CN115773103A - Ultrasonic real-time imaging acquisition control system for pressure induced cracking - Google Patents

Abstract

The invention relates to a pressure induced fracture ultrasonic real-time imaging acquisition control system, which comprises: the device comprises a signal transmitting module, a signal receiving module and a signal acquisition processing module; the signal transmitting module is used for transmitting ultrasonic signals to the fracturing section; the signal receiving module is used for receiving ultrasonic echo signals reflected by the cracks; the signal acquisition and processing module is used for processing ultrasonic signals reflected by the crack; the signal acquisition processing module comprises: a gain filtering unit and a signal processing unit; the gain filtering unit is used for amplifying and filtering ultrasonic signals reflected by the crack and transmitting the processed ultrasonic signals to the signal processing unit; and the signal processing unit is used for obtaining the echo amplitude and the echo arrival time of the ultrasonic wave reflected by the crack through a hardware circuit and transmitting the echo amplitude and the echo arrival time to the subsequent processing unit for ultrasonic imaging of the crack.

Description

A Real-time Ultrasonic Imaging Acquisition and Control System of Pressure Fracturing-Induced Cracks

technical field

The invention relates to the technical field of geostress measurement, in particular to an ultrasonic real-time imaging acquisition control system for cracks induced by pressure fracturing.

Background technique

During the process of fracturing the formation, the distribution of formation fractures will change in real time. However, the existing technologies (imprint directional technology, traditional ultrasonic imaging logging, etc.) cannot monitor the formation fracturing effect in real time, and as the depth increases, the defects of the existing technologies become more and more obvious, and the accuracy and reliability of the measurement results were very severely affected.

Conventional imaging logging is to image the surface of the static hole wall. Due to the fact that the fracture tends to close after the pressure is unloaded and the ultrasonic detection resolution is insufficient, the induced fracture is difficult to be detected and the applicability is not strong.

Contents of the invention

The purpose of the present invention is to be able to acquire the dynamic image of the spatial orientation of the fracture and its evolution process in real time during the cracking process, and proposes an ultrasonic real-time imaging system for the fracture.

In order to achieve the above object, the present invention is achieved through the following technical solutions.

The present invention proposes an ultrasonic real-time imaging acquisition control system for fractures induced by pressure fracturing. The system includes: a signal transmitting module, a signal receiving module, and a signal acquisition and processing module; the signal transmitting module is used to transmit Ultrasonic signal; the signal receiving module is used to receive the ultrasonic echo signal reflected by the crack; the signal acquisition and processing module is used to process the ultrasonic signal reflected by the crack;

The signal acquisition and processing module includes: a gain filter unit and a signal processing unit; wherein,

The gain filter unit is used to amplify and filter the ultrasonic signal reflected by the crack, and transmit the processed ultrasonic signal to the signal processing unit;

The signal processing unit is used to obtain the echo amplitude and echo arrival time of the ultrasonic wave reflected by the crack through the hardware circuit, and transmit it to the subsequent processing unit for ultrasonic imaging of the crack.

As one of the improvements of the above technical solution, the signal receiving module includes: at least two ultrasonic transducer probes and an analog switch;

The natural frequencies of the at least two ultrasonic transducer probes are different for adapting to different borehole diameter requirements;

The analog switches correspond one-to-one to the ultrasonic transducer probes, and are used to select suitable probes according to the borehole diameter.

As one of the improvements of the above technical solution, the signal receiving module also includes at least two pre-amplification matching units; The echo signal received by the detector probe is amplified and matched.

As one of the improvements of the above technical solution, the signal receiving module further includes a pressure sensor for detecting the pressure, and when the pressure reaches a set threshold, the signal receiving module is started or stopped to receive the ultrasonic echo signal reflected by the crack.

As one of the improvements of the above technical solution, the gain filter unit includes a first gain control circuit, a bandpass filter circuit and a second gain control circuit electrically connected in sequence.

As one of the improvements of the above technical solution, the signal processing unit includes: a full-wave acquisition circuit, an arrival time extraction circuit and a peak detection circuit;

The full-wave acquisition circuit is used for complete acquisition of the signal output by the gain filter unit;

The time-to-time extraction circuit is used to process the signal output by the gain filter unit to obtain the time-to-time of the echo;

The peak detection circuit is used to perform peak detection on the signal output by the gain filter unit to obtain the echo amplitude.

As one of the improvements of the above-mentioned technical solution, the time-of-day extraction circuit includes: an amplification and filter sub-circuit, a precision commutator sub-circuit, a detection sub-circuit, a differential comparison sub-circuit and a time-of-day acquisition sub-circuit connected in sequence; wherein,

The amplification and filtering sub-circuit, the precision rectifier sub-circuit and the detection sub-circuit are used to sequentially filter, rectify and detect the echo signal to obtain the echo envelope; during the processing, the echo signal is used as the probe operating frequency carrier AM signal to process;

The differential comparison sub-circuit is used to process the echo envelope to obtain the time when the signal crosses the zero point, which is the peak arrival time of the echo signal;

The arrival time acquisition sub-circuit is used to extract and obtain the arrival time of the echo.

As one of the improvements of the above technical solution, the time-out acquisition sub-circuit includes a timer for testing the time of the zero point position, that is, the time-out of the echo.

As one of the improvements of the above technical solution, the peak detection circuit includes sequentially connected: a program-controlled amplifier, a precision commutator sub-circuit, a charge discharge control sub-circuit, an emitter-follower buffer sub-circuit and an A/D acquisition sub-circuit; wherein ,

The program-controlled amplifier is used to perform automatic gain processing on the echo signal, so that the peak value of the amplified echo signal is always within the required range of the AD acquisition sub-circuit;

The precision commutator circuit includes a peak detector and a peak hold capacitor; wherein the peak detector is used to detect the peak value of the amplified signal; the peak hold capacitor is used to store the peak value of the detected signal charge;

The charge discharge control subcircuit is used to discharge the charge on the peak holding capacitor for the next peak detection;

The A/D acquisition sub-circuit is used for performing analog-to-digital conversion and acquisition of the peak value of the signal.

As one of the improvements of the above technical solution, the signal acquisition and processing module also includes an FPGA unit, which is used to process the echo amplitude and echo time obtained by the signal processing unit to obtain ultrasonic imaging of cracks, and store them; it is also used to control the charge Bleed control subcircuit.

Compared with the prior art, the present invention has the advantages of:

(1) There is no cable transmission, battery power supply, adopts underground storage mode, and wait for the system to read data on the ground;

(2) The working mechanism of pressure-triggered imaging scanning is adopted, and the acquisition circuit identifies the pressure signal to start or end the scanning work, so that not only can the scanning be started when the crack is opened under pressure and the crack width is the largest, so that the crack scanning effect is the best, but also Save power and storage space of the imaging device;

(3) The traditional ultrasonic imaging directly uploads the full wave train data. This design not only stores the full wave train data to facilitate the signal processing of the host computer in the later stage, but also realizes the extraction of echo amplitude and arrival time through circuit design, which can be directly imaged and consumes less time. Short time, high sensitivity and anti-interference, high precision. The amount of data is small, saving storage space.

Description of drawings

Fig. 1 Signal conditioning and acquisition module of the synchronous detection device for dynamic evolution of fractures;

When Fig. 2 arrives, extract the block diagram of the circuit;

Fig. 3 is the collection legend of echo arrival time;

Figure 4 is a rectification and detection circuit diagram;

Fig. 5 is a differential circuit;

Figure 6 is a comparison diagram of the echo envelope and the waveform after differentiation;

Fig. 7 is the realization block diagram of amplitude maintenance hardware circuit;

Fig. 8 is a specific circuit design diagram of the peak hold circuit;

Fig. 9 is a peak hold state diagram of a peak hold capacitor;

Fig. 10 is a discharge state diagram of the peak hold capacitor;

Figure 11 Amplitude Hold Circuit Block Diagram.

Detailed ways

The technical solutions provided by the present invention are further described below in conjunction with the examples.

The acquisition control circuit is the core of the whole circuit system. After the instrument reaches a certain depth, the acquisition control circuit starts the motor to rotate by processing the signal of the pressure sensor, then detects the angle of the tooth signal generated by the motor rotation, and then starts the emission control module to excite the transducer, and at the same time, the reflected wave signal of the well wall is matched Acquisition after amplification, filtering and gain.

Example

As shown in FIG. 1 , it is a structural diagram of the signal conditioning and acquisition module of the dynamic evolution synchronous detection device for fracturing fractures of the present invention. In order to adapt to different measurement conditions, the gain amplification control adopts the method of program-controlled adaptive gain.

The echo amplitude and echo time can be realized in the hardware circuit through the peak detection circuit and the first wave detection circuit.

(1) Design circuit for extraction of echo arrival time

Figure 2 is a block diagram of the hardware circuit for time extraction. The echo signal can be processed as the amplitude modulation signal of the probe’s operating frequency carrier. After the wave detection, the echo envelope is obtained. After the differential circuit, the time when the signal crosses the zero point is the echo. The arrival time of the peak value of the signal, the arrival time of the echo signal can be extracted by testing the zero point position with a high-precision timer.

The echo signal can be treated as an amplitude modulated signal of a certain frequency carrier, and the echo envelope can be obtained after detection, and the peak arrival time can be obtained after passing through the differential circuit.

In most cases, the echo signal is shown in Figure 3, although sometimes the envelope amplitude and frequency will have some changes, but it does not affect the processing of the subsequent circuit.

As shown in Figure 4, it is a rectification and detection circuit diagram; as shown in Figure 5, it is a differential circuit diagram.

As shown in Figure 6, it is a comparison diagram of the echo envelope and the waveform after differentiation. In the comparison chart after echo detection and differentiation, it can be seen that the echo peak arrival time is the same as the signal zero crossing time after differentiation.

(2) Echo amplitude extraction design circuit

Figure 7 is a block diagram of the amplitude holding hardware circuit. The amplified signal is sent to the precision rectification circuit, and the peak value of the signal is detected and stored in the peak holding capacitor. The program-controlled amplifier controls the program-controlled gain chip through the main control chip to realize automatic gain, so that the echo signal amplification is always within the AD acquisition range. After being shot and then sent to A/D for collection, the collected peak value is not affected by the sampling rate of the AD chip. The amplitude and arrival time are obtained by hardware circuit, which has the characteristics of high speed and high precision. Therefore, at the same time, the full wave train data is stored and uploaded to the host computer to be processed by an algorithm. As shown in Figure 8, the signal through the analog switch enters a peak hold function module composed of an integrating circuit, among which IC941 is used to realize integral compensation.

If the result of the threshold comparator is that the signal meets the requirements of the current threshold voltage, when the input signal is greater than zero, the capacitor C941 starts to charge, and due to the function of diodes D941 and D942, the voltage value of C941 will remain when the signal is less than zero. At this time, the voltage of the peak hold capacitor can be collected, as shown in Figure 9.

After the signal acquisition is completed, the holding capacitor should be cleared, the analog switch is closed under the control of the FPGA, and the voltage of the holding capacitor is cleared, as shown in Figure 10.

The magnitude of the echo amplitude is affected by the structure of the borehole wall, and the arrival time of the echo reflects the distance from the probe to the borehole wall. The color depth of the echo amplitude imaging map can reflect the high and low reflection characteristics of the borehole wall. Fractures belong to low reflection areas, and the echo amplitude imaging map can identify the orientation of rock formations and fractures.

In order to ensure the effective working time of the instrument, the acquisition and control circuit system should adopt low power consumption design on the one hand, and use pressure trigger to ensure that the ultrasonic imaging starts to work when the fracturing starts, reducing invalid working time. According to the power consumption and the time required for designing fracturing, adjust the number of battery packs to ensure that the instrument has a stable power supply during the required working period. The system of the invention can acquire the dynamic image of the spatial orientation of the fracture and its evolution process in the process of measuring the ground stress, and can greatly improve the detection efficiency at the same time.

As shown in FIG. 11 , according to the actual needs of the fracturing environment and based on the principle of ultrasonic imaging testing, a storage type ultrasonic real-time detection device for fractures induced by hydraulic fracturing is developed in this embodiment. Among them, the fracturing section adopts an ultrasonic scanning acoustic system structure, and the acquisition control circuit skeleton is placed inside the lower packer that does not need water to flow, and the data of the entire test process is collected and stored to realize real-time imaging of fractures during the fracturing process.

It can be seen from the above specific description of the present invention that when the system of the present application obtains the echo amplitude and echo time, it is realized by the peak detection circuit and the first wave detection circuit in the hardware circuit, and the time consumption is short and the accuracy is high. .

Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than limit them. Although the present invention has been described in detail with reference to the embodiments, those skilled in the art should understand that modifications or equivalent replacements to the technical solutions of the present invention do not depart from the spirit and scope of the technical solutions of the present invention, and all of them should be included in the scope of the present invention. within the scope of the claims.

Claims (10)

1. An ultrasonic real-time imaging acquisition control system of pressure fracturing induced cracks, said system comprising: a signal transmitting module, a signal receiving module and a signal acquisition and processing module; said signal transmitting module is used to transmit ultrasonic signals to the fracturing section The signal receiving module is used to receive the ultrasonic echo signal reflected by the crack; the signal acquisition and processing module is used to process the ultrasonic signal reflected by the crack; it is characterized in that, The signal acquisition and processing module includes: a gain filter unit and a signal processing unit; wherein, The gain filter unit is used to amplify and filter the ultrasonic signal reflected by the crack, and transmit the processed ultrasonic signal to the signal processing unit; The signal processing unit is used to obtain the echo amplitude and echo arrival time of the ultrasonic wave reflected by the crack through the hardware circuit, and transmit it to the subsequent processing unit for ultrasonic imaging of the crack. 2. The ultrasonic real-time imaging acquisition control system for pressure fracturing-induced cracks according to claim 1, wherein the signal receiving module comprises: at least two ultrasonic transducer probes and an analog switch; The natural frequencies of the at least two ultrasonic transducer probes are different for adapting to different borehole diameter requirements; The analog switches correspond one-to-one to the ultrasonic transducer probes, and are used to select suitable probes according to the borehole diameter. 3. The ultrasonic real-time imaging acquisition control system of pressure fracturing induced cracks according to claim 2, characterized in that, the signal receiving module also includes at least two pre-release matching units; each pre-release matching unit is respectively connected to a The electrical connection of the ultrasonic transducer probe is used to amplify and match the echo signal received by the corresponding electrical-connected ultrasonic transducer probe. 4. The ultrasonic real-time imaging acquisition control system for pressure fracturing-induced cracks according to claim 2, wherein the signal receiving module further includes a pressure sensor for detecting the pressure, and when the pressure reaches a set threshold Start or stop the signal receiving module to receive the ultrasonic echo signal reflected by the crack. 5. The ultrasonic real-time imaging acquisition control system for pressure fracturing induced cracks according to claim 1, wherein the gain filter unit includes a first gain control circuit, a band-pass filter circuit and a second gain control circuit that are electrically connected in sequence. gain control circuit. 6. The ultrasonic real-time imaging acquisition control system for pressure fracturing-induced cracks according to claim 1, wherein the signal processing unit includes: a full-wave acquisition circuit, an on-time extraction circuit and a peak detection circuit; The full-wave acquisition circuit is used for complete acquisition of the signal output by the gain filter unit; The time-to-time extraction circuit is used to process the signal output by the gain filter unit to obtain the time-to-time of the echo; The peak detection circuit is used to perform peak detection on the signal output by the gain filter unit to obtain the echo amplitude. 7. The ultrasonic real-time imaging acquisition control system for pressure fracturing-induced cracks according to claim 6, characterized in that, the timed extraction circuit includes sequentially connected electric circuits: amplification and filtering sub-circuits, precision commutator circuits, wave detection Sub-circuit, differential comparison sub-circuit and time acquisition sub-circuit; wherein, The amplification and filtering sub-circuit, the precision rectifier sub-circuit and the detection sub-circuit are used to sequentially filter, rectify and detect the echo signal to obtain the echo envelope; during the processing, the echo signal is used as the probe operating frequency carrier AM signal to process; The differential comparison sub-circuit is used to process the echo envelope to obtain the time when the signal crosses the zero point, which is the peak arrival time of the echo signal; The arrival time acquisition sub-circuit is used to extract and obtain the arrival time of the echo. 8 . The ultrasonic real-time imaging acquisition control system for pressure fracturing-induced cracks according to claim 7 , wherein the time-arrival acquisition sub-circuit includes a timer for testing the time at the zero position, that is, the time-out of the echo. 9. The ultrasonic real-time imaging acquisition control system for pressure fracturing induced cracks according to claim 6, characterized in that, the peak detection circuit includes sequentially electrically connected: a program-controlled amplifier, a precision commutator circuit, and a charge discharge control Subcircuit, shoot-and-follow buffer subcircuit and A/D acquisition subcircuit; Wherein, The program-controlled amplifier is used to perform automatic gain processing on the echo signal, so that the peak value of the amplified echo signal is always within the required range of the AD acquisition sub-circuit; The precision commutator circuit includes a peak detector and a peak hold capacitor; wherein the peak detector is used to detect the peak value of the amplified signal; the peak hold capacitor is used to store the peak value of the detected signal charge; The charge discharge control subcircuit is used to discharge the charge on the peak holding capacitor for the next peak detection; The A/D acquisition sub-circuit is used for performing analog-to-digital conversion and acquisition of the peak value of the signal. 10. The ultrasonic real-time imaging acquisition and control system of pressure fracturing induced cracks according to claim 9, wherein the signal acquisition and processing module also includes an FPGA unit, which is used to obtain the echo amplitude and echo frequency obtained by the signal processing unit. Ultrasonic imaging of cracks is obtained by processing the wave time and stored; it is also used to control the charge discharge control sub-circuit.

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