CN117055094A - Pulse sound source for seismoelectric logging - Google Patents

Abstract

The invention provides a pulse sound source for seismoelectric logging, which comprises a metal shielding box for placing an active amplifying circuit, an electroacoustic transducer formed by a piezoelectric ceramic plate array and a transducer shell, wherein the active amplifying circuit is connected with the piezoelectric ceramic plate array through a waterproof joint of the metal shielding box and the transducer shell. The piezoelectric ceramic sheet array is composed of a plurality of piezoelectric ceramic sheets coaxially arranged. The control signal of the power amplifier circuit and the direct current power supply are input from the outside, when the control signal is at a high level, the switch tube is conducted, and the primary end voltage of the transformer is approximately equal to the direct current source voltage; when the input signal Vin is in a low level, the switching tube is turned off, the primary voltage of the transformer is zero, a pulse signal is generated, and the pulse signal is amplified by the transformer to become a high-voltage pulse signal at the secondary end of the transformer and is used for driving the piezoelectric ceramic chip array to generate sound waves.

Description

A pulse sound source for seismoelectric logging

Technical field

The invention relates to well logging technology, and in particular to pulse sound sources used for seismoelectric well logging.

Background technique

Seismoelectric logging is used to explore underground geological structures. It is based on the principle of seismic wave propagation in the formation and the influence of the formation dielectric constant on the propagation speed of electromagnetic waves. It is developed on the basis of seismic exploration technology. The basic principle is that when elastic waves pass through porous media, due to the different reactions of the pore fluid and the solid matrix, the charges on the surfaces of the solid and liquid phases vibrate, thus generating seismic electrical signals. Seismic electrical signals are related to the acoustic and electrical properties of the medium and can be used to estimate various properties such as porosity, permeability, and fluid saturation. Used in oil and gas exploration and geological exploration.

Seismoelectric logging technology mainly uses pulse sound sources to generate high-energy acoustic signals, and then uses electrodes to receive the seismoelectric signals and amplify them, and then transmits them to surface equipment for recording and processing through the electrical measuring cable of the device. By analyzing the characteristics, direction and time of reflection and refraction, various geological information such as underground structure, layer thickness, lithology and oil and gas can be determined. By measuring the reflection time of the acoustic signal generated by the seismic source to the reservoir, as well as the corresponding reservoir acoustic wave velocity and electrical capability that changes with depth, the existence, reserves, and distribution of the reservoir can be judged and predicted. In addition, seismoelectric logging can also be used to locate hydrological water layers, groundwater levels, bedrock depths and other geological engineering and environmental research fields.

One of the key components of seismoelectric logging is the pulse sound source used to excite seismoelectric signals. Some problems with traditional pulse sound sources include: unstable quality of the emitted acoustic signal, high energy consumption, large volume, and electromagnetic interference wait.

Contents of the invention

The technical problem to be solved by the present invention is to provide a new type of pulse sound source to generate acoustic wave signals in the seismoelectric logging process in view of the shortcomings of the existing technology.

The technical solution adopted by the present invention to solve the above technical problems is a pulse sound source for seismoelectric well logging, which includes a power amplifier circuit, a metal shielding box, a piezoelectric ceramic array and a transducer casing; the power amplifier circuit is placed In the metal shielding box, the piezoelectric ceramic array is placed in the transducer housing; the power amplifier circuit and the piezoelectric ceramic array are connected to the waterproof connector on the transducer housing through the metal shielding box;

The power amplifier circuit includes a filter capacitor, a switch tube, a transformer and a regulating resistor; one end of the filter capacitor is connected to ground and the other end is connected to a DC power supply; the input end of the switch tube is connected to a DC power supply, the control end of the switch tube receives the external input control signal, and the output of the switch tube The end of the transformer primary is connected to one end of the transformer primary; the other end of the transformer primary is connected to ground, the transformer secondary is connected in parallel with the adjusting resistor, and the end with the same name as the output end of the switch tube connected to the transformer secondary is used as the output end of the high-voltage pulse signal. The other end is isolated and grounded to reduce interference;

The switching tube is used to control the on and off of the DC power supply to the primary of the transformer through the received control signal, thereby forming a pulse signal. After the pulse signal is amplified by the transformer, a high-voltage pulse signal is formed on the secondary side of the transformer.

The invention has the beneficial effects that it is suitable for providing a pulse sound source for exciting seismoelectric signals in electric well logging. The sound wave signal emitted by the sound source has stable quality, low energy consumption, small size, and can resist electromagnetic interference.

Description of the drawings

Figure 1 is a schematic diagram of the power amplifier circuit topology of the present invention;

Figure 2 is a schematic structural diagram of the metal shielding shell of the embodiment;

Figure 3 is a schematic structural diagram of a piece of piezoelectric ceramic sheet according to the embodiment;

Figure 4 is a schematic structural diagram of the piezoelectric ceramic array according to the embodiment;

Figure 5 is a schematic structural diagram of the electroacoustic transducer housing in the embodiment;

Figure 6 is a schematic diagram of the waterproof joint in the embodiment, including a male head and a female head;

Figure 7 shows the transmission cable structure in the embodiment.

Detailed ways

A pulse sound source used for seismoelectric well logging, including a power amplifier circuit, a metal shielding box, a piezoelectric ceramic chip array and a transducer shell; the power amplifier circuit is placed in the metal shielding box, and the piezoelectric ceramic chip array is placed in the transducer housing. Inside the transducer casing; the power amplifier circuit and the piezoelectric ceramic array are connected to the waterproof connector on the transducer casing through a metal shielding box; the entire pulse sound source has a simple structure, uses fewer components and has low power consumption.

As shown in Figure 1, the power amplifier circuit includes a filter capacitor, a switch tube, a transformer and a regulating resistor; one end of the filter capacitor is connected to ground, and the other end is connected to a DC power supply; the input end of the switch tube is connected to a DC power supply, and the control end of the switch tube receives control from an external input. signal, the output end of the switching tube is connected to one end of the primary of the transformer; the other end of the primary of the transformer is grounded, the secondary of the transformer is connected in parallel with the adjusting resistor, and the end of the output end of the switching tube connected to the secondary of the transformer and the primary of the transformer with the same name is used as the output of the high-voltage pulse signal terminal, the other terminal of the transformer secondary is grounded;

The control signal Vin and DC power supply VDD of the power amplifier circuit are input from the outside. The working principle of this power amplifier circuit is: when the control signal Vin is high level, the switch tube is turned on, and the primary voltage of the transformer is approximately equal to the DC source voltage VDD; when the input signal Vin is low level, the switch tube is turned off, and the primary voltage of the transformer is zero. Therefore, the voltage signal at the primary end of the transformer is a pulse signal with the same frequency, duty cycle, and number of cycles as Vin, and an amplitude of 0-VDD. The pulse signal is amplified by the transformer and becomes a high-voltage pulse signal at the secondary end of the transformer, which is used to drive the piezoelectric ceramic array to generate sound waves.

As shown in Figure 2, the function of the metal shielding shell is to shield the electromagnetic interference caused by the high-voltage pulses generated by the internal power amplifier circuit to the outside world, and to provide installation physical support and waterproofing for the internal power amplifier circuit. The metal shielding shell consists of a shell and a sealing cover. It is cylindrical in shape, with a length of 135mm and a diameter of 84mm. There are reserved places for waterproof joint installation and cable entry at the bottom of the casing, and there are screw holes on the top cover.

When using, first install the waterproof connector and transmission cable, put the power amplifier circuit into it and connect it with the waterproof connector and transmission cable, then install the top cover with screws, and use waterproof glue to enhance the sealing.

As shown in Figure 3, the piezoelectric ceramic sheet is a circular sheet with a diameter of 50mm and a thickness of 2.6mm, which is used to assemble a piezoelectric ceramic array. As shown in Figure 4, the piezoelectric ceramic array consists of four identical piezoelectric ceramics. The four piezoelectric ceramics are coaxially arranged to form a dipole source. The positive and negative electrodes of each are connected through wires and connected in parallel. to the waterproof connector, connected to the output end of the power amplifier circuit, and driven by the high-voltage pulse generated by the power amplifier circuit to generate sound waves. In practical applications, the number of piezoelectric ceramic sheets can be changed as needed to change the output power, and the arrangement of the piezoelectric ceramic sheets can also be changed to form other monopole or multipole forms.

As shown in Figure 5, the main function of the electroacoustic transducer shell is to protect the internal piezoelectric ceramic array and provide it with physical support and waterproof functions. The internal space of the transducer housing is a combination of a cylinder and a semi-cone. The semi-cone structure is used to increase the intensity of sound waves; the semi-cone opens at the small circle, and the diameter of the semi-cone at the small circle is smaller than the diameter of the cylinder. The large round bottom of the semi-cone faces outward, and a waterproof joint installation place is reserved at the bottom of the large round.

When using the electroacoustic transducer shell, first install the waterproof connector, put the piezoelectric ceramic array into it and connect it to the waterproof connector, then fix it with screws, and use waterproof glue to enhance the sealing.

As shown in Figure 6, the waterproof connector consists of a male head and a female head, which are connected by plugging and unplugging, respectively connecting the output end of the power amplifier circuit and the input end of the piezoelectric ceramic array. The advantage of using a connector to connect the power amplifier part and the electroacoustic transducer part is that it is easy to replace, and different power amplifiers or electroacoustic transducers can be selected according to actual needs.

As shown in Figure 7, the outermost layer of the transmission cable is the cable sheath, which has strong toughness and can protect the internal structure; the metal shielding layer can prevent external electromagnetic field interference or online electromagnetic field interference to the outside; the insulation layer is used Insulate wires; wires are used for circuit connections. The transmission cable should contain at least four wires, which connect the positive and negative poles of the control signal input and the positive and negative poles of the DC power supply to the corresponding contacts on the power amplifier circuit. Additional wires can be added as needed, such as connecting the shielding shell to the circuit ground wire to add a common ground. . Metal shielding shells and shielded cables make the sound source resistant to electromagnetic interference.

The above descriptions are only embodiments of the present invention, and do not limit the scope of the present invention. Any equivalent structure or equivalent process transformation made by using the description and drawings of the present invention, or directly or indirectly applied in other related technical fields, All are similarly included in the patent protection scope of the present invention.

Claims (6)

1. The pulse sound source for the seismoelectric logging is characterized by comprising a power amplification circuit, a metal shielding box, a piezoelectric ceramic chip array and a transducer shell; the power amplifier circuit is arranged in the metal shielding box, and the piezoelectric ceramic chip array is arranged in the transducer shell; the power amplifier circuit is connected with the piezoelectric ceramic chip array through a metal shielding box and a waterproof connector on the transducer shell;

the power amplifier circuit comprises a filter capacitor, a switching tube, a transformer and an adjusting resistor; one end of the filter capacitor is grounded, and the other end of the filter capacitor is connected with a direct current power supply; the input end of the switching tube is connected with a direct current power supply, the control end of the switching tube receives an externally input control signal, and the output end of the switching tube is connected with one end of the primary of the transformer; the other end of the primary side of the transformer is grounded, the secondary side of the transformer is connected with the regulating resistor in parallel, one end of the secondary side of the transformer, which is the same name as the output end of the switching tube connected with the primary side of the transformer, is used as the output end of the high-voltage pulse signal, and the other end of the secondary side of the transformer is grounded;

the switching tube is used for controlling the on-off of the direct current power supply to the primary of the transformer through the received control signal, so that a pulse signal is formed, and the pulse signal is amplified by the transformer and then forms a high-voltage pulse signal at the secondary of the transformer.

2. The pulsed acoustic source of claim 1, wherein the tuning resistor is configured to tune the output power of the high voltage pulsed signal.

3. The pulsed acoustic source of claim 1, wherein the filter capacitor is configured to increase voltage stability of the dc signal.

4. The pulse sound source according to claim 1, wherein the metal shielding box is cylindrical and comprises an open cylindrical shell and a sealing cover, a waterproof joint installation part and a cable access part are reserved at the bottom of the open cylindrical shell, and the sealing cover is tightly connected with the shell and waterproof by screws and waterproof glue;

the control signal and the direct current power supply which are input from the outside are connected with the power amplifier circuit through the cable access position at the bottom of the opening cylindrical shell.

5. The pulsed acoustic source of claim 1, wherein the array of piezoelectric ceramic plates is comprised of four identical piezoelectric ceramic plates coaxially aligned and forming a dipole.

6. The pulsed acoustic source of claim 1, wherein the interior space of the transducer housing is a combination of a cylinder and a half cone, the half cone structure being configured to enhance the intensity of the acoustic wave; the semicircle cone is opened at the small circle, the diameter of the semicircle cone is smaller than that of the cylinder at the small circle, the big round bottom of the semicircle cone faces outwards, and a waterproof joint installation part is reserved at the big round bottom.