Self-adaptive downhole rock annular cutting groove stress unloading percussion bit and well drilling method

Abstract

The invention discloses a self-adaptive downhole rock annular cutting groove stress unloading percussion bit and a drilling method, and belongs to the technical field of petroleum drilling engineering. The self-adaptive downhole rock annular cutting groove stress unloading percussion bit comprises a bit connector, a cutting groove unloading barrel body and a percussion bit body; the upper end of the percussion bit matrix is fixedly connected with the lower end of the bit joint; the upper end of the grooving unloading barrel matrix is in axial sliding fit with the lower end of the bit joint; a bit pressure transmission disc spring is arranged in an annular space between the bottom end face of the drill bit connector and the top end face of the annular step. A plurality of annular grooving unloading stress teeth are arranged at the lower end of the grooving unloading barrel matrix; impact crushing teeth are arranged at the lower end of the impact drill bit matrix; when the drill bit reaches the well bottom, the annular cutting groove unloading stress teeth make contact with the well bottom earlier than the impact crushing teeth. Through the structural arrangement of the drill bit, annular grooving of shaft bottom rock is achieved, shaft bottom stress is unloaded, the efficiency of impact rock breaking is improved by reducing the strength of the rock, and the drilling speed is increased.

Description

Technical Field

[0001] The present invention belongs to the technical field of oil drilling engineering, and particularly relates to an adaptive bottom-hole rock annular grooving stress unloading impact bit and a drilling method. Background Art

[0002] During deep drilling, formation rocks are under the combined action of overlying rock pressure, horizontal in-situ stress, static pressure of drilling fluid and pore pressure. As the well depth increases, the confining pressure on the rocks increases linearly, resulting in an increase in rock strength. Impact drilling technology can significantly improve the mechanical drilling rate, but it is necessary to increase the impact energy of the impact tool. Since the reverse impact energy of the impact tool increases under high confining pressure conditions, it will cause damage to the impact tool, and then reduce the mechanical drilling rate.

[0003] Therefore, how to reduce the compressive effect of in-situ stress on bottom-hole rocks, change the mechanical properties of bottom-hole rocks, and thus improve the mechanical drilling rate is the current mainstream way to increase the drilling speed.

[0004] Based on this, the present application proposes an adaptive bottom-hole rock annular grooving stress unloading impact bit and a drilling method. During impact drilling, the bit can use its own structural characteristics to complete the annular grooving of the bottom-hole rocks, unload the bottom-hole stress, improve the drilling speed, and at the same time reduce the compressive effect of the horizontal in-situ stress on the bottom-hole rocks after the annular grooving of the rocks, thereby reducing the reverse impact energy on the impact tool, having the effect of protecting the impact tool, and preventing the reduction of the mechanical drilling rate caused by the damage of the impact tool. Summary of the Invention

[0005] The purpose of the present invention is to overcome the deficiencies of the above-mentioned prior art and provide an adaptive bottom-hole rock annular grooving stress unloading impact bit.

[0006] To achieve the above purpose, the present invention adopts the following technical solutions:

[0007] An adaptive bottom-hole rock annular grooving stress unloading impact bit includes a bit sub, a grooving unloading cylinder body, and an impact bit body.

[0008] The upper end of the impact bit body is coaxially and fixedly connected to the radial inner side of the lower end of the bit sub, and the upper end of the grooving unloading cylinder body is axially slidably mated with the radial outer side of the lower end of the bit sub; an annular space is formed between the radial inner surface of the grooving unloading cylinder body and the radial outer surface of the impact bit body.

[0009] An annular step is coaxially and fixedly arranged on the radial inner surface of the grooving unloading cylinder body, and an axial sliding fit is carried out between the radial inner side of the annular step and the radial outer surface of the impact bit body.

[0010] A drill pressure transmission disc spring is arranged in the annular space between the bottom end face of the drill bit sub and the top end face of the annular step;

[0011] A number of annular grooving unloading stress teeth are evenly arranged along the circumferential direction at the lower end of the grooving unloading cylinder body, and impact crushing teeth are arranged at the lower end of the impact drill bit body; when the drill bit reaches the bottom of the well, the annular grooving unloading stress teeth contact the bottom of the well prior to the impact crushing teeth.

[0012] Preferably, a through first drilling fluid flow channel is arranged in the drill bit sub, and a second drilling fluid flow channel communicated with the first drilling fluid flow channel is arranged in the impact drill bit body;

[0013] A first flow channel extending to the bottom end and a second flow channel extending to the side surface are arranged in the impact drill bit body, the upper ends of the first flow channel and the second flow channel are both communicated with the second drilling fluid flow channel, and nozzles are arranged at the lower ends of the first flow channel and the second flow channel.

[0014] Preferably, a number of tooth brackets are evenly arranged along the circumferential direction at the lower end of the grooving unloading cylinder body, and an annular grooving unloading stress tooth is arranged on each tooth bracket.

[0015] Preferably, all the annular grooving unloading stress teeth are arranged on the same side in the circumferential direction of the corresponding tooth brackets.

[0016] Preferably, one end of the central axis of the annular grooving unloading stress tooth away from the tooth bracket inclines downward.

[0017] Preferably, the upper end of the impact drill bit body is threadedly connected to the radial inner side of the lower end of the drill bit sub.

[0018] Preferably, a spline groove matched with the spline on the radial outer side of the lower end of the drill bit sub is arranged on the radial inner side surface at the upper end of the grooving unloading cylinder body.

[0019] The present invention also discloses an impact drilling method for adaptively unloading the annular grooving stress of bottom-hole rock.

[0020] An impact drilling method for adaptively unloading the annular grooving stress of bottom-hole rock is implemented based on an impact drill bit for adaptively unloading the annular grooving stress of bottom-hole rock, and the drilling method includes the following steps:

[0021] Step 1, when the drill bit reaches the bottom of the well, the annular grooving unloading stress teeth contact the bottom of the well prior to the impact crushing teeth, and under the action of the drill pressure, the drill pressure transmission disc spring is compressed to transmit the drill pressure to the annular grooving unloading stress teeth;

[0022] Under the combined action of the drill pressure and the torque, the annular grooving unloading stress teeth cut a ring groove on the bottom end face of the drilling well bottom to unload the bottom-hole pressure;

[0023] Step 2: The drill bit continues to drill, the depth of the annular groove keeps increasing, and the impact crushing teeth start to contact the bottom-hole rock inside the annular groove and break it.

[0024] Step 3: Under the combined action of the drilling pressure and torque, the cutting of the annular groove by the stress unloading teeth of the annular groove and the crushing of the rock inside the annular groove by the impact crushing teeth continue, realizing combined rock breaking.

[0025] During this process:

[0026] The nozzles in the first flow channel and the second flow channel spray drilling fluid outwards. After the drilling fluid cleans the impact crushing teeth and the stress unloading teeth of the annular groove, it carries the crushed rock cuttings through the gaps of the tooth support to the annulus.

[0027] The beneficial effects of the present invention are as follows:

[0028] (1) Through the structural arrangement of the drill bit itself, the present invention realizes the annular grooving of the bottom-hole rock, unloads the bottom-hole stress, improves the impact rock-breaking efficiency by reducing the rock strength, and increases the drilling speed. At the same time, after the annular grooving of the rock, the compression effect of the horizontal in-situ stress on the bottom-hole rock is reduced, thereby reducing the reverse impact energy on the impact tool, playing a role in protecting the impact tool and preventing the reduction of the mechanical drilling speed caused by the damage of the impact tool.

[0029] (2) In the present invention, the drill pressure transmission disc spring converts the impact of the upper impact tool of the drill bit into a soft impact, that is, it plays a buffering role, thereby protecting the stress unloading teeth of the annular groove.

[0030] (3) In the present invention, a number of stress unloading teeth of the annular groove are uniformly arranged along the circumferential direction at the lower end of the cutting groove unloading cylinder body. With this arrangement method, when some stress unloading teeth of the annular groove are damaged, the cutting of the annular groove can still be carried out by other stress unloading teeth of the annular groove, without affecting the use. Description of the Drawings

[0031] The specification drawings forming a part of this application are used to provide a further understanding of this application. The schematic embodiments of this application and their descriptions are used to explain this application and do not constitute an improper limitation to this application.

[0032] Figure 1 is a schematic structural diagram of the self-adaptive bottom-hole rock annular groove stress unloading impact drill bit of the present invention;

[0033] Figure 2 is a schematic cooperation diagram of the drill bit sub and the cutting groove unloading cylinder body in the present invention;

[0034] Wherein:

[0035] 1 - Bit sub, 2 - Drill pressure transmission disc spring, 3 - Groove unloading cylinder body, 31 - Annular step, 4 - First drilling fluid flow channel, 5 - Second drilling fluid flow channel, 6 - Nozzle, 7 - Annular groove unloading stress tooth, 8 - Impact crushing tooth, 9 - Tooth bracket, 10 - Impact bit body, 101 - First flow channel, 102 - Second flow channel. Detailed implementation mode

[0036] It should be noted that the following detailed description is illustrative and is intended to provide further explanation of the present application. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the technical field to which the present application belongs.

[0037] It should be noted that the terms used herein are only for describing the specific implementation modes and are not intended to limit the exemplary implementation modes according to the present application. As used herein, unless the context clearly indicates otherwise, the singular forms are also intended to include the plural forms. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0038] In the present invention, terms such as "upper", "lower", "bottom", "top", etc. indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only relationship terms determined for the convenience of describing the structural relationship of each component or element of the present invention, rather than specifically referring to any component or element in the present invention, and should not be construed as a limitation to the present invention.

[0039] In the present invention, terms such as "connected" and "connected" should be understood in a broad sense, which may mean a fixed connection, an integral connection or a detachable connection; it may be directly connected or indirectly connected through an intermediate medium. For those related scientific research or technical personnel in the field, the specific meanings of the above terms in the present invention can be determined according to specific circumstances, and should not be construed as a limitation to the present invention.

[0040] The present invention will be further described below with reference to the drawings and embodiments.

[0041] Embodiment 1:

[0042] As Figure 1 shown, an adaptive bottom-hole rock annular groove stress unloading impact bit includes a bit sub 1, a groove unloading cylinder body 3, and an impact bit body 10; during use, the upper end of the bit sub 1 is connected to an impact tool, specifically, it can be connected to the lower sub of a down-the-hole hammer.

[0043] The upper end of the impact drill bit body 10 is coaxially fixedly connected with the radial inner side of the lower end of the drill bit joint 1, and the upper end of the groove unloading cylinder body 3 is axially slidably matched with the radial outer side of the lower end of the drill bit joint 1; an annular space is formed between the radial inner side of the groove unloading cylinder body 3 and the radial outer side of the impact drill bit body 10;

[0044] An annular step 31 is coaxially fixedly arranged on the radial inner side of the groove unloading cylinder body 3, and the radial inner side of the annular step 31 is axially slidably matched with the radial outer side of the impact drill bit body 10;

[0045] A drilling pressure transmission disc spring 2 is arranged in the annular space between the bottom end surface of the drill bit joint 1 and the top end surface of the annular step 31, wherein the upper end of the drilling pressure transmission disc spring 2 is abutted and fixedly connected to the bottom end surface of the drill bit joint 1, and the lower end of the drilling pressure transmission disc spring 2 is abutted and fixedly connected to the top end surface of the annular step 31; the drilling pressure transmission disc spring 2 converts the impact of the impact tool on the upper part of the drill bit into a soft impact, that is, it plays a role in buffering, thereby playing a role in protecting the annular groove unloading stress tooth 7;

[0046] The lower end of the groove unloading cylinder body 3 is evenly provided with a plurality of annular groove unloading stress teeth 7 along the circumferential direction, which are used to realize annular groove cutting of rocks, and the lower end of the impact drill bit body 10 is provided with impact crushing teeth 8, which are used to realize the crushing of rocks inside the annular groove; when the drill bit reaches the bottom of the well, the annular groove unloading stress teeth 7 contact the bottom of the well before the impact crushing teeth 8. In the present application, the annular groove unloading stress teeth 7 are PDC teeth.

[0047] Preferably, a first drilling fluid flow channel 4 is provided in the drill bit joint 1, and a second drilling fluid flow channel 5 connected to the first drilling fluid flow channel 4 is provided in the impact drill bit body 10;

[0048] The impact drill bit body 10 is provided with a first flow channel 101 extending to the bottom end and a second flow channel 102 extending to the side. The upper ends of the first flow channel 101 and the second flow channel 102 are connected to the second drilling fluid flow channel 5, and the lower ends of the first flow channel 101 and the second flow channel 102 are provided with nozzles 6.

[0049] Preferably, a plurality of tooth supports 9 are evenly arranged along the circumferential direction at the lower end of the groove unloading cylinder mother body 3, and an annular groove unloading stress tooth 7 is arranged on each tooth support 9.

[0050] Preferably, all the annular groove stress relief teeth 7 are arranged on the same side of the corresponding tooth bracket 9 in the circumferential direction, for example Figure 1 From the top view, all the annular groove stress unloading teeth 7 are arranged on the front side of the corresponding tooth bracket 9 in the clockwise circumferential direction.

[0051] Preferably, one end of the central axis of the annular grooving stress unloading tooth 7, which is far from the tooth support 9 where it is located, inclines downward, so that it has a better cutting effect on the rock.

[0052] Preferably, the upper end of the impact bit matrix 10 is threadedly connected to the radial inner side of the lower end of the bit sub 1, for transmitting the drilling pressure and torque, and transmitting the impact force generated by the down-the-hole hammer to the impact crushing tooth 8 for rock crushing.

[0053] Preferably, as Figure 2 shown, a spline groove which is matched with the spline on the radial outer surface of the lower end of the bit sub 1 is arranged on the radial inner surface of the upper end of the grooving unloading cylinder matrix 3, for transmitting the torque of the drill string and realizing axial sliding fit.

[0054] Embodiment 2:

[0055] An adaptive bottom-hole rock annular grooving stress unloading impact drilling method is implemented based on the adaptive bottom-hole rock annular grooving stress unloading impact bit in Embodiment 1. The drilling method includes the following steps:

[0056] Step 1, when the bit reaches the bottom hole, the annular grooving stress unloading tooth 7 contacts the bottom hole prior to the impact crushing tooth 8. Under the action of the drilling pressure, the drill pressure transmission disc spring 2 is compressed to transmit the drilling pressure to the annular grooving stress unloading tooth 7;

[0057] Under the combined action of the drilling pressure and torque, the annular grooving stress unloading tooth 7 cuts an annular groove on the bottom-end face of the drilling bottom hole to unload the bottom-hole pressure;

[0058] Step 2, the bit continues to drill, the depth of the annular groove is continuously deepened, and the impact crushing tooth 8 begins to contact the bottom-hole rock inside the annular groove and break it;

[0059] Step 3, under the combined action of the drilling pressure and torque, the cutting of the annular groove by the annular grooving stress unloading tooth 7 and the crushing of the rock inside the annular groove by the impact crushing tooth 8 continue, realizing combined rock breaking;

[0060] During this process:

[0061] The drilling fluid is sprayed outwards by the nozzles 6 in the first flow channel 101 and the second flow channel 102. After the drilling fluid washes the impact crushing tooth 8 and the annular grooving stress unloading tooth 7, it carries the crushed rock cuttings and transports them to the annulus through the gaps of the tooth support 9.

[0062] Through the structural settings of the drill bit itself, the present invention realizes the annular grooving of the bottom-hole rock, unloads the bottom-hole stress, and improves the efficiency of impact rock breaking by reducing the rock strength, thereby increasing the drilling speed. At the same time, after the annular grooving of the rock, the compression effect of the horizontal in-situ stress on the bottom-hole rock is reduced, thereby reducing the reverse impact energy on the impact tool, protecting the impact tool, and preventing the reduction of the mechanical drilling speed caused by the damage of the impact tool.

[0063] Although the specific implementation manners of the present invention have been described above in conjunction with the accompanying drawings, they are not limitations on the present invention. Those skilled in the art should understand that various modifications or deformations that can be made without creative efforts on the basis of the technical solutions of the present invention are still within the protection scope of the present invention.

Claims

1. An adaptive bottom hole rock annular grooving stress unloading impact drill bit, characterized in that: It includes a drill bit joint, a groove unloading cylinder body, and an impact drill bit body; The upper end of the impact drill bit body is coaxially fixedly connected with the radial inner side of the lower end of the drill bit joint, and the upper end of the groove unloading cylinder body is axially slidably matched with the radial outer side of the lower end of the drill bit joint; an annular space is formed between the radial inner side of the groove unloading cylinder body and the radial outer side of the impact drill bit body; An annular step is coaxially fixedly arranged on the radial inner side of the groove unloading cylinder body, and the radial inner side of the annular step is axially slidably matched with the radial outer side of the impact drill bit body; A drilling pressure transmission disc spring is arranged in the annular space between the bottom end surface of the drill bit joint and the top end surface of the annular step; The lower end of the groove unloading cylinder body is evenly provided with a plurality of annular groove unloading stress teeth along the circumferential direction, and the lower end of the impact drill bit body is provided with impact crushing teeth; when the drill bit reaches the bottom of the well, the annular groove unloading stress teeth contact the bottom of the well before the impact crushing teeth.

2. The adaptive bottom hole rock annular grooving stress unloading impact drill bit according to claim 1, characterized in that: A first drilling fluid flow channel is provided in the drill bit joint, and a second drilling fluid flow channel connected to the first drilling fluid flow channel is provided in the impact drill bit body; The impact drill bit body is provided with a first flow channel extending to the bottom end and a second flow channel extending to the side. The upper ends of the first flow channel and the second flow channel are connected to the second drilling fluid flow channel. The lower ends of the first flow channel and the second flow channel are provided with nozzles.

3. The adaptive bottom hole rock annular groove stress unloading impact drill bit according to claim 2, characterized in that: A plurality of tooth brackets are evenly arranged along the circumferential direction at the lower end of the groove unloading cylinder body, and each tooth bracket is provided with an annular groove unloading stress tooth.

4. The adaptive bottom hole rock annular grooving stress unloading impact drill bit according to claim 3, characterized in that: All the annular groove stress-unloading teeth are arranged on the same side of the circumferential direction of the corresponding tooth bracket.

5. The adaptive bottom hole rock annular grooving stress unloading impact drill bit according to claim 2, characterized in that: The center axis of the annular groove stress unloading tooth is inclined downward away from one end of the tooth support where it is located.

6. The adaptive bottom hole rock annular groove stress unloading impact drill bit according to claim 2, characterized in that: The upper end of the impact drill bit body is threadedly connected to the radial inner side of the lower end of the drill bit joint.

7. The adaptive bottom hole rock annular groove stress unloading impact drill bit according to claim 2, characterized in that: A spline groove is arranged on the radial inner side surface of the upper end of the groove unloading cylinder body, which is matched with the spline on the radial outer side surface of the lower end of the drill bit joint.

8. An adaptive bottom hole rock annular groove stress unloading impact drilling method, implemented based on the adaptive bottom hole rock annular groove stress unloading impact drill bit according to any one of claims 2 to 7, characterized in that: The drilling method comprises the following steps: Step 1: When the drill bit reaches the bottom of the well, the annular groove stress unloading tooth contacts the bottom of the well before the impact crushing tooth, and the drilling pressure transmission disc spring is compressed under the action of drilling pressure to transmit the drilling pressure to the annular groove stress unloading tooth; Under the combined effect of drilling pressure and torque, the annular groove unloading stress tooth cuts an annular groove on the end face of the drilling bottom to unload the bottom hole pressure; Step 2: The drill bit continues to drill, the depth of the annular groove continues to deepen, and the impact crushing teeth begin to contact the bottom rock inside the annular groove and crush it; Step 3: Under the combined action of drilling pressure and torque, the annular groove unloading stress teeth continuously cut the annular groove and the impact crushing teeth continuously crush the rock inside the annular groove, thereby achieving combined rock breaking; During the process: The nozzles in the first flow channel and the second flow channel spray drilling fluid outwards, and the drilling fluid cleans the impact crushing teeth and the annular groove unloading stress teeth, and then carries the crushed rock cuttings to the annulus through the gap of the tooth support.

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