Method and device for determining fracturing crack based on fracturing pump stop water hammer signal

Abstract

The invention provides a method and device for determining a fracturing crack based on a fracturing pump stop water hammer signal, and the method comprises the steps: firstly obtaining the fracturing pump stop water hammer signal of a target well, and determining a first cluster crack and the crack position of the first cluster crack through cepstrum analysis according to the fracturing pump stop water hammer signal; determining a plurality of candidate cracks according to the crack positions of the first cluster cracks; determining a plurality of actually opened fracturing fractures and fracture positions of the fracturing fractures from the plurality of candidate fractures according to the fracturing pump stop water hammer signal of the target well by determining and according to the related frequency spectrum envelope; according to the fracturing pump stop water hammer signal of the target well, determining a reflection coefficient of a fracturing crack by determining and according to a target reflection response sequence; and according to the reflection coefficient of the fracturing crack, determining the liquid inlet strength of the fracturing crack. Therefore, the number and the positions of the underground fracturing cracks can be accurately identified, and meanwhile, the liquid inlet strength of the underground fracturing cracks can be accurately determined.

Description

Technical Field

[0001] This specification belongs to the technical field of oil and gas extraction, and particularly relates to a method and device for determining hydraulic fracture based on hydraulic fracturing pump shutdown water hammer signal. Background Art

[0002] During the process of oil and gas extraction, hydraulic fracturing is often used to improve the oil and gas extraction rate. Specifically, hydraulic fracturing refers to the process of pumping fracturing fluid into the formation using equipment such as pump trucks on the ground to create fractures in the formation and form channels for oil and gas migration.

[0003] However, due to the complex downhole environment, it is often difficult to accurately identify and determine the actual development of downhole fractures obtained by hydraulic fracturing based on existing methods. As a result, it is impossible to effectively evaluate the effect of hydraulic fracturing, which affects subsequent hydraulic fracturing operations.

[0004] In response to the above problems, no effective solution has been proposed yet. Summary of the Invention

[0005] This specification provides a method and device for determining hydraulic fracture based on hydraulic fracturing pump shutdown water hammer signal, which can be well adapted to the hydraulic fracturing construction scenario. While accurately identifying the number and location of downhole fractures, it can also accurately determine the fluid injection intensity of downhole fractures.

[0006] This specification provides a method for determining hydraulic fracture based on hydraulic fracturing pump shutdown water hammer signal, including:

[0007] Obtain the hydraulic fracturing pump shutdown water hammer signal of the target well;

[0008] Based on the hydraulic fracturing pump shutdown water hammer signal of the target well, determine the first cluster of fractures and the fracture location of the first cluster of fractures through cepstrum analysis;

[0009] Determine a plurality of candidate fractures based on the fracture location of the first cluster of fractures;

[0010] Based on the hydraulic fracturing pump shutdown water hammer signal of the target well, determine the actually opened multiple hydraulic fractures and the fracture locations of the hydraulic fractures from the plurality of candidate fractures by determining and according to the relevant frequency spectrum envelope;

[0011] Based on the hydraulic fracturing pump shutdown water hammer signal of the target well, determine the reflection coefficient of the hydraulic fracture by determining and according to the target reflection response sequence;

[0012] Determine the fluid injection intensity of the hydraulic fracture based on the reflection coefficient of the hydraulic fracture.

[0013] In one embodiment, based on the hydraulic fracturing pump shutdown water hammer signal of the target well, determining the first cluster of fractures through cepstrum analysis includes:

[0014] Based on the hydraulic shock signal when the fracturing pump stops in the target well, through cepstrum analysis, determine the fracture reflection response time;

[0015] Based on the fracture reflection response time and the propagation speed of the hydraulic shock wave when the fracturing pump stops, determine the first cluster of fractures and the fracture positions of the first cluster of fractures.

[0016] In one embodiment, the method further includes:

[0017] Based on the hydraulic shock signal when the fracturing pump stops in the target well, perform deconvolution operation to obtain the reflection response sequence of the wellbore - fracture system as the auxiliary reflection response sequence.

[0018] In one embodiment, based on the hydraulic shock signal when the fracturing pump stops in the target well, determining and based on the relevant spectral envelope, determining the actually opened multiple fracturing fractures and the fracture positions of the fracturing fractures from multiple candidate fractures includes:

[0019] Solve the second - derivative data of the hydraulic shock signal when the fracturing pump stops in the target well; and perform Fourier transform on the second - derivative data to obtain the corresponding second - derivative spectral envelope curve;

[0020] Based on multiple candidate fractures, determine multiple fracture combinations; wherein, the fracture combinations at least include the first cluster of fractures;

[0021] Determine the spectral envelope curves of multiple fracture combinations;

[0022] Based on the second - derivative spectral envelope curve and the spectral envelope curves of multiple fracture combinations, through cross - correlation analysis, determine the target fracture combination that matches;

[0023] Based on the target fracture combination, determine the actually opened multiple fracturing fractures and the fracture positions of the fracturing fractures.

[0024] In one embodiment, based on the hydraulic shock signal when the fracturing pump stops in the target well, determining and based on the target reflection response sequence, determining the reflection coefficient of the fracturing fracture includes:

[0025] Solve the first - derivative data of the hydraulic shock signal when the fracturing pump stops in the target well;

[0026] Using the auxiliary reflection response sequence as a constraint, perform deconvolution operation on the first - derivative data to obtain the reflection response sequence of the downhole fracture as the target reflection response sequence;

[0027] Based on the fracture positions of the fracturing fractures and the target reflection response sequence, determine the reflection coefficient of the fracturing fracture.

[0028] In one embodiment, after determining the liquid injection intensity of the fracturing fracture based on the reflection coefficient of the fracturing fracture, the method further includes:

[0029] Evaluate the development of the fracturing fractures according to the liquid injection intensity of the fracturing fractures.

[0030] In one embodiment, after determining the liquid injection intensity of the fracturing fractures according to the reflection coefficient of the fracturing fractures, the method further includes:

[0031] Screen out the fracturing fractures with qualified development according to the liquid injection intensity as the temporary plugging fractures;

[0032] Set corresponding temporary plugging agents for the temporary plugging fractures;

[0033] Continue hydraulic fracturing on the target well.

[0034] This specification also provides a device for determining fracturing fractures, including:

[0035] An acquisition module, configured to acquire the fracturing pump shut-off water hammer signal of the target well;

[0036] A first determination module, configured to determine the first cluster of fractures and the fracture positions of the first cluster of fractures through cepstrum analysis according to the fracturing pump shut-off water hammer signal of the target well;

[0037] A second determination module, configured to determine a plurality of candidate fractures according to the fracture positions of the first cluster of fractures;

[0038] A third determination module, configured to determine the actually opened multiple fracturing fractures and the fracture positions of the fracturing fractures from the plurality of candidate fractures according to the fracturing pump shut-off water hammer signal of the target well by determining and according to the relevant spectral envelope;

[0039] A fourth determination module, configured to determine the reflection coefficient of the fracturing fractures according to the fracturing pump shut-off water hammer signal of the target well by determining and according to the target reflection response sequence;

[0040] A fifth determination module, configured to determine the liquid injection intensity of the fracturing fractures according to the reflection coefficient of the fracturing fractures.

[0041] This specification also provides a computer device, including a processor and a memory for storing processor-executable instructions, and when the processor executes the instructions, the relevant steps of the method for determining fracturing fractures based on the fracturing pump shut-off water hammer signal are implemented.

[0042] This specification also provides a computer-readable storage medium, on which computer instructions are stored, and when the instructions are executed by a processor, the relevant steps of the method for determining fracturing fractures based on the fracturing pump shut-off water hammer signal are implemented.

[0043] Based on the method and device for determining hydraulic fracturing cracks based on the hydraulic fracturing pump shut - down water - hammer signal provided in this specification, first, the hydraulic fracturing pump shut - down water - hammer signal of the target well can be obtained and analyzed. Through cepstrum analysis, the first cluster of cracks and the crack positions of the first cluster of cracks can be determined. Then, based on the crack positions of the first cluster of cracks, multiple candidate cracks can be determined. According to the hydraulic fracturing pump shut - down water - hammer signal of the target well, by determining and based on the relevant spectral envelopes, multiple actually opened hydraulic fracturing cracks and the crack positions of the hydraulic fracturing cracks can be determined from the multiple candidate cracks. Then, according to the hydraulic fracturing pump shut - down water - hammer signal of the target well, by determining and based on the target reflection response sequence, the reflection coefficient of the hydraulic fracturing cracks can be determined. And based on the reflection coefficient of the hydraulic fracturing cracks, the liquid injection intensity of the hydraulic fracturing cracks can be determined. Thus, it can be better adapted to the hydraulic fracturing construction scenario. While accurately identifying the number and positions of downhole hydraulic fracturing cracks, it can also accurately determine the liquid injection intensity of downhole hydraulic fracturing cracks. Furthermore, more refined and comprehensive complete crack information of downhole hydraulic fracturing cracks based on hydraulic fracturing, as well as the actual crack opening and development conditions, can be obtained, so that subsequent further hydraulic fracturing construction of the target well can be better carried out based on the above - mentioned information. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] To more clearly illustrate the embodiments of this specification, the drawings required for use in the embodiments will be briefly introduced below. The drawings described below are only some embodiments recorded in this specification. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0045] Figure 1 is a schematic flowchart of a method for determining hydraulic fracturing cracks based on the hydraulic fracturing pump shut - down water - hammer signal provided by an embodiment of this specification;

[0046] Figure 2 is a schematic diagram of an embodiment of applying the method for determining hydraulic fracturing cracks based on the hydraulic fracturing pump shut - down water - hammer signal provided by an embodiment of this specification in a scenario example;

[0047] Figure 3 is a schematic diagram of an embodiment of applying the method for determining hydraulic fracturing cracks based on the hydraulic fracturing pump shut - down water - hammer signal provided by an embodiment of this specification in a scenario example;

[0048] Figure 4 is a schematic diagram of an embodiment of applying the method for determining hydraulic fracturing cracks based on the hydraulic fracturing pump shut - down water - hammer signal provided by an embodiment of this specification in a scenario example;

[0049] Figure 5 is a schematic diagram of the structural composition of a computer device provided by an embodiment of this specification;

[0050] Figure 6It is a schematic diagram of the structural composition of a fracturing crack determination device provided by an embodiment of this specification;

[0051] Figure 7 It is a schematic diagram of an embodiment of applying the method for determining fracturing cracks based on fracturing pump shutdown water hammer signals provided by an embodiment of this specification in a scenario example;

[0052] Figure 8 It is a schematic diagram of an embodiment of applying the method for determining fracturing cracks based on fracturing pump shutdown water hammer signals provided by an embodiment of this specification in a scenario example;

[0053] Figure 9 It is a schematic diagram of an embodiment of applying the method for determining fracturing cracks based on fracturing pump shutdown water hammer signals provided by an embodiment of this specification in a scenario example;

[0054] Figure 10 It is a schematic diagram of an embodiment of applying the method for determining fracturing cracks based on fracturing pump shutdown water hammer signals provided by an embodiment of this specification in a scenario example;

[0055] Figure 11 It is a schematic diagram of an embodiment of applying the method for determining fracturing cracks based on fracturing pump shutdown water hammer signals provided by an embodiment of this specification in a scenario example;

[0056] Figure 12 It is a schematic diagram of an embodiment of applying the method for determining fracturing cracks based on fracturing pump shutdown water hammer signals provided by an embodiment of this specification in a scenario example;

[0057] Figure 13 It is a schematic diagram of an embodiment of applying the method for determining fracturing cracks based on fracturing pump shutdown water hammer signals provided by an embodiment of this specification in a scenario example;

[0058] Figure 14 It is a schematic diagram of an embodiment of applying the method for determining fracturing cracks based on fracturing pump shutdown water hammer signals provided by an embodiment of this specification in a scenario example;

[0059] Figure 15 It is a schematic diagram of an embodiment of applying the method for determining fracturing cracks based on fracturing pump shutdown water hammer signals provided by an embodiment of this specification in a scenario example;

[0060] Figure 16 It is a schematic diagram of an embodiment of applying the method for determining fracturing cracks based on fracturing pump shutdown water hammer signals provided by an embodiment of this specification in a scenario example;

[0061] Figure 17In a scenario example, it is a schematic diagram of an embodiment of the method for determining a fracturing crack based on a fracturing pump shutdown water hammer signal provided in the embodiments of this specification. Detailed implementation manners

[0062] To enable those skilled in the art to better understand the technical solutions in this specification, the following will clearly and completely describe the technical solutions in the embodiments of this specification with reference to the accompanying drawings in the embodiments of this specification. Obviously, the described embodiments are only a part of the embodiments of this specification, rather than all of them. All other embodiments obtained by those of ordinary skill in the art based on the embodiments in this specification without creative efforts shall fall within the scope of protection of this specification.

[0063] It should be noted that in the embodiments of this specification, some industry-existing solutions such as certain software, components, models, etc. may be mentioned. They should be regarded as exemplary, and their purpose is only to illustrate the feasibility in the implementation of the technical solutions of this application, but it does not mean that the applicant has already or necessarily used this solution.

[0064] Refer to Figure 1 As shown, the embodiments of this specification provide a method for determining a fracturing crack based on a fracturing pump shutdown water hammer signal. Specifically, when implementing this method, it may include the following contents:

[0065] S101: Obtain the fracturing pump shutdown water hammer signal of the target well;

[0066] S102: Determine the first cluster of cracks and the crack positions of the first cluster of cracks through cepstrum analysis according to the fracturing pump shutdown water hammer signal of the target well;

[0067] S103: Determine a plurality of candidate cracks according to the crack positions of the first cluster of cracks;

[0068] S104: Determine the actually opened multiple fracturing cracks and the crack positions of the fracturing cracks from the plurality of candidate cracks by determining and according to the relevant spectral envelopes according to the fracturing pump shutdown water hammer signal of the target well;

[0069] S105: Determine the reflection coefficient of the fracturing crack by determining and according to the target reflection response sequence according to the fracturing pump shutdown water hammer signal of the target well;

[0070] S106: Determine the liquid injection intensity of the fracturing crack according to the reflection coefficient of the fracturing crack.

[0071] Among them, the above-mentioned target well can specifically be understood as the well currently undergoing hydraulic fracturing.

[0072] The above-mentioned fracturing pump shutdown water hammer signal can be specifically understood as the pressure wave signal data of the fracturing pump shutdown water hammer wave. The above-mentioned fracturing pump shutdown water hammer wave is specifically a fluid oscillation pressure wave formed in the wellbore during the hydraulic fracturing process. When the fluid injection at the wellhead stops, the fluid velocity changes sharply. Due to the elasticity of the wellbore wall and the compressibility of the fluid, different wells have different influencing factors such as wellbore parameters, geological parameters, and fluid parameters. As a result, the fracturing pump shutdown water hammer signals exhibited by the fracturing pump shutdown water hammer waves (or water hammer pressure waves) formed in different wells under different conditions will also be different. Therefore, the fracturing pump shutdown water hammer signals exhibited by the fracturing pump shutdown water hammer wave can be used to analyze the characteristics of the fracture morphology, quantity, size, etc. underground, realize the identification of underground fracturing events (such as artificial fracturing fractures, bridge plug positions, casing diameter change damage, etc.), and further realize the evaluation of the fracturing effect of underground hydraulic fracturing and water hammer fracturing diagnosis.

[0073] The above-mentioned water hammer fracturing diagnosis can be specifically understood as a fracturing diagnosis technology based on water hammer waves, which has the characteristics of simple operation, low cost, and strong real-time performance. Specifically, based on the water hammer fracturing diagnosis technology, the water hammer effect generated by the water hammer wave can be used to diagnose the fracture morphology during the hydraulic fracturing process. The water hammer effect refers to the energy dissipation caused by the fracturing fracture to the pump shutdown pressure during the pump shutdown process, which in turn affects the characteristics exhibited by the fracturing pump shutdown water hammer signal. Based on this technology, by analyzing the relevant characteristics of the above-mentioned water hammer pressure wave, the attribute parameters of the fracture can be inversely calculated to realize the evaluation of the fracture morphology.

[0074] During specific implementation, hydraulic fracturing construction can be carried out on the target well according to the fracturing plan. Among them, the fracturing plan records the perforation clusters planned to be opened by hydraulic fracturing in the wellbore.

[0075] During the process of carrying out hydraulic fracturing construction on the target well, stop the operation of the pump injection assembly (such as a pump truck, etc.) to stimulate the formation of a fracturing pump shutdown water hammer wave in the wellbore. At this time, relevant pressure data can be collected through a sensor arranged at a position adjacent to the wellhead (such as at the manifold) to obtain the fracturing pump shutdown water hammer signal of the target well.

[0076] Furthermore, the method for determining fracturing fractures based on the fracturing pump shutdown water hammer signal provided in this specification can be applied. According to the above-mentioned fracturing pump shutdown water hammer signal, through corresponding data processing, accurately identify the quantity and position of the underground fracturing fractures actually opened due to the current hydraulic fracturing; at the same time, it can also precisely determine the liquid injection intensity of the above-mentioned underground fracturing fractures, so as to analyze the actual development of each opened underground fracturing fracture, and thus be able to more precisely and comprehensively determine the complete fracture information of the underground fracturing fractures based on hydraulic fracturing and the specific fracture opening situation.

[0077] In some embodiments, the above-mentioned acquisition of the hydraulic fracturing pump shutdown water hammer signal of the target well may specifically include the following when implemented:

[0078] S1: Stop the pump during the hydraulic fracturing process of the target well to form a hydraulic fracturing pump shutdown water hammer wave in the wellbore;

[0079] S2: Collect relevant pressure data through a sensor deployed at a position adjacent to the wellhead to obtain an initial pump shutdown water hammer signal;

[0080] S3: Perform filtering processing on the initial pump shutdown water hammer signal to eliminate noise components and retain the effective signal as the hydraulic fracturing pump shutdown water hammer signal of the target well.

[0081] Based on the above embodiments, a hydraulic fracturing pump shutdown water hammer signal of the target well with less noise and higher accuracy can be obtained, so that the hydraulic fracturing cracks can be more accurately determined based on the above signal subsequently.

[0082] Specifically, the directly collected initial pump shutdown water hammer signal can include two parts: an effective signal and a noise component. Among them, the composition of the effective signal (for example, the hydraulic fracturing pump shutdown water hammer signal of the target well) is similar to a seismic record and can be described in the form of convolution, which can be specifically expressed as the following form:

[0083] x(t) = s(t) * w(t)

[0084] Wherein, x(t) represents the effective signal, s(t) represents the source pressure pulse of the hydraulic fracturing pump shutdown water hammer wave excited during the hydraulic fracturing pump shutdown process, which is similar to the wavelet in a seismic record. w(t) represents the reflection response sequence of the wellbore-fracture system.

[0085] Specifically, the above-mentioned reflection response sequence of the wellbore-fracture system is determined by the hydraulic impedance characteristics at the fracture position and can be an important feature for identifying fracture reflections. However, the reflection response sequence of the wellbore-fracture system directly obtained by deconvolution based on the hydraulic fracturing pump shutdown water hammer signal of the target well cannot accurately characterize the reflection characteristics of the fracture because the attenuation effect based on the fracture is not considered. This problem is more serious especially for fractures far from the wellhead. Therefore, in the embodiments of this specification, only the above-mentioned reflection response sequence of the wellbore-fracture system is used as an auxiliary reference data, and the reflection response sequence of the wellbore-fracture system is not directly used to determine the hydraulic fracturing cracks.

[0086] Specifically determining multiple candidate fractures may refer to determining the number of multiple candidate fractures.

[0087] In some embodiments, the above-mentioned determination of the first cluster of fractures based on the hydraulic fracturing pump shutdown water hammer signal of the target well through cepstrum analysis may specifically include the following when implemented:

[0088] S1: Based on the hydraulic fracturing pump shut - down water hammer signal of the target well, determine the fracture reflection response time through cepstrum analysis.

[0089] S2: Based on the fracture reflection response time and the propagation speed of the hydraulic fracturing pump shut - down water hammer wave, determine the first cluster of fractures and the fracture position of the first cluster of fractures.

[0090] Among them, the above - mentioned cepstrum analysis, also known as the secondary spectrum analysis, mainly performs the inverse Fourier transform on the logarithm of the signal spectrum and has the ability to analyze homologous harmonic frequencies, non - homologous harmonic frequencies, and multi - component side frequencies.

[0091] In specific implementation, considering that the cepstrum analysis result based on the hydraulic fracturing pump shut - down water hammer signal of the target well will reflect the reflection characteristics of multiple downhole hydraulic fracturing fractures. Among them, the reflection characteristics of the fracture closest to the wellhead (i.e., the first cluster of fractures) among the fractures that have been opened through hydraulic fracturing are relatively the most obvious and the amplitude is relatively the highest; correspondingly, the reflection characteristics of the fracture farthest from the wellhead are relatively weak and may even be submerged in the signal data and cannot be identified.

[0092] Based on the above considerations, after obtaining the cepstrum analysis result through cepstrum analysis based on the hydraulic fracturing pump shut - down water hammer signal of the target well, first, based on the cepstrum analysis result, screen out the signal data with relatively the most obvious reflection characteristics as the signal data corresponding to the first cluster of fractures; then, based on this signal data in the cepstrum analysis result, determine the fracture reflection response time; then, based on the fracture reflection response time and the propagation speed of the hydraulic fracturing pump shut - down water hammer wave, calculate the distance between the first cluster of fractures and the wellhead, so as to determine the first cluster of fractures and the fracture position of the first cluster of fractures.

[0093] It should be noted that the first cluster of fractures here is the fracture closest to the wellhead among the fractures actually opened during hydraulic fracturing. The first cluster of fractures may be the perforation cluster originally planned to be the closest to the wellhead in the fracturing plan or other perforation clusters in the fracturing plan.

[0094] Based on the above - mentioned embodiments, the first cluster of fractures and the fracture position of the first cluster of fractures can be accurately and efficiently determined through cepstrum analysis.

[0095] In some embodiments, the above - mentioned candidate fractures include the first cluster of fractures and all other possible opened perforation clusters determined based on the first cluster of fractures.

[0096] In specific implementation, the above - mentioned determination of multiple candidate fractures based on the fracture position of the first cluster of fractures may include: querying the fracturing plan of the target well to determine the perforation clusters and the first cluster of fractures whose fracture positions are below the fracture position of the first cluster of fractures as multiple candidate fractures.

[0097] In specific implementation, multiple fractures with relatively obvious reflection characteristics (for example, multiple fractures with amplitudes greater than a preset amplitude threshold) can also be screened out based on a preset screening rule according to the cepstrum analysis result as the first fractures. Among them, the above-mentioned first fractures at least include the first cluster of fractures. The above-mentioned first fractures are based on the cepstrum analysis result of the pressure pump shutdown water hammer signal of the target well and can be clearly determined as the fractures that have been opened.

[0098] Furthermore, multiple first fractures can be used subsequently to participate in subsequent data processing instead of the first cluster of fractures. Specifically, the perforation clusters with fracture positions below the fracture positions of the multiple first fractures and the multiple first fractures can be determined by querying the fracturing plan of the target well as multiple candidate fractures.

[0099] This can reduce the number of fracture combinations to be detected and judged subsequently, and thus can effectively reduce the overall data processing volume and improve the overall processing efficiency.

[0100] In some embodiments, when the method is specifically implemented, the following content can also be included: performing deconvolution operation on the pressure pump shutdown water hammer signal of the target well to obtain the reflection response sequence of the wellbore-fracture system as the auxiliary reflection response sequence.

[0101] Specifically, the excitation response at the initial moment can be extracted from the pressure pump shutdown water hammer signal of the target well as the source pulse response (or source pressure pulse) in the deconvolution calculation; then, using this source pulse response, deconvolution operation is performed on the pressure pump shutdown water hammer signal of the target well to obtain the reflection response sequence of the wellbore-fracture system as the auxiliary reflection response sequence. Among them, the signal data amplitude in the auxiliary reflection response sequence can reflect the fracture reflection characteristics at the corresponding position (for example, the energy size of the reflection response). Therefore, the reflection response sequence of the wellbore-fracture system can be used as a kind of auxiliary data.

[0102] Based on the above embodiments, the reflection response sequence of the wellbore-fracture system can be obtained simultaneously using the pressure pump shutdown water hammer signal of the target well as the auxiliary reflection response sequence for subsequent use.

[0103] In some embodiments, as shown in Figure 2 When determining and determining the actually opened multiple fracturing fractures and the fracture positions of the fracturing fractures from multiple candidate fractures according to the pressure pump shutdown water hammer signal of the target well through the relevant frequency spectrum envelope, the following content can be specifically included:

[0104] S1: Solve the second derivative data of the pressure pump shutdown water hammer signal of the target well; and perform Fourier transform on the second derivative data to obtain the corresponding second derivative frequency spectrum envelope curve;

[0105] S2: Determine multiple fracture combinations based on multiple candidate fractures; wherein, the fracture combinations at least include the first cluster of fractures.

[0106] S3: Determine the spectral envelope curves of multiple fracture combinations.

[0107] S4: Determine the target fracture combination that matches through cross - correlation analysis based on the second - derivative spectral envelope curve and the spectral envelope curves of multiple fracture combinations.

[0108] S5: Determine multiple actually - opened fracturing fractures and the fracture positions of the fracturing fractures based on the target fracture combination.

[0109] Specifically, for example, based on the fracturing plan, the first cluster of fractures determined is fracture 1, and the remaining candidate fractures except the first cluster of fractures include: fracture 2, fracture 3. Correspondingly, perform permutation and combination based on the above - mentioned candidate fractures, and screen out the combinations that at least contain the first cluster of fractures as the multiple fracture combinations. Specifically, it includes: combination 1 (fracture 1 + fracture 2), combination 2 (fracture 1 + fracture 3), combination 3 (fracture 1 + fracture 2 + fracture 3).

[0110] During specific implementation, it is possible to obtain and, according to the fracturing data during hydraulic fracturing and the fracturing plan, through numerical simulation, obtain the simulation reference data for each candidate fracture; then use the simulation reference data of the candidate fractures to determine the spectral envelope curves of each fracture combination.

[0111] In addition, it is also possible to determine the estimated reference data for each candidate fracture according to the auxiliary reflection response sequence; then use the estimated reference data of the above - mentioned candidate fractures to determine the spectral envelope curves of each fracture combination.

[0112] During specific implementation, it is possible to determine the cross - correlation degree between the second - derivative spectral envelope curve and the spectral envelope curves of each fracture combination through cross - correlation analysis; then screen out the fracture combination with the highest cross - correlation degree as the target fracture combination that matches the second - derivative spectral envelope curve. Furthermore, based on the above - mentioned target fracture combination, combined with the fracturing pump - shut - down water - hammer signal and the fracturing plan of the target well, it is possible to further determine multiple actually - opened fracturing fractures after hydraulic fracturing and the fracture positions of the fracturing fractures.

[0113] Among them, the above - mentioned target fracture combination contains the fractures actually opened after hydraulic fracturing.

[0114] In specific implementation, after obtaining the second derivative frequency spectrum envelope curve and the frequency spectrum envelope curves of multiple fracture combinations, the second derivative frequency spectrum envelope curve and the frequency spectrum envelope curves of multiple fracture combinations can be respectively normalized to obtain the normalized second derivative frequency spectrum envelope curve and the frequency spectrum envelope curves of multiple normalized fracture combinations; then, cross-correlation analysis is performed using the normalized second derivative frequency spectrum envelope curve and the frequency spectrum envelope curves of multiple normalized fracture combinations, so that the target fracture combination can be determined more accurately.

[0115] Based on the above embodiments, through processing such as Fourier transform and correlation row analysis, the actually opened fracturing fractures can be further determined from multiple candidate fractures.

[0116] In some embodiments, after determining multiple fracturing fractures and the fracture positions of the fracturing fractures, further, whether there are perforation clusters that are not planned to be opened in the actually opened multiple fracturing fractures can be detected according to the fracturing plan and the fracture positions of the fracturing fractures; after detecting that there are perforation clusters that are not planned to be opened, further, such fractures can be marked as newly added fractures; then, according to the fracture positions of the newly added fractures, it can be detected and judged whether there is a risk of water leakage in the wellbore of the target well.

[0117] Specifically, it can be detected whether the fracture positions of the above-mentioned newly added fractures coincide with the key part positions in the wellbore of the target well; among them, the key part can include, for example, the bridge plug part. When it is determined that at least one fracture position of the newly added fractures coincides with the key part position in the wellbore of the target well, it can be determined that there is a risk of water leakage. Furthermore, the newly added fracture can be determined as a risk fracture, and a risk prompt message for the risk fracture can be generated to remind the construction operators to pay attention to and handle the risk fracture to ensure the construction safety of the target well.

[0118] In some embodiments, in specific implementation, when using multiple first fractures to replace the first cluster of fractures, when determining the fracture combination, it can be required that the determined fracture combination includes at least multiple first fractures. In this way, the number of fracture combinations can be effectively reduced.

[0119] For example, based on the fracturing plan, the determined multiple first fractures include: fracture 1, fracture 2, and the remaining candidate fractures except the multiple first fractures include: fracture 3. At this time, only 1 fracture combination is determined, that is, (fracture 1 + fracture 2 + fracture 3).

[0120] In some embodiments, referring to Figure 3 As shown, when determining the reflection coefficient of the fracturing fracture according to the fracturing pump shut-off water hammer signal of the target well by determining and according to the target reflection response sequence, specific implementation can include the following content:

[0121] S1: Solve the first-order derivative data of the water hammer signal of the target well during fracturing and pump stop;

[0122] S2: using the auxiliary reflection response sequence as a constraint, deconvolution operation is performed on the first-order derivative data to obtain the reflection response sequence of the downhole fracture as the target reflection response sequence;

[0123] S3: Determine the reflection coefficient of the hydraulic fracture according to the fracture position of the hydraulic fracture and the target reflection response sequence.

[0124] Based on the above embodiment, by using the auxiliary reflection response sequence as a constraint and then performing a deconvolution operation on the first-order derivative data of the fracturing pump stop water hammer signal of the target well, the influence of attenuation can be effectively eliminated, and a target reflection response sequence with relatively high accuracy and relatively small error can be obtained. Furthermore, based on the above target emission response sequence, a reflection coefficient with relatively high reference value and good accuracy can be obtained.

[0125] In specific implementation, the reflection coefficient of each hydraulic fracture can be determined by performing an inversion operation according to the fracture position of the hydraulic fracture and the target reflection response sequence.

[0126] The above reflection coefficient can characterize the fluid inflow intensity (or fluid inflow response) of the hydraulic fracture. Generally, the larger the reflection coefficient of a hydraulic fracture, the stronger the fluid inflow intensity is, and the better the development of the hydraulic fracture is. On the contrary, the smaller the reflection coefficient of a hydraulic fracture, the weaker the fluid inflow intensity is, and the worse the development of the hydraulic fracture is.

[0127] In some embodiments, after determining the fluid inflow intensity of the hydraulic fracture according to the reflection coefficient of the hydraulic fracture, the method may further include: evaluating the development of the hydraulic fracture according to the fluid inflow intensity of the hydraulic fracture.

[0128] Furthermore, the fracturing effect of hydraulic fracturing can be evaluated according to the development of each fracturing crack and the fracturing plan. According to the development of each fracturing crack, the fracturing strategy used in the previous hydraulic fracturing can be optimized and improved to obtain an optimized fracturing strategy; then, hydraulic fracturing can be continued on the target well based on the optimized fracturing strategy to obtain a better fracturing effect.

[0129] In addition, hydraulic fracturing diagnosis and other related processing can be carried out in combination with the development of each fracturing crack.

[0130] Furthermore, the effect state type of the current hydraulic fracturing can be determined according to the evaluation result of the hydraulic fracturing effect; then, according to the effect state type of the hydraulic fracturing, the preset fracturing strategy database can be queried to determine the matching target fracturing strategy; and then, the target well can be continuously hydraulically fractured according to the target fracturing measurement to obtain a relatively good fracturing effect.

[0131] Among them, the preset fracturing strategy database stores multiple preset fracturing strategies, and each preset fracturing strategy corresponds to at least one effect state type of hydraulic fracturing. Before specific implementation, a large number of historical hydraulic fracturing construction treatment records can be collected; the historical hydraulic fracturing construction treatment records that are successfully constructed and have no safety accidents can be screened out from the multiple historical hydraulic fracturing construction treatment records as the construction sample treatment records; then, based on the effect state of the hydraulic fracturing corresponding to each sample construction treatment record, clustering processing is performed on the multiple construction sample treatment records to obtain multiple construction treatment data groups; among them, each construction treatment data group corresponds to at least one effect state type of hydraulic fracturing and includes the common operation characteristics in the hydraulic fracturing construction treatment process corresponding to the corresponding effect state type; then, according to the operation characteristics included in each construction treatment data group, combined with expert experience, multiple preset fracturing strategies corresponding to different effect state types of hydraulic fracturing are constructed respectively; and the multiple preset fracturing strategies are combined to obtain the corresponding preset fracturing strategy database.

[0132] In some embodiments, referring to Figure 4 as shown, after determining the liquid injection intensity of the fracturing crack according to the reflection coefficient of the fracturing crack, when the method is specifically implemented, the following content may further be included:

[0133] S1: According to the liquid injection intensity, screen out the fracturing cracks with qualified development conditions as the temporary plugging cracks;

[0134] S2: Set corresponding temporary plugging agents for the temporary plugging cracks;

[0135] S3; Continuously perform hydraulic fracturing on the target well.

[0136] Specifically, when implemented, the fracturing cracks with a liquid injection intensity greater than or equal to the preset reference intensity threshold can be screened out as the temporary plugging cracks. Among them, the above-mentioned temporary plugging cracks can be understood as the cracks that have been normally opened based on the previous hydraulic fracturing and the development conditions have reached the expected requirements. Among them, the preset reference intensity threshold can be obtained according to the fracturing plan.

[0137] During specific implementation, corresponding temporary plugging agents can be set for the temporarily plugged fractures to temporarily plug the above-mentioned temporarily plugged fractures and increase the downhole pressure. After the plugging is completed, continue the hydraulic fracturing of the target well. At this time, the action will be relatively more concentrated on the unblocked fractures with relatively poor development conditions, so that the above-mentioned fracturing fractures can be better developed, thereby improving the overall fracturing effect on the target well.

[0138] Based on the above embodiments, the corresponding hydraulic fracturing construction can be carried out on the target well according to the liquid injection intensity to obtain a better fracturing effect.

[0139] As can be seen from the above, the method for determining fracturing fractures based on the fracturing pump shutdown water hammer signal provided by the embodiments of this specification can first obtain and analyze the fracturing pump shutdown water hammer signal of the target well, and determine the first cluster of fractures and the fracture positions of the first cluster of fractures through cepstrum analysis; then determine multiple candidate fractures according to the fracture positions of the first cluster of fractures; determine and analyze the relevant frequency spectrum envelopes according to the fracturing pump shutdown water hammer signal of the target well to determine the multiple actually opened fracturing fractures and the fracture positions of the fracturing fractures from the multiple candidate fractures; determine and analyze the target reflection response sequence according to the fracturing pump shutdown water hammer signal of the target well to determine the reflection coefficient of the fracturing fractures; determine the liquid injection intensity of the fracturing fractures according to the reflection coefficient of the fracturing fractures. Thus, it can be better adapted to the hydraulic fracturing construction scenario, accurately identify the number and positions of downhole fracturing fractures, and at the same time accurately determine the liquid injection intensity of downhole fracturing fractures. Furthermore, it can more precisely and comprehensively determine the complete fracture information of downhole fracturing fractures based on hydraulic fracturing and the actual fracture opening situation, so as to better carry out hydraulic fracturing construction on the target well in the future.

[0140] The embodiments of this specification provide a computer device, as shown in Figure 5 Figure. Among them, the computer device includes a network communication port 501, a processor 502, and a memory 503. The above structures are connected by internal cables so that each structure can perform specific data interactions.

[0141] Among them, the network communication port 501 can be specifically used to obtain the fracturing pump shutdown water hammer signal of the target well.

[0142] The processor 502 can specifically be configured to determine the first cluster of fractures and the fracture positions of the first cluster of fractures through cepstrum analysis based on the hydraulic shock signal at the pump shutdown during the fracturing of the target well; determine a plurality of candidate fractures based on the fracture positions of the first cluster of fractures; determine the actually opened multiple fracturing fractures and the fracture positions of the fracturing fractures from the plurality of candidate fractures by determining and based on the relevant frequency spectrum envelopes according to the hydraulic shock signal at the pump shutdown during the fracturing of the target well; determine the reflection coefficients of the fracturing fractures by determining and based on the target reflection response sequence according to the hydraulic shock signal at the pump shutdown during the fracturing of the target well; and determine the liquid injection intensity of the fracturing fractures based on the reflection coefficients of the fracturing fractures.

[0143] The memory 503 can specifically be configured to store corresponding instruction programs and relevant data such as the fracture positions and reflection coefficients of the first cluster of fractures.

[0144] Based on the above method, the relevant structural performance of the computer device can be effectively utilized to improve the data processing speed of the electronic device and efficiently implement the data processing for determining the fracturing fractures.

[0145] In this embodiment, the network communication port 501 can be bound to different communication protocols, so as to send or receive different data. For example, the network communication port can be a port responsible for web data communication, can also be a port responsible for FTP data communication, and can also be a port responsible for mail data communication. In addition, the network communication port can also be a physical communication interface or communication chip. For example, it can be a wireless mobile network communication chip, such as GSM, CDMA, etc.; it can also be a Wifi chip; it can also be a Bluetooth chip.

[0146] In this embodiment, the processor 502 can be implemented in any suitable manner. For example, the processor can take the form of, for example, a microprocessor or a processor and a computer-readable medium storing computer-readable program code (such as software or firmware) executable by the (micro)processor, logic gates, switches, application specific integrated circuit (ASIC), programmable logic controller, and embedded microcontroller, etc. This specification does not make any limitations.

[0147] In this embodiment, the memory 503 can include multiple levels. In a digital system, anything that can store binary data can be a memory; in an integrated circuit, a circuit with a storage function without a physical form is also called a memory, such as RAM, FIFO, etc.; in a system, a storage device with a physical form is also called a memory, such as a memory module, TF card, etc.

[0148] The embodiments of this specification also provide a computer-readable storage medium based on the above method for determining hydraulic fractures based on hydraulic shock signals during fracturing pump shutdown. The computer-readable storage medium stores computer program instructions, which when executed, implement the following steps: obtaining the hydraulic shock signal during fracturing pump shutdown of a target well; determining the first cluster of fractures and the fracture positions of the first cluster of fractures through cepstrum analysis based on the hydraulic shock signal during fracturing pump shutdown of the target well; determining a plurality of candidate fractures based on the fracture positions of the first cluster of fractures; determining the actually opened multiple hydraulic fractures and the fracture positions of the hydraulic fractures from the plurality of candidate fractures based on the hydraulic shock signal during fracturing pump shutdown of the target well by determining and according to the relevant spectral envelope; determining the reflection coefficient of the hydraulic fractures by determining and according to the target reflection response sequence based on the hydraulic shock signal during fracturing pump shutdown of the target well; and determining the liquid injection intensity of the hydraulic fractures based on the reflection coefficient of the hydraulic fractures.

[0149] In this embodiment, the above storage medium includes, but is not limited to, a random access memory (RAM), a read-only memory (ROM), a cache, a hard disk drive (HDD), or a memory card. The memory can be used to store computer program instructions. The network communication unit can be set according to the standards specified by the communication protocol and is used for the interface of network connection communication.

[0150] In this embodiment, the functions and effects specifically implemented by the program instructions stored in the computer-readable storage medium can be explained by comparison with other embodiments and will not be elaborated here.

[0151] The embodiments of this specification also provide a computer program product, which at least includes a computer program. When the computer program is executed by a processor, the following method steps are implemented: obtaining the hydraulic shock signal during fracturing pump shutdown of a target well; determining the first cluster of fractures and the fracture positions of the first cluster of fractures through cepstrum analysis based on the hydraulic shock signal during fracturing pump shutdown of the target well; determining a plurality of candidate fractures based on the fracture positions of the first cluster of fractures; determining the actually opened multiple hydraulic fractures and the fracture positions of the hydraulic fractures from the plurality of candidate fractures based on the hydraulic shock signal during fracturing pump shutdown of the target well by determining and according to the relevant spectral envelope; determining the reflection coefficient of the hydraulic fractures by determining and according to the target reflection response sequence based on the hydraulic shock signal during fracturing pump shutdown of the target well; and determining the liquid injection intensity of the hydraulic fractures based on the reflection coefficient of the hydraulic fractures.

[0152] Refer to Figure 6 As shown, the embodiments of this specification also provide a device for determining hydraulic fractures based on hydraulic shock signals during fracturing pump shutdown. The device can specifically include the following structural modules:

[0153] An acquisition module 601, which can be specifically used to acquire the hydraulic shock signal of the pump shutdown during the fracturing of the target well;

[0154] A first determination module 602, which can be specifically used to determine the first cluster of fractures and the fracture positions of the first cluster of fractures by cepstrum analysis according to the hydraulic shock signal of the pump shutdown during the fracturing of the target well;

[0155] A second determination module 603, which can be specifically used to determine a plurality of candidate fractures according to the fracture positions of the first cluster of fractures;

[0156] A third determination module 604, which can be specifically used to determine the actually opened multiple fracturing fractures and the fracture positions of the fracturing fractures from the plurality of candidate fractures by determining and according to the relevant spectral envelopes according to the hydraulic shock signal of the pump shutdown during the fracturing of the target well;

[0157] A fourth determination module 605, which can be specifically used to determine the reflection coefficient of the fracturing fracture by determining and according to the target reflection response sequence according to the hydraulic shock signal of the pump shutdown during the fracturing of the target well;

[0158] A fifth determination module 606, which can be specifically used to determine the liquid injection intensity of the fracturing fracture according to the reflection coefficient of the fracturing fracture.

[0159] In some embodiments, when the first determination module 602 is specifically implemented, the first cluster of fractures can be determined by cepstrum analysis according to the hydraulic shock signal of the pump shutdown during the fracturing of the target well in the following manner: the fracture reflection response time is determined by cepstrum analysis according to the hydraulic shock signal of the pump shutdown during the fracturing of the target well; the first cluster of fractures and the fracture positions of the first cluster of fractures are determined according to the fracture reflection response time and the propagation speed of the hydraulic shock wave of the pump shutdown.

[0160] In some embodiments: when the device is specifically implemented, it can also be used to perform deconvolution operation according to the hydraulic shock signal of the pump shutdown during the fracturing of the target well to obtain the reflection response sequence of the wellbore-fracture system as an auxiliary reflection response sequence.

[0161] In some embodiments, when the above-mentioned third determination module 604 is specifically implemented, it may determine multiple actually opened fracturing cracks and the crack positions of the fracturing cracks from multiple candidate cracks according to the following method based on the fracturing pump shut-off water hammer signal of the target well: solve the second derivative data of the fracturing pump shut-off water hammer signal of the target well; perform Fourier transform on the second derivative data to obtain the corresponding second derivative spectral envelope curve; determine multiple crack combinations according to the multiple candidate cracks, where the crack combination at least includes the first cluster of cracks; determine the spectral envelope curves of the multiple crack combinations; determine the target crack combination that matches through cross-correlation analysis according to the second derivative spectral envelope curve and the spectral envelope curves of the multiple crack combinations; determine multiple actually opened fracturing cracks and the crack positions of the fracturing cracks according to the target crack combination.

[0162] In some embodiments, when the above-mentioned fourth determination module 605 is specifically implemented, it may determine the reflection coefficient of the fracturing crack according to the following method based on the fracturing pump shut-off water hammer signal of the target well: solve the first derivative data of the fracturing pump shut-off water hammer signal of the target well; use the auxiliary reflection response sequence as a constraint to perform deconvolution operation on the first derivative data to obtain the reflection response sequence of the downhole crack as the target reflection response sequence; determine the reflection coefficient of the fracturing crack according to the crack position of the fracturing crack and the target reflection response sequence.

[0163] In some embodiments, after determining the liquid injection intensity of the fracturing crack according to the reflection coefficient of the fracturing crack, when the device is specifically implemented, it may also be used to: evaluate the development condition of the fracturing crack according to the liquid injection intensity of the fracturing crack.

[0164] In some embodiments, after determining the liquid injection intensity of the fracturing crack according to the reflection coefficient of the fracturing crack, when the device is specifically implemented, it may also be used to: screen out the fracturing cracks whose development conditions meet the requirements as the temporary plugging cracks according to the liquid injection intensity; set corresponding temporary plugging agents for the temporary plugging cracks; continue hydraulic fracturing of the target well.

[0165] It should be noted that the units, devices, modules, etc. described in the above embodiments can be specifically implemented by computer chips or entities, or by products with certain functions. For the convenience of description, when describing the above devices, they are divided into various modules according to functions and described separately. Of course, when implementing this specification, the functions of each module can be implemented in one or more software and / or hardware, or the modules that implement the same function can be implemented by a combination of multiple sub-modules or sub-units, etc. The device embodiments described above are only illustrative. For example, the division of the units is only a logical function division, and there may be other division methods in actual implementation. For example, multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the displayed or discussed coupling, direct coupling, or communication connection to each other can be through some interfaces, and the indirect coupling or communication connection of the devices or units can be in electrical, mechanical, or other forms.

[0166] As can be seen from the above, the device for determining hydraulic fracturing cracks based on the hydraulic fracturing pump shutdown water hammer signal provided in the embodiments of this specification can be well adapted to the hydraulic fracturing construction scenario. While accurately identifying the number and location of downhole hydraulic fracturing cracks, it can also accurately determine the liquid injection intensity of the downhole hydraulic fracturing cracks. Furthermore, it can more precisely and comprehensively determine the complete crack information of the downhole hydraulic fracturing cracks based on hydraulic fracturing, so as to better perform hydraulic fracturing construction on the target well subsequently.

[0167] In a specific scenario example, the method for determining hydraulic fracturing cracks based on the hydraulic fracturing pump shutdown water hammer signal provided in this specification can be applied to achieve the identification of multiple clusters of cracks based on the hydraulic fracturing pump shutdown water hammer signal. The specific implementation process can include the following content.

[0168] In this scenario example, considering that tight oil and gas are important unconventional resources, the main means for their development rely on hydraulic fracturing technology. During the fracturing construction process, timely evaluation of the fracturing construction effect is one of the key issues on site. Water hammer fracturing diagnosis is a fracturing monitoring technology that has emerged in recent years and has the characteristics of simple technical operation, low cost, and strong real-time performance. Accurately identifying the responses of each cluster of cracks from the hydraulic fracturing pump shutdown water hammer wave signal is the key to crack diagnosis. During the shutdown of the fracturing pump or the adjustment of the construction displacement, due to the inertia and compressibility of the fluid, pressure oscillations are generated in the wellbore, which is called the water hammer pressure wave. The formed water hammer pressure wave propagates in the wellbore and is reflected at downhole events. Different downhole crack opening conditions, crack scales, etc. result in different water hammer pressure signals. However, there is currently no method for identifying multiple clusters of cracks based on the hydraulic fracturing pump shutdown water hammer signal, resulting in the inability to accurately identify and evaluate multiple clusters of downhole fractures on site.

[0169] In view of the above problems, the applicant proposed a multi-cluster fracture identification method for the hydraulic fracture shut-in signal based on the method for determining hydraulic fractures from the hydraulic fracture shut-in signal. By performing cepstrum analysis on the high-frequency hydraulic pressure signal collected during hydraulic fracture shut-in (e.g., the hydraulic fracture shut-in signal of the target well), performing cross-correlation analysis on the spectral envelope characteristics after Fourier transform of the second derivative of the shut-in hydraulic signal, performing deconvolution operation on the first derivative of the shut-in hydraulic signal in the time domain, extracting the shut-in hydraulic response pulse as the source response in the deconvolution algorithm, and calculating the corresponding fracture reflection response sequence (e.g., the target reflection response sequence). Based on the amplitude of the fracture reflection response sequence and the attenuation relationship of the hydraulic shock wave between multi-cluster fractures, the reflection coefficients of all open fractures are inverted, and the relative relationship of the open fractures is judged by the magnitude of the reflection coefficient, so as to realize the identification and evaluation of the opening conditions of multi-cluster fractures in hydraulic fracturing.

[0170] In this scenario example, specifically, the first cluster of fractures can be located first, the maximum number of perforated clusters opened in the fracture section can be determined (e.g., candidate fractures), the degree of fracture opening can be predicted, and the fracture response attenuation can be fitted, and then the multi-cluster fractures in hydraulic fracturing can be accurately identified and evaluated to further analyze the problems existing in the construction process and optimize the next hydraulic fracturing design.

[0171] Among them, referring to Figure 7 As shown, the hydraulic shock wave pressure signal collected on the ground (e.g., the hydraulic fracture shut-in signal of the target well) can be expressed as the sum of the effective signal and the noise component. Among them, the composition of the effective signal is similar to that of a seismic record and can be described in the form of convolution. Specifically, it can be expressed as

[0172] x(t) = s(t) * w(t)

[0173] where x(t) is the effective signal, s(t) is the source pressure pulse that excites the hydraulic shock wave during the hydraulic fracture shut-in process, similar to the wavelet in a seismic record. w(t) is the reflection response sequence of the wellbore-multi-cluster fracture system (e.g., the auxiliary reflection response sequence), which is determined by the hydraulic impedance characteristics at the fracture position and can be used as an important feature for identifying fracture reflections.

[0174] During specific implementation, referring to Figure 8 As shown, cepstrum analysis can be performed on the shut-in hydraulic signal to obtain the corresponding cepstrum analysis result of the shut-in hydraulic signal. Then, according to the cepstrum analysis result of the shut-in hydraulic signal, the reflection time of the hydraulic shock wave from the wellhead to the downhole event (e.g., the reflection response time) is determined, and combined with the propagation speed of the hydraulic shock wave in the wellbore, the position of the downhole event is calculated.

[0175] To improve the resolution of cracks in the reflected signal of the water hammer wave, the core of identifying the crack response in the hydraulic fracturing pump shutdown water hammer lies in obtaining the reflection response sequence of the wellbore-fracture system. By extracting the source pressure pulse s(t) from the signal and then performing deconvolution on the effective signal x(t), the reflection response sequence of the wellbore-fracture system can be obtained. During the actual fracturing process, not every designed perforation position in each cluster will be opened. Therefore, it is necessary to predict the opening situation of the downhole fractures.

[0176] During specific implementation, the second derivative result of the pump shutdown water hammer signal in the time domain can be Fourier-transformed to obtain the envelope curve of the second derivative spectrum of the water hammer signal (for example, the envelope curve of the second derivative spectrum). According to the result of the maximum number of perforation clusters opened obtained in the first step, the reflection response sequences under all possible opening forms of the downhole perforation clusters are constructed and the envelopes of their spectra are calculated (for example, the envelope curve of the crack combination spectrum). For details, please refer to Figure 9 as shown. Then, cross-correlation analysis is performed on the envelope curve of the second derivative spectrum of the water hammer signal and the envelope curves of the spectra of all perforation cluster reflection response sequences, and the possible number of opened cracks and the opening position information of each crack are determined according to the cross-correlation coefficient.

[0177] During specific implementation, as shown in Figure 10 as shown, deconvolution and constraint are performed on the first derivative of the hydraulic fracturing pump shutdown water hammer signal to obtain the reflection response sequence of the cracks. Then, based on this emission response sequence, the reflection coefficients of each cluster of cracks are inverted through the crack reflection attenuation model, and the relative relationship of the opened cracks is judged by the magnitude of the reflection coefficient to identify and evaluate the hydraulic fracturing cracks. For details, please refer to Figure 11 as shown.

[0178] Specifically, when each crack is set the same, the reflection response amplitude of the first cluster of cracks shows the maximum value, and as the crack depth increases, the reflection response amplitudes of the rest gradually weaken and decay. To make the reflection response result completely characterize the downhole crack characteristics, it is necessary to deeply study the attenuation characteristics of the water hammer wave among each cluster of downhole cracks, clarify the variation law of the reflection response of each cluster of cracks, and accurately evaluate the characteristics of the cracks. For details, please refer to Figure 12 as shown. Among them, Figure 12 Specifically, it can represent a schematic diagram of the perforation reflection model considering losses.

[0179] During specific implementation, through the discovery of the reflection response law of the water hammer wave in the wellbore - multiple clusters of cracks, it is found that in the case of multiple identical cracks, the water hammer wave reflection response amplitude of the first cluster of cracks is the strongest, while the reflection response amplitudes of other clusters of cracks decay exponentially with the position sequence. The decay rate is affected by the reflection response amplitude of the first cluster of cracks. In order to fit the decay of the crack reflection response, a crack reflection attenuation fitting model is established.

[0180] Specifically, during the propagation of the water hammer wave in the system, when it encounters a crack, a part of the wave is reflected back to the wellhead, a part of the wave enters the crack and is dissipated, and the remaining part of the wave continues to transmit downward along the wellbore. When encountering the next cluster of cracks, reflection, dissipation, and transmission occur based on the remaining energy of the water hammer wave. The energies of reflection, dissipation, and transmission of the water hammer wave at each crack position in the wellbore-multi-cluster crack system are respectively composed of the reflection coefficient (R fn ), transmission coefficient (T fn ), and crack dissipation coefficient (L fn ). The numerical relationship among the three satisfies the following relationship:

[0181] R fn +L fn +T fn =1.

[0183] The amplitude of the reflection response reflected back to the wellhead by the first cluster of cracks in the pump shutdown water hammer wave can be calculated by the following formula:

[0184] E f1 =E 0 ×R f1 .

[0185] Among them, the energy E0 of the water hammer wave excited by the pump shutdown at the wellhead can be observed from the first peak value of the reflection response sequence of Figure 15 , and its value is 1. The calculation formula for the amplitude of the reflection response reflected back to the wellhead by the nth cluster of cracks is:

[0186]

[0187] Among them, E fn is the amplitude of the reflection response of the nth cluster of cracks in the pump shutdown water hammer wave.

[0188] During specific implementation, combined with the depth of the first cluster of cracks, the number of opened cracks, and the opening position information obtained in the previous two steps, the negative reflection response in the fracturing reflection response is constrained, so as to obtain the reflection response sequence of the downhole cracks (for example, the target reflection response sequence). Based on the amplitude of the reflection response sequence of the cracks and the attenuation relationship of the water hammer wave among multiple clusters of cracks, the reflection coefficients of all opened cracks are inverted; then, the relative relationship of the opened cracks is judged by the size of the reflection coefficient, so as to realize the identification and evaluation of the opening conditions of multiple clusters of fractures during fracturing.

[0189] Among them, the above-mentioned pump shutdown water hammer signal can be described by a convolution model. Calculate the rate of change of the pump shutdown water hammer pressure, and take the excitation response at the initial moment as the source pulse response in the deconvolution calculation, and the deconvolution operation can be performed on the rate of change of pressure signal to calculate the reflection response sequence of each cluster of cracks in the pump shutdown water hammer wave, and the amplitude reflects the energy size of the crack reflection response at the corresponding position.

[0190] The energy and fluctuation form of the spectral envelope of the above-mentioned pump-stopping water hammer signal can be used as an indication of the number and opening position of the fractured openings. The number and opening position of the fractured clusters are judged by the cross-correlation between the spectral envelope of the pump-stopping water hammer signal and all the perforation opening forms.

[0191] Specifically, when the same setting is made for each fracture, the reflection response results of multiple fractured clusters show that the reflection response of the fracture closest to the wellhead presents the maximum amplitude, and the reflection response amplitude gradually decays among multiple fractured clusters, and the law of amplitude decay shows a strong exponential form of decrease. The fracture reflection response in the pump-stopping water hammer wave can perform inversion calculations on the values of the fracture reflection coefficient, transmission coefficient, and fracture loss coefficient. The fracture reflection coefficient is affected by the fracture characteristics and is related to the fracture scale and cross-sectional area.

[0192] In this scenario example, for instance, it is planned to set a total of four clusters of perforations. According to the pump-stopping water hammer signal during fracturing, it can be preliminarily judged that no fracture is formed at the position of the second cluster of perforations.

[0193] First, perform cepstrum analysis on the signal to obtain the reflection position of the first cluster of fractures. The downhole fracture reflection time function calculated through the cepstrum diagram, combined with the propagation speed of the water hammer wave, obtains the depth of the first cluster of fractures as 4500m. Among them, the cepstrum analysis results are as Figure 13 shown.

[0194] Next, perform Fourier transform on the second derivative result of the pump-stopping water hammer signal during fracturing to obtain the spectral envelope curve. Calculate the correlation analysis between the signal envelope and the spectral envelope of the established perforation cluster reflection sequence. The correlation analysis results are as Figure 14 shown. The statistical results show that the highest cross-correlation coefficient of the spectral envelope occurs when the first, third, and fourth clusters of fractures are open, and the cross-correlation coefficient of the spectral envelope is the strongest at this time. Figure 15 The figure shows the normalized spectral envelope result diagram, showing spectral envelope curves with similar oscillation characteristics.

[0195] Finally, perform deconvolution operation on the first-stage derivative result of the pump-stopping water hammer signal during fracturing. The results are as Figure 16As shown. The source pulse of the pump shutdown water hammer response is extracted from the pressure change rate signal as the source response in the deconvolution algorithm, and the crack reflection response sequence is calculated according to the deconvolution algorithm. The reflection response sequence is constrained according to the number of open crack clusters determined by the spectral envelope and the crack opening position information to obtain the reflection response sequence of the crack. Based on the reflection energy magnitude of the first cluster of cracks and the attenuation relationship of the water hammer wave among multiple clusters of cracks, the reflection coefficients of the multiple open clusters of cracks are inverted. The reflection coefficient of the first crack can be determined according to the reflection energy of the first cluster of cracks. Based on the linear relationship between the loss coefficient and the reflection coefficient value of the crack, combined with the reflection energy of the second cluster of cracks, the loss coefficient and transmission coefficient of the first cluster of cracks can be iteratively calculated.

[0196] Through the above method, the reflection coefficients, transmission coefficients, and loss coefficient values of all cracks can be inverted. The inversion results of the crack reflection coefficient and the crack reflection response amplitude in this case are as Figure 17 shown. Among them, the inversion results of the reflection coefficients of the three cracks are 0.1248, 0.1225, and 0.1235 respectively. From the settings of the case, it can be known that the reflection coefficient values of the three cracks should be the same. Compared with the reflection coefficient of the first cluster of cracks, the error between the inversion result and the actual reflection coefficient is within 2%.

[0197] Through the above scenario example, it is verified that the method for determining hydraulic fracturing cracks based on the pump shutdown water hammer signal provided in this specification performs cepstrum analysis on the high-frequency water hammer pressure signal collected during pump shutdown, establishes a positioning model for the first cluster of cracks, and determines the position of the crack closest to the wellhead and the maximum number of perforation clusters that can be opened; performs Fourier transform on the second derivative result of the pump shutdown water hammer signal, and through spectral envelope cross-correlation analysis, establishes a crack opening prediction model, and determines the number of cracks opened and the opening position information of each crack; performs deconvolution operation and constraint on the first derivative of the pump shutdown water hammer signal to obtain the reflection response sequence of the crack, establishes a crack reflection attenuation model, inverses the reflection coefficients of each cluster of cracks, and judges the relative relationship of the open cracks according to the magnitude of the reflection coefficient, so as to identify and evaluate multiple clusters of hydraulic fracturing cracks.

[0198] Although the present specification provides method operation steps as described in the embodiments or flowcharts, more or fewer operation steps may be included based on conventional or non-creative means. The order of steps listed in the embodiments is only one way among the execution orders of numerous steps and does not represent the only execution order. When the actual device or client product is executed, it may be executed in the order of the method shown in the embodiments or the drawings or executed in parallel (for example, in an environment of parallel processors or multi-threaded processing, or even in a distributed data processing environment). The terms "comprising", "including" or any other variant thereof are intended to cover non-exclusive inclusion, such that a process, method, product or device comprising a series of elements not only includes those elements but also includes other elements not expressly listed, or further includes elements inherent to such process, method, product or device. Without further limitation, there is no exclusion of additional identical or equivalent elements in the process, method, product or device comprising the said elements. The terms such as "first", "second" are used to denote names and do not denote any particular order.

[0199] Those skilled in the art also know that in addition to implementing the controller in the form of pure computer-readable program code, the method steps can be logically programmed to enable the controller to implement the same functions in the form of logic gates, switches, application-specific integrated circuits, programmable logic controllers, embedded microcontrollers, etc. Therefore, such a controller can be regarded as a hardware component, and the devices included therein for implementing various functions can also be regarded as the structures within the hardware component. Or even, the devices for implementing various functions can be regarded as either software modules for implementing the method or structures within the hardware component.

[0200] The present specification can be described in the general context of computer-executable instructions executed by a computer, such as program modules. Generally, program modules include routines, programs, objects, components, data structures, classes, etc. that perform specific tasks or implement specific abstract data types. The present specification can also be practiced in a distributed computing environment where tasks are performed by remote processing devices connected through a communication network. In a distributed computing environment, program modules can be located in local and remote computer-readable storage media including storage devices.

[0201] As can be seen from the description of the above embodiments, those skilled in the art can clearly understand that this specification can be implemented by means of software plus a necessary general hardware platform. Based on such an understanding, the technical solution of this specification can essentially be embodied in the form of a software product, and this computer software product can be stored in a storage medium, such as ROM / RAM, magnetic disk, optical disk, etc., including several instructions for causing a computer device (which can be a personal computer, mobile terminal, server, or network device, etc.) to execute the methods described in each embodiment or some parts of the embodiments of this specification.

[0202] The embodiments in this specification are described in a progressive manner. For the same or similar parts between the embodiments, reference can be made to each other. The key point of each embodiment is to illustrate the differences from other embodiments. This specification can be used in many general or special computer system environments or configurations. For example: personal computers, server computers, handheld or portable devices, tablet devices, multi-processor systems, microprocessor-based systems, set-top boxes, programmable electronic devices, network PCs, minicomputers, mainframe computers, distributed computing environments including any of the above systems or devices, and so on.

[0203] Although this specification is depicted through embodiments, those of ordinary skill in the art know that this specification has many variations and changes without departing from the spirit of this specification. It is hoped that the appended claims will cover these variations and changes without departing from the spirit of this specification.

Claims

1. A method for determining a fracturing crack based on a fracturing pump stop water hammer signal, characterized in that: include: Obtain the fracturing pump stop water hammer signal of the target well; According to the pump-off water hammer signal of the target well during fracturing, the first cluster of fractures and the location of the first cluster of fractures are determined through cepstrum analysis. According to the crack positions of the first cluster of cracks, a plurality of candidate cracks are determined; According to the pump-off water hammer signal of the target well, multiple actually opened fracturing cracks and the crack positions of the fracturing cracks are determined from multiple candidate cracks by determining and according to the relevant frequency spectrum envelope; According to the pump-off water hammer signal of the target well, the reflection coefficient of the fracturing crack is determined by determining and according to the target reflection response sequence; The fluid inflow intensity of the hydraulic fracture is determined based on the reflection coefficient of the hydraulic fracture.

2. The method according to claim 1, characterized in that According to the water hammer signal of the target well during fracturing and pump stop, the first cluster of fractures is determined through cepstrum analysis, including: According to the water hammer signal of pump stop during fracturing of the target well, the fracture reflection response time is determined through cepstrum analysis; According to the crack reflection response time and the propagation speed of the water shock wave during fracturing pump stop, the first cluster of cracks and the crack positions of the first cluster of cracks are determined.

3. The method according to claim 2, characterized in that The method further comprises: According to the pump-stop water hammer signal of the target well during fracturing, a deconvolution operation is performed to obtain the reflection response sequence of the wellbore-fracture system as the auxiliary reflection response sequence.

4. The method according to claim 1, characterized in that According to the pump-off water hammer signal of the target well, multiple actually opened fracturing cracks and the crack positions of the fracturing cracks are determined from multiple candidate cracks by determining and according to the relevant spectrum envelope, including: Solve the second-order derivative data of the fracturing pump stop water hammer signal of the target well; and perform Fourier transform on the second-order derivative data to obtain the corresponding second-order derivative spectrum envelope curve; Determine a plurality of fracture combinations according to the plurality of candidate fractures; wherein the fracture combinations at least include a first cluster of fractures; Determine the spectrum envelope curves of multiple crack combinations; According to the envelope curve of the second-order derivative spectrum and the spectrum envelope curves of multiple crack combinations, the matching target crack combination is determined through cross-correlation analysis; According to the target fracture combination, the multiple fracturing fractures actually opened and the fracture positions of the fracturing fractures are determined.

5. The method according to claim 3, characterized in that: According to the pump-off water hammer signal of the target well, the reflection coefficient of the fracturing crack is determined by determining and according to the target reflection response sequence, including: Solve the first-order derivative data of the fracturing pump-off water hammer signal of the target well; Using the auxiliary reflection response sequence as a constraint, the first-order derivative data is deconvolved to obtain the reflection response sequence of the downhole fracture as the target reflection response sequence; The reflection coefficient of the hydraulic fracture is determined according to the fracture position of the hydraulic fracture and the target reflection response sequence.

6. The method according to claim 1, characterized in that After determining the fluid inflow intensity of the hydraulic fracture according to the reflection coefficient of the hydraulic fracture, the method further comprises: The development of the hydraulic fractures is evaluated based on the fluid inflow intensity of the hydraulic fractures.

7. The method according to claim 1, characterized in that After determining the fluid inflow intensity of the hydraulic fracture according to the reflection coefficient of the hydraulic fracture, the method further comprises: According to the fluid injection intensity, the fractures that meet the development requirements are selected as temporary plugging fractures; Set up corresponding temporary plugging agents for temporary plugging of cracks; Continue hydraulic fracturing of the target well.

8. A device for determining fracturing cracks based on fracturing pump stop water hammer signal, characterized in that: include: An acquisition module, used to acquire a fracturing pump stop water hammer signal of a target well; The first determination module is used to determine the first cluster of cracks and the crack positions of the first cluster of cracks according to the fracturing pump stop water hammer signal of the target well through cepstrum analysis; A second determination module is used to determine a plurality of candidate cracks according to the crack positions of the first cluster of cracks; The third determination module is used to determine the multiple actually opened fracturing cracks and the crack positions of the fracturing cracks from the multiple candidate cracks by determining and according to the relevant spectrum envelope according to the fracturing pump stop water hammer signal of the target well; A fourth determination module is used to determine the reflection coefficient of the fracturing crack according to the fracturing pump stop water hammer signal of the target well by determining and according to the target reflection response sequence; The fifth determination module is used to determine the fluid inflow intensity of the hydraulic fracture according to the reflection coefficient of the hydraulic fracture.

9. A computer device, characterized in that: The method comprises a processor and a memory for storing processor-executable instructions, wherein the processor implements the steps of the method according to any one of claims 1 to 7 when executing the instructions.

10. A computer-readable storage medium, characterized in that: Computer instructions are stored thereon, and when the instructions are executed by a processor, the steps of the method according to any one of claims 1 to 7 are implemented.

Images