Horizontal well segmented multi-cluster hydraulic fracturing cluster liquid inlet flow monitoring system and method

Abstract

The invention discloses a horizontal well segmented multi-cluster hydraulic fracturing cluster liquid inlet flow monitoring system which comprises a ground comprehensive regulation and control device, a multi-channel electric signal transmission device, a first acoustic sensor, a second acoustic sensor and a ground signal real-time processing device. The ground signal real-time processing device is used for calculating the average liquid flow speed according to the first propagation time, the second propagation time and the first preset interval, calculating the first real-time flow between the first perforation cluster and the second perforation cluster according to the average liquid flow speed, calculating the liquid inlet flow of the first perforation cluster, and calculating the liquid outlet flow of the second perforation cluster according to the first real-time flow. The system can carry out real-time quantitative monitoring on the liquid inlet amount of different perforation clusters, the precision is higher, reuse of the device can be achieved after monitoring is finished, the construction process can be simplified, other construction processes are not affected in the monitoring process, and therefore the single-time monitoring cost is reduced, and the monitoring efficiency is improved. The invention further discloses a horizontal well segmented multi-cluster hydraulic fracturing cluster liquid inlet flow monitoring method.

Description

Technical Field

[0001] The present invention belongs to the technical field of oil extraction equipment, and particularly relates to a horizontal well segmented multi-cluster hydraulic fracturing cluster liquid injection flow monitoring system and method. Background Art

[0002] During the process of performing segmented multi-cluster hydraulic fracturing construction, there are high pressures and high flows downhole. At the same time, there are two parameters in perforation construction, namely the type of perforating gun and the perforation density. Among them, different types of perforating guns will result in different hole sizes left on the casing by perforation, and the perforation density parameter affects the number of holes left on the casing within a length of 1 meter. However, during the fracturing construction process, it is impossible to determine how many holes are in the open state. For example, the perforation density of a perforation cluster is 16 holes / meter, but within this 1-meter length, perhaps only 8 holes are in the open state. Therefore, the flow conditions near the perforation cluster are very complex, and it is difficult to quantitatively monitor the flow rate at the perforation cluster position.

[0003] In the prior art, there is a method for monitoring the cluster liquid injection flow rate during hydraulic fracturing construction using distributed optical fiber technology. In this case, to complete the monitoring of the cluster liquid injection flow rate during segmented multi-cluster hydraulic fracturing construction, the optical fiber device needs to be permanently placed in the formation, resulting in the inability to reuse the device. Moreover, the single-time optical fiber data interpretation is complex, and the service cost is high, thus leading to an excessively high single-time monitoring cost. Also, if the laser transmitter located on the ground is shut down midway, when monitoring is performed again, the monitoring accuracy will drop significantly. Therefore, this method poses a certain degree of restriction on hydraulic fracturing construction and ground work. Moreover, the results of this method rely on empirical formulas measured in the laboratory, and it is difficult to theoretically explain multiple calculation parameters, reducing the application flexibility of this technology under different working conditions. Additionally, since the optical cable relied on by this method is placed outside the casing, there is a risk that the perforating charge will penetrate the optical cable during perforation construction, resulting in signal transmission failure. Therefore, during the construction process, it is necessary to adjust the perforation construction process to avoid piercing the optical cable, which is the so-called perforation avoidance. The adjustment of the construction process further increases the single-time monitoring cost, and the monitoring preparation work is cumbersome. Therefore, the monitoring efficiency of this monitoring method is relatively low and the cost is high. Summary of the Invention

[0004] To solve the above problems, the present invention provides a horizontal well segmented multi-cluster hydraulic fracturing cluster liquid injection flow monitoring system and method, which can perform real-time quantitative monitoring of the liquid injection volume of different perforation clusters during the process of performing horizontal well segmented multi-cluster hydraulic fracturing construction. The monitoring principle it relies on is more reliable and has higher precision. Moreover, the device can be reused after the monitoring is completed, and the construction process can be simplified. The monitoring process will not affect other construction processes, thereby reducing the single-time monitoring cost of segmented multi-cluster hydraulic fracturing construction and improving the monitoring efficiency.

[0005] A horizontal well segmented multi-cluster hydraulic fracturing cluster liquid inflow rate monitoring system provided by the present invention includes a ground comprehensive control device, a multi-channel electrical signal transmission device, a first acoustic sensor, a second acoustic sensor, and a ground signal real-time processing device;

[0006] The first acoustic sensor and the second acoustic sensor are located between the adjacent first perforation cluster and the second perforation cluster in the casing, the emission ends of the two are oppositely arranged, and there is a first preset distance between the two;

[0007] The multi-channel electrical signal transmission device is simultaneously communicatively connected to the ground comprehensive control device, the ground signal real-time processing device, the first acoustic sensor, and the second acoustic sensor;

[0008] The multi-channel electrical signal transmission device is used to transmit the control signal of the ground comprehensive control device to the first acoustic sensor and the second acoustic sensor, so as to control the first acoustic sensor to emit a first acoustic wave signal while controlling the second acoustic sensor to receive the first acoustic wave signal and convert it into a first electrical signal, or to control the second acoustic sensor to emit a second acoustic wave signal while controlling the first acoustic sensor to receive the second acoustic wave signal and convert it into a second electrical signal;

[0009] The multi-channel electrical signal transmission device is further used to transmit the electrical signal and the second electrical signal to the ground signal real-time processing device;

[0010] The ground signal real-time processing device is used to process the first electrical signal to obtain the first propagation time of the first acoustic wave signal, and process the second electrical signal to obtain the second propagation time of the second acoustic wave signal. According to the first propagation time, the second propagation time, and the first preset distance, the nominal maximum flow velocity is obtained, and the average liquid flow velocity is calculated according to the nominal maximum flow velocity and the flow profile correction factor. According to the average liquid flow velocity and the cross-sectional area of the casing, the first real-time flow rate between the first perforation cluster and the second perforation cluster is calculated, and the liquid inflow rate of the first perforation cluster is calculated according to the initial liquid inflow rate of the casing and the first real-time flow rate.

[0011] Preferably, in the above horizontal well segmented multi-cluster hydraulic fracturing cluster liquid inflow rate monitoring system, it further includes a third acoustic sensor and a fourth acoustic sensor with a second preset distance between the adjacent second perforation cluster and the third perforation cluster, and there is a bridge plug at the other end of the third perforation cluster. Both of them are communicatively connected to the multi-channel electrical signal transmission device, and based on the third acoustic sensor and the fourth acoustic sensor, the ground signal real-time processing device is further used to calculate the liquid inflow rate of the second perforation cluster and the liquid inflow rate of the third perforation cluster.

[0012] Preferably, in the above-mentioned horizontal well segmented multi-cluster hydraulic fracturing cluster liquid injection flow monitoring system, it further includes:

[0013] A mechanical fixing device for statically fixing the first acoustic sensor, the second acoustic sensor, the third acoustic sensor, and the fourth acoustic sensor inside the casing.

[0014] Preferably, in the above-mentioned horizontal well segmented multi-cluster hydraulic fracturing cluster liquid injection flow monitoring system, the multi-channel electrical signal transmission device is an armored cable with multiple electrical signal transmission channels inside.

[0015] Preferably, in the above-mentioned horizontal well segmented multi-cluster hydraulic fracturing cluster liquid injection flow monitoring system, the first acoustic sensor and the second acoustic sensor are acoustic wave transducers that can withstand extremely high-pressure working environments.

[0016] Preferably, in the above-mentioned horizontal well segmented multi-cluster hydraulic fracturing cluster liquid injection flow monitoring system, the ground signal real-time processing device is further connected to a ground pump truck group to obtain real-time ground construction parameters for data processing.

[0017] A method for monitoring the liquid injection flow of a horizontal well segmented multi-cluster hydraulic fracturing cluster provided by the present invention, using the above-mentioned horizontal well segmented multi-cluster hydraulic fracturing cluster liquid injection flow monitoring system, includes:

[0018] Communicatively connect the multi-channel electrical signal transmission device to the ground comprehensive control device, the ground signal real-time processing device, the first acoustic sensor, and the second acoustic sensor simultaneously;

[0019] Set the first acoustic sensor and the second acoustic sensor between the adjacent first perforation cluster and the second perforation cluster in the casing, with their transmitting ends facing each other and having a first preset distance therebetween;

[0020] While controlling the first acoustic sensor to emit a first acoustic wave signal, control the second acoustic sensor to receive the first acoustic wave signal and convert it into a first electrical signal, and process the first electrical signal to obtain the first propagation time of the first acoustic wave signal;

[0021] While controlling the second acoustic sensor to emit a second acoustic wave signal, control the first acoustic sensor to receive the second acoustic wave signal and convert it into a second electrical signal, and process the second electrical signal to obtain the second propagation time of the second acoustic wave signal;

[0022] Based on the first propagation time, the second propagation time, and the first preset distance, obtain the nominal maximum flow velocity, and calculate the average liquid flow velocity based on the nominal maximum flow velocity and the flow profile correction factor;

[0023] Calculate a first real-time flow rate between the first perforation cluster and the second perforation cluster according to the average fluid flow velocity and the cross-sectional area of the casing, and calculate the fluid intake flow rate of the first perforation cluster according to the initial fluid intake flow rate of the casing and the first real-time flow rate.

[0024] Preferably, in the above-mentioned method for monitoring the fluid intake flow rate of multiple clusters in staged hydraulic fracturing of horizontal wells, it further includes:

[0025] Connect the multi-channel electrical signal transmission device to the third acoustic sensor and the fourth acoustic sensor. The third acoustic sensor and the fourth acoustic sensor are located between the adjacent second perforation cluster and the third perforation cluster and have a second preset spacing, and a bridge plug is provided at the other end of the third perforation cluster;

[0026] While controlling the third acoustic sensor to emit a third acoustic wave signal, control the fourth acoustic sensor to receive the third acoustic wave signal and convert it into a third electrical signal, and process the third electrical signal to obtain the third propagation time of the third acoustic wave signal;

[0027] While controlling the fourth acoustic sensor to emit a fourth acoustic wave signal, control the third acoustic sensor to receive the fourth acoustic wave signal and convert it into a fourth electrical signal, and process the fourth electrical signal to obtain the fourth propagation time of the fourth acoustic wave signal;

[0028] Obtain another nominal maximum flow velocity according to the third propagation time, the fourth propagation time and the second preset spacing, and calculate another average fluid flow velocity according to the another nominal maximum flow velocity and the flow profile correction factor;

[0029] Calculate a second real-time flow rate between the second perforation cluster and the third perforation cluster according to the another average fluid flow velocity and the cross-sectional area of the casing, and calculate the fluid intake flow rate of the second perforation cluster according to the first real-time flow rate of the casing and the second real-time flow rate, and use the second real-time flow rate as the fluid intake flow rate of the third perforation cluster.

[0030] Preferably, in the above-mentioned method for monitoring the fluid intake flow rate of multiple clusters in staged hydraulic fracturing of horizontal wells, the obtaining the nominal maximum flow velocity according to the first propagation time, the second propagation time and the first preset spacing includes:

[0031] According to the formula Calculate the nominal maximum flow velocity v max ;

[0032] Wherein, t1 is the first propagation time, t2 is the second propagation time, and L is the first preset spacing.

[0033] Preferably, in the above horizontal well segmented multi-cluster hydraulic fracturing cluster fluid intake flow rate monitoring method, the calculating the average fluid flow velocity according to the nominal maximum flow velocity and the flow profile correction factor includes:

[0034] Using the iterative method, according to the formula , based on the relationship between the flow profile correction factor and the Reynolds number, calculate the average fluid flow velocity v a , where FPCF is the flow profile correction factor.

[0035] As can be seen from the above description, the above-mentioned horizontal well segmented multi-cluster hydraulic fracturing cluster liquid intake flow monitoring system provided by the present invention includes a ground comprehensive control device, a multi-channel electrical signal transmission device, a first acoustic sensor, a second acoustic sensor, and a ground signal real-time processing device; the first acoustic sensor and the second acoustic sensor are located between the adjacent first perforation cluster and the second perforation cluster in the casing, the transmitting ends of the two are arranged opposite to each other, and there is a first preset distance between the two; the multi-channel electrical signal transmission device is simultaneously communicatively connected to the ground comprehensive control device, the ground signal real-time processing device, the first acoustic sensor, and the second acoustic sensor; the multi-channel electrical signal transmission device is used to transmit the control signal of the ground comprehensive control device to the first acoustic sensor and the second acoustic sensor to control the first acoustic sensor to emit a first acoustic wave signal while controlling the second acoustic sensor to receive the first acoustic wave signal and convert it into a first electrical signal, or to control the second acoustic sensor to emit a second acoustic wave signal while controlling the first acoustic sensor to receive the second acoustic wave signal and convert it into a second electrical signal; the multi-channel electrical signal transmission device is further used to transmit the first electrical signal and the second electrical signal to the ground signal real-time processing device; the ground signal real-time processing device is used to process the first electrical signal to obtain the first propagation time of the first acoustic wave signal, and process the second electrical signal to obtain the second propagation time of the second acoustic wave signal, and obtain the nominal maximum flow velocity according to the first propagation time, the second propagation time, and the first preset distance, and calculate the average liquid flow velocity according to the nominal maximum flow velocity and the flow profile correction factor, and calculate the first real-time flow between the first perforation cluster and the second perforation cluster according to the average liquid flow velocity and the cross-sectional area of the casing, and calculate the liquid intake flow of the first perforation cluster according to the initial liquid intake flow of the casing and the first real-time flow. Therefore, during the implementation of the horizontal well segmented multi-cluster hydraulic fracturing construction process, the liquid intake of different perforation clusters can be monitored in real time and quantitatively. The monitoring principle it relies on is more reliable and has higher accuracy. Moreover, the device can be reused after the monitoring is completed, and the construction process can also be simplified. The monitoring process will not affect other construction processes, thereby reducing the single monitoring cost of the segmented multi-cluster hydraulic fracturing construction and improving the monitoring efficiency. A horizontal well segmented multi-cluster hydraulic fracturing cluster liquid intake flow monitoring method provided by the present invention has the same advantages as the above-mentioned device. 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 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, without creative efforts, other drawings can also be obtained according to the provided drawings.

[0037] Figure 1 Schematic diagram of the composition of an embodiment of a monitoring system for the fluid intake flow rate of multiple clusters in staged horizontal well hydraulic fracturing provided by the present invention;

[0038] Figure 2 Schematic diagram of a monitoring system for the fluid intake flow rate of multiple clusters in staged horizontal well hydraulic fracturing provided by the present invention during the execution of fracturing monitoring;

[0039] Figure 3 Schematic diagram of an embodiment of a method for monitoring the fluid intake flow rate of multiple clusters in staged horizontal well hydraulic fracturing provided by the present invention;

[0040] Figure 4 Schematic diagram of the iterative calculation process of the average fluid flow velocity. Detailed implementation manners

[0041] The core of the present invention is to provide a monitoring system and method for the fluid intake flow rate of multiple clusters in staged horizontal well hydraulic fracturing, which can perform real-time quantitative monitoring of the fluid intake volume of different perforation clusters during the execution of staged horizontal well hydraulic fracturing construction. The monitoring principle it relies on is more reliable and has higher accuracy. Moreover, it can realize the reuse of the device after the monitoring is completed, simplify the construction process, and will not affect other construction processes during the monitoring, thereby reducing the single monitoring cost of staged multiple cluster hydraulic fracturing construction and significantly improving the monitoring efficiency.

[0042] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with 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. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0043] An embodiment of a monitoring system for the fluid intake flow rate of multiple clusters in staged horizontal well hydraulic fracturing provided by the present invention is as Figure 1 、 Figure 2 shown, Figure 1 Schematic diagram of the composition of an embodiment of a monitoring system for the fluid intake flow rate of multiple clusters in staged horizontal well hydraulic fracturing provided by the present invention, Figure 2Schematic diagram of a horizontal well segmented multi-cluster hydraulic fracturing cluster fluid injection flow monitoring system provided by the present invention during the execution of fracturing monitoring. The horizontal well segmented multi-cluster hydraulic fracturing cluster fluid injection flow monitoring system may include a ground integrated control device 1, a multi-channel electrical signal transmission device 2, a first acoustic sensor 3, a second acoustic sensor 4, and a ground signal real-time processing device 5. The above-mentioned multi-channel electrical signal transmission device 2 is communicatively connected to the ground integrated control device 1, the ground signal real-time processing device 5, the first acoustic sensor 3, and the second acoustic sensor 4 at the same time. It should be noted that the ground integrated control device is also the GICD (Ground Integrated Control Device). Figure 2 It is identified by GICD in Figure 2 . The ground integrated control device can perform separate signal communication with a single acoustic sensor. The operator can modulate an electrical signal of a specific frequency, which can enable the acoustic sensor to emit acoustic signals at the rated power while ensuring that the acoustic sensor emits acoustic signals of a specific frequency. Moreover, the operator can control the acoustic sensor individually according to the set program or manually to confirm whether the acoustic sensor is in the state of emitting signals or receiving signals. The above-mentioned multi-channel electrical signal transmission device is also the MSTD (Multichannel Electrical Signal Transmission Device). Figure 2 It is identified by MSTD in Figure 2 . Moreover, the above-mentioned ground signal real-time processing device is also the GSPD (Ground Signal Real-time Processing Device). Figure 2 It is identified by GSPD in Figure 2 . It can be directly connected to the multi-channel electrical signal transmission device 2 and is used to store and process the signals transmitted from the wellbore, which are electrical signals converted from the acoustic signals received by the first acoustic sensor or the second acoustic sensor. At the same time, the above-mentioned ground signal real-time processing device can also be connected to the ground pump truck group to obtain real-time ground construction parameters for data processing, such as displacement, construction pressure, and so on.

[0044] From Figure 2 it can be seen that the GICD is sequentially connected to the second acoustic sensor 3 and the second acoustic sensor 4 located in the casing through the MSTD. This connection not only provides a channel for signal transmission but also enables power supply to the acoustic sensor to ensure its normal operation. Figure 2 It also shows the reservoir below and the formation above the reservoir, and shows the bridge plugs set in the current fracturing section and the bridge plugs set in the fracturing sections that have been completed. Figure 2 It also shows multiple perforation clusters in the current fracturing section, and Figure 2Also shown are the high-pressure pipe manifolds and fracturing pump trucks on the ground during the fracturing operation. As can be seen from the enlarged view of the single-stage fracturing position in the upper right corner, the first acoustic sensor 3 and the second acoustic sensor 4 are located between the adjacent first perforation cluster 5 and the second perforation cluster 6 in the casing. The transmitting ends of the two are arranged opposite to each other, so that the sound wave emitted by one acoustic sensor can be directly received by the other acoustic sensor. In this way, the two can better achieve signal transmission and reception, and there is a first preset distance between them. This first preset distance can be set in advance and is a known value for subsequent calculations. Specifically, such an acoustic sensor can perform the mutual conversion between electrical signals and acoustic signals. If one of the acoustic sensors is in the transmitting state, it will receive an electrical signal, work at a rated power, and then emit surface acoustic vibrations to generate an acoustic signal in the fluid medium. If the other acoustic sensor is in the receiving state, the acoustic signal transmitted in the fluid medium is received on its surface, and the vibration information of the received acoustic signal can be converted into an electrical signal and transmitted to the above-mentioned ground signal real-time processing device 5;

[0045] The above-mentioned multi-channel electrical signal transmission device 2 is used to transmit the control signal of the ground integrated control device 1 to the first acoustic sensor 3 and the second acoustic sensor 4, so as to control the first acoustic sensor 3 to emit the first acoustic signal while controlling the second acoustic sensor 4 to receive the first acoustic signal and convert it into the first electrical signal, or to control the second acoustic sensor 4 to emit the second acoustic signal while controlling the first acoustic sensor 3 to receive the second acoustic signal and convert it into the second electrical signal;

[0046] The above-mentioned multi-channel electrical signal transmission device 2 is also used to transmit the first electrical signal and the second electrical signal to the ground signal real-time processing device 5;

[0047] The above-mentioned ground signal real-time processing device 5 is used to process the first electrical signal to obtain the first propagation time of the first acoustic signal, and process the second electrical signal to obtain the second propagation time of the second acoustic signal. According to the first propagation time, the second propagation time and the first preset distance, the nominal maximum flow rate is obtained, and the average liquid flow velocity is calculated according to the nominal maximum flow rate and the flow profile correction factor. According to the average liquid flow velocity and the cross-sectional area of the casing, the first real-time flow rate between the first perforation cluster and the second perforation cluster is calculated, and the inflow rate of the first perforation cluster is calculated according to the initial inflow rate of the casing and the first real-time flow rate.

[0048] In Figure 2 it, looking down from top to bottom, the ground pump trucks pump a large amount of fracturing fluid into the high-pressure pipe manifolds. The other end of the high-pressure pipe manifolds injects the fracturing fluid into the casing. The fracturing fluid builds up high pressure at the target fracturing section and enters the formation from the perforation clusters, forming artificial fractures. Moreover Figure 2A bridge plug is set in the middle to separate the previous fracturing stage and the target fracturing stage. The first propagation time and the second propagation time obtained in the above process are the downstream propagation time and the upstream propagation time respectively.

[0049] It should be noted that the speed of sound wave propagating in a flowing liquid medium will change with the liquid flow speed. If the average liquid flow speed in the casing is and the flow speed at each point on the pipe cross-section is , then the propagation speed of the sound wave in the downstream case is . However, according to the theory of fluid mechanics, the flow velocities at each point on the pipe flow cross-section are not the same. Therefore, it is set that the influence value on the sound wave propagation speed in the case of the average liquid flow speed of is , which can be called the nominal maximum flow speed. It should be noted that this nominal maximum flow speed is not the maximum flow speed of the flow profile.

[0050] According to the above description, the propagation speed of the sound wave in the downstream case is:

[0051] ,

[0052] The propagation speed of the sound wave in the upstream case is:

[0053] ,

[0054] If a sound wave propagation distance L is fixed, then in the downstream case, the propagation time of the sound wave is:

[0055] ,

[0056] Similarly, in the upstream case, the propagation time of the sound wave is:

[0057] ,

[0058] It should also be noted that the propagation speed of the sound wave will be affected by the physical properties of the propagation medium. Factors such as the density, temperature, and salinity of the propagation medium will all have an impact. In the high-pressure environment of the fracturing construction, the propagation speed of the sound wave in the fracturing fluid needs to be measured. Otherwise, the error in the sound wave propagation speed will all act on the judgment of the fracturing fluid flow rate. Therefore, the above formula cannot be directly used for the calculation of the flow rate. Combining the two propagation times, we have:

[0059] ,

[0060] The nominal maximum flow speed can be obtained according to the above formula. However, the nominal maximum flow speed cannot reflect the flow rate information. Only the average liquid flow speed can the flow information be obtained, from the nominal maximum flow velocity converted to the average liquid flow velocity It is necessary to rely on the flow profile correction factor FPCF, which is expressed by the formula:

[0061] ,

[0062] With the help of the flow profile correction factor, the average liquid flow velocity can be obtained:

[0063] .

[0064] It can be seen that the above-mentioned horizontal well segmented multi-cluster hydraulic fracturing cluster liquid intake flow monitoring device can measure the liquid intake of each perforation cluster during a single-stage fracturing operation based on the acoustic wave propagation time difference method. Considering the complex flow state at the perforation cluster and the unknown situation of whether a single perforation is open, therefore, by measuring the flow rate in the casing of two adjacent perforation clusters, the liquid intake flow rate of a single perforation cluster can be indirectly monitored through the method of calculating the acoustic wave propagation time difference. This kind of indirect monitoring means that when it is impossible to directly obtain the flow rate entering a single hole and it is also unknown how many holes are opened and thus impossible to directly monitor the flow rate, the total entering flow rate can be measured first. For example, in the case of single-stage fracturing, if it only contains two perforation clusters, the total flow rate is the total displacement pumped by the surface pump, recorded as Q. Then, if the flow rate measured by the two acoustic sensors between the first cluster and the second cluster is Q1, then the liquid intake flow rate of the first cluster is Q - Q1, and the liquid intake flow rate of the second cluster is Q1. It can be seen that in this way, the liquid intake flow rate of a single perforation cluster is indirectly measured.

[0065] As can be seen from the above description, in the embodiment of the horizontal well segmented multi-cluster hydraulic fracturing cluster inflow rate monitoring system provided by the present invention, since it includes a ground comprehensive control device, a multi-channel electrical signal transmission device, a first acoustic sensor, a second acoustic sensor, and a ground signal real-time processing device; the first acoustic sensor and the second acoustic sensor are located between the adjacent first perforation cluster and the second perforation cluster in the casing, the emission ends of the two are arranged oppositely, and there is a first preset distance between the two; the multi-channel electrical signal transmission device is simultaneously communicatively connected to the ground comprehensive control device, the ground signal real-time processing device, the first acoustic sensor, and the second acoustic sensor; the multi-channel electrical signal transmission device is used to transmit the control signal of the ground comprehensive control device to the first acoustic sensor and the second acoustic sensor, so as to control the first acoustic sensor to emit a first acoustic wave signal while controlling the second acoustic sensor to receive the first acoustic wave signal and convert it into a first electrical signal, or, control the second acoustic sensor to emit a second acoustic wave signal while controlling the first acoustic sensor to receive the second acoustic wave signal and convert it into a second electrical signal; the multi-channel electrical signal transmission device is further used to transmit the received electrical signal to the ground signal real-time processing device; the ground signal real-time processing device is used to process the first electrical signal to obtain the first propagation time of the first acoustic wave signal, and process the second electrical signal to obtain the second propagation time of the second acoustic wave signal, and calculate the nominal maximum flow velocity therefrom according to the first preset distance, the first propagation time, and the second propagation time, and calculate the average liquid flow velocity according to the nominal maximum flow velocity and the flow profile correction factor, calculate the first real-time flow rate between the first perforation cluster and the second perforation cluster according to the average liquid flow velocity and the cross-sectional area of the casing, and calculate the inflow rate of the first perforation cluster according to the initial inflow rate of the casing and the first real-time flow rate. Therefore, during the horizontal well segmented multi-cluster hydraulic fracturing construction process, the inflow volume of different perforation clusters can be monitored in real time and quantitatively. The monitoring principle it relies on is more reliable and has higher accuracy. Moreover, the device can be reused after the monitoring is completed, the construction process can be simplified, and other construction processes will not be affected during the monitoring process, thereby reducing the single monitoring cost of the segmented multi-cluster hydraulic fracturing construction and improving the monitoring efficiency.

[0066] Continue to refer to Figure 2, in a specific embodiment of the above horizontal well segmented multi-cluster hydraulic fracturing cluster liquid injection flow monitoring system, it may further include a third acoustic sensor 8 and a fourth acoustic sensor 9 with a second preset spacing therebetween, located between the adjacent second perforation cluster 6 and the third perforation cluster 7. A bridge plug 10 is provided at the other end of the third perforation cluster. The bridge plug 10 is set to seal a single fracturing section. Both of them are communicatively connected to the multi-channel electrical signal transmission device 2. Based on the third acoustic sensor 8 and the fourth acoustic sensor 9, the ground signal real-time processing device 5 is further configured to calculate the liquid injection flow rate of the second perforation cluster 6 and the liquid injection flow rate of the third perforation cluster 7. In this case, on the basis of the foregoing embodiment, if the flow rate measured by the third acoustic sensor 8 and the fourth acoustic sensor 9 between the second perforation cluster 6 and the third perforation cluster 7 is Q2, then the liquid injection flow rate of the second perforation cluster 6 is Q1 - Q2, and the liquid injection flow rate of the third perforation cluster 7 is Q2. It can be seen that in this way, the liquid injection flow rate of each perforation cluster can be measured, providing accurate reference data for the adjustment of the working process.

[0067] By analogy, if there are n perforation clusters for single-stage fracturing, then the number of the above acoustic sensor combinations is n - 1 groups. This is because there are n - 1 intervals between these n perforation clusters, and 1 group of acoustic sensors is arranged in each interval. Therefore, the number of groups of acoustic sensors is n - 1. The acoustic sensor group mentioned here includes two acoustic sensors arranged face to face.

[0068] In another specific embodiment of the above horizontal well segmented multi-cluster hydraulic fracturing cluster liquid injection flow monitoring system, on the basis of the above specific embodiment, it may further include a mechanical fixing device for statically fixing the first acoustic sensor 3, the second acoustic sensor 4, the third acoustic sensor 8, and the fourth acoustic sensor 9 in the casing. Specifically, it is preferably to statically fix these acoustic sensors in the middle of the casing. The "middle" here refers to the middle of the axial direction of the casing, that is, to make each acoustic sensor collinear with the axial center line of the casing, ensuring no swing during the fracturing construction, so as to better ensure the accuracy of acoustic wave emission and reception. It should also be noted that the positions of the perforation clusters in the wellbore are accurately known. The sensor combination is placed at the corresponding position using coiled tubing. Regarding this corresponding position, the distance between the first acoustic sensor 3 and the first perforation cluster 5 is preferably equal to the distance between the second acoustic sensor 4 and the second perforation cluster 6. Such an acoustic sensor combination is located relatively far from the position where the perforation cluster is located. Since the fracturing fluid entering the formation through the perforations will generate large pressure fluctuations, this relatively long distance can better ensure that the influence of such pressure fluctuations on the monitoring process is smaller. Similarly, the possibility of geometric deformation of the casing at this position is relatively low, which can also improve the accuracy of flow rate monitoring.

[0069] In yet another specific embodiment of the above-mentioned horizontal well segmented multi-cluster hydraulic fracturing cluster liquid intake flow rate monitoring system, the multi-channel electrical signal transmission device 2 may preferably be an armored cable with multiple electrical signal transmission channels inside. It should be noted that the purpose of armoring here is to ensure integrity under the complex working conditions of construction, sufficient to adapt to the extreme environment downhole during construction. Of course, other protection methods can also be selected according to actual needs, and it is not limited here. In addition, the first acoustic sensor 3 and the second acoustic sensor 4 may preferably be acoustic wave transducers that can withstand extremely high-pressure working environments to achieve safe monitoring and will not be damaged during the monitoring process.

[0070] An embodiment of a method for monitoring the liquid intake flow rate of a horizontal well segmented multi-cluster hydraulic fracturing cluster provided by the present invention is as Figure 3 shown, Figure 3 is a schematic diagram of an embodiment of a method for monitoring the liquid intake flow rate of a horizontal well segmented multi-cluster hydraulic fracturing cluster provided by the present invention. This method uses the above-mentioned horizontal well segmented multi-cluster hydraulic fracturing cluster liquid intake flow rate monitoring system and may include the following steps:

[0071] S1: Communicatively connect the multi-channel electrical signal transmission device to the ground comprehensive control device, the ground signal real-time processing device, the first acoustic sensor, and the second acoustic sensor simultaneously;

[0072] It should be noted that this multi-channel electrical signal transmission device can not only transmit control information and monitoring information for these two acoustic sensors, but also supply power to them to enable them to work properly.

[0073] S2: Arrange the first acoustic sensor and the second acoustic sensor between the adjacent first perforation cluster and the second perforation cluster in the casing. Their transmitting ends are arranged opposite to each other, and there is a first preset distance between them;

[0074] It should be noted that this first preset spacing can be set in advance. After placing these two acoustic sensors into the casing, a specific distance can be maintained between them to provide a basis for subsequent calculations. It should also be noted that due to the large initial stress of formation rocks, the differences in the mechanical properties of rocks, and the complex stress conditions near the wellbore, using formation rocks as the wellbore wall after drilling will cause a series of problems. To ensure the geometric uniformity of the wellbore, no foreign objects affecting the construction, and the exploitation of geological resources, a high-grade steel pipe is artificially inserted, and cement is used to consolidate between the formation and the steel pipe to fix the steel pipe, so that the steel pipe plays a supporting role for the wellbore wall. This steel pipe is the casing. Moreover, due to cement consolidation and the insertion of the casing, there is no material exchange channel between the formation and the wellbore. Therefore, perforating charges made of special gunpowder are used, and the fired perforating charges can penetrate the casing and the cement sheath in an instant, leaving a hole in the casing, thus creating a material transfer channel between the formation and the wellbore. Perforation parameters include the type of perforating gun and the perforation density. The type of perforating gun determines the type of perforating charges used, and different perforating charges leave holes of different sizes in the casing. The perforation density is the number of perforations in a 1m-long casing. The commonly used perforation density is 16 holes / m. A perforation cluster is a cluster of perforations. For example, in the implementation of staged multi-cluster hydraulic fracturing construction, one stage contains 6 perforation clusters, the length of one perforation cluster is 2m, and the perforation density is 16 holes / m, then one perforation cluster contains 32 holes. It should be noted that although there are 32 holes, in hydraulic fracturing construction, not all perforations are effective. For example, the overall flow rate of a perforation cluster is 4.9m 3 / min, but it is possible that 20 holes allow the liquid to enter, or it is possible that 10 holes allow the liquid to enter. This is the reason for the complex flow situation near the perforation cluster mentioned above. Because it is unknown, the hydraulic fracturing technology pumps high-pressure fluid from the ground into the formation. The fluid builds up high pressure underground, and the high-pressure fluid enters the formation through the perforations of the casing to form artificial fractures, creating a seepage channel with low flow resistance for the formation fluid. This is an enhanced production technology to improve the exploitation efficiency of formation fluid. The staged multi-cluster hydraulic fracturing technology is a derivative technology of the hydraulic fracturing technology and is often used in combination with the horizontal well technology. The horizontal section of the horizontal well is divided into multiple stages, each stage is perforated with multiple clusters, and hydraulic fracturing construction is carried out stage by stage, thus forming many networked fractures in the horizontal section of the horizontal well to form a fracture network, thereby greatly improving the exploitation efficiency.

[0075] S3: While controlling the first acoustic sensor to emit the first acoustic wave signal, control the second acoustic sensor to receive the first acoustic wave signal and convert it into the first electrical signal, and process the first electrical signal to obtain the first propagation time of the first acoustic wave signal;

[0076] It should be noted that this first propagation time can be obtained when the directions of the acoustic wave and the liquid flow are the same, and the superimposed speed is faster. Therefore, this first propagation time is relatively small, which is the downstream propagation time.

[0077] S4: While controlling the second acoustic sensor to emit a second acoustic wave signal, control the first acoustic sensor to receive the second acoustic wave signal and convert it into a second electrical signal, and process the second electrical signal to obtain the second propagation time of the second acoustic wave signal;

[0078] It should be noted that this second propagation time can be obtained when the directions of the acoustic wave and the liquid flow are opposite, and the superimposed speed is slower. Therefore, this second propagation time is relatively long, which is the upstream propagation time.

[0079] S5: Obtain the nominal maximum flow velocity based on the first propagation time, the second propagation time, and the first preset spacing, and calculate the average liquid flow velocity based on the nominal maximum flow velocity and the flow profile correction factor;

[0080] Specifically, obtaining the nominal maximum flow velocity based on the first propagation time, the second propagation time, and the first preset spacing may include:

[0081] According to the formula calculate the nominal maximum flow velocity v max ;

[0082] where t1 is the first propagation time, t2 is the second propagation time, and L is the first preset spacing;

[0083] Calculating the average liquid flow velocity based on the nominal maximum flow velocity and the flow profile correction factor may include the following steps:

[0084] Using the iterative method, according to the formula , based on the relationship between the flow profile correction factor and the Reynolds number, calculate the average liquid flow velocity v a , where FPCF is the flow profile correction factor, and this iterative calculation process can be as Figure 4 shown, Figure 4 is a schematic diagram of the iterative calculation process of the average liquid flow velocity. This iterative method may include the following steps:

[0085] First, according to the output value of the acoustic sensor, calculate the nominal maximum flow velocity feedback by the device. Given an initial FPCF value of 1, that is, FPCF_1 = 1. Moreover, first let FPCF_1 = FPCF_2, calculate the average liquid flow velocity accordingly, then calculate the Reynolds number based on the average liquid flow velocity (there is a specific corresponding relationship between the two, which is known), and then calculate the value of FPCF_2 based on the Reynolds number. After that, judge the difference between FPCF_1 and FPCF_2 to see if the absolute value of this difference is less than 0.0001. If the result is yes, output the calculated average liquid flow velocity. If the result is no, then use the value of FPCF_2 calculated at this time as the value of FPCF_1, continue to calculate the average liquid flow velocity, calculate the Reynolds number based on the average liquid flow velocity, calculate the value of FPCF_2, and then judge whether the absolute value of the difference between the newly obtained FPCF_2 and FPCF_1 is less than 0.0001. Iterate in this way until the range of the absolute value of this difference is finally met, and output the calculated average liquid flow velocity.

[0086] S6: Calculate the first real-time flow rate between the first perforation cluster and the second perforation cluster according to the average liquid flow velocity and the cross-sectional area of the casing, and calculate the inflow rate of the first perforation cluster according to the initial inflow rate of the casing and the first real-time flow rate.

[0087] Specifically, multiplying the average liquid flow velocity by the cross-sectional area of the casing can calculate the above-mentioned first real-time flow rate, that is, the flow rate from the location of the first perforation cluster to the location of the second perforation cluster. Subtracting this flow rate from the initial inflow rate of the casing is the inflow rate of the first perforation cluster. Because the initial inflow rate of the casing finally flows to two locations, one is into the location of the second perforation cluster, and the other is flowing out from the second perforation cluster. Therefore, subtracting the above-mentioned first real-time flow rate from the initial inflow rate can obtain the inflow rate of the second perforation cluster.

[0088] In a specific embodiment of the above horizontal well segmented multi-cluster hydraulic fracturing cluster inflow rate monitoring method, the following steps may further be included:

[0089] Connect the multi-channel electrical signal transmission device to the third acoustic sensor and the fourth acoustic sensor. The third acoustic sensor and the fourth acoustic sensor are located between the adjacent second perforation cluster and the third perforation cluster and have a second preset spacing, and a bridge plug is provided at the other end of the third perforation cluster;

[0090] While controlling the third acoustic sensor to emit the third acoustic wave signal, control the fourth acoustic sensor to receive the third acoustic wave signal and convert it into a third electrical signal, and process the third electrical signal to obtain the third propagation time of the third acoustic wave signal;

[0091] While controlling the fourth acoustic sensor to emit a fourth acoustic wave signal, control the third acoustic sensor to receive the fourth acoustic wave signal and convert it into a fourth electrical signal, and process the fourth electrical signal to obtain the fourth propagation time of the fourth acoustic wave signal;

[0092] Based on the third propagation time, the fourth propagation time, and the second preset spacing, obtain another nominal maximum flow rate, and calculate another average liquid flow velocity based on the another nominal maximum flow rate and the flow profile correction factor;

[0093] Calculate the second real-time flow rate between the second perforation cluster and the third perforation cluster based on the another average liquid flow velocity and the cross-sectional area of the casing, and calculate the inflow rate of the second perforation cluster based on the first real-time flow rate and the second real-time flow rate of the casing. Take the second real-time flow rate as the inflow rate of the third perforation cluster.

[0094] It can be seen that the third acoustic sensor and the fourth acoustic sensor adopted here perform the same steps as the first acoustic sensor and the second acoustic sensor mentioned above. It can also obtain the corresponding second real-time flow rate between the second perforation cluster and the third perforation cluster, so as to obtain the inflow rate of the second perforation cluster and the third perforation cluster. Of course, more acoustic sensors can also be set, which can be selected according to actual needs and are not limited here.

[0095] The above method will be described in detail with a specific example below:

[0096] When performing a specific monitoring process, first, it is necessary to set the magnitudes of the inflow rates of three clusters. In the example shown in Figure 2 , there are three perforation clusters in this stage of fracturing, and the total liquid volume pumped by the surface pump is , the inflow rate of the first cluster is , the inflow rate of the second cluster is , and the inflow rate of the third cluster is . Since the number of perforation clusters is n = 3, the number of the acoustic sensor group is n - 1 = 2. To obtain the inflow rate of a single perforation cluster, according to the foregoing, it is necessary to obtain the liquid flow velocity in the casing between the first perforation cluster and the second perforation cluster, and the flow velocity in the casing between the second perforation cluster and the third perforation cluster, and convert them into the total inflow volume of each cluster, so as to realize the monitoring of the perforation cluster flow rate. Since the propagation speed of sound waves in the fracturing fluid is relatively fast, considering the equipment response, it only takes a few seconds to update the construction state of the cluster inflow, achieving real-time monitoring.

[0097] In the stage when the displacement of the hydraulic fracturing operation reaches the maximum and proppant has not been pumped yet, the fracture develops fully. The construction quality of the hydraulic fracturing almost depends on the development of the fracture in this stage. Therefore, this stage is the target stage monitored by this system. At this time, the ground comprehensive control device controls the first acoustic sensor and the third acoustic sensor to be in the working state of emitting sound waves, and controls the second acoustic sensor and the fourth acoustic sensor to be in the working state of receiving sound waves. The first acoustic sensor and the third acoustic sensor emit sound waves, and the ground comprehensive control device records this time point. The second acoustic sensor and the fourth acoustic sensor receive the sound waves and convert them into electrical signals and transmit them to the ground signal real-time processing device. The ground signal real-time processing device confirms the time point of the wave arrival point, and thus the time of the sound wave flowing in the same direction in two parts is obtained.

[0098] After obtaining the wave arrival point, the second acoustic sensor and the fourth acoustic sensor are converted into the emission working state, and the first acoustic sensor and the third acoustic sensor are converted into the working state of receiving sound waves. Consistent with the above steps, the reverse flow propagation time is obtained. After obtaining this reverse flow propagation time, the nominal maximum flow velocities at the above two positions are calculated.

[0099] Converting the nominal maximum flow velocity into the average flow velocity requires using the flow profile correction factor FPCF. The ground signal real-time processing device has a built-in set of algorithms, which includes the relationship between the flow profile correction factor and the Reynolds number. The ground signal real-time processing device uses an iterative method to calculate the average flow velocities at the two positions. What is built-in is the relationship between the flow profile correction factor and the Reynolds number. Because what this system obtains from the sensor output value is the nominal maximum flow velocity, only the iterative method can be used. Given an initial value of FPCF, iterative calculations are carried out step by step, and finally an average flow velocity value is obtained. This value is the finally obtained average flow velocity value. Then, according to the relationship between the monitoring value and the liquid injection volume described above, the monitoring result is finally obtained.

[0100] When performing the above monitoring process, in order to maximize the monitoring frequency, each group of acoustic sensors needs to prevent interference from the signals emitted by other groups of acoustic sensors. Therefore, when setting the emission signal, each group of signals uses a different emission frequency, but the acoustic sensors used to receive sound waves need to be set with the same sampling frequency. In this way, the method of filtering or wavelet transform (CWT) can be used to distinguish the wave arrival point of the signal to ensure the monitoring accuracy.

[0101] The propagation time in the case of the same direction flow of the sensor combination of the first perforation cluster and the second perforation cluster obtained by the above monitoring method is 1973.2 μs, and the propagation time obtained in the case of reverse flow is 2018 μs. The flow rate obtained using the above algorithm is 9.05 m 3 / min. The propagation time obtained by the sensor combination of the second perforation cluster and the third perforation cluster under the downstream flow condition is 1983.2 μs, and the propagation time obtained under the upstream flow condition is 2007.6 μs. The flow rate obtained using the above algorithm is 4.88 m 3 / min. The calculated inflow rate of the first perforation cluster is 4.95 m 3 / min, the inflow rate of the second perforation cluster is 4.17 m 3 / min, and the inflow rate of the third cluster is 4.88 m 3 / min.

[0102] Compared with the inflow rates of each part set in the first step above, the monitoring errors of the first perforation cluster, the second perforation cluster, and the third perforation cluster are 5%, 11.2%, and 6% respectively. It can be seen that the overall monitoring accuracy of the above system and method is higher than 85%.

[0103] 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 apparent 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 the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A multi-cluster hydraulic fracturing cluster liquid injection flow monitoring system for horizontal wells, characterized in that It includes a ground integrated control device, a multi-channel electrical signal transmission device, a first acoustic sensor, a second acoustic sensor, and a ground signal real-time processing device; The first acoustic sensor and the second acoustic sensor are located between the adjacent first perforation cluster and the second perforation cluster in the casing. Their transmitting ends are arranged opposite to each other, and there is a first preset distance between them; The multi-channel electrical signal transmission device is communicatively connected to the ground integrated control device, the ground signal real-time processing device, the first acoustic sensor, and the second acoustic sensor at the same time; The multi-channel electrical signal transmission device is used to transmit the control signal of the ground integrated control device to the first acoustic sensor and the second acoustic sensor, so as to control the first acoustic sensor to emit a first acoustic wave signal while controlling the second acoustic sensor to receive the first acoustic wave signal and convert it into a first electrical signal, or to control the second acoustic sensor to emit a second acoustic wave signal while controlling the first acoustic sensor to receive the second acoustic wave signal and convert it into a second electrical signal; The multi-channel electrical signal transmission device is also used to transmit the first electrical signal and the second electrical signal to the ground signal real-time processing device; The ground signal real-time processing device is used to process the first electrical signal to obtain the first propagation time of the first acoustic wave signal, and process the second electrical signal to obtain the second propagation time of the second acoustic wave signal. According to the first propagation time, the second propagation time, and the first preset distance, the nominal maximum flow velocity is obtained, and the average liquid flow velocity is calculated according to the nominal maximum flow velocity and the flow profile correction factor. According to the average liquid flow velocity and the cross-sectional area of the casing, the first real-time flow rate between the first perforation cluster and the second perforation cluster is calculated, and the inflow rate of the first perforation cluster is calculated according to the initial inflow rate of the casing and the first real-time flow rate.

2. The multi-cluster hydraulic fracturing cluster fluid intake flow monitoring system for horizontal well segments according to claim 1, characterized in that It further includes a third acoustic sensor and a fourth acoustic sensor with a second preset distance between the adjacent second perforation cluster and the third perforation cluster, and a bridge plug is provided at the other end of the third perforation cluster. Both of them are communicatively connected to the multi-channel electrical signal transmission device, and based on the third acoustic sensor and the fourth acoustic sensor, the ground signal real-time processing device is also used to calculate the inflow rate of the second perforation cluster and the inflow rate of the third perforation cluster.

3. The horizontal well segmented multi-cluster hydraulic fracturing cluster liquid injection flow rate monitoring system according to claim 2, characterized in that, It further includes: A mechanical fixing device for statically fixing the first acoustic sensor, the second acoustic sensor, the third acoustic sensor, and the fourth acoustic sensor in the casing.

4. The horizontal well segmented multi-cluster hydraulic fracturing cluster fluid injection flow rate monitoring system according to claim 1, wherein The multi-channel electrical signal transmission device is an armored cable with multiple electrical signal transmission channels inside.

5. The horizontal well segmented multi-cluster hydraulic fracturing cluster fluid injection flow monitoring system according to claim 1, wherein The first acoustic sensor and the second acoustic sensor are acoustic wave transducers that can withstand extremely high-pressure working environments.

6. The horizontal well segmented multi-cluster hydraulic fracturing cluster fluid injection flow rate monitoring system according to claim 1, wherein The ground signal real-time processing device is also connected to a ground pump truck group to obtain real-time ground construction parameters for data processing.

7. A method for monitoring the liquid injection flow rate of multiple clusters in staged hydraulic fracturing of horizontal wells, characterized in that, Using the horizontal well segmented multi-cluster hydraulic fracturing cluster inflow rate monitoring system as described in claim 1, including: Communicatively connect the multi-channel electrical signal transmission device to the ground integrated control device, the ground signal real-time processing device, the first acoustic sensor, and the second acoustic sensor simultaneously; Arrange the first acoustic sensor and the second acoustic sensor between the adjacent first perforation cluster and the second perforation cluster in the casing, with their transmitting ends facing each other and having a first preset distance therebetween; While controlling the first acoustic sensor to emit a first acoustic wave signal, control the second acoustic sensor to receive the first acoustic wave signal and convert it into a first electrical signal, and process the first electrical signal to obtain the first propagation time of the first acoustic wave signal; While controlling the second acoustic sensor to emit a second acoustic wave signal, control the first acoustic sensor to receive the second acoustic wave signal and convert it into a second electrical signal, and process the second electrical signal to obtain the second propagation time of the second acoustic wave signal; Based on the first propagation time, the second propagation time, and the first preset distance, obtain the nominal maximum flow velocity, and calculate the average liquid flow velocity based on the nominal maximum flow velocity and the flow profile correction factor; Calculate the first real-time flow rate between the first perforation cluster and the second perforation cluster based on the average liquid flow velocity and the cross-sectional area of the casing, and calculate the liquid inflow rate of the first perforation cluster based on the initial liquid inflow rate of the casing and the first real-time flow rate.

8. The method for monitoring the liquid injection flow rate of multiple clusters in horizontal well sectional multi-cluster hydraulic fracturing according to claim 7, wherein, It further includes: Connect the multi-channel electrical signal transmission device to the third acoustic sensor and the fourth acoustic sensor. The third acoustic sensor and the fourth acoustic sensor are located between the adjacent second perforation cluster and the third perforation cluster and have a second preset distance, and there is a bridge plug at the other end of the third perforation cluster; While controlling the third acoustic sensor to emit a third acoustic wave signal, control the fourth acoustic sensor to receive the third acoustic wave signal and convert it into a third electrical signal, and process the third electrical signal to obtain the third propagation time of the third acoustic wave signal; While controlling the fourth acoustic sensor to emit a fourth acoustic wave signal, control the third acoustic sensor to receive the fourth acoustic wave signal and convert it into a fourth electrical signal, and process the fourth electrical signal to obtain the fourth propagation time of the fourth acoustic wave signal; Based on the third propagation time, the fourth propagation time, and the second preset distance, obtain another nominal maximum flow velocity, and calculate another average liquid flow velocity based on the another nominal maximum flow velocity and the flow profile correction factor; Calculate the second real-time flow rate between the second perforation cluster and the third perforation cluster based on the another average liquid flow velocity and the cross-sectional area of the casing, and calculate the liquid inflow rate of the second perforation cluster based on the first real-time flow rate of the casing and the second real-time flow rate, and use the second real-time flow rate as the liquid inflow rate of the third perforation cluster.

9. The method for monitoring the fluid intake flow rate of multiple clusters in staged hydraulic fracturing of horizontal wells according to claim 7, wherein The obtaining the nominal maximum flow velocity based on the first propagation time, the second propagation time, and the first preset distance includes: According to the formula calculate the nominal maximum flow velocity v max ; Wherein, t1 is the first propagation time, t2 is the second propagation time, and L is the first preset distance.

10. The method for monitoring the liquid injection flow rate of multiple clusters in staged hydraulic fracturing of horizontal wells according to claim 7, characterized in that, Calculating the average liquid flow velocity based on the nominal maximum flow velocity and the flow profile correction factor includes: Using an iterative method, according to the formula , based on the relationship between the flow profile correction factor and the Reynolds number, calculate the average fluid flow velocity v a , where FPCF is the flow profile correction factor.

Images