LU102658B1 - downhole vibration generator - Google Patents

Abstract

A downhole vibration generator comprising bracket, piezoelectric cantilever plate, internal tooth, eccentric ring, outer casing, end expansion ring and conical compression ring. The piezoelectric cantilever sheet is attached to the outside of the bracket. The bracket is encased in the eccentric ring by the lower bearing and the upper bearing. The eccentric ring is inserted with internal teeth. The eccentric ring is located in the outer housing. The bottom plug and the top plug are threadedly connected to the bracket, and the outer case body is pressed between the bottom plug and the top plug. The end expansion ring is installed between the conical compression ring and the top plug. Under the action of gravity and inertia, the eccentric collar rotates relative to the drill string to drive the internal teeth of the eccentric collar and move the piezoelectric cantilever plate. Even if the vibration frequency of the drill string is not at the resonant frequency of the piezoelectric cantilever plate, it can also effectively absorb the energy of drill string rotation, pendulum vibration and torsional vibration.

Description

DESCRIPTION Downhole Vibration Generator Technical Section

The invention belongs to the field of petroleum engineering, and relates to a vibration generator which can stably supply power for electronic downhole instruments for a long period of time in drilling and producing oil and natural gas. State of the art

During rotary drilling, the rotational energy of the rotary disk or top drive is transmitted through the drill string to the drill bit. The energy of the turntable (the upper drive) is not only used to drive the drill to break rock. Part of the energy is converted into the kinetic energy of the drill string and the other part of the energy is dissipated by the friction between the drill string and the borehole wall. The kinetic energy of the drill string includes rotational energy and vibrational energy of the drill string. The rotational energy is used to transmit movements, which are a necessary and unavoidable part of the energy, while vibrational energy is an unavoidable and unnecessary part of the energy in the drilling process of wells. Drill string vibration can damage the drill string itself, the drill bit and even ground equipment. To reduce the negative effect of drill string vibration, a flexible shock absorber is typically installed between the drill bit and the drill collar to dissipate some of the vibration energy.

Because vibration is almost everywhere and has a high energy density, research on the collection, conversion, and utilization of vibrational energy has gradually increased in recent decades. The commonly used vibration generator can be simplified as a spring oscillator structure with damping, which has its own natural frequencies. When the natural frequency of the vibration generator is the same as the vibration frequency of the vibration source, resonance occurs and the energy absorbed is greatest. However, if the vibration frequency deviates slightly from the natural frequency, the absorbed energy will be greatly reduced. In other words, the bandwidth of the vibration generator is very narrow. Therefore, expanding the range of vibrational energy harvesting devices has become one of the problems that researchers are trying to solve. In addition, the directional selectivity of the vibration generator commonly used is very strong, and the vibration direction of most vibration sources changes. Therefore, it is an urgent problem to study the multidirectional vibration generator.

The energy generated by the vibration of the drill string is significant. Absorbing the vibration energy of the drill string to generate electricity is one of the effective ways to solve the problem of power supply for downhole instruments. In order to efficiently absorb the vibration energy of the drill string, two problems need to be solved in the above vibration generator. Due to the peculiarity of the drill string shape and vibration state (slender structure, longitudinal vibration, lateral pendulum oscillation and torsional vibration coexist), the direction of lateral pendulum oscillation has a certain randomness, which makes it difficult to apply the vibration generator designed for ground equipment downhole. The drill string has a small diameter and limited wall thickness. Increasing the outside diameter of the drill string increases the risk of clogging, and decreasing the inside diameter of the drill string increases the hydraulic pressure drop. Therefore the available radial dimension of the vibration generator is very small. The frequency response of the three drill string modes is different and their frequency band varies with changing drilling conditions. Therefore, the vibration generator should have a wider frequency band to adapt to different = drilling conditions. According to the characteristics of the drill string vibration and the drill string structure, the invention provides a vibration generator with a wide frequency band, which can absorb the vibration energy such as rotation, torsional vibration and pendulum vibration.

content of the invention

To overcome the shortcomings of the prior art, the invention provides a vibration generator with a wide frequency band, which can provide power for the downhole electronic instruments for a long time and absorb the vibration energy such as rotation, torsional vibration and weaving vibration of the drill string.

In order to achieve the above purpose, the invention adopts the following solution:

A downhole vibration generator includes bracket, piezoelectric cantilever plate, bottom plug, bottom bearing, internal tooth, eccentric ring, top bearing, outer housing, bottom plug, end expansion ring, and conical compression ring. The piezoelectric cantilever sheet is attached to the outside of the bracket. The bracket is encased in the eccentric ring by the lower bearing and the upper bearing. The eccentric ring is inserted with internal teeth. The eccentric ring is located in the outer housing. The bottom plug and the top plug are threadedly connected to the bracket, and the outer case body is pressed between the bottom plug and the top plug. The end expansion ring is installed between the conical compression ring and the top plug. The conical compression ring is connected to the top plug by screws. Under the action of the tightening force of the screw, the conical compression ring extrudes the end expander ring to cause the end expander ring to expand radially, so that the bracket is tightly clamped to the inner wall of the drill string and rotates with the drill string. The downhole vibration generator can realize a reliable connection without treatment and processing on the inner wall of the drill string.

Compared with the prior art, the advantageous effects of the present invention are as follows: Under the action of gravity and inertial force, the eccentric ring rotates relative to the drill string, which drives the internal teeth of the eccentric ring to move the piezoelectric cantilever plate. Even if the vibration frequency of the drill string is not at the resonant frequency of the piezoelectric cantilever plate, it can also effectively absorb the energy of rotation, pendulum vibration and torsional vibration of the drill string. When the internal teeth are spirally arranged on the eccentric ring and rotate around a circle, the piezoelectric cantilever plate can receive excitation of different amplitude, further expanding the frequency band of the vibration generator. Compared with the downhole turbine generator, the vibration generator has no moving parts in the drilling fluid, which increases the service life of the downhole electronic instrument power supply device, and can realize the purpose of one-time installation and long-term use. The invention has the advantages of simple and secure installation in the drill string and requires no additional treatment and processing for the drill string. Therefore, the defect that the structure of the existing piezoelectric vibration generator cannot efficiently collect the vibration energy of the drill string according to the vibration characteristics of the drill string can be compensated.

Description of the figures

Fig. 1 is the decomposition diagram of the vibration generator.

Figure 2 is the disassembly diagram of the vibration generator after the piezoelectric cantilever sheet has been removed.

Fig. 3 is a longitudinal sectional view of the vibration generator.

Fig. 4 is a cross-sectional view of the vibration generator.

Figure 5 is a schematic diagram of a piezoelectric cantilever sheet.

In the figure: 1. Bracket; 2. piezoelectric cantilever sheet; 3. Lower plug; 4. Lower Bearing; 5. inner tooth; 6. eccentric ring; 7. Upper bearing; 8. outer casing; 9. Top plug; 10. end expansion ring; 11. Conical compression ring.

Specific embodiment

As shown in Figures 1 to 5, a downhole vibration generator comprises bracket 1, cantilever piezoelectric sheet 2, bottom plug 3, bottom bearing 4, internal tooth 5, eccentric ring 6, top bearing 7, outer casing 8, bottom plug 9, end expansion ring 10 and conical pressure ring 11. The piezoelectric cantilever plate 2 is attached to the outside of the holder 1. The holder 1 is encased in the eccentric ring 6 by the lower bearing 4 and the upper bearing 7 . The eccentric ring 6 is inserted with internal teeth 5. The eccentric ring 6 is housed in the outer casing 8. The lower plug 3 and the upper plug 9 are threadedly connected to the bracket 1, and the outer casing body 8 is pressed between the lower plug 3 and the upper plug 9. The end expansion ring is installed between the conical pressure ring 11 and the top plug 9. The conical pressure ring 11 is connected to the top plug 9 by screws. Under the action of the tightening force of the screw, the conical compression ring 11 extrudes the end-expansion ring 10 to cause the end-expansion ring to expand radially, so that the bracket 1 is clamped to the inner wall of the drill string and rotates with the drill string. The downhole vibration generator can realize a reliable connection without treatment and processing on the inner wall of the drill string.

The outer wall of the holder 1 is a polyhedron, and the piezoelectric cantilever plate 2 is fixed to the lower end of the outer wall of the holder 1 with screws and evenly distributed over the circumference of the holder 1, and the piezoelectric cantilever plate 2 extends along the longitudinal direction parallel to the Axis of the holder 1 and the vibration energy in any direction perpendicular to the axis of the holder 1 can be absorbed by the arrangement.

The cantilever piezoelectric sheet 2 comprises a copper plate 21, a piezoelectric ceramic sheet 22 and a mass block 23. The lower end of the copper plate 21 is thickened and machined with a threaded hole, and is connected to the bracket 1 by screw. The piezoelectric ceramic sheet 22 is bonded to the upper and lower side faces of the copper plate 21 and bonded near the cantilever end of the copper plate 21 . The mass block 23 is located at the free end of the copper plate 21. There is a certain gap between the mass block 23 and the outer wall of the holder 1, which accommodates the bending deformation of the piezoelectric cantilever plate 2 and serves to prevent the piezoelectric cantilever plate 2 from falling due to excessive deformation will be damaged.

The bracket 1 and the lower plug 3 are connected by threads to press the lower bearing 4 onto the bracket 1. A large number of internal teeth 5 are inserted into the inner wall of the eccentric ring 6 and distributed evenly over the circumference of the eccentric ring 6 . The eccentric ring 6 inlaid with internal teeth 5 is encased outside the holder 1 with the piezoelectric cantilever plate 2 and remains concentric with the holder 1 due to the support function of the lower bearing 4 and the upper bearing 7 and can rotate freely relative to the holder. Under the action of gravity, the center of gravity of the eccentric ring 6 tends to point in the direction of gravity. Therefore, as the drill string rotates, the eccentric ring 6 rotates relative to the mount 1. Due to the slow speed of rotation of the drill string, the invention does not use the coil permanent magnet method to collect vibrational energy. Instead, a convex inner tooth 5 is installed on the inner wall of the eccentric ring 6. As the eccentric ring 6 rotates, the convex inner tooth 5 moves the piezoelectric cantilever plate 2 to alternately bend the piezoelectric ceramic plate 22 to absorb part of the energy of drill string rotation. When the drill string experiences lateral pendulum oscillation and torsional vibration, the eccentric collar 6 also rotates relative to the bracket 1 under the action of inertial force to absorb part of the energy of lateral pendulum oscillation and torsional vibration. The outer housing 8 is sheathed outside the eccentric ring 6 and matched with the maximum outer circle of the lower plug 3 and is pressed onto the lower plug 3 by the upper plug 9 screwed to the bracket 1 . The lower plug 3, the upper plug 9 and the outer case 8 are sealed by a sealing ring, and the lower plug 3, the upper plug 9 and the holder 1 are sealed by a sealing ring to seal the piezoelectric cantilever plate 2 and other electronic devices of isolate external drilling fluid.

The working principle of the downhole vibration generator is as follows: the eccentric ring rotates relative to the rotary drill string under the action of gravity and inertial force, and the projection on the inner wall of the eccentric ring moves the piezoelectric sheet with the cantilever structure to bend the piezoelectric sheet to to absorb the energy of rotation, torsional vibration and pendulum vibration of the drill string. The boom, which is uniformly arranged along the circumference, runs along the longitudinal direction parallel to the axis of the drill string, which allows it to absorb the energy of the lateral pendulum oscillation of the drill string.

Claims (5)

PATENT CLAIMS 1. A downhole vibration generator comprising bracket, piezoelectric cantilever plate, bottom plug, lower bearing, internal tooth, eccentric collar, upper bearing, outer casing, bottom plug, end expansion ring and conical compression ring, characterized in that the piezoelectric cantilever plate is attached to the outside of the bracket, the bracket in the eccentric ring is encased by the lower bearing and the upper bearing, the eccentric ring is inlaid with internal teeth, the eccentric ring is in the outer case, the lower plug and the upper plug are threadedly connected to the bracket, and the Outer casing body is pressed between the bottom plug and the top plug, with the end expansion ring installed between the conical pressure ring and the top plug, the conical pressure ring is connected to the top plug by screws. 2. A downhole vibration generator according to claim 1, characterized in that the outer wall of the bracket is a polyhedron, the piezoelectric cantilever sheet being fixed to the lower end of the outer wall of the bracket with screws and evenly distributed around the circumference of the bracket, the piezoelectric cantilever sheet along the Longitudinally parallel to the axis of the bracket. 3. A downhole vibration generator according to claim 1-2, characterized in that the cantilever piezoelectric sheet comprises a copper plate, a piezoelectric ceramic sheet and a mass block, with a certain gap between the mass block and the outer wall of the holder. 4. A downhole vibration generator according to claims 1 to 3, characterized in that the bracket and the lower plug are threadably connected to press the lower bearing onto the bracket with a plurality of internal teeth inlaid in the inner wall of the eccentric collar and evenly across distributed around the circumference of the eccentric ring, the eccentric ring inlaid with internal teeth being coated outside the bracket with the cantilever piezoelectric sheet and remaining concentric with the bracket by the supporting function of the lower bearing and the upper bearing and being free to rotate relative to the bracket. 5. A downhole vibration generator according to claims 1 to 4, characterized in that the bottom plug, the top plug and the outer housing are sealed by a sealing ring, wherein the bottom plug, the top plug and the holder are sealed by a sealing ring.