Reducing two-stage drill bit suitable for viscoplastic stratum and well drilling method

Abstract

The invention discloses a variable-diameter two-stage drill bit suitable for viscoplastic stratums and a well drilling method, and belongs to the technical field of petroleum and natural gas well drilling engineering.The variable-diameter two-stage drill bit comprises a drill bit body; a plurality of reaming blades are arranged on the side face of the bit body, a force storage spring is arranged at the bit end of the bit body, and a pilot bit body is arranged at the other end of the force storage spring. The reaming blades are in sliding fit with the drill bit body, and the reaming blades are in sliding fit with the pilot bit body in the radial direction of the drill bit body. When the force storage spring pushes the pilot bit body to be away from the bit body, all the reaming blades move inwards in the radial direction while axially moving along with the pilot bit body; and when the pilot bit body compresses the force storage spring to get close to the bit body, all the reaming blades move outwards in the radial direction while axially moving along with the pilot bit body. Under the cooperation of bit pressure, the reaming cutter wings can stretch out or retract, and the diameter of the drill bit can be automatically adjusted; the overall structure is simple, and the reliability is high.

Description

Technical Field

[0001] The invention belongs to the technical field of oil and gas drilling engineering, and in particular relates to a variable diameter double-stage drill bit suitable for viscoplastic formations and a drilling method. Background Art

[0002] In the field of oil and gas engineering, the continuous development of drilling technology is of great significance to improving the extraction efficiency of oil and gas reservoirs and reducing drilling costs. However, during the drilling process, the complexity of the formation often brings many challenges to the drilling operation, especially in viscoplastic formations. Due to the problems of easy deformation of the formation, shrinkage of the wellbore, and difficulty in removing cuttings, conventional drilling tools are difficult to ensure efficient and stable drilling results, and may even lead to serious consequences such as drill bit sticking and wellbore instability. Therefore, the development of efficient and stable drilling tools and supporting drilling methods for viscoplastic formations has become an important research direction in the industry. At present, the following two types of drill bits are mainly used in drilling operations in viscoplastic formations: The first is to use conventional drill bits such as traditional PDC (polycrystalline diamond composite) drill bits or roller bits for drilling. However, traditional PDC (polycrystalline diamond composite) drill bits or roller bits are easily affected by wellbore shrinkage in viscoplastic formations, resulting in a reduction in wellbore size, thereby increasing the probability of complex situations downhole. In addition, this type of drill bit usually does not have an adaptive variable diameter function, making it difficult to flexibly respond to changes in formation conditions.

[0003] The second method is to use an expandable drill bit for drilling. The drill bit adopts a mechanical or hydraulically driven expandable design to adapt to different well diameter requirements. However, this type of drill bit is often complex in structure and has low reliability. Mechanical failures may occur during long-term drilling, affecting the stability of drilling operations. At the same time, the expansion mechanism is difficult to control, making it difficult to achieve efficient hole expansion. Summary of the invention

[0004] The purpose of the present invention is to overcome the above-mentioned deficiencies of the prior art and provide a variable diameter two-stage drill bit suitable for viscoplastic formations.

[0005] To achieve the above object, the present invention adopts the following technical solution: A variable diameter dual-stage drill bit suitable for viscoplastic formations, comprising a drill bit body; A plurality of reaming blades are evenly arranged on the side of the drill body in the circumferential direction, a force storage spring is fixedly arranged at the drill end of the drill body, the force storage spring can be compressed and stored along the axial direction of the drill body, and a pilot drill body is fixedly arranged at the other end of the force storage spring; The reaming blade is in sliding cooperation with the drill bit body, and the reaming blade is in sliding cooperation with the pilot drill bit body along the radial direction of the drill bit body; When the force storage spring pushes the pilot drill body away from the drill body, all the reaming blades follow the pilot drill body to move axially and move radially inward; when the pilot drill body compresses the force storage spring to move closer to the drill body, all the reaming blades follow the pilot drill body to move axially and move radially outward; A plurality of reaming cutting teeth are arranged on the reaming blade along the generatrix direction, and the pilot drill bit body is provided with pilot cutting teeth.

[0006] Preferably, a drilling fluid collection chamber is provided in the middle of the drill bit body, and the drilling fluid collection chamber passes through to the drill string connection end; A circumferential flow channel connected to the drilling fluid collection chamber is arranged on the drill bit body between adjacent reaming blades, and a circumferential nozzle is arranged at the radial outer end of the circumferential flow channel.

[0007] Preferably, an eccentric flow channel penetrating to the drilling fluid collecting chamber is arranged on the end surface of the drill bit body facing the pilot drill bit body, and the central axis of the eccentric flow channel is in a non-planar straight line relationship with the central axis of the drill bit body.

[0008] Preferably, a through pilot drill flow passage is provided on the pilot drill bit body, and a pilot drill nozzle is provided in the pilot drill flow passage.

[0009] Preferably, a plurality of pilot drill blades are evenly arranged on the pilot drill body along the circumferential direction, and the pilot cutting teeth are arranged on the pilot drill blades and a plurality of them are arranged along the generatrix direction.

[0010] Preferably, the ends of all the pilot drill blades away from the drill body are close to each other, and a central conical cutting tooth is arranged at the center where all the pilot drill blades are close to each other.

[0011] Preferably, a plurality of radial slide rails corresponding to the reaming blades are arranged along the circumferential direction on the end surface of the pilot drill body facing the drill body; The end surface of the reaming blade facing the pilot drill body is provided with a radial slide groove which is radially slidably matched with the corresponding radial slide rail.

[0012] Preferably, a plurality of axial sliding grooves corresponding to the reaming blades are arranged on the side surface of the drill bit body along the circumferential direction; An axial slide rail is provided on the side of the reaming blade facing the drill bit body and is slidably matched with the corresponding axial slide groove; The distance between one end of the axial slot close to the pilot drill body and the central axis of the drill body is smaller than the distance between one end of the axial slot far from the pilot drill body and the central axis of the drill body.

[0013] Preferably, a thread is arranged on the side of the drill bit body away from the pilot drill bit body.

[0014] The invention also discloses a drilling method suitable for viscoplastic formations.

[0015] A drilling method suitable for viscoplastic formations is implemented based on a variable diameter dual-stage drill bit suitable for viscoplastic formations, and the drilling method comprises the following steps: Step 1: During initial drilling, start the conventional drilling mode and perform conventional drilling at a low drilling pressure, with the reamer blades in a retracted state; Step 2: When the viscoplastic formation is reached, the reaming operation mode is turned on, the drilling pressure is increased, the pilot drill body compresses the force storage spring close to the drill body, all the reaming blades move axially with the pilot drill body and move radially outward, and the reaming blades spread outward to perform the reaming operation; Step 3: After drilling in the viscoplastic formation is completed, the drilling pressure is reduced, and the force storage spring is extended to cause the pilot drill bit body to move away from the drill bit body. All the reaming blades move axially with the pilot drill bit body and move radially inward at the same time. The reaming blades are retracted inward to restore the normal drilling mode. In the above process, the drilling fluid is distributed through the drilling fluid collection chamber and sprayed through the circumferential nozzle and the pilot drill bit nozzle, carrying the crushed rock cuttings into the annulus; When the reaming operation mode is turned on, the drilling fluid pump pressure is increased, the angular momentum of the drilling fluid in the eccentric flow channel is increased, and the drill bit generates circumferential vibration during the reaming operation, thereby improving the reaming effect.

[0016] The beneficial effects of the present invention are: (1) The present invention can achieve the extension or retraction of the reaming blades by coordinating the reaming blades with the drill bit body, the reaming blades with the pilot drill bit body, and the arrangement of a force storage spring between the drill bit body and the pilot drill bit body under the cooperation of drilling pressure, so that the drill bit can automatically adjust its diameter to adapt to different formation conditions, thereby improving the flexibility and stability of drilling; the overall structure is simple and reliable, and the force storage spring is used in combination with drilling pressure to achieve diameter expansion, thereby avoiding the complexity of mechanical or hydraulic diameter expansion devices and improving the durability and stability of the drill bit.

[0017] (2) In the present invention, the setting of the eccentric flow channel causes the drilling fluid to generate angular momentum, causing the drill bit to generate circumferential vibration during the hole expansion operation, thereby reducing the adhesion between the drill tool and the formation and improving the hole expansion efficiency.

[0018] (3) In the present invention, the expansion of the reamer blades and the circumferential vibration caused by the eccentric flow channel are combined to weaken the wrapping effect of the viscoplastic formation on the drill bit, effectively reduce the drilling resistance, reduce the risk of drill bit sticking, and improve drilling safety.

[0019] (4) The present invention is applicable to viscoplastic formations, alternating soft and hard formations, and other complex formations prone to wellbore shrinkage, thereby increasing the scope of application of drilling technology and having broad engineering application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The drawings in the specification, which constitute a part of the present application, are used to provide further understanding of the present application. The illustrative embodiments of the present application and their descriptions are used to explain the present application and do not constitute improper limitations on the present application.

[0021] Figure 1 The structure schematic diagram of the variable diameter double-stage drill bit of the present invention is applicable to the viscoplastic formation Figure 1 ; Figure 2 The structure schematic diagram of the variable diameter double-stage drill bit of the present invention is applicable to the viscoplastic formation Figure 2 ; Figure 3 This is a schematic front view of the structure of a variable diameter dual-stage drill bit suitable for visco-plastic formations according to the present invention; Figure 4 yes Figure 3 AA section view; Figure 5 2. It is a schematic bottom view of the structure of a variable diameter dual-stage drill bit suitable for viscoplastic formations according to the present invention; Figure 6 yes Figure 5 BB section view; in: 1-drill bit body, 2-reaming blade, 3-force storage spring, 4-reaming cutting tooth, 5-leading cutting tooth, 6-axial slide, 7-axial slide rail, 8-drilling fluid collection chamber, 9-circumferential flow channel, 10-eccentric flow channel, 11-leading drill blade, 12-center cone cutting tooth, 13-leading drill flow channel, 14-radial slide rail, 15-radial slide. DETAILED DESCRIPTION

[0022] It should be noted that the following detailed descriptions are illustrative and are intended to provide further explanation of the present application. Unless otherwise specified, all technical and scientific terms used herein have the same meanings as those commonly understood by those skilled in the art to which the present application belongs.

[0023] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present application. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, it indicates the presence of features, steps, operations, devices, components and / or combinations thereof.

[0024] In the present invention, the directions or positional relationships indicated by terms such as "upper", "lower", "bottom", "top", etc. are based on the directions or positional relationships shown in the accompanying drawings. They are relational words determined only for the convenience of describing the structural relationships of the various parts or elements of the present invention. They do not specifically refer to any part or element in the present invention and cannot be understood as limitations on the present invention.

[0025] In the present invention, terms such as "connected" and "connection" should be understood in a broad sense, indicating that the connection can be fixed, integral or detachable; it can be directly connected or indirectly connected through an intermediate medium. Relevant scientific research or technical personnel in this field can determine the specific meaning of the above terms in the present invention according to specific circumstances, and they should not be understood as limiting the present invention.

[0026] The present invention is further described below in conjunction with the accompanying drawings and embodiments.

[0027] Embodiment 1: like Figure 1-Figure 6 As shown, a variable diameter dual-stage drill bit suitable for viscoplastic formations comprises a drill bit body 1; A plurality of reaming blades 2 are evenly arranged on the side of the drill body 1 along the circumferential direction, a force storage spring 3 is fixedly arranged at the drill end of the drill body 1, the force storage spring 3 can be compressed and stored along the axial direction of the drill body 1, and a pilot drill body is fixedly arranged at the other end of the force storage spring 3; The reaming blade 2 is slidably matched with the drill bit body 1, and the reaming blade 2 is slidably matched with the pilot drill bit body along the radial direction of the drill bit body 1, so that the pilot drill bit body and the reaming blade 2 are linked; When the force storage spring 3 pushes the pilot drill body away from the drill body 1, all the reaming blades 2 move axially with the pilot drill body and move radially inward, thereby realizing the inward contraction of the reaming blades 2; when the pilot drill body compresses the force storage spring 3 and approaches the drill body 1, all the reaming blades 2 move axially with the pilot drill body and move radially outward, thereby realizing the outward expansion of the reaming blades 2; A plurality of reaming cutting teeth 4 are arranged on the reaming blade 2 along the generatrix direction. The reaming cutting teeth 4 are mounted on the reaming blade 2. After the reaming blade 2 is unfolded, it contacts the well wall to perform reaming operation. The pilot drill bit body is provided with pilot cutting teeth 5. The reaming blade 2 and the reaming cutting teeth 4 can be made of high wear-resistant alloy or PDC material to improve durability and erosion resistance and extend the service life of the drill bit.

[0028] Preferably, a drilling fluid collection chamber 8 is provided in the middle of the drill bit body 1, and the drilling fluid collection chamber 8 is connected to the drill string connection end; the drilling fluid collection chamber 8 is used to collect and distribute the drilling fluid so that it can flow evenly to each nozzle and flow channel, thereby optimizing the flow field distribution of the drilling fluid; A circumferential flow channel 9 connected to the drilling fluid collection chamber 8 is arranged on the drill body 1 between adjacent reaming blades 2, and a circumferential nozzle is arranged at the radial outer end of the circumferential flow channel 9; the circumferential nozzle is used to spray high-pressure drilling fluid to enhance the cooling effect of the drill bit, assist in removing cutting debris, and improve drilling efficiency.

[0029] Preferably, an eccentric flow channel 10 penetrating to the drilling fluid collection chamber 8 is provided on the end face of the drill bit body 1 facing the pilot drill bit body, and the central axis of the eccentric flow channel 10 is in a non-planar straight line relationship with the central axis of the drill bit body 1. During the reaming operation, by adjusting the drilling fluid pump pressure, the drilling fluid obtains angular momentum when flowing through the eccentric flow channel 10, thereby generating circumferential vibration, enhancing the cutting ability of the reaming blade 2, and improving the reaming efficiency. Among them, the distance between the intersection of the central axis of the eccentric flow channel 10 and the bottom end face of the drilling fluid collection chamber 8 and the central axis of the drill bit body 1 is less than the distance between the intersection of the central axis of the eccentric flow channel 10 and the bottom end face of the drill bit body 1 and the central axis of the drill bit body 1.

[0030] Preferably, the pilot drill bit body is provided with a through pilot drill bit flow channel 13, and a pilot drill bit nozzle is provided in the pilot drill bit flow channel 13. The pilot drill bit nozzle is used to spray drilling fluid, improve the cooling effect of the pilot drill bit blade 11, and help discharge rock cuttings.

[0031] Preferably, a plurality of pilot drill blades 11 are evenly arranged on the pilot drill body along the circumferential direction, and the pilot cutting teeth 5 are arranged on the pilot drill blades 11 and arranged in a plurality along the generatrix direction. The pilot drill blades 11 are mainly used for initial drilling of the wellbore, and the pilot cutting teeth 5 are arranged on the pilot drill blades 11 for initial drilling of the formation. A through pilot drill flow channel 13 is arranged on the pilot drill body between adjacent pilot drill blades 11.

[0032] Preferably, the ends of all pilot drill blades 11 away from the drill body 1 are close together, and a central conical cutting tooth 12 is arranged at the center where all pilot drill blades 11 are close together. The central conical cutting tooth 12 is located at the center of the drill bit to ensure effective crushing of the bottom hole rock during drilling and improve drilling efficiency.

[0033] Preferably, a plurality of radial slide rails 14 corresponding to the reaming blades 2 are arranged along the circumferential direction on the end surface of the pilot drill body facing the drill body 1; The end surface of the reaming blade 2 facing the pilot drill body is provided with a radial slide groove 15 which is radially slidably matched with the corresponding radial slide rail 14.

[0034] Preferably, a plurality of axial sliding grooves 6 corresponding to the reaming blades 2 are arranged on the side surface of the drill body 1 along the circumferential direction; An axial slide rail 7 is provided on the side of the reaming blade 2 facing the drill body 1 and is slidably matched with the corresponding axial slide groove 6; The distance between the end of the axial slot 6 close to the pilot drill body and the central axis of the drill body 1 is smaller than the distance between the end of the axial slot 6 far from the pilot drill body and the central axis of the drill body 1 .

[0035] Preferably, a thread is provided on the side of the drill bit body 1 away from the pilot drill bit body for connection with a drill string.

[0036] Embodiment 2: A drilling method suitable for viscoplastic formations is implemented based on the variable diameter two-stage drill bit suitable for viscoplastic formations in Example 1, and the drilling method comprises the following steps: Step 1: During initial drilling, the conventional drilling mode is turned on, and conventional drilling is performed under low drilling pressure, with the reamer blade 2 in a retracted state; Step 2, when reaching the viscoplastic formation, start the reaming operation mode, increase the drilling pressure, compress the force storage spring 3 of the pilot drill bit body to approach the drill bit body 1, and all the reaming blades 2 move axially with the pilot drill bit body and move radially outward, and the reaming blades 2 spread outward to perform the reaming operation; Step 3, the drilling of the viscoplastic formation is completed, the drilling pressure is reduced, the force storage spring 3 is extended to cause the pilot drill body to move away from the drill body 1, all the reaming blades 2 move axially with the pilot drill body and move radially inward, the reaming blades 2 are retracted inward, and the normal drilling mode is restored; In the above process, the drilling fluid is distributed through the drilling fluid collection chamber 8 and sprayed through the circumferential nozzles and the pilot drill nozzle, carrying the crushed rock cuttings into the annulus; When the reaming operation mode is turned on, the drilling fluid pump pressure is increased to increase the angular momentum of the drilling fluid in the eccentric flow channel 10, so that the drill bit generates circumferential vibration during the reaming operation, thereby improving the reaming effect; in addition, increasing the drilling fluid pump pressure can further reduce the adhesion between the drill tool and the viscoplastic formation, thereby improving the drilling stability.

[0037] Although the above describes the specific implementation mode of the present invention in conjunction with the accompanying drawings, it is not a limitation of the present invention. Those skilled in the art should understand that various modifications or variations that can be made by those skilled in the art on the basis of the technical solution of the present invention without creative work are still within the protection scope of the present invention.

Claims

1. A variable diameter two-stage drill bit suitable for viscoplastic formations, comprising a drill bit body; characterized in that: A plurality of reaming blades are evenly arranged on the side of the drill body in the circumferential direction, a force storage spring is fixedly arranged at the drill end of the drill body, the force storage spring can be compressed and stored along the axial direction of the drill body, and a pilot drill body is fixedly arranged at the other end of the force storage spring; The reaming blade is in sliding cooperation with the drill bit body, and the reaming blade is in sliding cooperation with the pilot drill bit body along the radial direction of the drill bit body; When the force storage spring pushes the pilot drill body away from the drill body, all the reaming blades follow the pilot drill body to move axially and move radially inward; when the pilot drill body compresses the force storage spring to move closer to the drill body, all the reaming blades follow the pilot drill body to move axially and move radially outward; A plurality of reaming cutting teeth are arranged on the reaming blade along the generatrix direction, and the pilot drill bit body is provided with pilot cutting teeth.

2. The variable diameter dual-stage drill bit suitable for viscoplastic formations according to claim 1, characterized in that: A drilling fluid collection chamber is provided in the middle of the drill bit body, and the drilling fluid collection chamber passes through to the drill string connection end; A circumferential flow channel connected to the drilling fluid collection chamber is arranged on the drill bit body between adjacent reaming blades, and a circumferential nozzle is arranged at the radial outer end of the circumferential flow channel.

3. The variable diameter dual-stage drill bit suitable for viscoplastic formations according to claim 2, characterized in that: An eccentric flow channel penetrating to the drilling fluid collecting chamber is arranged on the end surface of the drill bit body facing the pilot drill bit body, and the central axis of the eccentric flow channel is in a non-planar straight line relationship with the central axis of the drill bit body.

4. The variable diameter dual-stage drill bit suitable for viscoplastic formations according to claim 3, characterized in that: The pilot drill body is provided with a through pilot drill flow passage, and a pilot drill nozzle is arranged in the pilot drill flow passage.

5. The variable diameter dual-stage drill bit suitable for viscoplastic formations according to claim 4, characterized in that: A plurality of pilot drill blades are evenly arranged on the pilot drill body along the circumferential direction, and the pilot cutting teeth are arranged on the pilot drill blades and a plurality of them are arranged along the generatrix direction.

6. The variable diameter dual-stage drill bit suitable for viscoplastic formations according to claim 5, characterized in that: Ends of all pilot drill blades away from the drill body are close to each other, and a central conical cutting tooth is arranged at the center where all pilot drill blades are close to each other.

7. The variable diameter dual-stage drill bit suitable for viscoplastic formations according to claim 4, characterized in that: A plurality of radial slide rails corresponding to the reaming blades are arranged along the circumferential direction on the end surface of the pilot drill body facing the drill body; A radial slide groove which is radially slidably matched with a corresponding radial slide rail is arranged on the end surface of the reaming blade facing the pilot drill body.

8. The variable diameter dual-stage drill bit suitable for viscoplastic formations according to claim 4, characterized in that: A plurality of axial sliding grooves corresponding to the reaming blades are arranged on the side surface of the drill bit body along the circumferential direction; An axial slide rail is provided on the side of the reaming blade facing the drill bit body and is slidably matched with the corresponding axial slide groove; The distance between one end of the axial slide groove close to the pilot drill body and the central axis of the drill body is smaller than the distance between one end of the axial slide groove far from the pilot drill body and the central axis of the drill body.

9. The variable diameter dual-stage drill bit suitable for viscoplastic formations according to claim 4, characterized in that: A thread is arranged on the side of the drill bit body away from the pilot drill bit body.

10. A drilling method suitable for viscoplastic formations, implemented based on the variable diameter two-stage drill bit suitable for viscoplastic formations as claimed in any one of claims 4 to 9, characterized in that: The drilling method comprises the following steps: Step 1: During initial drilling, start the conventional drilling mode and perform conventional drilling at a low drilling pressure, with the reamer blades in a retracted state; Step 2: When the viscoplastic formation is reached, the reaming operation mode is turned on, the drilling pressure is increased, the pilot drill body compresses the force storage spring close to the drill body, all the reaming blades move axially with the pilot drill body and move radially outward, and the reaming blades spread outward to perform the reaming operation; Step 3: After drilling in the viscoplastic formation is completed, the drilling pressure is reduced, and the force storage spring is extended to cause the pilot drill bit body to move away from the drill bit body. All the reaming blades move axially with the pilot drill bit body and move radially inward at the same time. The reaming blades are retracted inward to restore the normal drilling mode. In the above process, the drilling fluid is distributed through the drilling fluid collection chamber and sprayed through the circumferential nozzle and the pilot drill bit nozzle, carrying the crushed cuttings into the annulus; When the reaming operation mode is turned on, the drilling fluid pump pressure is increased, the angular momentum of the drilling fluid in the eccentric flow channel is increased, and the drill bit generates circumferential vibration during the reaming operation, thereby improving the reaming effect.

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