Oil drilling bidirectional eccentric reamer

Abstract

This utility model discloses a bidirectional eccentric reamer for oil drilling, belonging to the technical field of oil drilling tools. The reamer body has an upper small-diameter section at its upper part, an upper connector above the upper small-diameter section, a lower small-diameter section at its lower part, and a lower connector below the lower small-diameter section. The upper connector, upper small-diameter section, lower small-diameter section, and lower connector are coaxial and coincide with the main axis of the reamer. The middle section of the reamer body has an eccentric large-diameter section, the axis of which is offset from the axes of the upper and lower small-diameter sections. Upper small-diameter section cutting blades are evenly distributed around the outer periphery of the upper small-diameter section, lower small-diameter section cutting blades are evenly distributed around the outer periphery of the lower small-diameter section, and a main cutting blade is located around the outer periphery of the large-diameter section. This reamer can improve wellbore quality and stability through bidirectional reaming while drilling, effectively reducing the risk of borehole shrinkage and stuck pipe, and improving drilling efficiency.

Description

Technical Field

[0001] This utility model relates to a borehole reamer, and more particularly to a bidirectional eccentric borehole reamer for oil drilling, belonging to the field of oil drilling tool technology. Background Technology

[0002] As oil and gas field exploration and development expands into deep wells, ultra-deep wells, and high-pressure oil and gas wells, drilling wells face engineering and technical challenges such as long open-hole sections, multiple pressure layers, and narrow drilling fluid density windows. Due to factors such as wellbore instability and the coexistence of multiple pressure layers, problems frequently arise, such as reduced wellbore diameter or excessive accumulation of debris, making drilling difficult to continue. Currently, drilling tool assemblies mainly use single-bend screw assemblies, which easily create microsteps and micro-doglegs in the resulting helical wellbore. Furthermore, as the stabilization or horizontal sections lengthen, cuttings bed removal becomes difficult, and the frictional torque increases, resulting in more reaming operations and longer wellbore clearance times. The conventional solution is to perform reaming operations during drilling or tripping to repair the wellbore.

[0003] With technological advancements, the addition of micro-reamers or concentric bidirectional reamers to drill string assemblies has achieved certain results in eliminating wellbore steps, preventing borehole narrowing, and reducing tripping operations. However, the following problems still exist: 1. In terms of efficiency, traditional post-drilling reaming and reaming methods have long operation times, increasing drilling cycles and costs. Although reaming and reaming while drilling can be performed simultaneously, in complex formations, the reaming and reaming tools are easily affected by the complex formations, resulting in reduced reaming and reaming efficiency.

[0004] 2. In terms of safety, when carrying out reaming operations in complex formations, hard rock layers and fractured zones will accelerate the wear of reaming tools while drilling, leading to tool failure. Once a failure occurs, the retrieval is difficult and greatly increases the drilling risk.

[0005] 3. Traditional unidirectional eccentric reamers can only ream in one direction, requiring multiple trips to repair different well sections. They are inefficient in hard formations and prone to stuck drill bits. Torque distribution is uneven, with large torque fluctuations, making the cutter blades prone to breakage. The low tooth density of the cutter blades leads to easy wear, with a blade life of only 200 hours. Furthermore, the reaming diameter is fixed, resulting in a rough wellbore surface requiring secondary treatment. The small distance between the eccentric reamer's blades and the drill bit often leads to mutual interference of the flow field, reducing wellbore cleaning efficiency. Conventional concentric bidirectional reamers, while capable of bidirectional reaming, have significant differences in efficiency between the forward and reverse directions, limiting the reaming range and making them suitable only for medium-hard formations. The blade life is generally 300 hours, the reaming diameter is fixed, and the wellbore surface has moderate smoothness. Utility Model Content

[0006] The purpose of this section is to outline some aspects of embodiments of the present invention and to briefly describe some preferred embodiments. Simplifications or omissions may be made in this section, as well as in the abstract and title of this application, and such simplifications or omissions should not be construed as limiting the scope of the present invention.

[0007] In view of the problems existing in the above and / or prior art, this utility model is proposed.

[0008] The purpose of this invention is to overcome the problems of long time consumption for conventional post-drilling reaming and the low efficiency of repairing the well wall with micro reamers or concentric bidirectional reamers while drilling in the existing technology, and to provide a bidirectional eccentric reamer for oil drilling that can improve wellbore quality and stability through bidirectional reaming while drilling, effectively reduce the risk of diameter reduction and stuck pipe, and improve drilling efficiency.

[0009] To solve the above technical problems, this utility model provides a bidirectional eccentric reamer for oil drilling, comprising a reamer body, a through central hole 6 along the axis of the reamer body, an upper small diameter section 2 at the upper part of the reamer body, an upper connector 1 above the upper small diameter section 2, a lower small diameter section 4 at the lower part of the reamer body, and a lower connector 5 below the lower small diameter section 4. The upper connector 1, the upper small diameter section 2, the lower small diameter section 4, and the lower connector 5 are coaxial and all coincide with the main axis of the reamer. The middle section of the eye expander body is provided with an eccentric large diameter section 3, and the axis of the large diameter section 3 is offset from the axis of the upper small diameter section 2 and the lower small diameter section 4 of the body. The outer periphery of the upper small diameter section 2 of the body is evenly distributed with upper small diameter section cutting blades 2a, the outer periphery of the lower small diameter section 4 of the body is evenly distributed with lower small diameter section cutting blades 4a, and the outer periphery of the large diameter section 3 of the body is provided with main cutting blades 3a.

[0010] Furthermore, the crown surfaces of the upper small-diameter cutting blade 2a, the lower small-diameter cutting blade 4a, and the main cutting blade 3a are respectively short parabolic profiles that are high in the middle and low at both ends.

[0011] Furthermore, the upper small-diameter section cutting blade 2a, the lower small-diameter section cutting blade 4a, and the main cutting blade 3a are straight blades extending vertically or spiral blades extending along a helical line.

[0012] Furthermore, when the upper small-diameter section cutting blade 2a, the lower small-diameter section cutting blade 4a, and the main cutting blade 3a are helical blades, the upper and lower sets of helical blades have the same rotation direction.

[0013] Furthermore, the cutting surface of the main cutting blade 3a is provided with main cutting blade cutting teeth 3b, the cutting surface of the upper small diameter section cutting blade 2a is provided with upper small diameter section cutting blade cutting teeth 2b, and the cutting surface of the lower small diameter section cutting blade 4a is provided with lower small diameter section cutting blade cutting teeth 4b; the main cutting blade cutting teeth 3b, the upper small diameter section cutting blade cutting teeth 2b, and the lower small diameter section cutting blade cutting teeth 4b are all PDC cutting teeth.

[0014] Furthermore, the main blade cutting tooth 3b, the upper small-diameter blade cutting tooth 2b, and the lower small-diameter blade cutting tooth 4b are respectively arranged on the upper and lower crown surfaces of the blade, and the tooth height is 1.5mm above the blade body, and they are arranged in staggered rows.

[0015] Furthermore, the outer end face of each main cutting blade 3a is provided with multiple main blade diameter protection teeth 3c in the vertical direction; the root outer end face of the upper small diameter cutting blade 2a is provided with upper small diameter cutting blade diameter protection teeth 2c, and the root outer end face of the lower small diameter cutting blade 4a is provided with lower small diameter cutting blade diameter protection teeth 4c.

[0016] Furthermore, the upper small-diameter section blade retaining tooth 2c and the lower small-diameter section blade retaining tooth 4c are high wear-resistant cemented carbide columnar teeth, and the retaining tooth length is not less than 16mm.

[0017] Furthermore, the upper port of the upper connector 1 of the body is provided with a tapered female thread 1a, and the lower outer wall of the upper connector 1 of the body is a hydraulic clamping part 1b; the lower end of the lower connector 5 of the body is provided with a tapered male thread 5a.

[0018] Compared with the prior art, the advantages or beneficial effects of this utility model include at least the following: 1. By adopting a symmetrical bidirectional eccentric structure, it achieves simultaneous forward drilling and reverse reaming operations, and simultaneously cuts the well wall micro-steps in reverse while enlarging the well, effectively solving the problem of well diameter reduction caused by spiral wells and micro doglegs; it has a wide range of applications, covering mudstone, limestone and non-sedimentary rock formations.

[0019] 2. Utilizing a double-crown blade design with staggered tooth rows, it improves wellbore repair efficiency; combined with gauge protection blocks, the blade life exceeds 400 hours. Forward and reverse scraping and finishing result in a smooth wellbore wall.

[0020] 3. This tool can solve drilling problems in complex formations, reduce the risk of encountering obstacles or getting stuck, significantly reduce drilling time loss, and provide strong technical support for energy supply. Attached Figure Description

[0021] To more clearly illustrate the technical solutions of the embodiments of this utility model, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. The drawings are provided for reference and illustration only and are not intended to limit this utility model. Wherein: Figure 1 This is a front view of the bidirectional eccentric reamer for oil drilling of this utility model; Figure 2 This is a schematic diagram of the eccentric structure of the lower main cutting blade. Figure 3 This is a schematic diagram of the eccentric structure of the upper main cutting blade. Figure 4 This is a schematic diagram of the eccentric structure of the upper small-diameter section cutting blade. Figure 5 This is a schematic diagram of the eccentric structure of the cutting blade wing in the lower small-diameter section.

[0022] Reference numerals: 1. Connector on the body; 1a. Tapered female thread; 1b. Hydraulic clamping part; 2. Small diameter section on the body; 2a. Cutting blade on the small diameter section; 2b. Cutting teeth on the small diameter section blade; 2c. Diameter-maintaining teeth on the small diameter section blade; 3. Main body large diameter section; 3a. Main cutting blade; 3b. Main blade cutting teeth; 3c. Main blade diameter-maintaining teeth; 4. Lower small diameter section of the body; 4a. Cutting blade of the lower small diameter section; 4b. Cutting teeth of the cutting blade of the lower small diameter section; 4c. Diameter-maintaining teeth of the cutting blade of the lower small diameter section; 5. Lower connector of the body; 5a. Tapered male thread; 6. Center hole of the body. Detailed Implementation

[0023] In the following description of this utility model, the terms "upper", "lower", "front", "rear", "left", "right", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this utility model and simplifying the description, and do not mean that the device must have a specific orientation.

[0024] To make the technical means, creative features, achieved objectives and effects of this utility model easier to understand, the present utility model will be further described below with reference to specific illustrations. Obviously, the described embodiments are only some embodiments of this utility model, and not all embodiments.

[0025] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention.

[0026] like Figures 1 to 5 As shown, the present invention relates to a bidirectional eccentric reamer for oil drilling, comprising a reamer body with a through central hole 6 along its axis. The upper part of the reamer body has an upper small-diameter section 2, above which is an upper connector 1. The upper port of the upper connector 1 has a tapered female thread 1a for connection to the drill pipe above. The lower outer wall of the upper connector 1 is a hydraulic clamping part 1b. The lower part of the reamer body has a lower small-diameter section 4, below which is a lower connector 5. The lower end of the lower connector 5 has a tapered male thread 5a for connection to the drill pipe below.

[0027] The upper connector 1, the upper small diameter section 2, the lower small diameter section 4, and the lower connector 5 are coaxial and all coincide with the main axis of the expander. The outer circumference of the upper small diameter section 2 is evenly distributed with upper small diameter section cutting blades 2a, and the outer circumference of the lower small diameter section 4 is evenly distributed with lower small diameter section cutting blades 4a.

[0028] The main body of the expander has an eccentric large-diameter section 3 in the middle section, meaning that the axis of the large-diameter section 3 deviates from the axes of the upper small-diameter section 2 and the lower small-diameter section 4. The outer periphery of the large-diameter section 3 is provided with a main cutting blade 3a. The crown surfaces of the upper small-diameter section cutting blade 2a and the main cutting blade 3a are respectively short parabolic contours that are high in the middle and low at both ends. Each upper small-diameter section cutting blade 2a and the main cutting blade 3a can extend vertically to form a straight blade; or they can extend along a spiral line to form a spiral blade.

[0029] The bidirectional eccentric reamer features a multi-stage variable-diameter symmetrical bidirectional eccentric structure. When using helical blades, the upper and lower sets of helical blades rotate in the same direction, achieving self-force balance during tool operation. This enables simultaneous forward drilling and reverse reaming. The reamer blades generate stable and flexible bidirectional eccentric force as the drill string rotates, achieving 360° omnidirectional reaming and cuttings agitation for wellbore dressing and cleaning. The blades exhibit bidirectional, multi-stage, progressive expansion, precisely adapting to formations of varying hardness, reducing the risk of stuck pipe, and improving reaming uniformity. Furthermore, the eccentric angle and amplitude can be adjusted according to downhole conditions during processing, enhancing wellbore enlargement efficiency and stability in irregular formations. The bidirectional eccentric motion reduces friction between the drill string and the wellbore, effectively reducing torque, enhancing tool stability, minimizing vibration and malfunctions during drilling, and extending service life.

[0030] The cutting surfaces of the main cutting blade 3a are provided with main cutting blade cutting teeth 3b, the cutting surfaces of the upper small diameter section cutting blade 2a are provided with upper small diameter section cutting blade cutting teeth 2b, and the cutting surfaces of the lower small diameter section cutting blade 4a are provided with lower small diameter section cutting blade cutting teeth 4b. The main cutting blade cutting teeth 3b, the upper small diameter section cutting blade cutting teeth 2b, and the lower small diameter section cutting blade cutting teeth 4b are all PDC cutting teeth.

[0031] Each blade has 13mm PDC cutting teeth arranged on its upper crown surface as reverse cutting teeth, with the teeth protruding 1.5mm above the blade body; and 13mm PDC cutting teeth arranged on its lower crown surface, with the teeth protruding 1.5mm above the blade body, so as to better penetrate the strata, enhance the impact resistance, and arrange the teeth in a staggered arrangement to ensure uniform force and efficient rock breaking during bidirectional cutting.

[0032] Each main cutting blade 3a has multiple main blade gauge protection teeth 3c vertically arranged on the middle section of its outer end face, typically four main blade gauge protection teeth 3c. The root of the upper small-diameter section cutting blade 2a, near the outer end face of the main body's large-diameter section 3, has upper small-diameter section blade gauge protection teeth 2c, and the root of the lower small-diameter section cutting blade 4a, near the outer end face of the main body's large-diameter section 3, has lower small-diameter section blade gauge protection teeth 4c. The upper and lower small-diameter section blade gauge protection teeth 2c and 4c are 13mm high-wear-resistant cemented carbide columnar teeth, with a gauge protection tooth length of not less than 16mm. This unique tooth arrangement on the upper and lower crown surfaces of the blades improves wellbore repair efficiency. Combined with a short parabolic profile crown surface design, the contact area between the blades and the formation is increased. The use of a compound alloy tooth layout and gauge protection tooth design extends blade life and reduces tripping frequency.

[0033] During the downward drilling process, the lower small-diameter section cutting blade 4a on the lower small-diameter section 4 of the main body plays a positive reaming role. It can also perform preliminary cutting and breaking of large chunks that are brought up with the drilling fluid, making them smaller pieces, which are then easier for the main cutting blade 3a to further cut and break, thus avoiding getting stuck.

[0034] During the upward reaming process, the upper small-diameter section cutting blade 2a of the main body acts as a reverse reaming blade, and then the main cutting blade 3a enlarges the hole. By adopting a symmetrical bidirectional eccentric structure, the forward drilling and reverse reaming operations are achieved simultaneously. While enlarging the hole, the well wall micro-steps are cut in reverse, effectively solving the problem of well diameter reduction caused by spiral wells and micro-doglegs.

[0035] In drilling assemblies, the placement of the bidirectional eccentric reamer should generally ensure that when the drill bit contacts the bottom of the well, the reamer is outside the upper casing layer, with the distance from the drill bit equal to the initial drilling depth minus the casing depth. In well cleaning assemblies, the placement is typically 150-200 meters from the drill bit.

[0036] Given the varying well depths and complex formations, a single eccentric reamer may not be sufficient for reaming operations at all depths and in complex formations. Therefore, two eccentric reamers can be used. The first reamer is positioned between the drill bit and the expected drill bit pull-out depth minus the bottom depth of the complex formation, ensuring it reams to the bottom depth of the complex formation. The second reamer is positioned between the drill bit and the drill bit depth minus the top depth of the complex formation, ensuring it reams from the top of the complex formation to repair the wellbore.

[0037] Well cleaning operation: Drill string assembly consisting of roller cone bit, stabilizer, and bidirectional eccentric reamer while drilling. Connecting this bidirectional eccentric reamer to the drilling tools allows the cutting teeth on the reamer body to rotate with the drilling tools. During active forward reaming in complex well sections, the lower crown surface (EE section) of the lower small-diameter cutting blade 4a contacts the wellbore first, clearing minor protrusions and cuttings beds. Subsequently, the lower main cutting blade 3a contacts the wellbore for secondary repair, maintaining wellbore stability. During reverse reaming, the upper crown surface (DD section) of the upper small-diameter cutting blade 2a contacts the wellbore first, clearing minor protrusions and cuttings beds. Subsequently, the upper main cutting blade 3a (C-C section) contacts the wellbore for secondary repair, clearing accumulated cuttings beds and improving wellbore quality.

[0038] Drilling operation: Drill string assembly consisting of a PDC drill bit, a single-bend screw rod, and a bidirectional eccentric reamer while drilling. Connect this bidirectional eccentric reamer to the drilling tool, allowing the cutting teeth on the reamer's body to rotate with the tool. During drilling or active forward reaming, the lower crown surface (EE section) of the lower small-diameter cutting blade 4a first contacts the wellbore, clearing away minor protrusions and cuttings beds. Subsequently, the lower main cutting blade 3a (B-B section) contacts the wellbore, performing secondary repair and maintaining wellbore stability. During reverse reaming, the upper crown surface (DD section) of the upper small-diameter cutting blade 2a first contacts the wellbore, clearing away minor protrusions and cuttings beds. Subsequently, the upper main cutting blade 3a (C-C section) contacts the wellbore, performing secondary repair and maintaining wellbore stability.

[0039] During the repair process, the main cutting blades, upper small-diameter cutting blade 2b, and lower small-diameter cutting blade 4b cut and break up the collapsed material, preventing large pieces of debris from accumulating and causing stuck drill bits, thus solving the problem of stuck drill bits caused by downhole collapse. Simultaneously, it clears accumulated cuttings beds, improves wellbore quality, and reduces the occurrence of stuck drill bits. During reaming, the upper crown surface of the upper small-diameter cutting blade 2a first contacts the wellbore wall, clearing any small protrusions and cuttings beds. Then, the main cutting blade 3a contacts the wellbore wall for secondary repair.

[0040] The total length of this bidirectional eccentric reamer is 1369mm, of which the length of the large diameter section 3 is 340mm. The outer diameters of the upper connector 1 and the lower connector 5 are both Φ168mm. The tapered male thread 5a is an NC50 male thread machined according to API standards, and similarly, the tapered female thread 1a is an NC50 female thread. The diameter of a wellbore with a diameter of Φ215.9mm after reaming can reach Φ226mm. The above description is merely a preferred embodiment of the present utility model, showing and describing the basic principles, main features, and advantages of the present utility model. It is not intended to limit the scope of patent protection of the present utility model. Those skilled in the art should understand that the present utility model is not limited to the above embodiments. In addition to the above embodiments, the present utility model may have other implementations without departing from the spirit and scope of the present utility model. Various changes and improvements to the present utility model are also possible. All technical solutions formed by equivalent substitutions or equivalent transformations fall within the scope of protection claimed by the present utility model. The scope of protection claimed by the present utility model is defined by the appended claims and their equivalents. Technical features not described in the present utility model can be implemented by or using existing technology, and will not be elaborated here.

Claims

1. A bidirectional eccentric reamer for drilling oil wells while drilling, comprising a reamer body provided with a through-going body central hole (6) along the axis of the reamer body, characterized in that: The upper part of the eye expander body is provided with an upper small diameter section (2), the upper connector (1) is provided above the upper small diameter section (2), the lower part of the eye expander body is provided with a lower small diameter section (4), the lower connector (5) is provided below the lower small diameter section (4), the upper connector (1), the upper small diameter section (2), the lower small diameter section (4) and the lower connector (5) are coaxial and all coincide with the main axis of the eye expander. The middle section of the eye expander body is provided with an eccentric large diameter section (3), and the axis of the large diameter section (3) is offset from the axis of the upper small diameter section (2) and the lower small diameter section (4) of the body. The outer periphery of the upper small diameter section (2) of the body is evenly distributed with upper small diameter section cutting blades (2a), the outer periphery of the lower small diameter section (4) of the body is evenly distributed with lower small diameter section cutting blades (4a), and the outer periphery of the large diameter section (3) of the body is provided with main cutting blades (3a).

2. The dual eccentric under-reamer for drilling oil wells while drilling according to claim 1, characterized in that: The crown surfaces of the upper small-diameter cutting blade (2a), the lower small-diameter cutting blade (4a), and the main cutting blade (3a) are respectively short parabolic contours that are high in the middle and low at both ends.

3. The dual eccentric under-reamer for drilling oil wells while drilling according to claim 1, characterized in that: The upper small-diameter section cutting blade (2a), the lower small-diameter section cutting blade (4a), and the main cutting blade (3a) are straight blades extending vertically or spiral blades extending along a spiral line.

4. The dual eccentric under-reamer for drilling oil wells while drilling according to claim 3, characterized in that: When the upper small-diameter section cutting blade (2a), the lower small-diameter section cutting blade (4a) and the main cutting blade (3a) are helical blades, the upper and lower sets of helical blades have the same rotation direction.

5. The dual eccentric under-reamer for drilling oil wells while drilling according to claim 3, characterized in that: The cutting surface of the main cutting blade (3a) is provided with main blade cutting teeth (3b), the cutting surface of the upper small diameter section cutting blade (2a) is provided with upper small diameter section cutting teeth (2b), and the cutting surface of the lower small diameter section cutting blade (4a) is provided with lower small diameter section cutting teeth (4b). The main blade cutting tooth (3b), the upper small-diameter blade cutting tooth (2b), and the lower small-diameter blade cutting tooth (4b) are all PDC cutting teeth.

6. The dual eccentric under-reamer for drilling oil wells while drilling according to claim 5, characterized in that: The main blade cutting teeth (3b), the upper small-diameter blade cutting teeth (2b), and the lower small-diameter blade cutting teeth (4b) are respectively arranged on the upper and lower crown surfaces of the blade, and the teeth are 1.5mm higher than the blade body, and are arranged in a staggered row.

7. The dual eccentric under-reamer for drilling oil wells while drilling according to claim 1, characterized in that: The outer end face of each main cutting blade (3a) is provided with multiple main blade diameter protection teeth (3c) in the middle section along the vertical direction; the root outer end face of the upper small diameter cutting blade (2a) is provided with upper small diameter cutting blade diameter protection teeth (2c), and the root outer end face of the lower small diameter cutting blade (4a) is provided with lower small diameter cutting blade diameter protection teeth (4c).

8. The dual eccentric under-reamer for drilling oil wells while drilling according to claim 7, characterized in that: The upper small-diameter section blade retaining tooth (2c) and the lower small-diameter section blade retaining tooth (4c) are high wear-resistant cemented carbide columnar teeth, and the retaining tooth length is not less than 16mm.

9. The bidirectional eccentric reamer for oil drilling according to claim 1, characterized in that: The upper port of the upper connector (1) of the body is provided with a tapered female thread (1a), and the lower outer wall of the upper connector (1) of the body is a hydraulic clamping part (1b); the lower end of the lower connector (5) of the body is provided with a tapered male thread (5a).

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