A method and device for calculating multi-scale natural crack stiffness coefficient

Abstract

The present specification relates to the field of rock physics technology, and provides a method and device for calculating the stiffness coefficient of a multi-scale natural fracture. The method includes: obtaining the positional relationship between the target horizontal well and the natural fracture, and determining the angle between the natural fracture and the wellbore in the first construction section of the first interval; performing fracturing construction on the target horizontal well, and determining the fracturing displacement in the second construction section of the second interval; determining the third construction section according to the overlapping part of the first construction section and the second construction section; monitoring and obtaining the microseismic data of the formation where the target horizontal well and the natural fracture are located in the third construction section; using the surface where the natural fracture is located as the reference plane, screening the microseismic event points in the microseismic data; calculating the rupture area of ​​the natural fracture according to the screened microseismic data; measuring the casing deformation of the target horizontal well; and calculating the stiffness coefficient of the natural fracture according to the casing deformation and the rupture area of ​​the natural fracture. Through the embodiments of the present invention, the stiffness coefficient of the natural fracture can be efficiently and accurately measured.

Description

Technical Field

[0001] The present specification relates to the field of rock physics technology, and in particular to a method and device for calculating multi-scale natural fracture stiffness coefficients. Background Art

[0002] With the continuous deepening of oil and gas exploration, it is becoming increasingly difficult to increase the reserves and production of conventional oil and gas resources. The strategic position of unconventional oil and gas resources is becoming increasingly important. The reservoirs of unconventional oil and gas resources have the characteristics of low permeability and poor seepage capacity. When conventional fracturing technology cannot meet the ideal production capacity, it is necessary to further fractur the reservoirs of unconventional oil and gas resources to form high permeability channels. Since the reservoirs of unconventional oil and gas resources generally have multi-scale natural fractures, the stiffness coefficient of natural fractures is an important prerequisite for determining a reasonable fracturing construction process. Therefore, accurately obtaining the stiffness coefficient of natural fractures is very important for the construction of a high-permeability channel. The exploitation of unconventional oil and gas resources is of vital importance. At present, the stiffness coefficient of natural fractures is mainly measured by measuring indoor cores or conducting direct shear tests on in-situ outcrop rocks. However, it is difficult to obtain complete cores in the method of measuring indoor cores. The outcrop rocks in the direct shear test of in-situ outcrop rocks can only reflect the properties of natural fractures in part of the actual underground reservoir. For natural fractures as a whole, the measurement accuracy is greatly limited. Therefore, a calculation method for the stiffness coefficient of multi-scale natural fractures is urgently needed to efficiently and accurately measure the stiffness coefficient of multi-scale natural fractures. Summary of the invention

[0003] In view of the fact that the current measurement process of natural fracture stiffness coefficient is complicated and the measurement accuracy is limited, this solution is proposed to overcome the above problems or at least partially solve the above problems.

[0004] In one aspect, some embodiments of the present specification provide a method, comprising:

[0005] Obtaining the positional relationship between the target horizontal well and the natural fracture, and determining the wellbore angle between the natural fracture and the target horizontal well in the first construction section of the first interval;

[0006] Performing a fracturing operation on the target horizontal well, and determining a second construction section in the second interval of the fracturing operation at a fracturing displacement;

[0007] Determine a third construction section according to the overlapping portion of the first construction section and the second construction section;

[0008] Monitoring and obtaining microseismic data of the target horizontal well and the formation where the natural fracture is located in the third construction section;

[0009] Taking the surface where the natural fracture is located as the reference surface, screening and removing the microseismic event points in the microseismic data whose distances from the microseismic event points to the corresponding reference surface are greater than a first threshold;

[0010] Calculate the rupture area of ​​natural fractures based on the screened microseismic data;

[0011] Measuring the casing deformation of the target horizontal well;

[0012] The stiffness coefficient of the natural fracture is calculated according to the deformation of the casing and the rupture area of ​​the natural fracture.

[0013] Furthermore, the first interval is 15°-60°; the second interval is 18m 3 / min-22m 3 / min.

[0014] Further, calculating the wellbore angle between the natural fracture and the target horizontal well includes:

[0015] The angle between the natural fracture and the wellbore of the target horizontal well is obtained by the following formula:

[0016]

[0017] Among them, σ1 is the maximum horizontal ground stress, σ2 is the minimum horizontal ground stress, S w is the cohesion of the natural fracture, u w is the internal friction coefficient of the weak surface, It is the angle between the normal direction of the natural fracture and the horizontal maximum geostress, that is, the angle between the horizontal wellbore and the natural fracture.

[0018] Furthermore, the monitoring obtains microseismic data of the target horizontal well and the formation where the natural fracture is located in the third construction section, including:

[0019] Measuring the seismic signal of the third construction section by using a seismic geophone;

[0020] Performing waveform clustering analysis preprocessing on the seismic signal to suppress noise;

[0021] Inputting the preprocessed seismic signal into a microseismic positioning imaging algorithm to obtain the microseismic data;

[0022] The microseismic data includes a plurality of microseismic event points, and each microseismic event point is represented by a corresponding spatial position and a seismic moment.

[0023] Furthermore, the seismic signal is preprocessed by waveform clustering analysis, including clustering analysis of the first arrival time regularity, spectrum characteristics and polarization characteristics of the seismic signal received by each seismic detector to distinguish and eliminate noise signals.

[0024] Furthermore, the stiffness coefficient of the natural fracture is calculated according to the casing deformation and the rupture area of ​​the natural fracture, including:

[0025] The stiffness coefficient of natural cracks is calculated using the following formula:

[0026]

[0027] Among them, M i is the seismic moment of a single microseismic event point, n is the number of all microseismic event points, M0 is the total seismic moment of all microseismic event points, u is the stiffness coefficient of the natural fracture, A is the rupture area of ​​the natural fracture, and D is the slip amount of the natural fracture.

[0028] On the other hand, some embodiments of the present specification also provide a device for calculating a multi-scale natural fracture stiffness coefficient, the device comprising:

[0029] An acquisition module, used to acquire the positional relationship between the target horizontal well and the natural fracture, and determine the wellbore angle between the natural fracture and the target horizontal well in the first construction section of the first interval;

[0030] A fracturing module, used for performing fracturing construction on the target horizontal well and determining a second construction section of a second interval of a fracturing displacement during the fracturing construction;

[0031] A construction section determination module, used to determine a third construction section according to an overlapping portion of the first construction section and the second construction section;

[0032] A monitoring module, used for monitoring and obtaining microseismic data of the target horizontal well and the formation where the natural fracture is located in the third construction section;

[0033] A screening module, for screening and removing microseismic event points in the microseismic data whose distance from the microseismic event point to the corresponding reference surface is greater than a first threshold, using the surface where the natural fracture is located as a reference surface;

[0034] A rupture area calculation module is used to calculate the rupture area of ​​natural fractures based on the screened microseismic data;

[0035] A casing deformation measurement module, used to measure the casing deformation of the target horizontal well;

[0036] The stiffness coefficient calculation module is used to calculate the stiffness coefficient of the natural fracture according to the casing deformation and the rupture area of ​​the natural fracture.

[0037] On the other hand, some embodiments of the present specification further provide a computer device, including a memory, a processor, and a computer program stored in the memory, wherein when the computer program is executed by the processor, the instructions of the above method are executed.

[0038] On the other hand, some embodiments of the present specification further provide a computer storage medium having a computer program stored thereon, wherein when the computer program is executed by a processor of a computer device, the instructions of the above method are executed.

[0039] On the other hand, some embodiments of the present specification further provide a computer program product, wherein the computer program product comprises a computer program, and when the computer program is executed by a processor of a computer device, the instructions of the above method are executed.

[0040] One or more technical solutions provided by some embodiments of this specification have at least the following technical effects:

[0041] The embodiments of the present specification first obtain the positional relationship between the target horizontal well and the natural fracture, automatically determine the wellbore angle between the natural fracture and the target horizontal well in the first construction section of the first interval, then perform pressure construction on the target horizontal well, and automatically determine the fracturing displacement in the second construction section of the second interval. The relative possibility of natural fracture slippage in the first construction section and the second construction section is greater. Then, the overlapping part of the first construction section and the second construction section is selected as the third construction section, and the microseismic signal during the third construction section is monitored, which is conducive to ensuring that the signal data obtained by monitoring is caused by construction fracturing and originates from the natural fracture, thereby improving the accuracy and efficiency of microseismic signal monitoring, and accurately eliminating clutter in the microseismic signal through waveform clustering analysis, and obtaining the corresponding microseismic positioning imaging algorithm using the microseismic positioning imaging algorithm. In order to further ensure the accuracy of the microseismic data, the surface where the natural fracture is located is used as the reference plane, and the microseismic event points in the microseismic data whose distance from the microseismic event point to the corresponding reference plane is greater than a first threshold are screened and removed, and then the rupture area of ​​the natural fracture is calculated according to the screened microseismic data, and the casing deformation of the target horizontal well is measured. The stiffness coefficient of the multi-scale natural fracture is calculated by the casing deformation and the rupture area of ​​the natural fracture. Different from the stiffness coefficient of the natural fracture measured by drilling core (affected by the scale effect), the embodiments of the present specification can realize the real-time, efficient and accurate calculation of the multi-scale natural fracture stiffness coefficient at the in-situ scale of the formation during fracturing construction (not affected by the scale effect), so as to adjust the construction status in real time according to the calculated natural fracture stiffness coefficient.

[0042] The above description is only an overview of the technical solutions of some embodiments of this specification. In order to more clearly understand the technical means of some embodiments of this specification, they can be implemented in accordance with the contents of the specification. In order to make the above and other purposes, features and advantages of some embodiments of this specification more obvious and easy to understand, the specific implementation methods of some embodiments of this specification are listed below. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] In order to more clearly illustrate some embodiments of this specification or technical solutions in the prior art, the following briefly introduces the drawings required for the embodiments or prior art descriptions. Obviously, the drawings described below are only some embodiments recorded in this specification. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative labor. In the drawings:

[0044] Figure 1 A flow chart showing a method for calculating a multi-scale natural fracture stiffness coefficient in some embodiments of this specification;

[0045] Figure 2 A schematic diagram of the process of characterizing the distribution characteristics of natural fractures in some embodiments of this specification;

[0046] Figure 3 A schematic diagram of the angle between the natural fracture and the wellbore of the target horizontal well in some embodiments of this specification;

[0047] Figure 4 This is a schematic diagram of the steps of monitoring and obtaining microseismic data in some embodiments of this specification;

[0048] Figure 5 A schematic diagram of a microseismic event point corresponding to a single natural fracture reference plane in some embodiments of this specification;

[0049] Figure 6 Schematic diagram of the disc dislocation surface in some embodiments of this specification;

[0050] Figure 7 A schematic diagram of the relationship between the projection circle and the rectangular frame in some embodiments of this specification;

[0051] Figure 8 This is a schematic diagram of the relationship between casing deformation and fault slip in some embodiments of this specification;

[0052] Fig. 9 A schematic diagram of microseismic event points corresponding to multiple natural fracture reference surfaces in some embodiments of this specification;

[0053] Fig.10 A schematic diagram of the structure of a device for calculating a multi-scale natural fracture stiffness coefficient in some embodiments of this specification;

[0054] Fig.11 This is a schematic diagram of the computer device structure provided in some embodiments of this specification.

[0055] [Description of Reference Numerals]

[0056] 201. Related attribute interpretation results;

[0057] 202. Curvature body attribute interpretation results;

[0058] 203. Likelihood body attribute explanation results;

[0059] 204. Distribution characteristics of natural fractures;

[0060] 51. Target horizontal wellbore;

[0061] 52. Casing deformation point;

[0062] 53. Microseismic event points;

[0063] 54. Natural fracture datum surface;

[0064] 61. Upper surface of the disk;

[0065] 62, lower surface of the disc;

[0066] 63. Dislocation surface;

[0067] 71. Projection circle;

[0068] 72. Rectangular frame;

[0069] 91. Target horizontal well;

[0070] 92. Natural fracture datum surface;

[0071] 93. Natural fracture datum surface;

[0072] 94. Natural fracture datum surface;

[0073] 95. Microseismic event points;

[0074] 96. Casing deformation point;

[0075] 97. Casing deformation point;

[0076] 98. Casing deformation point;

[0077] 1001. Get module;

[0078] 1002. Fracturing module;

[0079] 1003. Construction section determination module;

[0080] 1004. Monitoring module;

[0081] 1005. Screening module;

[0082] 1006. Fracture area calculation module;

[0083] 1007. Casing deformation measurement module;

[0084] 1008. Stiffness coefficient calculation module;

[0085] 1102. Computer equipment;

[0086] 1104. Processor;

[0087] 1106. Memory;

[0088] 1108, driving mechanism;

[0089] 1110, input / output interface;

[0090] 1112. Input device;

[0091] 1114. Output device;

[0092] 1116. Presentation equipment;

[0093] 1118. Graphical user interface;

[0094] 1120. Network interface;

[0095] 1122. Communication link;

[0096] 1124. Communication bus. DETAILED DESCRIPTION

[0097] In order to enable those skilled in the art to better understand the technical solutions in this specification, the technical solutions in the embodiments of this specification will be clearly and completely described below in conjunction with the drawings in some embodiments of this specification. Obviously, the described embodiments are only part of the embodiments of this specification, not all of the embodiments. Based on some embodiments in this specification, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of this specification.

[0098] It should be noted that the terms "first", "second", etc. in the specification and claims of this article and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchangeable where appropriate, so that the embodiments of this article described here can be implemented in an order other than those illustrated or described here. In addition, the terms "including" and "having" and any of their variations are intended to cover non-exclusive inclusions, for example, a process, method, device, product or equipment that includes a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or equipment. It should be noted that the acquisition, storage, use, processing, etc. of data in the technical solution of this application are in compliance with the relevant provisions of national laws and regulations.

[0099] Figure 1 It is a flow chart of a method for calculating the multi-scale natural fracture stiffness coefficient provided in an embodiment of the present invention. This specification provides the method operation steps described in the embodiment or flow chart, but may include more or fewer operation steps based on conventional or non-creative labor. The order of steps listed in the embodiment is only one way of executing the steps among many orders, and does not represent the only order of execution. When the actual system or device product is executed, it can be executed in the order or in parallel according to the method shown in the embodiment or the accompanying drawings. Specifically, Figure 1 As shown, the method may include:

[0100] S101: Acquire the positional relationship between the target horizontal well and the natural fracture, and determine the wellbore angle between the natural fracture and the target horizontal well in the first construction section of the first interval;

[0101] S102: performing a fracturing operation on the target horizontal well, and determining a second operation section in a second interval of a fracturing displacement during the fracturing operation;

[0102] S103: determining a third construction section according to the overlapping portion of the first construction section and the second construction section;

[0103] S104: monitoring and obtaining microseismic data of the target horizontal well and the formation where the natural fracture is located in the third construction section;

[0104] S105: taking the surface where the natural fracture is located as the reference surface, screening and removing the microseismic event points in the microseismic data whose distances from the microseismic event points to the corresponding reference surface are greater than a first threshold;

[0105] S106: calculating the rupture area of ​​the natural fracture according to the screened microseismic data;

[0106] S107: measuring the casing deformation of the target horizontal well;

[0107] S108: Calculate the stiffness coefficient of the natural fracture according to the casing deformation and the rupture area of ​​the natural fracture.

[0108] The embodiments of the present specification first obtain the positional relationship between the target horizontal well and the natural fracture, automatically determine the wellbore angle between the natural fracture and the target horizontal well in the first construction section of the first interval, then perform pressure construction on the target horizontal well, and automatically determine the fracturing displacement in the second construction section of the second interval. The relative possibility of natural fracture slippage in the first construction section and the second construction section is greater. Then, the overlapping part of the first construction section and the second construction section is selected as the third construction section, and the microseismic signal during the third construction section is monitored, which is conducive to ensuring that the signal data obtained by monitoring is caused by construction fracturing and originates from the natural fracture, thereby improving the accuracy and efficiency of microseismic signal monitoring, and accurately eliminating clutter in the microseismic signal through waveform clustering analysis, and obtaining the corresponding microseismic positioning imaging algorithm using the microseismic positioning imaging algorithm. In order to further ensure the accuracy of the microseismic data, the surface where the natural fracture is located is used as the reference plane, and the microseismic event points in the microseismic data whose distance from the microseismic event point to the corresponding reference plane is greater than a first threshold are screened and removed, and then the rupture area of ​​the natural fracture is calculated according to the screened microseismic data, and the casing deformation of the target horizontal well is measured. The stiffness coefficient of the multi-scale natural fracture is calculated by the casing deformation and the rupture area of ​​the natural fracture. Different from the stiffness coefficient of the natural fracture measured by drilling core (affected by the scale effect), the embodiments of the present specification can realize the real-time, efficient and accurate calculation of the multi-scale natural fracture stiffness coefficient at the in-situ scale of the formation during fracturing construction (not affected by the scale effect), so as to adjust the construction status in real time according to the calculated natural fracture stiffness coefficient.

[0109] Specifically, in some embodiments, referring to the attached Figure 2 , the positional relationship between the target horizontal well and the natural fracture can be obtained by using seismic interpretation to characterize the distribution characteristics of natural fractures in the formation. For example, based on 3D seismic data, the distribution characteristics of natural fractures can be obtained by extracting three attributes: coherence, curvature and likelihood body, and then the relative positional relationship between natural fractures and the target horizontal wellbore can be clarified. Figure 2As shown, by combining the coherent attribute interpretation result 201, the curvature body attribute interpretation result 202 and the likelihood body attribute interpretation result 203 of the geological structure in the stratum, the distribution characteristics 204 of the natural fractures can be characterized, and then the positional relationship between the natural fractures and the target horizontal well in space can be characterized based on the distribution characteristics 204 of the natural fractures, so as to determine the first construction section of the first interval between the wellbore angle of the natural fracture and the target horizontal well. It should be noted that when determining the wellbore angle of the natural fracture and the target horizontal well in the first construction section of the first interval according to the positional relationship between the natural fracture and the target horizontal well, the distribution characteristics of the natural fractures that have been characterized are used as a reference basis, and the distribution characteristics of the natural fractures that have been characterized are themselves a prediction or estimation result, which can reflect the actual geological structure of the stratum to a certain extent, but cannot fully represent the actual geological structure of the stratum. Therefore, the first construction section is a construction section that is further distinguished based on the prediction result, and the first construction section can include multiple sub-construction sections. In addition, the characterization of the distribution characteristics of natural fractures can also be completed based on intelligent algorithms such as deep learning, which is not limited in this article.

[0110] In some embodiments, after determining the first construction section, the target horizontal well is subjected to fracturing construction. At different stages of fracturing construction, the fracturing displacement will be different. According to the fracturing displacement design scheme before the fracturing construction, and the displacement is monitored in real time during the fracturing construction, the second construction section of the fracturing displacement in the second interval is determined. It should be noted that the second construction section may include multiple sub-construction sections, because the fracturing displacement can be expressed as a function that changes continuously over time. For a continuously changing function, when the function value is in a fixed interval, there may be multiple intervals of the corresponding independent variable. In addition, the fracturing construction may be hydraulic fracturing, or liquid carbon dioxide fracturing, etc., which is not limited in this article.

[0111] In some embodiments, the first interval is 15°-60°; the second interval is 18m 3 / min-22m 3 / min.

[0112] Specifically, in some embodiments, when the angle between the natural fracture and the wellbore of the target horizontal well is in the first interval and the fracturing displacement is in the second interval, in the face of fracturing construction, the possibility of slippage in the natural fracture is greater, that is, the relative possibility of slippage in the natural fracture in the first construction section and the second construction section is greater, and determining the first construction section and the second construction section is conducive to further determining that the signal data obtained by monitoring is caused by construction fracturing and originates from the construction section where the natural fracture is located, and the relative possibility of slippage in the natural fracture in the overlapping part of the first construction section and the second construction section (i.e., the third construction section) is not less than that in the first construction section and the second construction section, and the seismic signal data monitored in the third construction section is most likely to be caused by construction fracturing and originate from the location of the natural fracture.

[0113] In some embodiments, calculating the wellbore angle between the natural fracture and the target horizontal well may include:

[0114] The angle between the natural fracture and the wellbore of the target horizontal well is obtained by the following formula:

[0115]

[0116] Among them, σ1 is the maximum horizontal ground stress, σ2 is the minimum horizontal ground stress, S w is the cohesion of the natural fracture, u w is the internal friction coefficient of the weak surface, It is the angle between the normal direction of the natural fracture and the horizontal maximum geostress, that is, the angle between the horizontal wellbore and the natural fracture.

[0117] It can be understood that, in some embodiments, after obtaining the positional relationship between the target horizontal well and the natural fracture, it is necessary to determine the wellbore angle between the natural fracture and the target horizontal well in the first construction section of the first interval. The accuracy of obtaining the angle based only on the distribution characteristics of the natural fractures that have been characterized is low. By introducing an angle calculation formula for formations containing natural fractures, a more accurate wellbore angle between the natural fracture and the target horizontal well is calculated based on the distribution characteristics of the natural fractures that have been characterized. Specifically, first, based on the distribution characteristics of the natural fractures that have been characterized, a part of the construction sections where the wellbore angle between the natural fracture and the target horizontal well is greatly different from that in the first interval are excluded. Then, the wellbore angle between the natural fracture and the target horizontal well is more accurately calculated in combination with the formation geological parameters of the natural fracture. Refer to the attached Figure 3 , σ1 is the maximum horizontal ground stress, σ2 is the minimum horizontal ground stress, It is the angle between the normal direction of the natural fracture and the horizontal maximum geostress. The magnitude and direction of the horizontal maximum geostress and the horizontal minimum geostress can be obtained through the interpretation of logging data, the shape of well wall collapse and indoor rock mechanics experiments. The cohesion of natural fractures and the internal friction coefficient of the weak surface can be obtained by conducting indoor triaxial compression and direct shear rock mechanics experiments on downhole cores.

[0118] Refer to the attached Figure 4 In some embodiments, the monitoring to obtain microseismic data of the target horizontal well and the formation where the natural fracture is located in the third construction section may include:

[0119] S401: measuring the seismic signal of the third construction section by using a seismic geophone;

[0120] S402: performing waveform clustering analysis preprocessing on the seismic signal to suppress noise;

[0121] S403: inputting the preprocessed seismic signal into a microseismic positioning imaging algorithm to obtain the microseismic data;

[0122] S404: The microseismic data includes a plurality of microseismic event points, and each microseismic event point is represented by a corresponding spatial position and a seismic moment.

[0123] Specifically, in some embodiments, a seismic detector is an electromechanical conversion device that converts seismic waves transmitted to the ground or water into electrical signals, and is a key component for field data collection of a seismograph. In some embodiments, the seismic detector may be one or more of a ground detector, a well detector, and a shallow well buried detector. One or more seismic detectors may be deployed, and this document does not limit this.

[0124] In some embodiments, after the seismic detector monitors and obtains the seismic signal of the third construction section, it is necessary to perform waveform clustering analysis preprocessing on the seismic signal to suppress noise. The noise may include wellbore waves and instrument noise signals, well site drilling rigs, construction vehicles, and falling objects. The waveform clustering analysis preprocessing can perform clustering analysis on the signal segments interfered by noise to distinguish the noise signal from the microseismic signal, and remove the noise signal from the seismic signal. Thereafter, the preprocessed seismic signal (microseismic signal) is input into the microseismic positioning imaging algorithm. The microseismic positioning imaging algorithm can determine the position and seismic moment of the corresponding microseismic event point in the formation according to the microseismic signal. Specifically, the microseismic data includes multiple microseismic event points, and each microseismic event point is jointly represented in the form of a corresponding spatial position and a seismic moment. See the attached Figure 5, fracturing construction is carried out on the target horizontal well, and casing deformation occurs when fracturing fluid is pumped into the target horizontal wellbore 51. The appearance of the casing deformation point 52 is due to the slippage of the natural fracture during the fracturing construction. The multiple microseismic event points 53 caused by the slippage of the natural fracture are generally distributed irregularly in the shape of strips near the natural fracture reference plane 54. The positions and seismic moments of different microseismic event points 53 in the formation are different. The positions in the formation can be represented by establishing a three-dimensional coordinate axis, and the seismic moment can be represented by the diameter or radius of the sphere of the microseismic event point, which is not limited in this article.

[0125] Further, see Attachment Figure 5 It can be seen that when multiple microseismic event points 53 are generally irregularly distributed in strips near the natural fracture reference plane 54, the distances between different microseismic event points 53 and the natural fracture reference plane 54 are different. Considering that not all microseismic event points obtained by monitoring and analysis are stimulated by fracturing construction, or the microseismic event points are generated by non-corresponding natural fracture slip but happen to be monitored, it is necessary to eliminate some microseismic event points whose distance from the natural fracture reference plane is greater than the first threshold to further ensure the accuracy of the microseismic data.

[0126] Furthermore, in some embodiments, the seismic signal is preprocessed by waveform clustering analysis, including clustering analysis of the first arrival time regularity, spectrum characteristics and polarization characteristics of the seismic signal received by each seismic detector to distinguish and eliminate noise signals.

[0127] It can be understood that, in some embodiments, cluster analysis refers to the analysis process of grouping a collection of physical or abstract objects into multiple classes composed of similar objects. Waveform cluster analysis is based on the waveform similarity between signals of the same type and the attribute feature differences between signals of different types to achieve type discrimination of different types of microseismic signals or noise signals. Specifically, waveform cluster analysis can analyze the differences between the first arrival time rules, spectrum characteristics, and polarization characteristics of microseismic signals and the characteristics corresponding to noise signals, calculate the similarity distance for different features in turn, and perform clustering to extract features. For the first arrival time rules: analyze the signal source position and propagation path; for polarization characteristics: noise signals have no obvious polarization direction while microseismic signals have obvious linear polarization characteristics; for spectrum characteristics: microseismic signals have broadband characteristics in the spectrum while noise signals have narrowband or single-frequency characteristics in the spectrum. According to the first arrival time rules, spectrum characteristics, and polarization characteristics of the received seismic signals, effective identification and filtering of noise signals can be achieved.

[0128] In some embodiments, the calculating of the stiffness coefficient of the natural fracture according to the deformation of the casing and the rupture area of ​​the natural fracture may include:

[0129] The stiffness coefficient of natural cracks is calculated using the following formula:

[0130]

[0131] Among them, M i is the seismic moment of a single microseismic event point, n is the number of all microseismic event points, M0 is the total seismic moment of all microseismic event points, u is the stiffness coefficient of the natural fracture, A is the rupture area of ​​the natural fracture, and D is the slip amount of the natural fracture.

[0132] It can be understood that, in some embodiments, after the microseismic data is determined, each microseismic event point in the microseismic data represents a rupture of a natural fracture. Based on the disk displacement algorithm, the rupture surface of the natural fracture corresponding to a microseismic event point is regarded as the displacement surface when the disk is displaced. Figure 6 As shown in FIG. 1 , the upper surface 61 and the lower surface 62 of the disk respectively represent the upper surface and the lower surface corresponding to the rupture occurrence point in the stratum, the dislocation surface 63 is the rupture surface formed at a single microseismic event point, and the dislocation surface 63 is circular, and the radius of the dislocation surface 63 is the same as the radius of the small ball representing the single microseismic event point. Then, based on the three-dimensional coordinate axis, the projections of the small balls represented by all microseismic event points on the natural fracture reference plane (corresponding to multiple projection circles) are obtained, and the rectangular frame is used to frame and gradually shrink the rectangular frame until the edges of all projection circles are closely connected to each other, so as to obtain the rupture surfaces of all microseismic event points and obtain the corresponding total rupture area of ​​the natural fracture. Refer to FIG. Figure 7 The multiple projected circles 71 and rectangular frames 72 shown, the area of ​​the rectangular frame 72 is the rupture area of ​​the natural fracture, thereby achieving a quantitative characterization of the actual rupture area of ​​the natural fracture during the fracturing process under the premise of ensuring that each microseismic event point is closely related to the natural fracture, and taking into account the problem that each microseismic event point affects each other, resulting in a larger total rupture surface, and the non-projected circle area in the rectangular frame is also regarded as a part of the natural fracture area, which has higher accuracy than directly adding the projection circle area.

[0133] In some embodiments, the casing deformation can be measured by using a multi-arm caliper and / or a maximum bridge plug passing method. If a multi-arm caliper is used for measurement, the casing deformation is the difference between the original casing inner diameter and the minimum inner diameter at the casing deformation point. If the maximum bridge plug passing method is used for measurement, the casing deformation is the difference between the casing inner diameter at the casing deformation point and the maximum bridge plug outer diameter that can pass through after encountering resistance. The present invention does not limit the method for measuring the casing deformation. One measurement method can be used, or multiple measurement methods can be used and the average can be taken. After measuring the casing deformation, the natural fracture slip can be calculated based on the casing deformation. Specifically, when the natural fracture is displaced or slipped, the casing will be subjected to strong shearing and undergo local sharp shrinkage deformation. The geological parameters during fracturing construction can be used to establish a finite element model to obtain the following. Figure 8 The relationship between casing deformation and fault slip (i.e., natural fracture slip) is shown in Figure 1. The relationship between casing deformation and fault slip corresponding to different natural fracture and wellbore angles (15 degrees, 30 degrees, 45 degrees) is different. In general, casing deformation increases with the increase of natural fracture slip. This enables efficient and accurate determination of natural fracture slip based on the measured casing deformation.

[0134] In some embodiments, the total seismic moment is obtained by summing up the seismic moments of all microseismic event points, and then the stiffness coefficient of natural fractures in the formation can be calculated in real time, efficiently and accurately based on the rupture area and slip amount of natural fractures. It should be noted that during fracturing construction, a target horizontal well may face multiple casing deformations. Fig. 9 During the fracturing process, the target horizontal well 91 successively passes through the natural fracture datum plane 92, the natural fracture datum plane 93 and the natural fracture datum plane 94. There are multiple microseismic event points 95 with different seismic moments on each natural fracture plane, wherein the natural fracture datum plane 92 corresponds to the casing deformation point 96, the natural fracture datum plane 93 corresponds to the casing deformation point 97, and the natural fracture datum plane 94 corresponds to the casing deformation point 98. Moreover, the natural fracture distribution characteristics (including faults, formation bending, microcracks and micro-fracture zones) corresponding to the natural fracture datum plane 92, the natural fracture datum plane 93 and the natural fracture datum plane 94 are different. Moreover, during the fracturing construction process of the same target horizontal well, the natural fracture stiffness coefficients corresponding to multiple natural fractures can be measured. Compared with the stiffness coefficient of the drilled core or outcrop rock, it is not affected by the limitations of the rock size and can reflect the characteristics of multi-scale natural fractures in the formation.

[0135] In some embodiments, as shown in the calculation results in Table 1, the slip amount of the natural fracture is calculated by the casing deformation, the total seismic moment is calculated according to the seismic moment of all microseismic event points, and the rupture area of ​​the natural fracture is calculated according to the seismic moment and distribution position of all microseismic event points, thereby achieving real-time, efficient and accurate calculation of multi-scale natural fracture stiffness coefficients, providing real-time and effective judgment basis for subsequent fracturing construction, which is of great significance to improving the accuracy of the fracturing prediction model and optimizing the construction parameters.

[0136] Table 1 Schematic diagram of calculation results of natural crack stiffness coefficient

[0137]

[0138] It should be noted that, although the operations of the method of the present invention are described in a specific order in the above embodiments and the accompanying drawings, this does not require or imply that the operations must be performed in the specific order, or that all the operations shown must be performed to achieve the desired results. Additionally or alternatively, some steps may be omitted, multiple steps may be combined into one step, and / or one step may be decomposed into multiple steps.

[0139] Corresponding to the above method, some embodiments of this specification also provide a calculation device for multi-scale natural fracture stiffness coefficient, referring to Fig.10 As shown, in some embodiments, the apparatus may include:

[0140] An acquisition module 1001 is used to acquire the positional relationship between the target horizontal well and the natural fracture, and determine the wellbore angle between the natural fracture and the target horizontal well in the first construction section of the first interval;

[0141] A fracturing module 1002 is used to perform fracturing construction on the target horizontal well and determine the fracturing displacement in the second construction section of the second interval during the fracturing construction;

[0142] A construction section determination module 1003, configured to determine a third construction section according to an overlapping portion of the first construction section and the second construction section;

[0143] Monitoring module 1004, used to monitor and obtain microseismic data of the target horizontal well and the formation where the natural fracture is located in the third construction section;

[0144] A screening module 1005 is used to screen and remove microseismic event points in the microseismic data whose distance from the microseismic event point to the corresponding reference surface is greater than a first threshold, taking the surface where the natural fracture is located as a reference surface;

[0145] A rupture area calculation module 1006 is used to calculate the rupture area of ​​natural fractures based on the filtered microseismic data;

[0146] The casing deformation measurement module 1007 is used to measure the casing deformation of the target horizontal well;

[0147] The stiffness coefficient calculation module 1008 is used to calculate the stiffness coefficient of the natural fracture according to the casing deformation and the rupture area of ​​the natural fracture.

[0148] For the convenience of description, the above device is described in various units according to their functions. Of course, when implementing this specification, the functions of each unit can be implemented in the same or multiple software and / or hardware.

[0149] It should be noted that in the embodiments of this specification, the user information (including but not limited to user device information, user personal information, etc.) and data (including but not limited to data used for analysis, stored data, displayed data, etc.) involved are all information and data authorized by the user and fully authorized by all parties.

[0150] The embodiments of this specification also provide a computer device. Fig.11 As shown, in some embodiments of the present specification, the computer device 1102 may include one or more processors 1104, such as one or more central processing units (CPUs) or graphics processing units (GPUs), and each processing unit may implement one or more hardware threads. The computer device 1102 may also include any memory 1106, which is used to store any kind of information such as code, settings, data, etc. In a specific embodiment, the computer program on the memory 1106 and can be run on the processor 1104, when the computer program is run by the processor 1104, the instructions of the method described in any of the above embodiments may be executed. Non-limitingly, for example, the memory 1106 may include any one or more combinations of the following: any type of RAM, any type of ROM, flash memory device, hard disk, optical disk, etc. More generally, any memory can use any technology to store information. Further, any memory can provide volatile or non-volatile retention of information. Further, any memory can represent a fixed or removable component of the computer device 1102. In one embodiment, when the processor 1104 executes the associated instructions stored in any memory or combination of memories, the computer device 1102 can perform any operation of the associated instructions. The computer device 1102 also includes one or more drive mechanisms 1108 for interacting with any memory, such as a hard disk drive mechanism, an optical disk drive mechanism, etc.

[0151] The computer device 1102 may also include an input / output interface 1110 (I / O) for receiving various inputs (via input devices 1112) and for providing various outputs (via output devices 1114). A specific output mechanism may include a presentation device 1116 and an associated graphical user interface 1118 (GUI). In other embodiments, the input / output interface 1110 (I / O), input device 1112, and output device 1114 may not be included, and the computer device 1102 may be used as a computer device in a network. The computer device 1102 may also include one or more network interfaces 1120 for exchanging data with other devices via one or more communication links 1122. One or more communication buses 1124 couple the components described above together.

[0152] The communication link 1122 may be implemented in any manner, for example, through a local area network, a wide area network (e.g., the Internet), a point-to-point connection, etc., or any combination thereof. The communication link 1122 may include any combination of hardwired links, wireless links, routers, gateway functions, name servers, etc. governed by any protocol or combination of protocols.

[0153] The present application is described with reference to the flowcharts and / or block diagrams of the methods, devices (systems), computer-readable storage media, and computer program products of some embodiments of the present specification. It should be understood that each process and / or box in the flowchart and / or block diagram, as well as the combination of the processes and / or boxes in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processor to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processor generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0154] These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processor to operate in a specific manner, so that the instructions stored in the computer-readable memory produce an article of manufacture including an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0155] These computer program instructions can also be loaded onto a computer or other programmable data processor so that a series of operational steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for executing on the computer or other programmable device to implement the process. Figure 1A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.

[0156] In a typical configuration, a computer device includes one or more processors (CPU), input / output interfaces, network interfaces, and memory.

[0157] The memory may include non-permanent storage in a computer-readable medium, random access memory (RAM) and / or non-volatile memory in the form of read-only memory (ROM) or flash RAM. The memory is an example of a computer-readable medium.

[0158] Computer-readable media include permanent and non-permanent, removable and non-removable media that can be used to store information by any method or technology. Information can be computer-readable instructions, data structures, program modules or other data. Examples of computer storage media include, but are not limited to, phase change memory (PRAM), static random access memory (SRAM), dynamic random access memory (DRAM), other types of random access memory (RAM), read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), flash memory or other memory technology, compact disk read-only memory (CD-ROM), digital versatile disk (DVD) or other optical storage, magnetic cassettes, disk storage or other magnetic storage devices or any other non-transmission media that can be used to store information that can be accessed by a computer device. As defined in this specification, computer-readable media does not include temporary computer-readable media (transitory media), such as modulated data signals and carrier waves.

[0159] Those skilled in the art will appreciate that the embodiments of this specification may be provided as methods, systems or computer program products. Therefore, the embodiments of this specification may take the form of complete hardware embodiments, complete software embodiments or embodiments combining software and hardware. Moreover, the embodiments of this specification may take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program codes.

[0160] The present specification embodiments may 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, etc. that perform specific tasks or implement specific abstract data types. The present specification embodiments may also be practiced in distributed computing environments where tasks are performed by remote processors connected through a communication network. In a distributed computing environment, program modules may be located in local and remote computer storage media, including storage devices.

[0161] It should also be understood that in the embodiments of this specification, the term "and / or" is only a description of the association relationship of the associated objects, indicating that three relationships can exist. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. In addition, the character " / " in this article generally indicates that the associated objects before and after are in an "or" relationship.

[0162] Each embodiment in this specification is described in a progressive manner, and the same or similar parts between the embodiments can be referred to each other, and each embodiment focuses on the differences from other embodiments. In particular, for the system embodiment, since it is basically similar to the method embodiment, the description is relatively simple, and the relevant parts can be referred to the partial description of the method embodiment.

[0163] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the embodiments of this specification. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0164] The above is only an embodiment of the present application and is not intended to limit the present application. For those skilled in the art, the present application may have various changes and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application should be included in the scope of the claims of the present application.

Claims

1. A method for calculating the stiffness coefficient of multi-scale natural fractures, characterized in that: The method comprises: Obtaining the positional relationship between the target horizontal well and the natural fracture, and determining the wellbore angle between the natural fracture and the target horizontal well in the first construction section of the first interval; Performing a fracturing operation on the target horizontal well, and determining a second construction section in the second interval of the fracturing operation at a fracturing displacement; Determine a third construction section according to the overlapping portion of the first construction section and the second construction section; Monitoring and obtaining microseismic data of the target horizontal well and the formation where the natural fracture is located in the third construction section; Taking the surface where the natural fracture is located as the reference surface, screening and removing the microseismic event points in the microseismic data whose distances from the microseismic event points to the corresponding reference surface are greater than a first threshold; Calculate the rupture area of ​​natural fractures based on the screened microseismic data; Measuring the casing deformation of the target horizontal well; The stiffness coefficient of the natural fracture is calculated according to the deformation of the casing and the rupture area of ​​the natural fracture.

2. The method according to claim 1, characterized in that: The first interval is 15°-60°; the second interval is 18m 3 / min-22m 3 / min.

3. The method according to claim 1, characterized in that Calculating the wellbore angle between the natural fracture and the target horizontal well, including: The angle between the natural fracture and the wellbore of the target horizontal well is obtained by the following formula: Among them, σ1 is the maximum horizontal ground stress, σ2 is the minimum horizontal ground stress, S w is the cohesion of natural fractures, u w is the internal friction coefficient of the weak surface, It is the angle between the normal direction of the natural fracture and the horizontal maximum geostress, that is, the angle between the horizontal wellbore and the natural fracture.

4. The method according to claim 1, characterized in that: The monitoring obtains microseismic data of the target horizontal well and the formation where the natural fracture is located in the third construction section, including: Measuring the seismic signal of the third construction section by using a seismic geophone; Performing waveform clustering analysis preprocessing on the seismic signal to suppress noise; Inputting the preprocessed seismic signal into a microseismic positioning imaging algorithm to obtain the microseismic data; The microseismic data includes a plurality of microseismic event points, and each microseismic event point is represented by a corresponding spatial position and a seismic moment.

5. The method according to claim 4, characterized in that The seismic signal is preprocessed by waveform clustering analysis, including clustering analysis of the first arrival time regularity, spectrum characteristics and polarization characteristics of the seismic signal received by each seismic detector to distinguish and eliminate noise signals.

6. The method according to claim 1, characterized in that The stiffness coefficient of the natural fracture is calculated according to the deformation of the casing and the rupture area of ​​the natural fracture, including: The natural fracture slippage is calculated based on the casing deformation, and the stiffness coefficient of the natural fracture is calculated using the following formula: Among them, M i is the seismic moment of a single microseismic event point, n is the number of all microseismic event points, M0 is the total seismic moment of all microseismic event points, u is the stiffness coefficient of the natural fracture, A is the rupture area of ​​the natural fracture, and D is the slip amount of the natural fracture.

7. A calculation system for multi-scale natural fracture stiffness coefficients, characterized in that: include: An acquisition module, used to acquire the positional relationship between the target horizontal well and the natural fracture, and determine the wellbore angle between the natural fracture and the target horizontal well in the first construction section of the first interval; A fracturing module, used for performing fracturing construction on the target horizontal well and determining a second construction section of a second interval of a fracturing displacement during the fracturing construction; A construction section determination module, used to determine a third construction section according to an overlapping portion of the first construction section and the second construction section; A monitoring module, used for monitoring and obtaining microseismic data of the target horizontal well and the formation where the natural fracture is located in the third construction section; A screening module, for screening and removing microseismic event points in the microseismic data whose distance from the microseismic event point to the corresponding reference surface is greater than a first threshold, using the surface where the natural fracture is located as a reference surface; A rupture area calculation module is used to calculate the rupture area of ​​natural fractures based on the screened microseismic data; A casing deformation measurement module, used to measure the casing deformation of the target horizontal well; The stiffness coefficient calculation module is used to calculate the stiffness coefficient of the natural fracture according to the casing deformation and the rupture area of ​​the natural fracture.

8. A computer device comprising a memory, a processor, and a computer program stored in the memory, characterized in that: When the computer program is executed by the processor, the computer program executes the instructions of the method according to any one of claims 1 to 6.

9. A computer storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor of a computer device, the computer program executes instructions of the method according to any one of claims 1 to 6.

10. A computer program product, characterized in that The computer program product comprises a computer program, and when the computer program is executed by a processor, the computer program executes instructions of the method according to any one of claims 1 to 6.

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