An efficient directional milling and drilling tool

Abstract

The present invention discloses an efficient directional milling and drilling tool, which includes a drill bit body, an outer casing, a universal shaft assembly, and a positive displacement motor assembly. Cutting teeth are inlaid on the drill bit body. The positive displacement motor assembly is composed of a positive displacement stator and a positive displacement rotor. The upper part of the universal shaft assembly is fixedly connected to the positive displacement rotor, and the lower part is fixedly connected to the drill bit body. The present invention also provides a directional elbow, which is connected between the outer casing and the drill bit body. An internal gear structure is arranged inside the directional elbow. The universal shaft assembly is an eccentric shaft structure, and an external gear structure is arranged on its outside. Driven by the eccentric rotating shaft, the internal gear structure and the external gear structure form a planetary gear drive mechanism with a small tooth difference. The beneficial effect of the present invention is that the planetary gear drive mechanism with a small tooth difference can drive the directional elbow to rotate, thereby adjusting the direction of the drill bit body, achieving flexible adjustment of the directional direction, and realizing the purpose of efficient directional milling and drilling.

Description

Technical Field

[0001] The present invention relates to an efficient directional milling and drilling tool for use in the field of window cutting and sidetracking in the oil and gas industry. Background Art

[0002] As the oilfield development enters the middle and late stages, due to long-term injection-production, fish falling, formation movement and other reasons, there are more and more inefficient wells, casing damaged wells, and abandoned wells. Drilling infill wells or renewal wells will cause a substantial increase in the oil production cost. At the same time, a large number of studies on fine reservoir description, remaining reservoir distribution, etc. carried out in recent years have proved that there are still a large number of remaining reservoirs in the near-well zone of a large number of abandoned old wells, and the production cost can be greatly reduced by window cutting and sidetracking through the original well.

[0003] The window cutting and sidetracking technology uses a whipstock and a window cutting mill to grind through the casing at the designed position to form a sidetracking window, and then uses a sidetracking tool to drill a new wellbore. As a repair method for casing damaged wells, the window cutting and sidetracking technology has become a powerful measure for increasing oilfield production and efficiency. It can drill a wellbore with a long well section and a large displacement in the original wellbore, and can also exploit the remaining oil or new reservoirs that cannot be exploited by the original wellbore. At present, there are two methods for casing sidetracking technology at home and abroad, namely section milling sidetracking and window cutting sidetracking. However, the section milling sidetracking has a long construction time, complex processes and is prone to accidents, so the window cutting sidetracking is mostly used on site. The window cutting sidetracking needs to use a milling tool to grind through one side of the casing to form a window and open a channel for subsequent open hole drilling.

[0004] To grind through the casing at the specified position, the milling tool needs to have good directional performance.

[0005] Aiming at the technical problems existing in the directional process of the milling tool in the above window cutting and sidetracking process, the present invention provides an efficient directional milling and drilling tool. Summary of the Invention

[0006] The purpose of the present invention is to provide an efficient directional milling and drilling tool to solve the problems of difficult orientation of the milling tool and low milling efficiency in the window cutting and sidetracking process.

[0007] To achieve the above purpose, the present invention adopts the following technical solutions: An efficient directional milling and drilling tool includes a drill bit body, an outer casing body, a universal shaft assembly, and a positive displacement motor assembly. Cutting teeth are inlaid on the drill bit body. The positive displacement motor assembly consists of a positive displacement stator and a positive displacement rotor. The universal shaft assembly includes an upper sub, a lower sub, and a connecting rod body. The connecting rod body includes an upper connecting rod body and a lower connecting rod body. The upper part of the universal shaft assembly is fixedly connected to the positive displacement rotor, and the lower part is fixedly connected to the drill bit body. A directional bend pipe is arranged between the outer casing body and the drill bit body. An internal gear is arranged in the directional bend pipe. The universal shaft assembly is an eccentric shaft structure. The universal shaft assembly is provided with an external gear. The internal gear and the external gear form a planetary gear drive mechanism with a small tooth difference.

[0008] In the above solution, the universal shaft assembly is connected to the screw rotor through the upper joint and to the drill bit body through the lower joint. The rotation of the drill bit body is provided by the power from the screw rotor through the universal shaft assembly. The directional elbow is composed of two elbows with intersecting axes. The upper part of the directional elbow forms a rotational and translational connection with the screw stator, and the lower part of the directional elbow forms a fixed connection with the outer casing of the drill bit body. Since an internal gear is provided inside the directional elbow and an external gear is provided on the universal shaft assembly, when the internal gear meshes with the external gear, the directional elbow rotates together with the screw stator, and the drill bit rotates together with the screw rotor. At this time, the orientation of the directional elbow, that is, the orientation of the drill bit body, can be flexibly adjusted, thus preparing for directional milling drilling. When the drilling pressure is increased, the screw moves downward (towards the bottom of the well) and compresses the elastic reset. At this time, the meshing relationship between the internal gear and the external gear is disengaged, and the position of the directional elbow does not change. The rotation of the screw rotor only transmits the rotational motion to the drill bit body through the universal shaft assembly. At this time, the drill bit body can perform milling drilling in the specified direction under the action of the directional elbow, thereby achieving the purpose of directional milling drilling. When the drilling pressure is reduced or the tool is lifted, the internal gear and the external gear are in the meshing state again.

[0009] Preferably, the meshing of the internal gear and the external gear constitutes a differential gear drive mechanism with few teeth difference.

[0010] In the above solution, the differential gear drive with few teeth difference is a special gear drive method, mainly composed of an internal meshing gear pair with a very small tooth difference and an output mechanism. The characteristic of this drive method is that the tooth difference between the internal gear and the external gear is usually 1 to 4 teeth. The principle of the differential gear drive with few teeth difference is to transmit power through a gear pair with a very small tooth difference and utilize the meshing of the internal gear and the external gear. Due to the very small tooth difference, the transmission ratio is large, and a relatively high torque output can be provided. The smaller the tooth difference between the two, the larger the reduction ratio; the larger the tooth difference, the larger the speed increase ratio, which can achieve the purpose of adjusting the drill bit rotation speed.

[0011] Preferably, the universal shaft assembly includes an upper joint, a lower joint, and a connecting rod body. The connecting rod body includes an upper connecting rod body and a lower connecting rod body. The upper connecting rod body and the lower connecting rod body are connected by a spline. Flow channels are provided inside both the upper connecting rod body and the lower connecting rod body, and the outer part of the upper connecting rod body has an eccentric shaft feature.

[0012] In the above solution, the upper connecting rod body and the lower connecting rod body are connected by a spline. On the one hand, the spline has strong torque transmission ability. On the other hand, the spline allows a relative sliding amount between the upper connecting rod body and the lower connecting rod body, so that the upper connecting rod body will not affect the lower connecting rod body during the downward or upward movement. The flow channels provided inside the connecting rod body can enable the drilling fluid to smoothly enter the water eye of the drill bit body and the wellbore annulus, thereby forming a fluid channel. The eccentric shaft feature on the outer part of the upper connecting rod body provides rotational power for the external gear part of the differential gear drive mechanism with few teeth difference.

[0013] Preferably, a reset elastic element is provided between the directional elbow and the outer housing, and the directional elbow is movably connected to the outer housing.

[0014] In the above solution, the reset elastic element can play the role of energy storage and buffering. On the one hand, it avoids the rigid impact caused by the direct contact between the directional elbow and the outer housing, playing a role in protecting the directional elbow and the outer housing; on the other hand, it provides additional resilience when the drill string is lifted or the drilling pressure is reduced, making the reset more flexible.

[0015] Preferably, the directional elbow and the screw stator are connected by a ball bearing.

[0016] In the above solution, on the one hand, the ball bearing can bear a large load and has high safety; on the other hand, it can make the relative rotation between the directional elbow and the screw stator more flexible; at the same time, it plays the role of connection and anti-falling.

[0017] Preferably, the directional elbow and the bit body are connected by a ball bearing.

[0018] Preferably, a bypass water eye is provided on the lower joint of the universal shaft assembly.

[0019] In the above solution, the bypass water eye provides a larger space for the flow of drilling fluid.

[0020] Preferably, the cutting teeth include at least one of PDC teeth, impregnated teeth, and cemented carbide teeth.

[0021] In the above solution, different cutting teeth or bits can be selected according to different sidetracking processes.

[0022] Preferably, the crown profile of the bit body is conical, spherical, or flat-bottomed.

[0023] In the above solution, different crown profile types can be selected according to different sidetracking processes or formation properties.

[0024] The beneficial effects of the present invention are as follows: (1) The orientation placement of the bit body of the present invention is independent of the milling and drilling process, and it can achieve flexible and precise orientation of the milling tool, avoiding the phenomenon that the orientation of the bit body changes during the drilling process of the conventional milling tool, resulting in frequent adjustment of the orientation of the bit body due to orientation deviation, and improving the efficiency of directional milling and drilling; (2) The present invention uses a planetary gear drive mechanism with a small tooth difference to achieve power transmission, with a large transmission ratio, capable of providing a high torque output and transmission efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 is a schematic structural diagram of an efficient directional milling and drilling tool of the present invention.

[0026] Figure 2 is a schematic diagram of the planetary gear drive mechanism with a small tooth difference.

[0027] Figure 3 It is a schematic diagram of the crown profile of the drill bit body being conical.

[0028] Figure 4 It is a schematic diagram of the crown profile of the drill bit body being spherical.

[0029] Figure 5 It is a schematic diagram of the crown profile of the drill bit body being flat-bottomed.

[0030] Figure 6 It is a schematic diagram of the loading drilling state of an efficient directional milling and drilling tool of the present invention.

[0031] Among them, 1 - drill bit body; 11 - cutting teeth; 2 - outer casing; 3 - universal joint assembly; 31 - lower sub; 311 - side water holes; 32 - upper sub; 33 - lower connecting rod body; 34 - upper connecting rod body; 4 - positive displacement motor assembly; 41 - stator of the positive displacement motor; 42 - rotor of the positive displacement motor; 5 - directional elbow; 6 - internal gear; 7 - external gear; 8 - reset elastic element; 9 - ball bearing. Specific embodiments

[0032] Such as Figure 1 , Figure 2 , Figure 6As shown in the figure, an efficient directional milling drilling tool of the present invention is composed of a bit body 1, a housing body 2, a universal shaft assembly 3, and a positive displacement motor assembly 4. Cutting teeth 11 are inlaid on the bit body 1. The positive displacement motor assembly 4 is composed of a positive displacement stator 41 and a positive displacement rotor 42. The upper part of the universal shaft assembly 3 is fixedly connected to the positive displacement rotor 42, and the lower part is fixedly connected to the bit body 1. A directional elbow 5 is arranged between the housing body 2 and the bit body 1. An internal gear 6 is arranged inside the directional elbow 5. The universal shaft assembly 3 is of an eccentric shaft structure. The universal shaft assembly 3 is provided with an external gear 7. The external gear 7 and the internal gear 6 are in a meshing relationship, and when meshing, they form a differential drive mechanism. The differential drive is a special gear drive method, mainly composed of a pair of internally meshing gears with a small tooth difference and an output mechanism. The characteristic of this drive method is that the tooth difference between the internal gear and the external gear is usually 1 to 4 teeth. The principle of the differential drive is to transmit power through a pair of gears with a small tooth difference, and utilize the meshing of the internal gear and the external gear to achieve power transmission. Due to the small tooth difference, the transmission ratio is large, and a high torque output can be provided. The smaller the tooth difference between the two, the larger the reduction ratio; the larger the tooth difference, the larger the speed increase ratio, which can achieve the purpose of adjusting the bit rotation speed. The universal shaft assembly 3 includes an upper joint 32, a lower joint 31, and a connecting rod body. The connecting rod body includes an upper connecting rod body 34 and a lower connecting rod body 33. The upper connecting rod body 34 and the lower connecting rod body 33 are connected by splines. Flow channels are arranged inside both the upper connecting rod body 34 and the lower connecting rod body 33. The outside of the upper connecting rod body 34 has an eccentric shaft feature, and the upper connecting rod body 34 and the lower connecting rod body 33 can slide relative to each other. A reset elastic element 8 is arranged between the directional elbow 5 and the housing body 2, and the directional elbow 5 forms a movable connection relative to the housing body 2. To make the relative rotation between the directional elbow and the positive displacement stator more flexible, and at the same time play a role in connection and anti-falling, the directional elbow 5 and the positive displacement stator 41 are connected by a ball bearing, and at the same time the directional elbow 5 and the bit body 1 are connected by a ball bearing. To provide a larger flow space for the flow of drilling fluid, a bypass water eye is arranged on the lower joint 31 of the universal shaft assembly 3.

[0033] As Figure 3 , Figure 4 , Figure 5As shown in the figure, in order to enable the milling tool to adapt to different drilling requirements, the crown profile of the milling drilling tool is set to be conical, spherical and flat-bottomed. During the drill bit design process, a plane passing through the central axis of the drill bit is usually arbitrarily determined as the tooth-arrangement axis plane (also simply referred to as the axis plane), and the radial and axial positions of each cutting tooth on the drill bit can be accurately expressed on this axis plane. When the drill bit rotates around its own axis under the condition of unchanged axial position, the tooth-edge contour line of the cutting tooth intersects with the axis plane to form an intersection line, which is the axis-plane contour line of the cutting tooth. Then, the axis-plane contour lines of all the main cutting teeth (or all the main cutting teeth on several specified blades) on the drill bit are gathered in this axis plane to form the axis-plane tooth-arrangement diagram of the drill bit (or the axis-plane tooth-arrangement diagram of several specified blades). Because the axis-plane tooth-arrangement diagram can accurately reflect the radial coverage of the cutting teeth on the drill bit on the bottom-hole rock, it is also called the bottom-hole coverage tooth-arrangement diagram, simply referred to as the coverage tooth-arrangement diagram or the bottom-hole coverage diagram. In the bottom-hole coverage diagram of the drill bit, an outer envelope curve tangent to the axis-plane contour lines of all the main cutting teeth is made, which is the cutting contour line of the drill bit (that is, the crown profile of the drill bit).

[0034] As Figure 1 and Figure 6 shown, the working principle of an efficient directional milling drilling tool of the present invention is as follows: The universal shaft assembly 3 is connected to the screw rotor 42 through the upper sub 32 and connected to the bit body 1 through the lower sub 31. The rotation of the bit body 1 is provided by the power provided by the screw rotor 42 through the universal shaft assembly 3. The directional bend 5 is composed of two bends with intersecting axes. The upper part of the directional bend 5 forms a rotational and translational connection with the screw stator 41, and the lower part of the directional bend 5 forms a fixed connection with the outer casing of the bit body 1. Since an internal gear 6 is arranged in the directional bend 5 and an external gear 7 is arranged on the universal shaft assembly 3, a planetary gear drive mechanism is formed when the internal gear 6 and the external gear 7 are engaged. When the downhole drilling tool is lowered (without drilling pressure), at this time when the internal gear 6 and the external gear 7 are engaged, the directional bend 5 rotates together with the screw stator 41, and the bit body 1 rotates together with the screw rotor 42 under the action of the rotary table. At this time, the orientation of the directional bend 5, that is, the orientation of the bit body 1, can be flexibly adjusted, thus preparing for directional milling drilling. When the drilling pressure is increased, the screw motor assembly 4 moves downward (towards the bottom hole) under the action of the drilling pressure and compresses the reset elastic element 8. At this time, the engagement relationship between the internal gear 6 and the external gear 7 is disengaged, the rotary table rotation is stopped, and drilling fluid is introduced to drive the screw rotor 42 of the screw motor assembly 4 to rotate. However, at this time, since the screw stator 41 does not rotate, the position of the directional bend 5 will not change either, and the rotation of the screw rotor 42 will only transmit the rotational movement to the bit body 1 through the universal shaft assembly 3. At this time, the bit body 1 can perform milling drilling in a specified direction under the action of the directional bend 5, thus achieving the purpose of directional milling drilling. When the drilling pressure is reduced or the tool is lifted, the internal gear 6 and the external gear 7 are re-engaged to prepare for adjusting the orientation of the bit body 1.

Claims

1. An efficient directional milling drilling tool, comprising a drill bit body, an outer casing, a universal shaft assembly, and a positive displacement motor assembly. Cutting teeth are inlaid on the drill bit body. The positive displacement motor assembly consists of a stator and a rotor. The upper part of the universal shaft assembly is fixedly connected to the rotor, and the lower part is fixedly connected to the drill bit body. It is characterized in that: The universal shaft assembly includes an upper joint, a lower joint and a connecting rod body. The connecting rod body includes an upper connecting rod body and a lower connecting rod body. The upper connecting rod body and the lower connecting rod body are connected by splines, and can slide relative to each other. Flow channels are arranged inside both the upper connecting rod body and the lower connecting rod body. The outer part of the upper connecting rod body has an eccentric shaft feature. A directional elbow is arranged between the outer casing and the drill bit body. An internal gear is arranged inside the directional elbow. The universal shaft assembly has an eccentric shaft structure. An external gear is arranged outside the upper connecting rod body of the universal shaft assembly. The external gear and the internal gear are in a meshing relationship. The meshing of the internal gear and the external gear forms a planetary gear drive mechanism with a small tooth difference. A reset elastic element is arranged between the directional elbow and the outer casing. The directional elbow is movably connected to the outer casing.

2. An efficient directional milling and drilling tool according to claim 1, characterized in that: The directional elbow and the screw stator are connected by a ball bearing.

3. An efficient directional milling and drilling tool according to claim 1, characterized in that: The directional elbow and the drill bit body are connected by a ball bearing.

4. An efficient directional milling and drilling tool according to claim 1, characterized in that: A side water eye is arranged on the lower joint of the universal shaft assembly.

5. An efficient directional milling and drilling tool according to claim 1, characterized in that: The cutting teeth include at least one of PDC teeth, impregnated teeth and cemented carbide teeth.

6. An efficient directional milling and drilling tool according to claim 1, characterized in that: The crown profile of the drill bit body is conical, spherical or flat-bottomed.

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