Low-bending-point equal-wall-thickness screw drill

Abstract

The utility model discloses a screw drill with a low bending point and equal wall thickness. The device comprises a transmission shaft assembly, a universal shaft assembly, a motor assembly, a rotor anti-falling device and a bypass valve assembly which are connected in sequence. The whole screw is a single-bend screw with the bending degree of 1.25 degrees, the bending point is arranged on the outer cylinder wall of the universal shaft assembly, and the distance between the bending point and the end face of the transmission shaft assembly is 940 mm. The transmission shaft assembly is used for transmitting power provided by the motor to the drill bit. The universal shaft assembly is used for transmitting the torque and the rotating speed to the transmission shaft. And the motor assembly adopts an equal-wall-thickness motor. The bypass valve assembly is used for enabling the space in the drill column to be communicated with the annulus when the pump is stopped, and the situation that drilling fluid in the drill column overflows to pollute a drill floor during tripping and single connection is avoided. The drill bit has the advantages that the low bending point can provide a larger dog leg degree, the composite drilling proportion is improved, the distance between the bending point and the drill bit is shortened due to downward movement of the bending point, other speed increasing tools can be added between the drill bit and the screw rod, and the mechanical drilling speed of drilling can be continuously improved without affecting the orientation capacity.

Description

Technical Field

[0001] The utility model relates to a downhole tool for petroleum exploration, in particular to a low-bending-point and constant-wall-thickness screw drill. Background Art

[0002] The screw drill is currently the most widely used downhole power drilling tool in drilling operations. It can be used in conjunction with roller bits, PDC bits, and other specialized drill bits to perform vertical, directional, horizontal, and window-sidetrack drilling operations. The screw typically consists of five components: a drive shaft assembly, a universal joint assembly, a motor assembly, a rotor anti-drop device, and a bypass valve assembly. The lower end of the screw is connected to the drill bit. When high-pressure mud output by the mud pump flows through the motor of the screw drill, a certain pressure differential is created at the motor inlet and outlet, driving the motor's rotor to rotate. The torque and speed are then transmitted to the drill bit through the universal joint and drive shaft, thus achieving drilling operations.

[0003] The screw is an effective tool for increasing the mechanical penetration rate (ROP). By reducing the sliding ratio during directional drilling, increasing the ROP is of great significance for further promoting efficient composite directional drilling. The directional capability of the screw is generally related to the length from the screw bend point to the bottom of the screw. Currently, the length from the bend point to the bottom of the screw is generally 1.50 to 1.75 meters. In directional well sections, a high bend point results in low dogleg accuracy and a high proportion of sliding drilling, which increases drilling time and reduces the mechanical penetration rate. If other downhole speed-increasing tools, such as rotary and torsional impact tools, are used in conjunction with the drill bit, the distance from the bend point to the drill bit will increase further, further reducing the directional capability and significantly compromising the directional effect. Utility Model Content

[0004] The technical problem to be solved by the utility model is to provide a screw drill with low bending point and equal wall thickness, which has stable drilling, good directional ability and can realize the purpose of improving mechanical drilling speed.

[0005] In order to solve the above technical problems, the low-bending-point and equal-wall-thickness screw drill tool of the utility model includes a drive shaft assembly, a universal shaft assembly, a motor assembly, a rotor anti-drop device and a bypass valve assembly connected in sequence. The screw as a whole is a single-bend screw with a curvature of 1.25°. The bending point is set on the outer cylinder wall of the universal shaft assembly, and the distance between the bending point and the end face of the drive shaft assembly is 940 mm.

[0006] The transmission shaft assembly is used to transmit the power provided by the motor to the drill bit, while bearing axial and radial loads.

[0007] A plurality of stabilizers are installed on the transmission shaft assembly.

[0008] The cardan shaft assembly is used to transmit torque and rotational speed to the transmission shaft.

[0009] The motor assembly adopts a motor with uniform wall thickness.

[0010] The bypass valve assembly is used to connect the space inside the drill string with the annulus when the pump is stopped, so as to prevent the drilling fluid in the drill string from overflowing and contaminating the drilling platform when tripping and connecting single wells.

[0011] The advantages of the present invention are: the low bending point can provide a greater dogleg degree and improve the composite drilling ratio; the downward movement of the bending point shortens the distance between the bending point and the drill bit, and other speed-increasing tools can be added between the drill bit and the screw, such as a rotary punch short section, a torsional punch short section, etc., to continue to improve the mechanical drilling speed without affecting the directional ability of the drill tool assembly; the equal wall thickness motor has better anti-deformation ability, heat dissipation performance and sealing performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 It is a structural diagram of the present utility model. DETAILED DESCRIPTION

[0013] The low bending point and equal wall thickness screw drill of the present invention will be further described in detail below with reference to the accompanying drawings and specific implementation methods.

[0014] As shown in the figure, the low-bend-point, uniform-wall-thickness screw drill tool of the present invention comprises a sequentially connected drive shaft assembly 1, a universal joint assembly 2, a motor assembly 3, a rotor anti-drop device 4, and a bypass valve assembly 5. The screw is a single-bend screw with a 1.25° bend. The bend point is located on the outer wall of the universal joint assembly 2, and the distance between the bend point and the end face of the drive shaft assembly 1 is 940 mm. The screw is made of steel and rubber.

[0015] The transmission shaft assembly 1 is used to transmit the power provided by the motor to the drill bit, while bearing axial and radial loads, and is equipped with multiple stabilizers.

[0016] The universal joint assembly 2 is used to convert the planetary motion of the motor into the fixed axis rotation of the transmission shaft, and transmit the torque and speed to the transmission shaft.

[0017] The motor assembly 3 utilizes a uniform-wall motor and consists of a stator and rotor that mesh together to form a sealed chamber. A thin rubber bushing is injection-molded onto the stator surface, ensuring uniform stress distribution. The rotor's surface undergoes a reinforced treatment for high wear and corrosion resistance. The stator has one more head than the rotor, meshing together to form a sealed chamber that converts the slurry's hydraulic energy into mechanical energy.

[0018] The rotor anti-drop device 4 is used to ensure the safety of the screw drill working underground.

[0019] The bypass valve assembly 5 is used to communicate the space inside the drill string with the annulus when the pump is stopped, so as to prevent the drilling fluid in the drill string from overflowing and contaminating the drilling platform when tripping and connecting single roots.

[0020] Low-bend screw drill bits are used in conjunction with drill bits for drilling operations such as vertical wells, directional wells, horizontal wells, and window sidetracking. When used in a φ215.9mm wellbore, the high-pressure mud output by the mud pump flows through the screw drill bit's motor, creating a certain pressure differential at the motor inlet and outlet, driving the motor's rotor to rotate. The torque and speed are then transmitted to the drill bit through the universal joint and drive shaft, enabling drilling operations. The low bend point provides greater dogleg accuracy and improves the composite drilling ratio. The downward shift of the bend point shortens the distance between the bend point and the drill bit, allowing the addition of other speed-boosting tools, such as rotary impact subs and torsional impact subs, between the drill bit and the screw, further increasing the mechanical penetration rate without affecting the directional capability of the drill tool assembly. The constant-wall thickness motor has better deformation resistance, heat dissipation, and sealing properties.

[0021] Of course, the above description is not a limitation of the present invention, and the present invention is not limited to the above examples. Changes, modifications, additions or substitutions made by technicians in this technical field within the essential scope of the present invention should also fall within the scope of protection of the present invention.

Claims

1. A low-bending-point and uniform-wall-thickness screw drill, comprising a transmission shaft assembly (1), a universal shaft assembly (2), a motor assembly (3), a rotor anti-drop device (4), and a bypass valve assembly (5) connected in sequence, characterized in that: The screw as a whole is a single-bend screw with a curvature of 1.25°. The bending point is set on the outer cylinder wall of the universal shaft assembly (2), and the distance between the bending point and the end face of the transmission shaft assembly (1) is 940 mm.

2. The low bending point and constant wall thickness screw drill according to claim 1, characterized in that: The transmission shaft assembly (1) is used to transmit the power provided by the motor to the drill bit, while bearing axial and radial loads.

3. The low bending point and constant wall thickness screw drill according to claim 2, characterized in that: A plurality of stabilizers are installed on the transmission shaft assembly (1).

4. The low bending point and constant wall thickness screw drill according to claim 3, characterized in that: The universal joint assembly (2) is used to transmit torque and rotational speed to the transmission shaft.

5. The low bending point and constant wall thickness screw drill according to claim 4, characterized in that: The motor assembly (3) adopts a motor with a constant wall thickness.

6. The low bending point and constant wall thickness screw drill according to claim 5, characterized in that: The bypass valve assembly (5) is used to allow the space inside the drill string to communicate with the annulus when the pump is stopped, so as to prevent the drilling fluid in the drill string from overflowing and contaminating the drilling platform when drilling and connecting single drills.

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