Oil and gas well screw drill assembly acceleration method

Abstract

The invention relates to an oil exploration well drilling operation technology in the field of geological exploration drilling tools, in particular to an oil and gas well screw drilling tool combination acceleration method. According to the method, a drilling tool comprises a screw rod, and the screw rod comprises a bypass valve assembly, a motor assembly, a universal shaft assembly and a transmission shaft assembly which are sequentially connected from top to bottom in a conventional mode; the whole screw rod is a single-bend screw rod with the bending degree of 1-2.25 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 900-960 mm; and the transmission shaft assembly is sequentially connected with the conventional torsion impacter and the PDC drill bit. On the basis of application of the torsional punching and PDC drill bit, a low-bending-point equal-wall-thickness screw drill is additionally arranged in a drill assembly, and the aim of improving the mechanical drilling speed is achieved.

Description

Technical Field

[0001] The invention relates to a petroleum exploration well drilling operation technology in the field of geological exploration drilling tools, and in particular to a speed-increasing method for a screw drilling tool assembly for an oil and gas well. Background Art

[0002] The movement of the PDC drill bit is extremely disordered during the drilling process. When drilling in hard or super-hard formations, the PDC drill bit will temporarily stop due to insufficient torque. When the torsional stress on the drill string suddenly reaches the torque required to shear and crush the formation, the energy accumulated on the drill string is suddenly released. This is the stick-slip phenomenon of the PDC drill bit. The stick-slip phenomenon of the PDC drill bit causes torsional oscillation of the drill string and instability in the drilling process, which has a serious impact on the mechanical drilling rate and the life of the drill bit. The torque impactor + PDC drill bit operation mode can significantly slow down or eliminate this problem. The torsion impactor gives the PDC drill bit a high-frequency, uniform torsion impact, and the top drive or turntable provides the drill bit with radial shear force. At the same time, the torque impactor applies a radial shear force to the drill bit. The superposition of the two shear forces can effectively crush the rock, which has a certain effect on improving the mechanical drilling rate and can extend the life of the drill bit. However, the top drive or turntable speed can only reach 50-60rpm, and the torsion impactor does not have a directional function. In order to apply the torsion punch to directional wells, if the screw and torsion punch are used in combination to meet the higher requirements of the drill speed and radial shear force in directional drilling, there is no suitable implementation solution in the existing technology. Because the bending point of the conventional single-bend screw is usually 1.5-1.75m away from the bottom of the screw, and the length of the torsion punch tool is about 0.6m, if it is directly combined, the distance from the bending point to the drill bit reaches 2.1-2.35m. How this will affect the drilling speed and directional ability of the drill tool is difficult to predict. Summary of the invention

[0003] The technical problem to be solved by this patent is to overcome the defects of existing operating methods and drilling tools, and to provide a method for increasing the speed of oil and gas well screw drill tool combinations while ensuring the life of the drilling tools and drilling reliability.

[0004] The speed-up method of the oil and gas well screw drill assembly of the patent of the present invention is: the drill tool includes a screw, and the screw includes a bypass valve assembly, a motor assembly, a universal shaft assembly and a transmission shaft assembly connected in sequence from top to bottom in a conventional manner; the screw is set as a single-bend screw with a bend of 1°-2.25°, 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 transmission shaft assembly is 900-960mm; the transmission shaft assembly is then connected in sequence to a conventional torque impactor and a PDC drill bit.

[0005] Preferably, the screw structure adopts a screw with equal wall thickness, and the motor assembly adopts a motor with equal wall thickness.

[0006] Preferably, the distance from the bending point to the lower end surface of the torque impactor is 1500-1750 mm.

[0007] Preferably, the screw body is 7m long and has an outer diameter of 172mm. The screw is provided with a 212mm centralizer, and the centralizer is 450mm away from the bottom of the screw.

[0008] The above method of the present invention can be used in the drilling process of a φ215.9mm wellbore.

[0009] The method of the present invention can be used in the vertical well section, directional section or stable inclination section of hard formation drilling operation.

[0010] The advantages of the present invention are: based on the theoretical judgment that the increase in the distance from the bending point to the drill bit will lead to a decrease in the directional ability of the screw drill tool and affect the mechanical drilling speed, on the basis of the application of the torsion punch + PDC drill bit, a screw drill tool with low bending point and equal wall thickness is added to the drill tool combination, and the high rotation speed of the screw with low bending point and equal wall thickness and the torsional impact force of the torsion punch tool are combined to achieve the goal of improving the mechanical drilling speed. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 Schematic diagram of the structure of the drilling tool assembly in an embodiment of the present invention. DETAILED DESCRIPTION

[0012] As shown in the figure, the embodiment of the present invention uses a low bending point and equal wall thickness screw and a torsion impact drill tool combination to achieve drilling speed increase. The drill tool combination includes a low bending point and equal wall thickness screw 1, a torsion impactor 2 and a PDC drill bit 3; the screw includes a bypass valve assembly 11, a motor assembly 12, a universal shaft assembly 13 and a transmission shaft assembly 14 connected in sequence from top to bottom in a conventional manner; the screw is a single-bend screw, the length L1 of the bending point from the bottom of the screw is 940mm, and the curvature of the screw is 1.25°; the distance L2 from the bending point to the lower end face of the torsion impactor is 1500-1750mm; the lower end of the torsion impactor 2 is directly connected to the PDC drill bit 3, and the upper end is directly connected to the low bending point and equal wall thickness screw 1.

[0013] The torque impactor + PDC bit operation mode can apply a high-frequency, uniform torque impact to the PDC bit, solving the stick-slip problem encountered by the PDC bit when drilling in hard formations. The low-bending point equal-wall thickness screw will not affect the directional capability by lowering the bending point and using it in combination with the torque impactor. At the same time, the rotation of the screw can increase the drill bit speed, thereby achieving the purpose of increasing the mechanical drilling speed.

[0014] During the drilling process of the above-mentioned drill tool combination of the embodiment of the present invention, the low-bending-point equal-wall-thickness screw of the drilling equipment is composed of five parts: a transmission shaft assembly, a universal shaft assembly, an equal-wall-thickness motor assembly, a rotor anti-drop device and a bypass valve assembly. When the high-pressure mud output by the mud pump flows through the motor of the screw drill, a certain pressure difference is formed at the inlet and outlet of the motor to drive the rotor of the equal-wall-thickness motor to rotate, and the torque and speed are transmitted to the drill bit through the universal shaft and the transmission shaft to realize the drilling operation. The low bending point can provide a greater dogleg degree and improve the composite drilling ratio. The equal-wall-thickness motor assembly design has better deformation resistance, heat dissipation performance and sealing performance. Due to the downward shift of the bending point, the distance between the bending point and the drill bit is shortened, and a torque impactor can be added between the drill bit and the screw without affecting the directional ability of the drill tool combination. The function of the transmission shaft assembly is to transmit the rotational power of the motor to the drill bit, while bearing axial and radial loads; the outer shell of the transmission shaft assembly can be equipped with stabilizers of different sizes and forms; the function of the universal joint is 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. The universal joint assembly is composed of a housing and a universal joint; the equal-wall thickness motor assembly is composed of a stator and a rotor. The stator is a thin rubber bushing injected on the surface, and the surface of the rotor is strengthened and has high wear resistance and corrosion resistance; the number of heads of the stator is one more than that of the rotor, and the two mesh with each other to form a sealed chamber to convert the hydraulic energy of the mud into mechanical energy; the rotor anti-drop device ensures the safety of the screw drilling tool working underground, and is located between the bypass valve and the motor; when the pump is stopped, the bypass valve allows the space inside the drill string to communicate with the annulus to avoid the overflow of drilling fluid in the drill string and contamination of the drilling platform when drilling and connecting a single root. The bypass valve is composed of a valve body, a valve core, a spring and a filter.

[0015] The screw body is 7m long and 172mm in outer diameter. The screw is equipped with a 212mm centralizer, which is 450mm away from the bottom of the screw. The screw is a single-bend screw, with the bending point 940mm away from the bottom of the screw and a screw curvature of 1.25°. The motor assembly adopts a uniform wall thickness design, and a thin rubber bushing is injected on the surface of the stator. The rubber layer is thin and the stress distribution is uniform. The surface of the rotor is strengthened and has high wear resistance and corrosion resistance. The screw is used for directional guidance and speed-up of drilling.

[0016] Torque impactor is a rock-breaking tool that converts the fluid energy of the drilling fluid in the drill string into torsional, high-frequency (750-1500 times / min), uniform and stable mechanical impact energy. The tool has a strong adaptability to the downhole environment. The torque impactor + PDC drill bit operation mode can significantly slow down or eliminate the downhole stick-slip problem encountered by the PDC drill bit. The torsion impactor gives the PDC drill bit a high-frequency, uniform torsion impact, and the top drive or rotary table provides the drill bit with radial shear force. At the same time, the torque impactor applies a radial shear force to the drill bit. The superposition of the two shear forces can effectively break the rock, which has a certain effect on improving the mechanical drilling speed and can extend the life of the drill bit.

Claims

1. A method for increasing the speed of a screw drill assembly for oil and gas wells, wherein the drill assembly comprises a screw, and the screw comprises a bypass valve assembly, a motor assembly, a universal shaft assembly and a transmission shaft assembly connected in sequence from top to bottom; wherein: The screw rod is set as a single-bend screw rod with a curvature of 1°-2.25°, 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 transmission shaft assembly is 900-960mm; the transmission shaft assembly is then connected to a conventional torque impactor and a PDC drill bit in sequence.

2. The method for increasing the speed of a screw drilling tool assembly for oil and gas wells according to claim 1 is characterized by: The screw structure adopts a screw with equal wall thickness, and the motor assembly adopts a motor with equal wall thickness.

3. The method for increasing the speed of a screw drilling tool assembly for oil and gas wells according to claim 1 is characterized by: The distance from the bending point to the lower end surface of the torque impactor is 1500-1750 mm.

4. The method for increasing the speed of a screw drilling tool assembly for oil and gas wells according to claim 1 is characterized by: The screw body has a length of 7m and an outer diameter of 172mm. The screw is provided with a 212mm centralizer, and the centralizer is 450mm away from the bottom of the screw.

5. The method according to any one of claims 1 to 4 is used in the drilling process of a φ215.9 mm wellbore.

6. The method of any one of claims 1 to 4 is used in a vertical well section, a directional well section, or a stable well section of a hard formation drilling operation.

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