Hydraulic fracturing construction bridge plug working condition real-time monitoring system and method

Abstract

The invention discloses a hydraulic fracturing construction bridge plug working condition real-time monitoring system which comprises a ground comprehensive control device, a signal transmission device and an acoustic sensor, the signal transmission device is in communication connection with the ground comprehensive control device and the acoustic sensor at the same time, and the acoustic sensor is located in a sleeve. The ground comprehensive control device is used for converting the reflected electric signal into a digital signal, the digital signal is used for representing the reflected sound wave signal, and the position of the bridge plug is calculated according to the time between the digital signal and the initial electric signal and the sound wave propagation speed; and inputting the position of the bridge plug and characteristic parameters obtained by preprocessing the digital signal into the trained preset model to obtain leakage information of the bridge plug. The system can rapidly and quantitatively monitor the position of the bridge plug and the leakage amount information of the bridge plug in the hydraulic fracturing construction process, construction parameters can be conveniently and rapidly adjusted, and the monitoring cost is reduced. The invention further discloses a hydraulic fracturing construction bridge plug working condition real-time monitoring method.

Description

Technical Field

[0001] The present invention belongs to the technical field of oil extraction equipment, and particularly relates to a real-time monitoring system and method for the working conditions of a hydraulic fracturing operation bridge plug. Background Art

[0002] When performing a hydraulic fracturing operation, in order to create a closed environment downhole to build up pressure so that the hydraulic pressure in this environment is greater than the formation fracture pressure, thereby generating artificial fractures, it is necessary to lower a bridge plug downhole to prevent the fracturing fluid from leaking along the casing. However, during the actual construction process, the bridge plug cannot ensure complete sealing of a single fracturing stage area. If there is a certain degree of leakage in the bridge plug, it will lead to a reduction in the fluid intake of the formation, thereby reducing the effect of formation stimulation. Therefore, when the leakage amount of the bridge plug reaches a certain level, timely adjustment and treatment are required.

[0003] In the prior art, construction personnel can monitor the pressure curve of the fracturing operation. This pressure curve of the fracturing operation is a curve showing the variation of the high-pressure pipe manifold over time obtained at the wellhead when multiple fracturing pump trucks supply hydraulic pressure to the fracturing fluid during the execution of the hydraulic fracturing operation. It is a key data in the fracturing project and can reflect various stages in the fracturing process and the response of the formation. By analyzing this curve, important information such as whether the fracture is opened, whether it extends, whether the formation is penetrated, and whether there is blockage can be judged. In the prior art, only a significant drop in the above-mentioned pressure curve of the fracturing operation can be relied on to judge whether the bridge plug has reached a sealed state. Moreover, a significant drop in pressure during the fracturing operation can only qualitatively indicate that the bridge plug has completely failed, and the working conditions reflected qualitatively are also relatively limited because it cannot quantitatively feedback the position information of the bridge plug and the leakage amount information of the fracturing fluid at the bridge plug. Additionally, even if there is a small drop in the construction pressure curve, there is already a situation of fracturing fluid leakage, which indicates that there is a "coexistence state" between the normal working condition and the completely failed condition of the bridge plug, that is, a state where the bridge plug has not completely failed but there is leakage. However, such a working condition cannot be monitored and identified in real time relying on the above prior art. Furthermore, even if the pressure shown by the construction pressure curve does not drop or drops by a small value, for example, when the pressure drop value is within the range of less than 30 MPa, there may be abnormal situations in the setting of the bridge plug. The abnormalities mentioned here usually include the position slippage and leakage of the bridge plug. Therefore, it is impossible to accurately judge the working conditions of the bridge plug only based on the construction pressure curve. Summary of the Invention

[0004] To solve the above problems, the present invention provides a real-time monitoring system and method for the working conditions of bridge plugs in hydraulic fracturing construction, which can quickly and quantitatively monitor the position of the bridge plug and the leakage amount information at the bridge plug during the hydraulic fracturing construction process, facilitate the construction personnel to adjust the construction parameters in a timely and accurate manner, and can realize the reuse of the device, reducing the monitoring cost of single-well construction.

[0005] A real-time monitoring system for the working conditions of bridge plugs in hydraulic fracturing construction provided by the present invention includes a ground integrated control device, a signal transmission device, and an acoustic sensor. The signal transmission device is communicatively connected to both the ground integrated control device and the acoustic sensor. The acoustic sensor is located in the casing, and both the acoustic wave transmitting end and the acoustic wave receiving end of the acoustic sensor face the bridge plug. The ground integrated control device is configured to transmit an initial electrical signal to the acoustic sensor through the signal transmission device. The acoustic sensor is configured to convert the initial electrical signal into an initial acoustic wave signal and transmit the initial acoustic wave signal to the bridge plug. The ground integrated control device is further configured to control the acoustic sensor to switch from the transmitting state to the receiving state through the signal transmission device. The acoustic sensor is further configured to receive the reflected acoustic wave signal reflected from the bridge plug and convert it into a reflected electrical signal. The signal transmission device is further configured to transmit the reflected electrical signal to the ground integrated control device. The ground integrated control device is further configured to convert the reflected electrical signal into a digital signal. The digital signal is used to characterize the reflected acoustic wave signal, and the position of the bridge plug is calculated based on the time elapsed between the digital signal and the initial electrical signal and the acoustic wave propagation speed. The position of the bridge plug and the characteristic parameters obtained after preprocessing the digital signal are input into a trained preset model to obtain the leakage amount information of the bridge plug.

[0006] Preferably, in the above real-time monitoring system for the working conditions of bridge plugs in hydraulic fracturing construction, the ground integrated control device further includes a signal preprocessing component;

[0007] The signal preprocessing component includes:

[0008] A wave arrival point judgment unit for judging the time when the first wave reaches the acoustic sensor according to the digital signal;

[0009] A signal intercepting unit for intercepting a preset signal after the wave arrival point;

[0010] A filtering unit for filtering the preset signal to obtain a filtered signal;

[0011] A modal decomposition unit for performing modal decomposition on the filtered signal, extracting the characteristic parameters of each modal, and forming an initial matrix;

[0012] A principal component analysis unit, configured to reduce the dimension of the initial matrix to obtain a projection matrix corresponding to the initial matrix, where the projection matrix includes the main information in the initial matrix;

[0013] A data group generation unit, configured to combine the projection matrix and the bridge plug position into a feature matrix, and input the feature matrix into the trained preset model.

[0014] Preferably, in the above real-time monitoring system for the working condition of the bridge plug in hydraulic fracturing construction, the wave arrival point judgment unit is configured to use wavelet transform to judge the time when the first wave reaches the acoustic sensor.

[0015] Preferably, in the above real-time monitoring system for the working condition of the bridge plug in hydraulic fracturing construction, the filtering unit is configured to filter the preset signal by using high-pass filtering.

[0016] Preferably, in the above real-time monitoring system for the working condition of the bridge plug in hydraulic fracturing construction, the ground comprehensive control device further includes:

[0017] An acoustic wave propagation velocity calculation unit, configured to calculate the propagation velocity of acoustic waves in the casing according to the construction pressure information.

[0018] A real-time monitoring method for the working condition of the bridge plug in hydraulic fracturing construction provided by the present invention includes:

[0019] Communicatively connect a signal transmission device to both the ground comprehensive control device and the acoustic sensor at the same time, place the acoustic sensor in the casing, and both the acoustic wave transmitting end and the acoustic wave receiving end of the acoustic sensor face the bridge plug;

[0020] Transmit an initial electrical signal to the acoustic sensor, convert the initial electrical signal into an initial acoustic wave signal, and transmit the initial acoustic wave signal to the bridge plug;

[0021] Control the acoustic sensor to switch from the transmitting state to the receiving state, receive the reflected acoustic wave signal reflected from the bridge plug and convert it into a reflected electrical signal;

[0022] Transmit the reflected electrical signal to the ground comprehensive control device, convert the reflected electrical signal into a digital signal, the digital signal is used to characterize the reflected acoustic wave signal, and calculate the position of the bridge plug according to the time elapsed between the digital signal and the initial electrical signal and the acoustic wave propagation velocity;

[0023] Input the bridge plug position and the characteristic parameters obtained after preprocessing the digital signal into the trained preset model to obtain the leakage amount information of the bridge plug.

[0024] Preferably, in the above real-time monitoring method for the working conditions of the hydraulic fracturing operation bridge plug, the preprocessing of the digital signal includes:

[0025] Judging the time when the first wave reaches the acoustic sensor according to the digital signal;

[0026] Intercepting a preset signal after the wave arrival point;

[0027] Filtering the preset signal to obtain a filtered signal;

[0028] Performing modal decomposition on the filtered signal, extracting the characteristic parameters of each mode, and forming an initial matrix;

[0029] Reducing the dimension of the initial matrix to obtain a projection matrix corresponding to the initial matrix, where the projection matrix includes the main information in the initial matrix;

[0030] Combining the projection matrix and the bridge plug position into a characteristic matrix, and inputting the characteristic matrix into the preset model that has been trained.

[0031] Preferably, in the above real-time monitoring method for the working conditions of the hydraulic fracturing operation bridge plug, the wavelet transform method is used to judge the time when the first wave reaches the acoustic sensor.

[0032] Preferably, in the above real-time monitoring method for the working conditions of the hydraulic fracturing operation bridge plug, the high-pass filtering method is used to filter the preset signal.

[0033] Preferably, in the above real-time monitoring method for the working conditions of the hydraulic fracturing operation bridge plug, it further includes:

[0034] Calculating the propagation speed of sound waves in the casing according to the construction pressure information.

[0035] As can be seen from the above description, the real-time monitoring system for the working conditions of the hydraulic fracturing plug provided by the present invention includes a ground comprehensive control device, a signal transmission device, and an acoustic sensor. The signal transmission device is communicatively connected to both the ground comprehensive control device and the acoustic sensor. The ground comprehensive control device can convert the reflected electrical signal into a digital signal, which is used to represent the reflected acoustic wave signal. The position of the plug is calculated based on the time elapsed between the digital signal and the initial electrical signal and the acoustic wave propagation speed, and the plug position and the characteristic parameters obtained after preprocessing the digital signal are input into a preset model that has been trained to obtain the leakage amount information of the plug. It can be seen that it is possible to know whether the plug has moved and whether there is leakage in a very short time. Therefore, the system can quickly and quantitatively monitor the plug position and the leakage amount information at the plug during the hydraulic fracturing construction process, facilitating the construction personnel to timely and accurately adjust the construction parameters, and can also realize the reuse of the device, reducing the monitoring cost of single-well construction. The real-time monitoring method for the working conditions of the hydraulic fracturing plug provided by the present invention has the same advantages as the above system. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the drawings in the following description are only the embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on the provided drawings without creative efforts.

[0037] Figure 1 Schematic diagram of an embodiment of a real-time monitoring system for the working conditions of a hydraulic fracturing plug provided by the present invention;

[0038] Figure 2 Schematic diagram of the specific composition of the ground comprehensive control device;

[0039] Figure 3 Schematic diagram of four working states of the plug during the fracturing construction;

[0040] Figure 4 Schematic diagram of an embodiment of a real-time monitoring method for the working conditions of a hydraulic fracturing plug provided by the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0041] The core of the present invention is to provide a real-time monitoring system and method for the working conditions of a hydraulic fracturing plug, which can quickly and quantitatively monitor the plug position and the leakage amount information at the plug during the hydraulic fracturing construction process, facilitating the construction personnel to timely and accurately adjust the construction parameters, and can also realize the reuse of the device, reducing the monitoring cost of single-well construction.

[0042] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0043] An embodiment of a real-time monitoring system for the working conditions of a hydraulic fracturing operation bridge plug provided by the present invention is as Figure 1 shown Figure 1FIG. 0 is a schematic diagram of an embodiment of a real-time monitoring system for the working conditions of a hydraulic fracturing operation bridge plug provided by the present invention. The real-time monitoring system for the working conditions of a hydraulic fracturing operation bridge plug may include a ground comprehensive control device 1, a signal transmission device 2, and an acoustic sensor 3. The signal transmission device 2 is communicatively connected to both the ground comprehensive control device 1 and the acoustic sensor 3. In this case, the signal transmission device 2 can send the control signal sent by the ground comprehensive control device 1 to the acoustic sensor 3, and can also transmit the data collected by the acoustic sensor 3 back to the ground comprehensive control device 1 for corresponding processing. The acoustic sensor 3 is located in the casing 4. The position of this acoustic sensor 3 in the casing 4 can be controlled in advance, that is to say, it is known. The length of the cable lowered into the well can be used as the position calibration of the acoustic sensor. When the acoustic sensor is fixed in the well, it is preferably placed in the middle of the casing. Here, the "middle" refers to the middle of the axial direction of the casing, that is, to make the acoustic sensor collinear with the axial center line of the casing to complete the position calibration of the acoustic sensor. Both the acoustic wave transmitting end and the acoustic wave receiving end of the acoustic sensor 3 face the bridge plug 5, so that acoustic waves can be emitted directly at the bridge plug 5 and the reflected acoustic waves can be received. After the hydraulic fracturing operation starts, the ground comprehensive control device 1 is used to transmit an initial electrical signal to the acoustic sensor 3 through the signal transmission device 2. This initial electrical signal can be an analog signal modulated manually, which has a certain rated power. This rated power can enable the acoustic sensor 3 to emit the required acoustic wave signal, and corresponding control signals can also be transmitted at the same time. At this time, the control signal transmitted is the control signal for the acoustic sensor 3 to enter the acoustic wave emission state. The function of the acoustic sensor 3 is to convert between acoustic wave signals and electrical signals. The acoustic sensor 3 is used to convert the initial electrical signal into an initial acoustic wave signal and emit the initial acoustic wave signal to the bridge plug 5. In this way, the bridge plug 5 can reflect this initial acoustic wave signal back to the acoustic sensor 3. The ground comprehensive control device 1 is also used to control the acoustic sensor 3 to switch from the emission state to the reception state through the signal transmission device 2. The acoustic sensor 3 is also used to receive the reflected acoustic wave signal reflected from the bridge plug 5 and convert it into a reflected electrical signal. The signal transmission device 2 is also used to transmit the reflected electrical signal to the ground comprehensive control device 1. The ground comprehensive control device 1 is also used to convert the reflected electrical signal into a digital signal and store this digital signal in the storage component. This digital signal is used to characterize the reflected acoustic wave signal, that is to say, this digital signal contains the characteristics in the reflected acoustic wave signal. And the position of the bridge plug is calculated based on the time elapsed between the digital signal and the initial electrical signal and the acoustic wave propagation speed. Specifically, the time and the speed can be multiplied to obtain the distance between the acoustic sensor 3 and the bridge plug 5, and by combining this distance with the position where the acoustic sensor 3 is located, the position of the bridge plug 5 at this time can be obtained. And the bridge plug position and the characteristic parameters obtained after preprocessing the digital signal are input into the preset model that has been trained.The input quantity in this preset model is the digital signal that can characterize the reflected acoustic wave signal, and the output quantity is the leakage information of the bridge plug. Therefore, the leakage information of the bridge plug can be obtained. If there is a certain leakage in the bridge plug at this time, the reflected acoustic wave signal reflected back can contain the corresponding leakage information. Therefore, this leakage information can be obtained through the signal processing process later. It can be seen that the position and leakage information of the bridge plug can be obtained quickly, further improving the monitoring efficiency. This leakage information and the bridge plug position information together constitute the quantified working conditions of the bridge plug construction.

[0044] It should be noted that the monitoring of the bridge plug position is judged by the propagation time of the reciprocating acoustic wave. If there is a leakage at the bridge plug, there will be liquid flow in the casing between the acoustic sensor and the bridge plug. If the propagation speed of the acoustic wave under the current pressure and temperature conditions is c0, and if the fracturing fluid is water-based, its order of magnitude is 1.5*10 3 m / s fluctuating around. If there is a leakage in the bridge plug, the influence value of the liquid flow in the casing on the acoustic wave propagation is v0. Assuming the distance between the bridge plug and the acoustic sensor is l, then the propagation time when the acoustic wave propagates towards the bridge plug is:

[0045] ,

[0046] Since the bridge plug is generally made of metal, the acoustic wave propagating in the liquid environment is almost completely reflected after encountering the metal bridge plug. The propagation time of the acoustic wave in the casing space between the bridge plug and the acoustic sensor after reflection is:

[0047] ,

[0048] After the acoustic sensor receives the reflected acoustic wave, a total propagation time can be obtained. This total propagation time is:

[0049] ,

[0050] After simplifying the above formula, we can get:

[0051] ,

[0052] Among them, the order of magnitude of v0 is 10 2 and is relatively small compared to c0. Therefore, we can get:

[0053] ,

[0054] It can be seen from this formula that as long as the product of the propagation speed c0 of the acoustic wave under the current pressure and temperature conditions and the total propagation time is multiplied and then divided by 2, the distance between the current acoustic sensor and the bridge plug can be obtained. Adding this distance to the position where the acoustic sensor is set can obtain the position of the bridge plug. If the obtained position of the bridge plug relative to the initial state is larger than the distance from the acoustic sensor, it proves that the bridge plug has been displaced; otherwise, it proves that the position of the bridge plug is normal.

[0055] It should also be noted that the above-mentioned ground comprehensive control device 1 can also be connected to the construction control system of the ground pump truck group to receive its real-time construction data, such as construction pressure, displacement, composition of the fracturing fluid, etc., as a reference for correcting the monitoring parameters. For example, the propagation speed of the acoustic wave under the current pressure and temperature conditions can be corrected to make its monitoring result more accurate. Moreover, the above-mentioned signal transmission device 2 can be composed of armored cables. The purpose of armoring is to ensure the integrity of the cable under extreme high-pressure fracturing construction conditions, so that it can still work normally under the hydraulic fracturing construction state. The acoustic sensor 3 can adopt an acoustic transducer that can adapt to the extreme high-pressure environment of hydraulic fracturing construction. In the emission state, it can complete the conversion of electrical signals into acoustic wave signals in the environment, and in the receiving state, it can convert the acoustic wave vibration signals in the environment into electrical signals and transmit them to the ground. When the acoustic wave is reflected and propagated after passing through the position of the bridge plug, it carries information about the propagation environment. Intercepting a part of this reflected echo and extracting the information about the leakage amount at the bridge plug can thus achieve the purpose of monitoring the leakage amount at the bridge plug, and the quantitative working condition of the bridge plug can be obtained through the corresponding signal processing process. The monitoring process of the above system does not exceed 5 seconds each time, and it can realize real-time monitoring of the working condition of the bridge plug at a high monitoring frequency. According to the monitored data, the construction personnel can send construction normal and abnormal signals according to the set program, thereby helping the construction personnel to make real-time adjustments to the hydraulic fracturing construction process.

[0056] As can be seen from the above description, in the embodiment of the real-time monitoring system for the working conditions of the hydraulic fracturing operation bridge plug provided by the present invention, since it includes a ground comprehensive control device, a signal transmission device, and an acoustic sensor, the signal transmission device is communicatively connected to both the ground comprehensive control device and the acoustic sensor. The ground comprehensive control device can convert the reflected electrical signal into a digital signal, and the digital signal is used to represent the reflected acoustic wave signal. The position of the bridge plug is calculated based on the time elapsed between the digital signal and the initial electrical signal and the acoustic wave propagation speed, and the position of the bridge plug and the characteristic parameters obtained after preprocessing the digital signal are input into the preset model that has been trained to obtain the leakage amount information of the bridge plug. It can be seen that it is possible to know whether the bridge plug has moved and whether there is leakage in a very short time. Therefore, the system can quickly and quantitatively monitor the position of the bridge plug and the leakage amount information at the bridge plug during the hydraulic fracturing operation, facilitating the construction personnel to adjust the construction parameters in a timely and accurate manner, and enabling the reuse of the device, reducing the monitoring cost of single-well construction.

[0057] In a specific embodiment of the above real-time monitoring system for the working conditions of the hydraulic fracturing operation bridge plug, referring to Figure 2 , Figure 2 is a schematic diagram of the specific composition of the ground comprehensive control device. The above ground comprehensive control device 1 may further include a signal preprocessing component 11;

[0058] The signal preprocessing component 11 may include:

[0059] A wave arrival point judgment unit 111 for judging the time when the first wave reaches the acoustic sensor according to the digital signal, and this time is the wave arrival point;

[0060] A signal intercepting unit 112 for intercepting a section of preset signal after the wave arrival point;

[0061] A filtering unit 113 for filtering the preset signal to obtain a filtered signal;

[0062] A modal decomposition unit 114 for performing modal decomposition on the filtered signal, extracting the characteristic parameters of each mode, and forming an initial matrix. It should be noted that in actual operation, when the leakage amount difference is small under the condition of the same bridge plug position, the difference in simple acoustic wave characteristic parameters is small. In order to improve the monitoring accuracy, it is necessary to amplify the difference between different signals. Therefore, the acoustic wave is decomposed by modal decomposition, and the characteristic parameters of different modes are extracted to amplify the difference between signals;

[0063] The principal component analysis unit 115 is used to reduce the dimension of the initial matrix by using the principal component analysis method to obtain a projection matrix corresponding to the initial matrix. The projection matrix includes the main information in the initial matrix. Specifically, 5 modes can be extracted, and each mode has 5 characteristic parameters, so there are 25 dimensions in total. In the case of a large number of dimensions, using a machine learning algorithm will cause a decrease in the accuracy of the model. Therefore, the principal component analysis method is used to project the 5*5 initial matrix onto a 1*5 projection matrix. This projection matrix contains the main information of the original 5*5 initial matrix. It can be seen that in this way, the 25 dimensions are reduced to 5 dimensions, so it is more convenient for training, improves the accuracy and has a fast response time;

[0064] The data group generation unit 116 is used to combine the projection matrix and the bridge plug position into a feature matrix, and input the feature matrix into the preset model that has been trained. Then, the value of the leakage amount at the bridge plug can be returned. It should be noted that since the high-frequency sound wave attenuates as the propagation distance increases and also attenuates as the leakage amount increases, using the bridge plug position as a correction parameter can improve the accuracy of bridge plug leakage amount monitoring and prevent the error caused by this superposition effect.

[0065] In another specific embodiment of the above real-time monitoring system for the working conditions of the bridge plug in hydraulic fracturing construction, on the basis of the above specific embodiment, the wave arrival point judgment unit 111 can specifically be used to judge the time when the first wave reaches the acoustic sensor by using the wavelet transform method. It should be noted that this wavelet transform can show the change of the frequency of the arriving sound wave with time, and using the wavelet transform can see the time when the high-frequency sound wave emitted by the acoustic sensor arrives.

[0066] In yet another specific embodiment of the above real-time monitoring system for the working conditions of the bridge plug in hydraulic fracturing construction, on the basis of the above specific embodiment, the filtering unit 113 can specifically be used to filter the preset signal by using the high-pass filtering method. It should be noted that the received sound wave is a combination of low-frequency natural sound waves and high-frequency active sound waves (that is, the sound waves emitted by the acoustic sensor). Using the high-frequency filtering method can filter out the low-frequency natural sound waves and only process the active sound waves.

[0067] On the basis of any embodiment of the above real-time monitoring system for the working conditions of the bridge plug in hydraulic fracturing construction, the above ground comprehensive control device 1 may further include:

[0068] An acoustic wave propagation velocity calculation unit is used to calculate the propagation velocity of acoustic waves in the casing according to the construction pressure information. Specifically, the inherent propagation time of acoustic waves in a medium is related to pressure and temperature. Dissolved substances and other factors in the medium will cause changes in the propagation velocity of acoustic waves in the medium. Therefore, the propagation velocity of acoustic waves in the downhole environment can be calculated based on the composition of the fracturing fluid and the downhole temperature and pressure during the fracturing construction. By combining more influencing factors, a more accurate acoustic wave propagation velocity under the current conditions can be obtained. Of course, this can be selected according to actual needs and is not limited here.

[0069] In summary, by using the above real-time monitoring system for the bridge plug working conditions in hydraulic fracturing construction, any one of the four working states of the bridge plug can be monitored. Refer to Figure 3 , Figure 3 is a schematic diagram of the four working states of the bridge plug during fracturing construction. Among them, the first part shows the normal working state of the bridge plug. Under the normal working conditions of the bridge plug, the bridge plug is set in place at the predetermined construction position, does not slip during construction, and there is no leakage of fracturing fluid at the bridge plug position. The second part reflects the first possible abnormal working condition, that is, the bridge plug is set in place at the designated position, but the bridge plug rubber barrel and the casing are not fully fitted, resulting in leakage of fracturing fluid. The third part describes the second possible abnormal working condition of the bridge plug, that is, the bridge plug is not set in place at the designated position, but is re-anchored after slipping, the rubber barrel and the casing wall are closely fitted, and there is no leakage of fracturing fluid. The fourth part describes the situation where two abnormal working conditions occur simultaneously. Under this working condition, the bridge plug not only slips to a non-engineered set position, but also the rubber barrel of the bridge plug is not fully fitted with the casing wall, resulting in leakage of fracturing fluid. Since the above system can not only detect the position of the bridge plug but also detect the leakage amount information of the bridge plug, the monitoring of the bridge plug working conditions is more comprehensive and the real-time performance is better, which is convenient for timely handling in case of abnormal situations.

[0070] An embodiment of a real-time monitoring method for the bridge plug working conditions in hydraulic fracturing construction provided by the present invention is as Figure 4 shown, Figure 4 is a schematic diagram of an embodiment of a real-time monitoring method for the bridge plug working conditions in hydraulic fracturing construction provided by the present invention. The method may include the following steps:

[0071] S1: Communicatively connect the signal transmission device to both the ground integrated control device and the acoustic sensor at the same time. Place the acoustic sensor in the casing, and both the acoustic wave transmitting end and the acoustic wave receiving end of the acoustic sensor face the bridge plug;

[0072] In this case, the signal transmission device can send the control signal sent by the ground integrated control device to the acoustic sensor, and can also transmit the data collected by the acoustic sensor back to the ground integrated control device for corresponding processing. The position of this acoustic sensor in the casing can be controlled in advance, that is to say, it is known. The length of the cable lowered into the well can be used as the position calibration of the acoustic sensor. When fixing the acoustic sensor in the well, it is preferably placed in the middle of the casing to complete the position calibration of the acoustic sensor. Both the acoustic wave transmitting end and the acoustic wave receiving end of the acoustic sensor face the bridge plug, so that acoustic waves can be emitted directly at the bridge plug and the reflected acoustic waves can be received.

[0073] S2: Transmit an initial electrical signal to the acoustic sensor, convert it into an initial acoustic wave signal according to the initial electrical signal, and transmit the initial acoustic wave signal to the bridge plug;

[0074] It should be noted that after the hydraulic fracturing construction starts, the ground integrated control device is used to transmit an initial electrical signal to the acoustic sensor through the signal transmission device. This initial electrical signal can be an analog signal modulated artificially, which has a certain rated power. This rated power can enable the acoustic sensor to emit the required acoustic wave signal, and the corresponding control signal can be transmitted at the same time. At this time, the control signal for controlling the acoustic sensor to enter the acoustic wave emission state is transmitted. The function of the acoustic sensor is to convert between the acoustic wave signal and the electrical signal. The acoustic sensor is used to convert the initial electrical signal into an initial acoustic wave signal and transmit the initial acoustic wave signal to the bridge plug.

[0075] S3: Control the acoustic sensor to switch from the emission state to the reception state, receive the reflected acoustic wave signal reflected from the bridge plug and convert it into a reflected electrical signal;

[0076] It should be noted that the bridge plug can reflect this initial acoustic wave signal back to the acoustic sensor. The ground integrated control device is also used to control the acoustic sensor to switch from the emission state to the reception state through the signal transmission device. The acoustic sensor is also used to receive the reflected acoustic wave signal reflected from the bridge plug and convert it into a reflected electrical signal.

[0077] S4: Transmit the reflected electrical signal to the ground integrated control device, convert the reflected electrical signal into a digital signal. The digital signal is used to represent the reflected acoustic wave signal, and calculate the position of the bridge plug according to the time elapsed between the digital signal and the initial electrical signal and the acoustic wave propagation speed;

[0078] It should be noted that the signal transmission device can transmit the reflected electrical signal to the ground integrated control device, and the ground integrated control device can also convert the reflected electrical signal into a digital signal and store the digital signal in a storage component. The digital signal is used to characterize the reflected sound wave signal. That is to say, the digital signal contains the characteristics of the reflected sound wave signal, and the position of the bridge plug is calculated based on the time elapsed between the digital signal and the initial electrical signal and the sound wave propagation speed. Specifically, the time and speed can be multiplied to obtain the distance between the acoustic sensor and the bridge plug, and this distance can be combined with the position of the acoustic sensor to obtain the position of the bridge plug at this time.

[0079] S5: Input the bridge plug position and characteristic parameters obtained after preprocessing the digital signal into the trained preset model to obtain leakage information of the bridge plug.

[0080] It should be noted that if there is a certain amount of leakage in the bridge plug at this time, the reflected sound wave signal reflected back will contain the corresponding leakage information. Therefore, the leakage information can be obtained through the subsequent signal processing process. In other words, when the leakage is larger, the specific leakage amount can be monitored. When the leakage is small, the leakage value can also be quantitatively obtained. It can be seen that the bridge plug position and leakage information can be quickly obtained in this way, further improving the monitoring efficiency. The leakage information and bridge plug position information together constitute the quantitative working conditions of the bridge plug construction.

[0081] It should also be noted that the above-mentioned ground integrated control device can also be connected to the construction control system of the ground pump truck group to receive its real-time construction data, such as construction pressure, displacement, composition of fracturing fluid, etc., as a reference for correcting the monitoring parameters. For example, the propagation speed of sound waves under the current pressure and temperature conditions can be corrected to make its monitoring results more accurate. The acoustic sensor can adopt an acoustic transducer that can adapt to the extreme high-pressure environment of hydraulic fracturing construction. In the transmitting state, it can complete the conversion of electrical signals into sound wave signals in the environment, and in the receiving state, it can convert the sound wave vibration signal in the environment into an electrical signal and transmit it to the ground. When the sound wave is reflected and propagated through the bridge plug position, it carries information about the propagation environment. By intercepting a part of the reflected echo and extracting the information about the leakage at the bridge plug, the purpose of monitoring the leakage at the bridge plug can be achieved. The quantitative working condition of the bridge plug can be obtained through the corresponding signal processing process. The monitoring process of the above system does not exceed 5 seconds each time, and real-time monitoring of the bridge plug working condition under high monitoring frequency can be realized. According to the monitored data, the construction personnel can transmit normal and abnormal construction signals according to the set program, thereby helping the construction personnel to make real-time adjustments to the hydraulic fracturing construction process.

[0082] In summary, the above method can quickly and quantitatively monitor the position of the bridge plug and the leakage information at the bridge plug during the hydraulic fracturing construction process, facilitating the construction personnel to adjust the construction parameters in a timely and accurate manner. Moreover, it can realize the reuse of the device and reduce the monitoring cost of single-well construction.

[0083] In a specific embodiment of the above real-time monitoring method for the working conditions of the bridge plug in hydraulic fracturing construction, the steps of preprocessing the digital signal may include:

[0084] Judge the time when the first wave arrives at the acoustic sensor according to the digital signal, and this time is the wave arrival point;

[0085] Intercept a section of preset signal after the wave arrival point;

[0086] Filter the preset signal to obtain the filtered signal;

[0087] Perform modal decomposition on the filtered signal, extract the characteristic parameters of each mode, and form an initial matrix. It should be noted that in actual operation, under the condition of the same bridge plug position, when the leakage amount difference is small, the difference in simple acoustic wave characteristic parameters extracted is small. In order to improve the monitoring accuracy, it is necessary to amplify the difference between different signals. Therefore, by using modal decomposition for acoustic waves and extracting the characteristic parameters of different modes, the difference between signals can be amplified;

[0088] Reduce the dimension of the initial matrix to obtain a projection matrix corresponding to the initial matrix. The projection matrix includes the main information in the initial matrix. Specifically, 5 modes can be extracted, and each mode has 5 characteristic parameters, so it is 25 dimensions. In the case of a large dimension, using a machine learning algorithm will cause the model accuracy to decline. Therefore, the principal component analysis method is used to project the 5*5 initial matrix onto a 1*5 projection matrix. This projection matrix contains the main information of the original 5*5 initial matrix. It can be seen that in this way, the 25 dimensions are reduced to 5 dimensions, so it is more convenient for training, improves the accuracy and has a fast response time;

[0089] Combine the projection matrix and the bridge plug position into a characteristic matrix, and input the characteristic matrix into the preset model that has been trained. Then, the value of the leakage amount at the bridge plug can be returned. It should be noted that because the high-frequency acoustic wave attenuation increases with the increase of the propagation distance and also increases with the increase of the leakage amount, there is the following extreme possibility: the superposition of the two attenuation effects will produce the same returned acoustic wave. Therefore, using the bridge plug position as a correction parameter can improve the accuracy of bridge plug leakage amount monitoring and prevent the error caused by this superposition effect.

[0090] In another specific embodiment of the above real-time monitoring method for the working conditions of the hydraulic fracturing operation bridge plug, based on the above specific embodiment, the wavelet transform method is used to determine the time when the first wave arrives at the acoustic sensor. It should be noted that this wavelet transform can show the change of the frequency of the arriving sound wave with time, and by using the wavelet transform, the time when the high-frequency sound wave emitted by the acoustic sensor arrives can be seen.

[0091] In yet another specific embodiment of the above real-time monitoring method for the working conditions of the hydraulic fracturing operation bridge plug, based on the above specific embodiment, the high-pass filtering method is used to filter the preset signal. It should be noted that the received sound wave is a combination of low-frequency natural sound waves and high-frequency active sound waves (i.e., the sound waves emitted by the acoustic sensor). By using the high-frequency filtering method, the low-frequency natural sound waves can be filtered out, and only the active sound waves are processed.

[0092] Based on any of the above embodiments of the real-time monitoring method for the working conditions of the hydraulic fracturing operation bridge plug, the following steps may further be included:

[0093] Calculate the propagation speed of the sound wave in the casing according to the construction pressure information. Specifically, the inherent propagation time of the sound wave in the medium is related to the pressure and temperature. Dissolved substances and other factors in the medium will cause changes in the propagation speed of the sound wave in the medium. Therefore, the propagation speed of the sound wave under the downhole environment can be calculated according to the composition of the fracturing fluid and the temperature and pressure downhole during the fracturing operation. In this way, by combining more influencing factors, a more accurate sound wave propagation speed under the current situation can be obtained. Of course, this can all be selected according to actual needs, and there is no limitation here.

[0094] The above description of the disclosed embodiments enables those skilled in the art to implement or use the present invention. Various modifications to these embodiments will be obvious to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to these embodiments shown herein, but rather will be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A real-time monitoring system for the working conditions of a hydraulic fracturing bridge plug, characterized in that, It includes a ground integrated control device, a signal transmission device and an acoustic sensor. The signal transmission device is communicatively connected to both the ground integrated control device and the acoustic sensor. The acoustic sensor is located in the casing, and both the acoustic wave transmitting end and the acoustic wave receiving end of the acoustic sensor face the bridge plug. The ground integrated control device is configured to transmit an initial electrical signal to the acoustic sensor through the signal transmission device. The acoustic sensor is configured to convert the initial electrical signal into an initial acoustic wave signal and transmit the initial acoustic wave signal to the bridge plug. The ground integrated control device is further configured to control the acoustic sensor to switch from the transmitting state to the receiving state through the signal transmission device. The acoustic sensor is further configured to receive the reflected acoustic wave signal reflected from the bridge plug and convert it into a reflected electrical signal. The signal transmission device is further configured to transmit the reflected electrical signal to the ground integrated control device. The ground integrated control device is further configured to convert the reflected electrical signal into a digital signal. The digital signal is used to characterize the reflected acoustic wave signal, and the position of the bridge plug is calculated based on the time elapsed between the digital signal and the initial electrical signal and the acoustic wave propagation speed. The position of the bridge plug and the characteristic parameters obtained after preprocessing the digital signal are input into the trained preset model to obtain the leakage amount information of the bridge plug.

2. The real-time monitoring system for the working conditions of a hydraulic fracturing operation bridge plug according to claim 1, wherein The ground integrated control device further includes a signal preprocessing component; The signal preprocessing component includes: A wave arrival point judgment unit, configured to judge the time when the first wave reaches the acoustic sensor according to the digital signal; A signal interception unit, configured to intercept a section of preset signal after the wave arrival point; A filtering unit, configured to filter the preset signal to obtain a filtered signal; A modal decomposition unit, configured to perform modal decomposition on the filtered signal, extract the characteristic parameters of each mode, and form an initial matrix; A principal component analysis unit, configured to reduce the dimension of the initial matrix to obtain a projection matrix corresponding to the initial matrix, and the projection matrix includes the main information in the initial matrix; A data group generation unit, configured to combine the projection matrix and the position of the bridge plug into a characteristic matrix, and input the characteristic matrix into the trained preset model.

3. The real-time monitoring system for the working conditions of a hydraulic fracturing operation bridge plug according to claim 2, characterized in that, The wave arrival point judgment unit is configured to judge the time when the first wave reaches the acoustic sensor by using the wavelet transform method.

4. The real-time monitoring system for the working conditions of a hydraulic fracturing operation bridge plug according to claim 2, characterized in that, The filtering unit is configured to filter the preset signal by using the high-pass filtering method.

5. The real-time monitoring system for the working conditions of a hydraulic fracturing operation bridge plug according to any one of claims 1-4, characterized in that, The ground integrated control device further includes: An acoustic wave propagation speed calculation unit, configured to calculate the propagation speed of the acoustic wave in the casing according to the construction pressure information.

6. A real-time monitoring method for the working conditions of a hydraulic fracturing operation bridge plug, characterized in that, It includes: Communicatively connect the signal transmission device to both the ground integrated control device and the acoustic sensor, place the acoustic sensor in the casing, and both the acoustic wave transmitting end and the acoustic wave receiving end of the acoustic sensor face the bridge plug; Transmit an initial electrical signal to the acoustic sensor, convert the initial electrical signal into an initial acoustic wave signal, and transmit the initial acoustic wave signal to the bridge plug; Control the acoustic sensor to switch from the transmitting state to the receiving state, receive the reflected acoustic wave signal reflected from the bridge plug, and convert it into a reflected electrical signal; Transmit the reflected electrical signal to the ground integrated control device, convert the reflected electrical signal into a digital signal, the digital signal is used to characterize the reflected acoustic wave signal, and calculate the position of the bridge plug according to the time elapsed between the digital signal and the initial electrical signal and the acoustic wave propagation speed; Input the position of the bridge plug and the characteristic parameters obtained after preprocessing the digital signal into the trained preset model to obtain the leakage amount information of the bridge plug.

7. The real-time monitoring method for the working conditions of a hydraulic fracturing operation bridge plug according to claim 6, characterized in that, The preprocessing of the digital signal includes: Judge the time when the first wave arrives at the acoustic sensor according to the digital signal; Intercept a section of preset signal after the wave arrival point; Filter the preset signal to obtain a filtered signal; Perform modal decomposition on the filtered signal, extract the characteristic parameters of each mode, and form an initial matrix; Reduce the dimension of the initial matrix to obtain a projection matrix corresponding to the initial matrix, and the projection matrix includes the main information in the initial matrix; Combine the projection matrix and the position of the bridge plug into a characteristic matrix, and input the characteristic matrix into the trained preset model.

8. The real-time monitoring method for the working conditions of the hydraulic fracturing operation bridge plug according to claim 7, characterized in that Use the wavelet transform method to judge the time when the first wave arrives at the acoustic sensor.

9. The real-time monitoring method for the working conditions of a hydraulic fracturing operation bridge plug according to claim 7, characterized in that, Use the high-pass filtering method to filter the preset signal.

10. The real-time monitoring method for the working conditions of a hydraulic fracturing operation bridge plug according to any one of claims 6-9, characterized in that, It also includes: Calculate the propagation speed of sound waves in the casing according to the construction pressure information.

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