Method for monitoring fracturing crack by using active high-frequency water hammer pressure wave and electronic equipment

Abstract

The invention provides a method and electronic equipment for monitoring a fracturing crack by using an active high-frequency water hammer pressure wave. The method comprises the steps that active water hammer pressure waves are emitted to a target well; echo information corresponding to the active water hammer pressure waves is received; based on the echo information, evaluating a fracturing effect to obtain a fracturing monitoring result; wherein the fracturing monitoring result comprises the geometric dimension of a fracturing crack. According to the scheme, the fracturing effect can be accurately evaluated, and the method has the advantages of being low in cost, easy and convenient to operate, high in timeliness and large in monitoring depth.

Description

Technical Field

[0001] The present application relates to the technical field of crack monitoring, and in particular to a method and electronic equipment for monitoring fracturing cracks using active high-frequency water hammer pressure waves. Background Art

[0002] At present, most of the newly added oil and gas reserves in my country are low-permeability and difficult-to-use reserves. The exploitation of unconventional oil and gas such as shale oil and gas, tight oil and gas, and coal rock gas is becoming more and more the development focus and new growth point of various oilfield companies, and the buried depth of the target reservoir has a tendency to deepen year by year. The staged fracturing and transformation technology of horizontal wells or high-angle wells has basically become the main technical means for exploiting such unconventional oil and gas reservoirs. At the same time, with the further promotion of staged fracturing and transformation technology for horizontal wells or high-angle wells, the shortcomings of low single well production, rapid production decline, low final recovery rate, complex downhole operations, casing deformation, and uneven transformation of each section are becoming more and more obvious. In addition, the vigorous promotion of volume fracturing version 2.0 has put forward new requirements for the further development of staged fracturing and transformation of horizontal wells. The new technology of long horizontal sections and multi-cluster volume fracturing within the section has been applied on-site in many wells and has the characteristics of high initial production, long stable production cycle, high total production, less downhole tool use, and high construction time efficiency. The core of the technology is the uniform and full transformation of each cluster and section to achieve efficient development of horizontal wells.

[0003] Since hydraulic fracturing cracks are formed in the underground formation, the morphology of hydraulic fracturing cracks cannot be obtained by direct observation. Conventional fracture monitoring methods are expensive and have limited accuracy. Especially for the increasingly deepening geological conditions, conventional fracture monitoring processes and methods are greatly limited. Therefore, there is no economical, efficient, real-time and accurate monitoring method for fracture morphology assessment. Summary of the invention

[0004] In view of the above problems, the present application is proposed. According to one aspect of the present application, a method for monitoring fracturing cracks using active high-frequency water hammer pressure waves is provided, comprising: Launch active water hammer pressure waves to target wells; receiving echo information corresponding to the active water hammer pressure wave; Based on the echo information, the fracturing effect is evaluated to obtain a fracturing monitoring result; The fracturing monitoring results include geometric dimensions of the fracturing cracks.

[0005] Exemplarily, before transmitting the active water hammer pressure wave to the target well, the method further includes: A wellbore and fluid parameter analysis is performed on the target well to determine the wellbore parameters and fluid parameters of the target well.

[0006] Exemplarily, the transmitting of active water hammer pressure waves to the target well includes: Before fracturing, emitting a first active water hammer pressure wave to the target well; Wherein, the echo information corresponding to the first active water hammer pressure wave is the first echo information; The method further comprises: Fitting the first echo information using the Bayesian formula to obtain a probability density function of the first water hammer pressure wave echo information; Before evaluating the fracturing effect based on the echo information, the method further includes: The echo information is denoised according to the probability density function.

[0007] Exemplarily, the evaluating the fracturing effect based on the echo information includes: Processing the echo information to obtain a data processing result; Evaluating the fracturing effect based on the data processing result to obtain the fracturing monitoring result; Wherein, the processing of the echo information includes processing the echo information by at least one of the following methods: cepstrum analysis, well test analysis, data inversion, pressure wave attenuation rate fitting, wellbore wave velocity correction; The fracturing effect is evaluated based on the data processing result, including evaluating the fracturing effect through at least one of the following evaluation methods: perforation perfection evaluation, opening degree evaluation of each cluster of horizontal well fracturing, temporary plugging and diversion fracturing effect evaluation, bridge plug sealing performance evaluation, wellbore abnormality evaluation, fracturing crack geometry evaluation, fracture network complexity index evaluation, geological parameter evaluation, and fracturing process parameter evaluation.

[0008] Exemplarily, the processing of the echo information includes: processing the echo information by data inversion to obtain the fracture half-length, fracture width and fracture height of the hydraulic fracture; The data processing result includes the fracture half-length, fracture width and fracture height of the hydraulic fracture.

[0009] Exemplarily, the processing of the echo information by data inversion to obtain the fracture half-length, fracture width and fracture height of the hydraulic fracture comprises obtaining the fracture half-length, fracture width and fracture height of the hydraulic fracture by the following formula: , , , , , , , , in, It represents hydraulic potential energy, in Pa; Indicates the density of the fluid in kg / m 3 ; Indicates the acceleration due to gravity in m / s 2 ; Indicates the pressure head, in m; Indicates the elevation of the reference surface, in m; Indicates pressure, the unit is Pa; Indicates the flow velocity in the pipe, in m / s; Indicates the pressure potential energy difference, in Pa; Indicates the flow rate in and out of the crack, in m 3 / s; It represents the friction pressure drop near the wellbore, in Pa; Indicates the flow rate before the pump stops, in m 3 / s; represents the crack impedance, Indicates the pressure head difference, in m; It represents the ratio of fracture volume change to pressure difference, It represents the half-length of the hydraulic fracture, in meters; It represents the average net pressure of the crack, in Pa; Indicates the height of the hydraulic fracture, in meters; represents the plane strain elastic modulus, represents the elliptic integral of the second kind, Indicates the width of the fracturing crack, in mm.

[0010] Exemplarily, the processing of the echo information includes: performing the cepstrum analysis on the echo information by using fast Fourier transform.

[0011] Exemplarily, the performing the cepstrum analysis on the echo information by using fast Fourier transform includes performing the cepstrum analysis on the echo information by using the following formula: .

[0012] According to another aspect of the present application, an electronic device is provided, including a processor and a memory, wherein a computer program is stored in the memory, and the processor is used to execute the computer program to implement the above method.

[0013] According to another aspect of the present application, a computer-readable storage medium is provided, storing a computer program / instruction, and the computer program / instruction implements the above method when executed by a processor.

[0014] In the above technical solution, active water hammer pressure waves are used to monitor fracturing cracks. Such active water hammer pressure waves have specific frequency, amplitude and pulse time, and can be emitted under relatively quiet and stable conditions. Compared with the interference of water hammer waves generated by stopping the pump of the fracturing truck, the corresponding echo information can more accurately represent the information related to the crack morphology (such as the geometric size of the crack). In short, this solution can evaluate the fracturing effect more accurately, and has the advantages of low cost, simple operation, strong timeliness and large monitoring depth.

[0015] The above description is only an overview of the technical solution of the present application. In order to more clearly understand the technical means of the present application, it can be implemented in accordance with the contents of the specification. In order to make the above and other purposes, features and advantages of the present application more obvious and easy to understand, the specific implementation methods of the present application are listed below. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] By describing the embodiments of the present application in more detail in conjunction with the accompanying drawings, the above and other purposes, features and advantages of the present application will become more apparent. The accompanying drawings are used to provide a further understanding of the embodiments of the present application and constitute a part of the specification. Together with the embodiments of the present application, they are used to explain the present application and do not constitute a limitation of the present application. In the accompanying drawings, the same reference numerals generally represent the same components or steps.

[0017] Figure 1 A schematic flow chart showing a method for monitoring hydraulic fractures using active high-frequency water hammer pressure waves according to one embodiment of the present application; Figure 2 A schematic diagram showing a 3D inversion result according to an embodiment of the present application is shown; Figure 3 A schematic diagram showing a 3D inversion result according to another embodiment of the present application is shown; Figure 4 A schematic block diagram of an electronic device according to an embodiment of the present application is shown. DETAILED DESCRIPTION

[0018] In order to make the purpose, technical solutions and advantages of the present application more obvious, the example embodiments according to the present application will be described in detail with reference to the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments of the present application, and it should be understood that the present application is not limited to the example embodiments described herein. Based on the embodiments of the present application described in the present application, all other embodiments obtained by those skilled in the art without creative work should fall within the scope of protection of the present application.

[0019] As mentioned above, conventional fracture monitoring methods are expensive and have limited accuracy. In particular, conventional fracture monitoring processes and methods are greatly limited in view of the increasingly deepening geological conditions. Water hammer fracturing diagnostic technology is an emerging diagnostic technology in recent years that can evaluate the fracture morphology of water hammer fracturing. This technology evaluates fractures through pump-off water hammer signals. The pump-off water hammer signal is caused by the fracturing pump truck stopping work in a short period of time, resulting in the fluid flow at the wellhead quickly becoming zero. The pressure fluctuations caused by this sudden change in flow and pressure will be transmitted back and forth between the wellbore and the fracture. Due to the continuous consumption of pipeline flow friction and fracture near-well friction, it is manifested in the change of water hammer waveform. However, this change will be affected by the speed of ground pumping, the distance of the pumping vehicle, the power load of the pumping vehicle, etc. Therefore, the errors and interferences that occur each time the pump is stopped are different, and it is difficult to normalize and evaluate the true situation of the fracture after fracturing. In short, there is no monitoring method that is both economical, efficient, real-time and accurate in the assessment of fracture morphology. In view of this, the present application provides a method for monitoring fracturing cracks using high-frequency water hammer pressure waves, which has the advantages of low cost, simple operation, strong timeliness, high accuracy, and large monitoring depth. The specific steps of the method are described in detail below.

[0020] According to one aspect of an embodiment of the present application, a method for monitoring hydraulic fractures using active high-frequency water hammer pressure waves is provided. Figure 1 FIG. 1 is a schematic flow chart showing a method for monitoring fracturing cracks using active high-frequency water hammer pressure waves according to an embodiment of the present application. Figure 1 As shown, the method includes the following steps S110, S120 and S130.

[0021] In step S110, an active water hammer pressure wave is emitted to the target well.

[0022] In the present application, the active water hammer pressure wave is an actively emitted water hammer pressure wave, which is different from the passive pressure wave generated by stopping the pump. The frequency, amplitude and pulse time of the active water hammer pressure wave can be specifically selected according to the actual working conditions and will not be elaborated.

[0023] Optionally, the active water hammer pressure wave can be transmitted through any existing or future transmitter that can transmit active water hammer pressure waves. For example, an active water hammer transmitter (hereinafter referred to as the transmitter) can be used. It can be understood that the active water hammer transmitter is a key device for transmitting active water hammer pressure waves, and its frequency, intensity, and pressure resistance have a direct impact on the on-site monitoring of construction operations and the data collection quality of subsequent high-frequency pressure waves. In some embodiments, before the operation, the active water hammer transmitter can participate in the overall pressure test operation of the high-pressure process. In this embodiment, it is preferred that the maximum pressure resistance of this active water hammer transmitter is 25KPSI, which has the ability to meet the fracture monitoring and fracturing assessment capabilities of domestic wells with a vertical depth of 4500-8000m, so as to ensure better monitoring capabilities at different monitoring depths.

[0024] In some embodiments, a remote controller can be used to control the active water hammer transmitter to generate the power of active water hammer. The remote controller can be selected according to the actual application conditions. In a specific embodiment, the remote controller can be a controller with the characteristics of small size, strong power, stable output, etc., so that it can be used as a stable and reliable power source to meet the power of controlling the active water hammer transmitter to generate active water hammer, and can ensure the smooth and continuous operation of the power source. In this embodiment, the maximum working pressure of the hydraulic system is 25KPSI. At the same time, combined with the power supply conditions at the fracturing construction site, the optimized voltage input is three-phase 380V, which meets the power supply environment at the site; at the same time, according to the requirements of simultaneous operation of multiple wells, the remote controller needs to set multiple channels to meet the ability of 4-8 wells on the same platform to operate simultaneously.

[0025] In this embodiment, a monitoring reserved port can be set at the wellhead high-pressure manifold, and an active water hammer pressure wave is sent to the target well through the monitoring reserved port. Optionally, the monitoring reserved port is set within a preset distance from the wellhead of the target well. The preset distance can be in the range of 5-20m. In a specific embodiment, the preset distance can be 10m. This helps to reduce the interference of the complex high-pressure pipe network on the ground and the wellhead to the pressure wave and the "dilution" of the intensity of the transmitted active water hammer pressure wave, thereby ensuring the accuracy of monitoring.

[0026] Optionally, a plug or a check valve can be installed near the monitoring reserved outlet of the pump inlet pipeline. This helps to isolate and block the diffusion of pressure waves to the pipeline network during monitoring, and to weaken or block water hammer or vibration interference caused by cross-operations such as pump inspection as much as possible. In a specific embodiment, the isolation valve supporting the field monitoring equipment adopts a 3-inch 2002 or 2502 large plug. This large plug has higher safety, requires fewer buckles, occupies less space, and has optimized space for simultaneous operation of multiple wells, which is more suitable for large-scale fracturing operation environment of multi-pipeline networks in field platform wells.

[0027] In step S120, echo information corresponding to the active water hammer pressure wave is received.

[0028] It can be understood that the echo information is the echo signal obtained after the emitted active water hammer pressure wave propagates and reflects through the wellbore, cracks, etc. The echo information contains a lot of information related to the crack morphology, which can provide a more accurate basis for the evaluation of the fracturing effect in the subsequent steps.

[0029] In some embodiments, an ultra-high frequency pressure sensor transmitter may be used to receive echo information. In a specific embodiment, a Viatran ultra-high pressure sensor may be selected, and for higher precision analysis of target well data, an ultra-high pressure sensor with a pressure level of 25KPSI, a sampling frequency of not less than 2000 times / second, a comprehensive accuracy of 0.25% FSO, and a long-term stability of 0.1% FS may be selected.

[0030] In step S130, the fracturing effect is evaluated based on the echo information to obtain a fracturing monitoring result; wherein the fracturing monitoring result includes the geometric size of the fracturing crack.

[0031] After obtaining the echo information, the fracturing effect can be evaluated based on the echo information. For example, by using modules such as sensor frequency response test, modal analysis, multi-dimensional force test analysis, vibration table calibration system, acoustic analysis, etc. to realize dynamic signal acquisition, real-time analysis of data can be performed, and 3D inversion of cracks can be performed, which greatly improves the accuracy of the interpretation results and comprehensively and effectively evaluates the fracturing effect. Of course, there are other ways to evaluate the echo information, which will not be elaborated.

[0032] In the above technical solution, active water hammer pressure waves are used to monitor fracturing cracks. Such active water hammer pressure waves have specific frequency, amplitude and pulse time, and can be emitted under relatively quiet and stable conditions. Compared with the interference of water hammer waves generated by stopping the pump of the fracturing truck, the corresponding echo information can more accurately represent the information related to the crack morphology (such as the geometric size of the crack). In short, this solution can evaluate the fracturing effect more accurately, and has the advantages of low cost, simple operation, strong timeliness and large monitoring depth.

[0033] Exemplarily, before transmitting the active water hammer pressure wave to the target well, the method further includes: performing wellbore and fluid parameter analysis on the target well to determine the wellbore parameters and fluid parameters of the target well.

[0034] Optionally, the wellbore and fluid parameter analysis of the target well may include: wellbore structure analysis (casing size, running depth), wellbore trajectory analysis (depth measurement, well inclination, azimuth and other data), perforation and bridge plug depth parameter analysis (perforation position, cluster spacing, hole density, aperture, bridge plug setting position, cluster perforation length, etc.), formation fluid parameter analysis (content of components such as methane, ethane, carbon dioxide, formation water composition), fracturing fluid composition analysis (water salinity, turbidity, six ion contents, water type, fracturing fluid viscosity, density, rheology, etc.), proppant index analysis (apparent density, volume density, crushed material, compressive strength, etc.), etc. In this embodiment, the wellbore parameters may include wellbore structure parameters (such as the size of each casing, the depth of insertion, etc.), wellbore trajectory parameters (depth measurement, well inclination, azimuth, etc.), perforation and bridge plug depth parameters (perforation position, cluster spacing, hole density, aperture, bridge plug setting position, cluster perforation length, etc.), etc., and the fluid parameters may include formation fluid parameters (content of components such as methane, ethane, carbon dioxide, and formation water composition), fracturing fluid composition (water salinity, turbidity, six ion contents, water type, fracturing fluid viscosity, density, rheology, etc.), proppant indicators (apparent density, volume density, crushed material, compressive strength, etc.), etc.

[0035] In this embodiment, the wellbore and fluid parameter analysis of the target well can be performed in advance to determine the wellbore parameters and fluid parameters of the target well. These parameters can provide a basis for subsequent steps. For example, the best active water hammer transmitter access point can be evaluated through these parameter analysis, so that the active water hammer can be directly transmitted to the fracturing well section through the wellbore after being emitted, and the echo can be efficiently received, effectively avoiding interference from other pipelines on the ground.

[0036] Exemplarily, transmitting an active water hammer pressure wave to a target well includes: before fracturing, transmitting a first active water hammer pressure wave to the target well; wherein the echo information corresponding to the first active water hammer pressure wave is the first echo information.

[0037] The method also includes: fitting the first echo information using the Bayesian formula to obtain a probability density function of the first water hammer pressure wave echo information (ie, the first echo information).

[0038] Before evaluating the fracturing effect based on the echo information, the method further includes: denoising the echo information according to a probability density function.

[0039] In this embodiment, the first active water hammer pressure wave can be emitted to the target well before fracturing. In a specific embodiment, the first active water hammer pressure wave can be emitted after the wellbore pressure test is completed and the coiled tubing perforation is completed. The first echo information obtained can explain the connectivity between the wellbore and the formation after perforation, which can provide a reference for the fracturing process, so that fracturing can be performed more reasonably. For example, if the first echo information determines that the fracture has a certain degree of complexity and scale, the amount of pre-acid can be reduced or removed during the main fracturing.

[0040] In this example, the Bayesian formula can be used to fit the first echo information to obtain the probability density function of the first active water hammer pressure wave. In this way, the active water hammer pressure wave can be used to model the background and noise of the wellbore, especially the wellbore and wellhead with variable diameters, before fracturing, so that more accurate filtering and denoising can be achieved in subsequent monitoring, thereby improving the accuracy of the picked data (i.e., echo information).

[0041] The above scheme can accurately obtain the probability density function by emitting the first active water hammer pressure wave before fracturing, thereby providing a more accurate basis for filtering and denoising in the subsequent monitoring process. This adaptive filtering method can improve the accuracy of the acquired echo information, thereby helping to further improve the accuracy of the evaluation of the fracturing effect.

[0042] Exemplarily, based on the echo information, the fracturing effect is evaluated, including: processing the echo information to obtain a data processing result; evaluating the fracturing effect based on the data processing result to obtain a fracturing monitoring result; wherein, processing the echo information includes processing the echo information by at least one of the following methods: inverse spectrum analysis, well test analysis, data inversion, pressure wave attenuation rate fitting, wellbore wave velocity correction; evaluating the fracturing effect based on the data processing result includes evaluating the fracturing effect by at least one of the following evaluation methods: perforation perfection evaluation, opening degree evaluation of each cluster of horizontal well fracturing, temporary plugging and steering fracturing effect evaluation, comprehensive evaluation of fracturing cracks, bridge plug sealing performance evaluation, wellbore abnormality evaluation, geological parameter evaluation, and fracturing process parameter evaluation.

[0043] In some embodiments, the echo information can be processed by cepstrum analysis, well test analysis, data inversion, pressure wave attenuation rate fitting, and wellbore wave velocity correction, which helps to process the echo information more comprehensively, thereby helping to more accurately evaluate the fracturing effect. At the same time, combined with well test analysis, fracturing data inversion, water hammer pressure wave attenuation rate fitting and other methods, the basic parameters in the echo data processing process can be set to have better complementary effects.

[0044] In one embodiment, the echo information can be processed by wellbore wave velocity correction. In this embodiment, the wellbore pump stop water hammer wave velocity can be solved according to different fluid types, well depths, temperatures and pressures in the wellbore by integrating the wellbore wave velocity mechanism model and the time domain wave velocity calculation method, and the wellbore wave velocity can be corrected based on the Bayesian method. In some embodiments, the wellbore wave velocity correction can be performed by performing time domain-frequency domain analysis on the echo information, identifying the characteristics and types of the noise signal, performing Hampel filtering and FIR low-pass filtering according to the time and signal characteristics of the reflected pressure wave, and performing wave velocity correction.

[0045] In one embodiment, the echo information can be processed by fitting the pressure wave attenuation rate. It can be understood that an increase in the number of fractures or the complexity of fractures will lead to an increase in the water hammer attenuation rate. Under the same circumstances, more fractures may show faster water hammer attenuation. An increase in the number of perforations or the diameter of perforations will lead to a decrease in the water hammer attenuation rate. Under the same circumstances, more perforations may show slower water hammer attenuation. Fractures have a positive effect on the water hammer attenuation rate, and perforations have a negative effect on the water hammer attenuation rate. Therefore, in the process of inverting water hammer attenuation, the requirements of fracturing perforation parameters should be fully considered, and the numerical relationship between fractures and perforations should be reasonably selected for simulation.

[0046] In some embodiments, the fracturing effect is evaluated based on the data processing results, including evaluating the fracturing effect by the following evaluation methods: evaluation of the degree of perforation perfection, evaluation of the degree of opening of each cluster of horizontal well fracturing, evaluation of temporary plugging and diverting fracturing effect, comprehensive evaluation of fracturing cracks, evaluation of bridge plug sealing performance, evaluation of wellbore abnormal conditions, evaluation of geological parameters, and evaluation of fracturing process parameters.

[0047] In one embodiment, the perforation perfection can be evaluated based on the data processing results. In the related art, the perforation perfection evaluation is a technical shortcoming in the field of fracture monitoring. Because there is basically no formation fracture response and no liquid is injected into the formation after perforation, there is no effective technology to evaluate the perforation perfection, let alone guide the optimization of pre-pressure measures (pre-acid dosage, pre-gel design, displacement increase speed optimization, pre-proppant grinding optimization, etc.). In this embodiment, after the perforation is completed, the emission of active water hammer pressure waves and echo monitoring can be implemented. Through the obtained echo information, the background value and noise of the wellbore can be picked up, and the wellbore and formation connectivity, the compaction of the near-wellbore formation after perforation, the formation crushing or natural fractures in the near-wellbore area, etc. can also be evaluated, effectively guiding the optimization of the process and parameters of the main pressure pre-treatment measures. In some embodiments, after the perforation of the fracturing well is completed, an active water hammer pressure wave can be emitted, and the connectivity between the wellbore and the formation after perforation can be evaluated by interpreting the pressure echo. If the interpreted fractures have a certain degree of complexity and scale, it can guide the reduction or removal of the amount of pre-acid during the main fracturing. If the connectivity is not good, it can guide the optimization of the amount of pre-acid and the implementation of the pre-fracture making process. In one embodiment, the opening degree of each cluster of horizontal well fracturing can be evaluated based on the data processing results. In the related technology, microseismic method and wide-area electromagnetic method are usually used to evaluate the opening degree of each cluster of horizontal well fracturing, wherein microseismic method determines the fracture initiation and extension position according to the response of the formation rupture event, and wide-area electromagnetic method determines the approximate fracture initiation and extension position of the fracture according to the change of the electromagnetic field in the range of the fracturing fluid. In this embodiment, the specific fracture depth can be analyzed according to the echo information (time, intensity, frequency, amplitude, etc.), so as to more accurately evaluate the fracture opening position, and the accuracy can reach within 0.1m, which can more accurately evaluate the opening degree of each cluster. In some embodiments, during the fracturing process, when the construction displacement and pressure are stable, the water hammer wave can be created by instantly reducing the displacement, and the active water hammer can also be emitted by the water hammer transmitter. The active water hammer pressure wave and pressure echo can be used at the same time to analyze and interpret the cluster opening efficiency during the fracturing process to determine the dynamic changes of the liquid inlet point. The displacement needs to be controlled at 2-4m during monitoring. 3 / min, and remain stable for 30-90s, emit 3-5 groups of active water hammer waves, and after monitoring is completed, restore the displacement and continue construction.

[0048] In one embodiment, the temporary plugging and diverting fracturing effect evaluation can be performed based on the data processing results. Thus, the initiation depth, fracture scale, complexity, and liquid inflow ratio before and after the temporary plugging process can be quantitatively evaluated, and the temporary plugging and diverting effect can be comprehensively evaluated from the fracture initiation position, fracture expansion geometry, changes in the complexity of the fracture network system, and the degree of connectivity of the far well diversion. This solution is different from the analysis and evaluation of single factors (temporary plugging and boosting, microseismic event points, and accidental changes in electromagnetic fields) of conventional monitoring technology, and can make the evaluation results more objective and credible. In some embodiments, the temporary plugging steering effect evaluation can be performed by stopping the pump. After the pump is stopped, 6-8 groups of active water hammer pressure waves are emitted by the transmitter, and the pressure drop data and echo data are collected. This monitoring requires comparison of the changes in the opening of each cluster, crack extension, crack geometry and complexity before and after the temporary plugging. Therefore, it is necessary to optimize the monitoring time node during on-site implementation. Usually, the temporary plugging of multi-cluster perforation sections is divided into temporary plugging at the far end of the fracture and temporary plugging near the fracture mouth according to the type and size of the temporary plugging material. The temporary plugging in the fracture can be monitored by reducing the discharge rate to emit active water hammer waves, while the temporary plugging at the fracture mouth can be monitored by emitting active water hammer waves by stopping the pump.

[0049] In one embodiment, a comprehensive evaluation of the fracturing cracks can be performed based on the data processing results. It can be understood that the comprehensive evaluation of the fractures is a comprehensive evaluation of the fracture geometry, fracture liquid loss (liquid efficiency), fracture closure pressure, formation pressure, etc., which can more comprehensively display the state of the fracturing cracks. In this embodiment, the echo information can be processed and analyzed by a variety of methods such as adaptive filtering, wave velocity correction, FRCI data inversion, pressure wave attenuation rate fitting and spectrum analysis to obtain the overall parameters of the fractures after fracturing (including the geometric dimensions of the fracturing cracks). At the same time, the fitting and inversion of the fracturing construction data, the fitting calculation of the net pressure, G function analysis, Horner analysis, etc. can be combined to more comprehensively analyze and evaluate the fracturing liquid efficiency, pressure drop rate, filtration, closure pressure, etc., to form a comprehensive evaluation of the fracturing cracks.

[0050] In one embodiment, a 3D inversion evaluation of fracture monitoring can be performed based on the data processing results. In this embodiment, a high-frequency active water hammer pressure wave fracture monitoring 3D inversion platform can be used to achieve 3D presentation of monitored fractures based on geological modeling. Figure 2 A schematic diagram of a 3D inversion result according to an embodiment of the present application is shown, and this embodiment is a 3D inversion result in a single well case. Figure 3 A schematic diagram of 3D inversion results according to another embodiment of the present application is shown, which is a 3D inversion result in the case of multiple wells (H1, H2 and H3). It can be seen that the schematic diagram of the inversion results obtained by performing 3D inversion evaluation of fracture monitoring can more intuitively display the fracture conditions of each section after fracturing, which is of great significance for optimizing geological and process parameters.

[0051] In the above technical solution, the echo information can be processed, and the fracturing effect can be evaluated based on the data processing result. This solution can determine the fracturing effect more accurately.

[0052] Exemplarily, processing the echo information includes: processing the echo information by data inversion to obtain the fracture half-length, fracture width and fracture height of the hydraulic fracture; wherein the data processing result includes the fracture half-length, fracture width and fracture height of the hydraulic fracture.

[0053] In this example, based on the principle of hydroelectric similarity, the downhole fracture boundary can be equivalent to a circuit system, and the mapping relationship between the fracture characteristics F (length, width, height) and the circuit characteristics (resistance R, capacitance C, impedance I) can be inferred. Then, based on the FRCI downhole fracture boundary equation, the measured ultra-high frequency pump-off water hammer pressure wave can be inverted, and the fracture half-length, fracture width, and fracture height of the post-construction fracturing fracture can be calculated by solving the FRCI equation.

[0054] The above technical solution can quickly and accurately determine the fracture half-length, fracture width and fracture height of the fracturing fracture, thereby providing a more accurate basis for the evaluation of the fracturing effect in the step.

[0055] Exemplarily, the echo information is processed by data inversion to obtain the fracture half-length, fracture width and fracture height of the hydraulic fracture, including obtaining the fracture half-length, fracture width and fracture height of the hydraulic fracture by the following formula: , , , , , , , , Among them, in formulas (1)-(8), It represents hydraulic potential energy (i.e. hydrostatic column pressure), in Pa; Indicates the density of the fluid (i.e. the liquid used in fracturing) in kg / m 3 ; Indicates the acceleration due to gravity in m / s 2 ; Indicates the pressure head, in m; Indicates the elevation of the reference surface, in m; Indicates pressure, the unit is Pa; Indicates the flow velocity in the pipe, in m / s; Indicates the pressure potential energy difference, in Pa; Indicates the flow rate in and out of the crack, in m 3 / s; It represents the friction pressure drop near the wellbore, in Pa; Indicates the flow rate before the pump stops, in m 3 / s; represents the crack impedance, Indicates the pressure head difference, in m; It represents the ratio of fracture volume change to pressure difference, It represents the half-length of the hydraulic fracture, in meters; It represents the average net pressure of the crack, in Pa; Indicates the height of the hydraulic fracture, in meters; represents the plane strain elastic modulus, represents the elliptic integral of the second kind, Indicates the width of the fracturing crack, in mm. Each parameter can be determined according to the actual fracturing conditions and will not be described in detail.

[0056] In this embodiment, the crack impedance It is related to the total amount of liquid in the fracture system and is proportional to the change in pressure difference in the absence of friction. It can be understood that the fracture impedance expresses the reflection of the fracture to the active water hammer pressure wave. The larger the injected liquid and the more complex the fracture, the greater the absorption of the active water hammer pressure wave and the weaker the reflection. Conversely, the stronger the reflection.

[0057] The above technical solution can relatively accurately determine the fracture half-length, fracture width and fracture height of the fracturing fracture, thereby providing a relatively accurate basis for the evaluation of the fracturing effect in the step.

[0058] Exemplarily, processing the echo information includes: performing cepstrum analysis on the echo information using fast Fourier transform.

[0059] It can be understood that cepstrum analysis is to analyze the echo signal of the active water hammer pressure wave signal through the processes of time domain signal-signal spectrum-log spectrum-inverse DFT cepstrum. In the scheme of this example, fast Fourier transform (FFT) can be used to perform cepstrum analysis on the echo information. It can be understood that FFT is a fast algorithm for calculating discrete Fourier transform (DFT) and inverse discrete Fourier transform (IDFT). In some embodiments, cepstrum analysis can also be combined with well test analysis. It can be understood that active water hammer pressure wave monitoring and cepstrum analysis can obtain parameters such as the geometric size, complexity and conductivity of the fracture, which can also be obtained through pressure drop and well test analysis, but well test analysis is often multi-solution and has multiple assumptions. In this case, the cepstrum analysis results of the active water hammer pressure wave can be used to set the boundary conditions, so that the interpretation results of the well test analysis are closer to the actual situation. At the same time, the geological parameters obtained by the well test analysis can correct the geological data of the active high-frequency water hammer pressure wave. Therefore, in special cases, the analysis complementarity of the active water hammer pressure wave and the pressure drop data can be achieved.

[0060] Exemplarily, the fast Fourier transform is used to perform cepstrum analysis on the echo information, including performing cepstrum analysis on the echo information by the following formula: .

[0061] In the above formula, the constant It represents the DC component in the Fourier series, that is, the series value when the amplitude of all AC components (sine and cosine components) is zero, which corresponds to the average value of the signal or the DC bias; x is the period of the periodic function; n represents the summation index, which represents the sequence number of each item in the series, and each item is a linear combination of a sine function or a cosine function; L is half of the period. These parameters can be automatically fitted according to the shape and period of the wave when the echo information is Fourier transformed, so I will not go into details.

[0062] Fourier coefficients and These coefficients describe the amplitudes of the sine and cosine waves of different frequencies in the signal (i.e., the echo information). Specifically, The coefficients correspond to the part of the even function, and The coefficients correspond to the odd parts of the function. The calculation of these coefficients involves integrating the original periodic function, and the respective coefficient values ​​are obtained by integrating the original function with the sine and cosine functions of different frequencies. These coefficients reflect the amplitude of the different frequency components in the original signal, thus providing a description of the signal in the frequency domain.

[0063] Exemplarily, transmitting an active water hammer pressure wave to a target well includes: transmitting a second active water hammer pressure wave to the target well during a fracturing process; wherein the echo information corresponding to the second active water hammer pressure wave is the second echo information.

[0064] In some embodiments, when the displacement and pressure are stable, water hammer waves (which may be called passive water hammer pressure waves) may be generated by instantaneously reducing the displacement, and active water hammer pressure waves (i.e., second active water hammer pressure waves) may also be emitted by a water hammer transmitter. In this embodiment, the second echo information corresponds to the passive water hammer pressure wave and the second active water hammer pressure wave, i.e., includes the echo information generated by the passive water hammer pressure wave and the echo information generated by the second active water hammer pressure wave. In this embodiment, when evaluating the fracturing effect based on the echo information, the echo information generated by the passive water hammer pressure wave and the echo information generated by the second active water hammer pressure wave may be combined. It can be understood that the echo information obtained during the fracturing process may be used to analyze and explain the cluster opening efficiency, temporary plugging and diversion effectiveness, and to judge the dynamic changes of the inlet point and the sealing performance of the bridge plug during the fracturing process (i.e., the data may be used to evaluate the opening degree of each cluster in horizontal well fracturing, the evaluation of the temporary plugging and diversion fracturing effect, and the evaluation of the sealing performance of the bridge plug). In a specific embodiment, the displacement may be controlled within a preset displacement range (e.g., 2-4 m 3 / min) and stabilize for 30-90s, then emit 3-5 groups of active water hammer pressure waves (i.e., the second active water hammer pressure wave). After monitoring is completed (i.e., the second echo information is obtained), the displacement can be restored to continue construction. During monitoring, the injection displacement and the fluid properties in the wellbore can be kept relatively stable, and the bridge plug sealing ball can maintain a sufficient pressure difference to ensure that the ball is seated, thereby minimizing the impact of objective factors on the conduction of pressure waves.

[0065] The above scheme can evaluate the fracturing effect in real time and dynamically during the fracturing process, which helps to guide the dynamic adjustment of on-site fracturing parameters in real time, thereby helping to improve the fracturing effect.

[0066] Exemplarily, emitting an active water hammer pressure wave to a target well includes: after the temporary plugging operation is completed, emitting a third active water hammer pressure wave to the target well; wherein the echo information corresponding to the third active water hammer pressure wave is the third echo information.

[0067] It can be understood that in the process of hydraulic fracturing, in order to improve the fracture network, allow the fracturing fluid to enter new fractures more effectively, increase the length and complexity of the fractures, and improve the conductivity of the fractures, temporary plugging operations are usually used to treat the already formed fractures. In the scheme of this example, after each temporary plugging operation is completed, a third active water hammer pressure wave can be emitted, and the corresponding third echo information can be obtained. The third echo information can be used to explain the opening of each cluster, the extension of the fracture, the geometric size and complexity of the fracture after the temporary plugging is completed, and can be used to explain the temporary plugging diversion effect by comparing it with the opening of each cluster, the extension of the fracture, the geometric size and complexity of the fracture before the temporary plugging.

[0068] Optionally, the third active water hammer pressure wave can be emitted after the pump is stopped. In this embodiment, after the pump is stopped, 6-8 groups of active water hammer pressure waves (i.e., the third active water hammer pressure wave) are emitted by the transmitter, and pressure drop data and echo data are collected. As mentioned above, when explaining the temporary plugging and diversion effect, it is necessary to compare the changes in the opening of each cluster, the extension of the crack, the geometric size and complexity of the crack before and after the temporary plugging. Therefore, it is necessary to optimize the monitoring time node during the on-site implementation. Usually, for the temporary plugging of multi-cluster perforation sections, according to the type and size of the temporary plugging material, it is divided into temporary plugging at the far end of the crack and temporary plugging near the crack mouth. Temporary plugging in the crack can be monitored by reducing the displacement and emitting active water hammer pressure waves, while temporary plugging at the crack mouth is monitored by emitting active water hammer pressure waves by stopping the pump. Exemplarily, transmitting an active water hammer pressure wave to a target well includes: after fracturing is completed, transmitting a fourth active water hammer pressure wave; wherein the echo information corresponding to the fourth active water hammer pressure wave is the fourth echo information.

[0069] In the scheme of this example, a fourth active water hammer pressure wave can be emitted after the fracturing is completed, and the fourth echo information can be obtained. The fourth echo information can be used to evaluate the opening efficiency of each perforation cluster, the effective geometric size of the fracturing cracks, the complexity of the fracturing cracks, the effectiveness of the temporary plugging process, and the relative proportion of the fluid inflow of each fracturing cluster, and can be used to further carry out comparative analysis of geological and fracturing process parameters, which helps to guide the design of optimization and adjustment of fracturing process parameters.

[0070] According to another aspect of the embodiments of the present application, an electronic device is also provided. Figure 4 FIG. 1 is a schematic block diagram of an electronic device according to an embodiment of the present application. Figure 4 As shown, the electronic device 400 includes: a processor 410 and a memory 420. The memory 420 stores a computer program, and the processor 410 is used to execute the computer program to implement the above method.

[0071] According to another aspect of the embodiment of the present application, a computer-readable storage medium is also provided. The storage medium stores a computer program / instruction, and the computer program / instruction implements the above method when executed by the processor. The storage medium may include, for example, a read-only memory (ROM), an erasable programmable read-only memory (EPROM), a portable compact disk read-only memory (CD-ROM), a USB memory, or any combination of the above storage media. The computer-readable storage medium may be any combination of one or more computer-readable storage media.

[0072] A person skilled in the art can easily understand the implementation structure, working principle and beneficial effects of the electronic device and the computer-readable storage medium by reading the above method for monitoring fracturing cracks using high-frequency water hammer pressure waves. For the sake of brevity, it will not be described in detail here.

[0073] Although example embodiments have been described herein with reference to the accompanying drawings, it should be understood that the above example embodiments are merely exemplary and are not intended to limit the scope of the present application to this. Those of ordinary skill in the art may make various changes and modifications therein without departing from the scope and spirit of the present application. All these changes and modifications are intended to be included within the scope of the present application as required by the appended claims.

[0074] Those of ordinary skill in the art will appreciate that the units and algorithm steps of each example described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Professional and technical personnel can use different methods to implement the described functions for each specific application, but such implementation should not be considered to be beyond the scope of this application.

[0075] In the several embodiments provided in this application, it should be understood that the disclosed devices and methods can be implemented in other ways. For example, the device embodiments described above are only schematic, for example, the division of units is only a logical function division, and there may be other division methods in actual implementation, such as multiple units or components can be combined or integrated into another device, or some features can be ignored or not executed.

[0076] In the description provided herein, a large number of specific details are described. However, it is understood that the embodiments of the present application can be practiced without these specific details. In some instances, well-known methods, structures and techniques are not shown in detail so as not to obscure the understanding of this description.

[0077] Similarly, it should be understood that in order to streamline the present application and help understand one or more of the various application aspects, in the description of the exemplary embodiments of the present application, the various features of the present application are sometimes grouped together into a single embodiment, figure, or description thereof. However, the method of the present application should not be interpreted as reflecting the following intention: the claimed application requires more features than the features clearly stated in each claim. More specifically, as reflected in the corresponding claims, the application point is that the corresponding technical problem can be solved with less than all the features of a single disclosed embodiment. Therefore, the claims following the specific embodiment are hereby explicitly incorporated into the specific embodiment, wherein each claim itself serves as a separate embodiment of the present application.

[0078] Those skilled in the art will understand that, except for mutually exclusive features, all features disclosed in this specification (including the accompanying claims, abstract and drawings) and all processes or units of any method or device disclosed in this specification may be combined in any combination. Unless otherwise explicitly stated, each feature disclosed in this specification (including the accompanying claims, abstract and drawings) may be replaced by an alternative feature that provides the same, equivalent or similar purpose.

[0079] In addition, those skilled in the art will appreciate that, although some embodiments described herein include certain features included in other embodiments but not other features, the combination of features of different embodiments is meant to be within the scope of the present application and form different embodiments. For example, in the claims, any one of the claimed embodiments can be used in any combination.

[0080] The various component embodiments of the present application may be implemented in hardware, or in software modules running on one or more processors, or in a combination thereof. It should be understood by those skilled in the art that a microprocessor or a digital signal processor (DSP) may be used in practice to implement some or all functions of some modules in the electronic device according to the embodiment of the present application. The present application may also be implemented as a device program (e.g., a computer program and a computer program product) for executing part or all of the methods described herein. Such a program implementing the present application may be stored on a computer-readable medium, or may be in the form of one or more signals. Such a signal may be downloaded from an Internet website, or provided on a carrier signal, or provided in any other form.

[0081] It should be noted that the above embodiments illustrate the present application rather than limit the present application, and that those skilled in the art may design alternative embodiments without departing from the scope of the appended claims. In the claims, any reference symbol between brackets should not be constructed as a limitation to the claims. The word "comprising" does not exclude the presence of elements or steps not listed in the claims. The word "one" or "an" preceding an element does not exclude the presence of multiple such elements. The present application may be implemented by means of hardware including several different elements and by means of a suitably programmed computer. In a unit claim that lists several devices, several of these devices may be embodied by the same hardware item. The use of the words first, second, and third, etc. does not indicate any order. These words may be interpreted as names.

[0082] The above is only a specific implementation or description of a specific implementation of the present application, and the protection scope of the present application is not limited thereto. Any technician familiar with the technical field can easily think of changes or substitutions within the technical scope disclosed in the present application, which should be included in the protection scope of the present application. The protection scope of the present application shall be based on the protection scope of the claims.

Claims

1. A method for monitoring fracturing cracks using active high-frequency water hammer pressure waves, characterized in that: include: Launch active water hammer pressure waves to target wells; receiving echo information corresponding to the active water hammer pressure wave; Based on the echo information, the fracturing effect is evaluated to obtain a fracturing monitoring result; Wherein, the fracturing monitoring result includes the geometric dimensions of the fracturing cracks.

2. The method according to claim 1, characterized in that: Before transmitting the active water hammer pressure wave to the target well, the method further includes: A wellbore and fluid parameter analysis is performed on the target well to determine the wellbore parameters and fluid parameters of the target well.

3. The method according to claim 1, characterized in that The transmitting of active water hammer pressure wave to the target well comprises: Before fracturing, emitting a first active water hammer pressure wave to the target well; Wherein, the echo information corresponding to the first active water hammer pressure wave is the first echo information; The method further comprises: Using the Bayesian formula to fit the first echo information to obtain a probability density function of the first water hammer pressure wave echo information; Before evaluating the fracturing effect based on the echo information, the method further includes: The echo information is denoised according to the probability density function.

4. The method according to claim 1, characterized in that The evaluating of the fracturing effect based on the echo information includes: Processing the echo information to obtain a data processing result; Evaluating the fracturing effect based on the data processing result to obtain the fracturing monitoring result; Wherein, the processing of the echo information includes processing the echo information by at least one of the following methods: cepstrum analysis, well test analysis, data inversion, pressure wave attenuation rate fitting, wellbore wave velocity correction; The fracturing effect is evaluated based on the data processing result, including evaluating the fracturing effect through at least one of the following evaluation methods: perforation perfection evaluation, opening degree evaluation of each cluster of horizontal well fracturing, temporary plugging and diversion fracturing effect evaluation, bridge plug sealing performance evaluation, wellbore abnormality evaluation, fracturing crack geometry evaluation, fracture network complexity index evaluation, geological parameter evaluation, and fracturing process parameter evaluation.

5. The method according to claim 4, characterized in that The processing of the echo information includes: processing the echo information by data inversion to obtain the fracture half-length, fracture width and fracture height of the hydraulic fracture; The data processing result includes the fracture half-length, fracture width and fracture height of the hydraulic fracture.

6. The method according to claim 5, characterized in that The processing of the echo information by data inversion to obtain the fracture half-length, fracture width and fracture height of the hydraulic fracture comprises obtaining the fracture half-length, fracture width and fracture height of the hydraulic fracture by the following formula: ， ， ， ， ， ， ， ， in, It represents hydraulic potential energy, in Pa; Indicates the density of the fluid in kg / m 3 ; Indicates the acceleration due to gravity in m / s 2 ; Indicates the pressure head, in m; Indicates the elevation of the reference surface, in m; Indicates pressure, the unit is Pa; Indicates the flow velocity in the pipe, in m / s; Indicates the pressure potential energy difference, in Pa; Indicates the flow rate in and out of the crack, in m 3 / s; It represents the friction pressure drop near the wellbore, in Pa; Indicates the flow rate before the pump stops, in m 3 / s; represents the crack impedance, Indicates the pressure head difference, in m; It represents the ratio of fracture volume change to pressure difference, It represents the half-length of the hydraulic fracture, in meters; It represents the average net pressure of the crack, in Pa; Indicates the height of the hydraulic fracture, in meters; represents the plane strain elastic modulus, represents the elliptic integral of the second kind, Indicates the width of the fracturing crack, in mm.

7. The method according to claim 4, characterized in that The processing of the echo information includes: performing the cepstrum analysis on the echo information by using fast Fourier transform.

8. The method according to claim 7, characterized in that The adopting fast Fourier transform to perform the cepstrum analysis on the echo information comprises performing the cepstrum analysis on the echo information by the following formula: 。 9. An electronic device, characterized in that: The method comprises a processor and a memory, wherein the memory stores a computer program, and the processor is used to execute the computer program to implement the method according to any one of claims 1 to 8.

10. A computer-readable storage medium, characterized in that: A computer program / instruction is stored, and when the computer program / instruction is executed by a processor, the method according to any one of claims 1 to 8 is implemented.

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