portion of the negative pressure oscillation tool 100, andFigure 2 The second part of the negative pressure oscillation tool 100 is shown. It should be noted that the division of the first part and the second part of the negative pressure oscillation tool 100 is only for the convenience of the display of the drawings, and does not have any limiting effect on the actual structure of the negative pressure oscillation tool 100.

[0024] As shown in Figure 1 , the negative pressure oscillation tool 100 includes an upper joint 10 at the most upstream, and is connected with other parts of the drilling tool through the upper joint 10. A central passage 25 is defined in the upper joint 10 for the passage of downhole fluid. The downhole fluid is, for example, drilling fluid, and for the sake of convenience, the drilling fluid will be taken as an example in the following description. A bypass valve 20 is installed in the upper joint 10. The upper joint 10 and the bypass valve 20 are both components well known in the art, and the relevant detailed description is omitted here.

[0025] The negative pressure oscillation tool 100 according to the present application further includes a negative pressure pulse generating unit 30, and a power generation unit 40. As shown in Figure 1 , the power generation unit 40 includes a stator housing 42, which is configured as a hollow cylinder. The upstream end of the stator housing 42 is fixedly connected with the downstream end of the upper joint 10, for example by threaded connection. A screw rotor 44 is arranged in the stator housing 42.

[0026] According to the present application, the negative pressure pulse generating unit 30 is arranged in the stator housing 42 of the power generation unit 40, and is fixedly connected with the screw rotor 44. Preferably, the negative pressure pulse generating unit 30 is connected with the screw rotor 44 through a first universal shaft assembly 50. The first universal shaft assembly 50 can take the form of a cross-shaped universal shaft or a petal-shaped universal shaft, etc. By using the first universal shaft assembly 50 to connect the negative pressure pulse generating unit 30 and the screw rotor 44 of the power generation unit 40, it can be ensured that the planetary motion of the screw rotor 44 is converted into stable rotation and coaxiality of the negative pressure pulse generating unit 30.

[0027] As shown in Figure 1 , the negative pressure pulse generating unit 30 includes a cylindrical body 35, which is mounted in the corresponding inner cavity of the stator housing 42. The body 35 defines a central passage 32, which is always in communication with the central passage 25 of the upper joint 10, for receiving the drilling fluid from the central passage 25 of the upper joint 10.

[0028] As shown in Figure 3 , according to the present application, the body 35 of the negative pressure pulse generating unit 30 includes a first through hole 38 extending radially, which is in communication with the central passage 32 and extends through the entire body 35. At the same time, the stator housing 42 of the power generation unit 40 includes a second through hole 48 extending radially.

[0029] Therefore, during operation, the screw rotor 44 is rotated by the impact of the drilling fluid and drives the body 35 of the negative pressure pulse generating unit 30 to rotate via the first universal shaft assembly 50. After rotating for a certain angle, the first through hole 38 of the body 35 and the second through hole 48 of the stator housing 42 are in communication with each other. In this case, part of the drilling fluid will be discharged from the central passage 32 of the body 35 to the annulus outside the stator housing 42 through the first through hole 38 of the body 35 and the second through hole 48 of the stator housing 42. After continuing to rotate, the first through hole 38 of the body 35 and the second through hole 48 of the stator housing 42 are disconnected from each other. At this time, all the drilling fluid will flow in the downstream direction only through the central passage 32 of the body 35. With the rotation of the body 35 of the negative pressure pulse generating unit 30, the first through hole 38 of the body 35 and the second through hole 48 of the stator housing 42 will be alternately communicated and disconnected, forming a periodic opening and closing effect.

[0030] Therefore, on the one hand, the discharge of the drilling fluid to the annulus can reduce the overall pressure drop of the drilling tool. On the other hand, the remaining drilling fluid will form a hydraulic pulse pressure inside the negative pressure oscillation tool 100, which will generate a periodic axial impact force on the power output main shaft 72 (to be introduced below) located downstream. Figure 2 At the same time, since the discharge of the drilling fluid inside the negative pressure oscillation tool 100 is periodically changed, the circumferential torque output by the screw rotor 44 to the power output main shaft 72 will also be periodically changed, thereby generating a periodic torsional impact force. In this way, the periodically changed axial impact force and the periodically changed torsional impact force, as described above, together form a periodically changed composite impact force, which can greatly reduce friction and reduce the "stick-slip" phenomenon, and effectively reduce the occurrence of complex situations such as directional overpressure or sticking.

[0031] It is easy to understand that although only one first through hole 38 and one second through hole 48 are shown in the Figure 3 , the number of first through holes 38 and second through holes 48 can be appropriately selected according to actual needs. Both the first through holes 38 and the second through holes 48 can be provided in multiple numbers, and the number of first through holes 38 can be equal to, more than, or less than the number of second through holes 48.

[0032] In an embodiment not shown, the first through hole 38 and the second through hole 48 are both configured to have a variable diameter. Specifically, the diameters of the first through hole 38 and the second through hole 48 are both arranged to gradually increase in the radial outward direction (i.e., towards the annulus). Through this arrangement, the periodic change of the drilling fluid discharge can be enhanced, while the resistance of fluid discharge is reduced, further enhancing the effect of the periodic composite impact force.

[0033] In addition, according to one embodiment of the present application, the first through hole 38 is arranged to be smaller than the second through hole 48. In this way, when the first through hole 38 and the second through hole 48 are in communication with each other, the drilling fluid in the first through hole 38 can be discharged through the second through hole 48 in a very short time, thereby intensifying the periodic variation of the drilling fluid discharge and further enhancing the effect of the periodic combined impact force.

[0034] The negative pressure oscillation tool 100 according to the present application further comprises a flow converging unit 60 and a power output unit 70. As shown in Figure 2 the flow converging unit 60 comprises a hollow cylindrical shell 61 defining an internal passage 63, a second universal shaft assembly 62 and a flow converging member 65 mounted in the shell 61. The second universal shaft assembly 62 is connected to the screw rotor 44 of the power generation unit 40, which can be in the form of a cross-shaped universal shaft or a petal-shaped universal shaft.

[0035] The flow converging member 65 is connected downstream of the second universal shaft assembly 62, which comprises an upstream portion 66 with a smaller diameter and a downstream portion 67 with a larger diameter, as shown in Figure 4 The flow converging member 65 has a central passage 69. A transition slope or curved surface is provided between the upstream portion 66 with a smaller diameter and the downstream portion 67 with a larger diameter. On the one hand, such an arrangement can reduce stress concentration and increase the connection strength between the two portions. On the other hand, the upstream portion 66 with a smaller diameter reduces fluid resistance, which is beneficial to reduce the overall pressure drop of the drilling tool.

[0036] As shown in Figure 4 According to the present application, a plurality of flow converging holes 68 are arranged in the upstream portion 66 with a smaller diameter of the flow converging member 65 in a circumferentially uniform manner. Each flow converging hole 68 is arranged in a manner that it is inclined towards the downstream along the radially inward direction. In this way, a portion of the drilling fluid located inside the flow converging unit 60 but outside the flow converging member 65 will enter the central passage 69 of the flow converging member 65 from the internal passage 63 of the flow converging unit 60 through the flow converging holes 68, so that all the drilling fluid will flow downstream from the central passage 69 of the flow converging member 65. This significantly improves the utilization efficiency of the drilling fluid.

[0037] As shown in Figure 2As shown, the power output unit 70 of the negative pressure oscillation tool 100 according to the present application mainly comprises a housing 75 and a power output spindle 72 installed in the housing 75. The upstream end of the housing 75 is fixedly connected with the housing 61 of the flow combining unit 60, and the downstream end is fixedly connected with the lower joint 80. The power output spindle 72 is fixedly connected with the flow combining member 65 and has a central passage communicating with the central passage 69 of the flow combining member 65. The power output spindle 72 is connected with a lower drill bit (not shown) in the drill string and transmits the impact force from the power generating unit 40 to the drill bit. The power output unit 70 and the lower joint 80 are both components well known in the art, and the relevant detailed description is omitted here.

[0038] The negative pressure oscillation tool according to the present application can be installed on a downhole drill string to improve the rock breaking efficiency of a drill bit. Specifically, the negative pressure oscillation tool according to the present application comprises a negative pressure pulse generating unit capable of periodically discharging a portion of drilling fluid into the annulus. In this way, the screw in the negative pressure oscillation tool generates periodic pressure fluctuations, forming hydraulic pulses. On one hand, due to the action of the hydraulic pressure, the lower end of the screw generates a periodically changing axial impact force, which acts on the power output spindle and is further transmitted to the drill bit. On the other hand, the pressure fluctuations of the drilling fluid cause the torque of the screw to change, generating a changing torsional impact force. The axial impact force and the torsional impact force combine to form a periodically changing combined impact force, which can play an auxiliary rock breaking role and greatly improve the rock breaking efficiency of the drill bit. At the same time, due to the pressure relief effect of the drilling fluid discharged into the annulus, the overall pressure drop of the screw is reduced to some extent. Therefore, especially in directional wells and complex trajectory wellbores, the negative pressure oscillation tool according to the present application can reduce friction and reduce the "stick-slip" phenomenon, and effectively reduce the occurrence of complex situations such as directional pressure holding or sticking.

[0039] The above merely describes the preferred embodiments of the present application, but the protection scope of the present application is not limited thereto. Those skilled in the art can easily make changes or modifications within the scope of the present application, and such changes or modifications shall be encompassed in the protection scope of the present application. Therefore, the protection scope of the present application shall be subject to the protection scope of the claims.

Claims

1. A negative pressure oscillation tool (100) for a drilling tool, comprising a negative pressure pulse generating unit (30), a power generating unit (40) and a power output unit (70) connected in sequence, wherein, The power generation unit (40) comprises a stator shell (42) in the form of a hollow cylinder, and a screw rotor (44) mounted inside the stator shell (42), the negative pressure pulse generation unit (30) comprises a body (35) with a central passage (32), the body (35) is mounted in the stator shell (42) and connected with the screw rotor (44), the body (35) is provided with radially extending first through holes (38), the stator shell (42) is provided with radially extending second through holes (48), the first through holes and / or the second through holes are configured to gradually increase in diameter towards the radial outside, Wherein, the body (35) rotates under the driving of the screw rotor (44), causing the first through holes (38) and the second through holes (48) to periodically communicate or not communicate, thereby causing a part of the fluid flowing through the central passage (32) to be discharged into the annulus outside the stator shell (42) through the first through holes (38) and the second through holes (48), and further causing the body (35) to be configured to periodically change the flow of the fluid flowing through the central passage (32) into the stator shell (42), so that the screw rotor (44) generates periodic pressure fluctuations, thereby forming a composite impact force of axial and torsional and transmitting to the power output unit (70).

2. The negative pressure oscillation tool of claim 1, wherein, The diameter of the first through hole is smaller than the diameter of the second through hole.

3. A negative pressure oscillation tool according to claim 1 or 2, characterized in that, A plurality of first through holes (38) and second through holes (48) are arranged uniformly in the circumferential direction.

4. The negative pressure oscillation tool of claim 1 or 2, wherein, The body (35) is connected with the screw rotor (44) through a first universal shaft assembly (50).

5. The negative pressure oscillation tool of claim 1 or 2, wherein, The power generation unit (40) is connected with the power output unit (70) through a current collecting unit (60), Wherein, the current collecting unit (60) comprises a hollow cylindrical shell (61), and a second universal shaft assembly (62) and a current collecting piece (65) mounted in the cylindrical shell (61), the second universal shaft assembly (62) is connected with the screw rotor (44), and the current collecting piece (65) is connected with the power output spindle (72) of the power output unit (70).

6. The negative pressure oscillation tool of claim 5, wherein, The current collecting piece (65) comprises an upstream portion (66) with a smaller diameter and a downstream portion (67) with a larger diameter, wherein the upstream portion (66) and the downstream portion (67) are connected with each other through a transition slope or arc surface.

7. The negative pressure oscillation tool of claim 6, wherein, A plurality of current collecting holes (68) are arranged uniformly in the circumferential direction in the upstream portion (66), and each current collecting hole (68) is arranged in a way that it is inclined towards the downstream along the radially inward direction.

8. The negative pressure oscillation tool of claim 1 or 2, wherein, The negative pressure oscillation tool (100) further comprises a bypass valve (20) arranged upstream of the negative pressure pulse generation unit (30).

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