Crack prediction method, system, machine-readable storage medium, and data processing device

Abstract

The present invention discloses a fracture prediction method, system, machine-readable storage medium, and data processing device. The fracture prediction method of the present invention is a three-dimensional pre-stack fracture prediction method based on an azimuthal anisotropy factor. By proposing the concept of an azimuthal anisotropy factor and predicting three-dimensional pre-stack fractures by calculating and analyzing the value of the azimuthal anisotropy factor, the present invention has higher prediction accuracy and more reliable prediction results than existing three-dimensional pre-stack fracture prediction methods. The system of the present invention executes the method of the present invention and has the same advantages as the method. The machine-readable storage medium and data processing device of the present invention can implement the method of the present invention through a machine, saving a large amount of data calculation time and improving the efficiency of fracture prediction.

Description

Technical Field

[0001] The present invention belongs to the technical field of formation fracture prediction, and in particular relates to a three-dimensional pre-stack fracture prediction method, system, machine-readable storage medium and data processing equipment based on azimuthal anisotropy factor. Background Art

[0002] Formations containing oil and natural gas are called oil and gas reservoirs. These formations typically have a certain porosity. Reservoirs containing numerous or predominantly fractures are called fractured reservoirs. Fractures are ubiquitous in the Earth's crust, formed by geological forces such as long-term tectonic movements. Fractured reservoirs are widely developed across the Earth. Currently, fractured oil and gas reservoirs account for over half of the world's total oil and gas production. In China, the discovery of fractured oil and gas reservoirs has increased significantly in recent years, with nearly every major oil province containing them. Fractured oil and gas reservoir exploration is becoming an increasingly important area of strategic energy exploration in my country.

[0003] Geophysical seismic technology is a key technology in oil and gas exploration. By inverting and analyzing noisy and incomplete geophysical data, it ultimately provides a qualitative or quantitative description of geological targets. Key areas of expertise include: geological structural imaging, identification of lithologic and physical properties, and prediction of fluid types in reservoirs. Focusing on these three objectives, geophysical theory and technology have advanced rapidly internationally, achieving significant results in oil and gas exploration and development. However, research in domestic geophysical advance reserve technology is relatively weak. Major breakthroughs in oil and gas exploration rely on advances in geophysical technology, and the development of seismic frontier technology plays a crucial role.

[0004] Common seismic methods for crack detection include: shear wave, converted wave and multi-component detection of cracks, multi-azimuth VSP (vertical seismic profile) detection of cracks and longitudinal wave analysis detection of cracks; among them: the first type of method has problems such as low shear wave signal-to-noise ratio, low frequency, high cost of multi-wave acquisition and processing, and complicated processing of converted waves; the multi-azimuth VSP (vertical seismic profile) method of crack detection is complicated to acquire and process, high cost, and has a limited range of application; using longitudinal wave data to predict cracks is always more economical than using shear wave data; the data is relatively easy to obtain; and the existing data can be used for feasibility studies, which is the commonly used method in existing crack prediction.

[0005] The method of predicting fractures using post-stack longitudinal wave data is becoming more and more perfect, but there are common problems such as insufficient information, many human factors, difficult qualitative analysis and low prediction accuracy, which leads to low prediction reliability. Summary of the Invention

[0006] To address the above problems, the present invention provides a three-dimensional pre-stack fracture prediction method, system, machine-readable storage medium, and data processing device based on azimuthal anisotropy factors, which have high prediction accuracy and reliable prediction results.

[0007] A crack prediction method of the present invention comprises the following steps:

[0008] Obtain gather data of each azimuth angle of the target layer;

[0009] Calculating the value of the azimuthal anisotropy factor in each azimuth according to the gather data of each azimuth angle;

[0010] Fracture prediction is performed on the target layer segment according to the value of the azimuthal anisotropy factor in each azimuth to obtain a prediction result.

[0011] Furthermore, the method further includes the step of verifying the prediction result:

[0012] comparing the predicted results with geological development laws;

[0013] Determine whether the predicted result is contrary to the geological development law according to the comparison result;

[0014] When it is determined that the prediction result is contrary to the geological development law, parameters of the various azimuth gather data are adjusted.

[0015] Furthermore, the acquisition of the angular gather data of each azimuth of the target layer segment includes the following steps:

[0016] Obtain CRP gather data at every direction in the entire work area;

[0017] Processing the CRP gather data to obtain angle gather data at each azimuth of the entire work area;

[0018] The angular gather data at each azimuth of the entire work area are truncated.

[0019] Furthermore, the data processing of the CRP gather data includes the following steps:

[0020] Remove low-frequency noise processing;

[0021] High-resolution sequence stratigraphic processing.

[0022] Furthermore, the calculation formula of the azimuthal anisotropy factor is:

[0023]

[0024] in, is the azimuth; ε x is the ε Thomson parameter parallel to the crack surface; εy is the ε Thomson parameter perpendicular to the crack surface; δ x is the delta Thomson parameter parallel to the crack surface; y is the delta Thomson parameter perpendicular to the crack surface, and Δ represents the difference between physical quantities.

[0025] Furthermore, the step of predicting fractures in the target layer according to the value of the azimuthal anisotropy factor in each azimuth is as follows:

[0026] Compare and sort the values of the azimuthal anisotropy factor in each orientation;

[0027] Obtain the value of the maximum azimuthal anisotropy factor and the value of the minimum azimuthal anisotropy factor;

[0028] The crack strength information is obtained according to the value of the maximum azimuthal anisotropy factor, and the crack development direction information is obtained according to the value of the minimum azimuthal anisotropy factor.

[0029] Furthermore, the angle gather data includes incident angle, azimuth angle and number of coverages.

[0030] The present invention also provides a crack prediction system, comprising:

[0031] Data statistics module, used to obtain gather data of each azimuth angle of the target layer;

[0032] A calculation module, used for calculating the value of the azimuthal anisotropy factor of each azimuth according to the gather data of each azimuth angle;

[0033] The prediction module is used to predict the fractures of the target layer according to the value of the azimuthal anisotropy factor in each azimuth and obtain the prediction result.

[0034] Furthermore, the data statistics module includes:

[0035] Acquisition unit, used to obtain CRP gather data at every direction in the entire work area;

[0036] A data processing unit, configured to process the CRP gather data to obtain angle gather data at each azimuth of the entire work area;

[0037] The truncation unit is used to truncate the angle gather data at each azimuth of the entire work area to obtain the angle gather data of each sub-azimuth of the target layer segment.

[0038] Furthermore, the data processing unit includes:

[0039] A low-frequency noise removal processing subunit, configured to remove low-frequency noise from the CRP gather data to improve the signal-to-noise ratio of the seismic data;

[0040] The high-resolution sequence stratigraphic processing subunit is used to perform high-resolution sequence stratigraphic processing on the CRP gather data to improve the resolution of the seismic data.

[0041] Furthermore, the prediction module includes:

[0042] A sorting unit is used to compare and sort the values of the azimuthal anisotropy factor of each orientation;

[0043] The analysis unit is used to obtain the value of the maximum azimuthal anisotropy factor and the value of the minimum azimuthal anisotropy factor, and obtain crack strength information according to the value of the maximum azimuthal anisotropy factor, and obtain crack development direction information according to the value of the minimum azimuthal anisotropy factor.

[0044] Furthermore, it also includes a verification module for verifying the prediction result according to the geological development law, and adjusting the parameters of the various azimuth gather data when the prediction result is contrary to the geological development law.

[0045] Furthermore, the verification module includes:

[0046] Comparison unit, used to compare the prediction results with geological development laws;

[0047] A judgment unit is used to judge whether the prediction result is contrary to the geological development law based on the comparison result of the comparison unit;

[0048] The parameter adjustment unit is used to adjust the parameters of the various azimuth gather data when it is determined that the prediction result is contrary to the geological development law.

[0049] The present invention further provides a machine-readable storage medium having machine-executable instructions stored thereon. When the machine-executable instructions are executed by one or more processors, the crack prediction method of the present invention is implemented.

[0050] The present invention also provides a data processing device, comprising a processor and a machine-readable storage medium, wherein the machine-readable storage medium stores machine-executable instructions, and when the machine-executable instructions are executed by the processor, the crack prediction method of the present invention is implemented.

[0051] The three-dimensional pre-stack fracture prediction method based on azimuthal anisotropy factor of the present invention proposes the concept of azimuthal anisotropy factor and predicts three-dimensional pre-stack fractures by calculating and analyzing the azimuthal anisotropy factor. Compared with existing three-dimensional pre-stack fracture prediction methods, the prediction accuracy is higher and the prediction effect is more reliable. It can better reflect the development of fracture formation and the development pattern of fractures in the target layer, and the prediction results are accurate and reliable. The system of the present invention executes the method of the present invention and has the same advantages as the method; the machine-readable storage medium and data processing equipment of the present invention can implement the method of the present invention through a machine, saving a large amount of data calculation time and improving the efficiency of fracture prediction.

[0052] Other features and advantages of the present invention will be described in the following description, and in part will become apparent from the description, or will be understood by practicing the present invention. The purpose and other advantages of the present invention can be realized and obtained by the structures pointed out in the description, claims and drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0053] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following is a brief introduction to the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0054] Figure 1 A schematic diagram of a crack prediction method according to the present invention is shown;

[0055] Figure 2 A schematic diagram of a crack prediction method according to an embodiment of the present invention is shown;

[0056] Figure 3 The AVA amplitude variation curves at different orientations calculated according to formula (1) are shown;

[0057] Figure 4 The AVA amplitude variation curves at different orientations calculated according to formula (3) are shown;

[0058] Figure 5 The AVA amplitude variation curves at different orientations calculated according to formula (4) are shown;

[0059] Figure 6 The figure shows the gather directory and disk file of the CRP gather data of 6 directions in the embodiment of the present invention;

[0060] Figure 7 A schematic diagram of the CRP gathers and spectrum analysis of the INLine510 high-resolution sequence stratigraphic processing at 165 degrees in an embodiment of the present invention is shown;

[0061] Figure 8 The HANDVEL format root mean square velocity in an embodiment of the present invention is shown;

[0062] Figure 9 It shows the INLine510 high-resolution sequence stratigraphic processing angle gather of the 165-degree azimuth main survey line in an embodiment of the present invention;

[0063] Figure 10 It shows the 165-degree azimuth main survey line INLine510 high-resolution sequence stratigraphic processing truncated angle gather in an embodiment of the present invention;

[0064] Figure 11 The 0-30_180-210 degree azimuth high-resolution sequence stratigraphic processing angle gather database file in an embodiment of the present invention is shown;

[0065] Figure 12 It shows the azimuthal supergather of the main survey line INLine510 high-resolution sequence stratigraphic processing angle gather in an embodiment of the present invention;

[0066] Figure 13 It shows the high-resolution sequence stratigraphic processing angle gather azimuth super gather database file in an embodiment of the present invention;

[0067] Figure 14 It shows the target constraint layer file for pre-stack fracture prediction in an embodiment of the present invention;

[0068] Figure 15 The incident angle and azimuth angle files according to an embodiment of the present invention are shown;

[0069] Figure 16 Shows the coverage times file in an embodiment of the present invention;

[0070] Figure 17 It shows the high-resolution sequence stratigraphic processing angle gather and azimuth super gather in an embodiment of the present invention;

[0071] Figure 18 It shows the azimuth-azimuth coverage analysis diagram of the high-resolution sequence stratigraphic processing angle gather azimuth super gather in an embodiment of the present invention;

[0072] Figure 19 A schematic diagram of azimuth gather division in an embodiment of the present invention is shown. DETAILED DESCRIPTION

[0073] To make the objectives, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts shall fall within the scope of protection of the present invention.

[0074] Terminology Notes:

[0075] Entire work area / full work area: includes the geographical scope of the entire exploration area and the entire complete seismic data acquisition time range from the surface to the underground vertical depth, such as 0 to 6000 milliseconds;

[0076] Target layer segment: It is a time range segment in the entire complete seismic acquisition data time range, such as 0 to 6000 milliseconds, that is, a part of the entire work area, and is the vertical time range in which the geological layers to be studied are distributed.

[0077] like Figure 1 FIG. 1 is a specific embodiment of the present invention. The steps of a three-dimensional pre-stack crack prediction method based on azimuthal anisotropy factor of the present invention include:

[0078] 1. Obtain gather data for each azimuth angle of the target layer

[0079] 1.1 Obtain CRP (common reflection point) gather data at every direction in the entire work area;

[0080] First, the angle gather is partitioned according to azimuth, which can be divided equally to form multiple azimuth gathers. Figure 19 , is a schematic diagram of azimuth gather division in one embodiment of the present invention: the CRP angle gather is divided into several narrow sector-shaped data areas, forming multiple sub-azimuth gathers. The division can be performed equally according to azimuth, or the division method can be customized.

[0081] Before carrying out the work of pre-stack fracture prediction, all CRP gather files at each single azimuth must first be merged to form a complete CRP gather data volume at that azimuth.

[0082] A computer can be used to complete the merging of CRP gather files. Due to the large amount of data in the entire work area, when a CRP gather for each orientation generates a file, the file is very large and inconvenient to carry, copy, and transmit. Therefore, it is generally divided into several INLINE lines for output, and multiple sub-files are output. The CRP gather data is saved on the disk, which is convenient for carrying, copying, and transmission.

[0083] 1.2 Process the CRP gather data to obtain the angular gather data at each direction in the entire work area;

[0084] Data processing of CRP gather data includes low-frequency noise removal and high-resolution sequence stratigraphic processing:

[0085] Obtain the low-frequency information of the merged CRP gather data volume in each azimuth, remove low-frequency noise such as oblique interference, weaken medium and low-quality noise, and improve the data signal-to-noise ratio.

[0086] Perform high-resolution sequence stratigraphic processing on the merged CRP gather data volume in each azimuth to improve the resolution of the CRP gather data.

[0087] Finally, the loaded velocity (HANDVEL format velocity is a velocity recorded in the form of a text file. HANDVEL format layer velocity or RMS root mean square velocity is collected and loaded for subsequent angular gather generation.) is used to convert the merged single azimuth high-resolution sequence stratigraphic processing CRP gather into an angular gather.

[0088] 1.3 The angular gather data at each azimuth of the entire work area are truncated.

[0089] Since fracture prediction is performed for a specific target layer, only the gather data of the target layer segment needs to be truncated to perform the work. In other words, the high-resolution sequence stratigraphic processing angle gathers in each azimuth after merging need to be truncated. This will result in high-resolution sequence stratigraphic processing angle gathers with truncated azimuths in several azimuths after merging.

[0090] In a specific embodiment of the present invention, the fracture prediction system of the present invention is used to implement fracture prediction. After obtaining the angular gather data of each orientation of the target layer segment, the following operation steps are also performed to generate data / file format suitable for processing by the program module of the fracture prediction system of the present invention.

[0091] 1.4 Export the merged, truncated, single azimuth high-resolution sequence stratigraphic processing angle gather data in the "SGY IBM32float" format.

[0092] 1.5 Generate a single azimuth gather database file

[0093] Generate a database file for the merged, single-azimuth truncated high-resolution sequence stratigraphic processing angle gathers output by SGY to effectively manage the pre-stack gather data and improve the operating efficiency of subsequent modules.

[0094] 1.6 Generate azimuth supergather and modify trace header

[0095] For the merged, truncated, high-resolution sequence stratigraphic data, the single azimuth gather data are processed and all the single azimuth gathers with the same INLINE line number and the same XLINE line number and the same position are merged together to generate an azimuth super gather.

[0096] And modify the SEG-Y header of the azimuth super gather so that when this method is implemented through the program module, the corresponding prediction module can correctly use this data.

[0097] 1.7 Generate azimuth supergather database file

[0098] A database file is generated for the angular gathers and azimuth super gathers of the merged and truncated high-resolution sequence stratigraphic layers to form an effective management of the pre-stack gather data and improve the operating efficiency of the subsequent prediction module.

[0099] 1.8 Target layer segment file processing

[0100] Pre-stack fracture prediction is performed for the target layer, and the position of the target layer is interpreted as the target constraint file for the subsequent pre-stack fracture program operation to instruct and guide the main program to carry out pre-stack fracture prediction work.

[0101] Horizon file processing includes: ① seismic synthetic record calibration; ② seismic horizon interpretation; ③ horizon format conversion.

[0102] 2. Calculate the value of the azimuth anisotropy factor for each azimuth according to the above-mentioned azimuth gather data

[0103] 2.1 Parameter Acquisition

[0104] Obtain parameters such as incident angle, azimuth angle, and coverage times to prepare for subsequent parameter analysis.

[0105] 2.2 Finding parameter range

[0106] Obtain the maximum and minimum values of relevant parameters such as incident angle, azimuth angle, etc., and analyze and obtain their distribution range.

[0107] 2.3 Parameter Analysis

[0108] An incident angle and azimuth angle cross-plot analysis is performed to analyze the incident angle azimuth distribution characteristics of the data, and to select a suitable, appropriate incident angle range with a 360-degree distribution for pre-stack fracture prediction, in order to improve the accuracy of pre-stack fracture prediction; a coverage number plane analysis is performed to select a suitable work area for pre-stack fracture prediction.

[0109] Azimuthal anisotropy factor The calculation formula is:

[0110]

[0111] in, is the azimuth; ε x is the ε Thomson parameter parallel to the crack surface; ε y is the ε Thomson parameter perpendicular to the crack surface; δ x δ Thomson parameter parallel to the crack plane; δ y is the delta Thomson parameter perpendicular to the crack surface, and Δ represents the difference between physical quantities.

[0112] Azimuthal anisotropy factor The derivation principle is:

[0113] The calculation formula for the longitudinal wave azimuth response amplitude is:

[0114]

[0115] in:

[0116]

[0117]

[0118]

[0119]

[0120]

[0121]

[0122]

[0123]

[0124] / / represents the wave propagation velocity parallel to the crack surface, ⊥ represents the wave propagation velocity perpendicular to the crack surface, is the response amplitude, θ is the incident angle, is the azimuth angle, ρ is the average density, V p 、V s are the average longitudinal wave and average shear wave velocities, V sh is the horizontal shear wave velocity, ε x , ε y is the ε Thomson parameter parallel to and perpendicular to the crack surface; δ x , δ y is the delta Thomson parameter perpendicular to and parallel to the crack surface; γ xy is the average value of the γ Thomson parameter parallel to and perpendicular to the crack surface, C 11 、C 12 、C 13 、C 23 、C22 、C 33 、C 44 、C 55 、C 66 is the elastic coefficient.

[0125] At a fixed position and a small incident angle, cosθ≈1. Simplifying (1) yields:

[0126]

[0127] make:

[0128]

[0129]

[0130] Then formula (2) can be simplified as:

[0131]

[0132] Where, is a coefficient that is independent of the angle of incidence, where is the azimuthal impedance coefficient, which is mainly related to the impedance change; is the azimuthal anisotropy factor, which is mainly related to the anisotropy change.

[0133] Let a=C, x=sin 2 θ, Then there is

[0134] y=a+bx+cx 2 (4)

[0135] Formula (4) is a quadratic function of the amplitude response at a fixed azimuth with the sine square of the incident angle as the variable. According to formulas (1), (3) and (4), the AVA amplitude change curves at different azimuths are calculated, as shown in the following example: Figure 3 and 4 The following are the curves of earthquake response intensity variation with the incident angle θ at different azimuths (azi). The amplitude gradient of the earthquake response intensity (Amplitude Versus Incidence Angle, AVA) variation curve with the incident angle at each azimuth is linear. Figure 5 , the horizontal axis of the AVA change curve is sin 2 θ, the AVA change curve trend of different azimuth angles is Figure 3 、 Figure 4 The same, from this we can analyze and deduce: azimuthal anisotropy factor It is the main reason for the change of the fixed azimuth amplitude gradient and its influence increases with the increase of the incident angle. The larger the incident angle, the larger the absolute value of the azimuth anisotropy factor and the greater its anisotropic influence.

[0136] The amplitude parallel to the crack surface (azimuth angle of 0°) is the strongest, the amplitude perpendicular to the crack surface (azimuth angle of 90°) is the weakest, and the amplitude in other directions between the two gradually increases with the azimuth, and the amplitude decreases from strong to weak. This shows that when the seismic wave propagates parallel to the crack surface, the energy attenuation is the least and the response amplitude energy is the strongest. When the seismic wave propagates perpendicular to the crack surface, the energy attenuation is the greatest and the response amplitude energy is the weakest. In other directions between the two, the amplitude gradually increases with the azimuth, and the amplitude decreases from strong to weak.

[0137] For the same incident angle, the amplitude decreases with the increase of the azimuth angle, and the amplitude difference between different azimuths becomes larger and larger with the increase of the incident angle, indicating that the amplitude response of the fracture medium changes with both the incident angle and the azimuth angle, and the larger the incident angle, the greater the azimuth amplitude difference.

[0138] For ordinary actual seismic exploration, the reflection angle is generally within the range of 0° to 45°, especially for medium and deep earthquakes, the reflection angle generally does not exceed 30 degrees. Figure 3 and Figure 5 From the analysis, we can see that formula (4) can be applied in the same way as formula (1), and its accuracy can fully meet the needs of actual earthquake work.

[0139] For angle gather seismic data, the response amplitude y is known. Since the incident angle is also known, x is also known. Then, we can selectively select multiple pairs of known response amplitudes y and their corresponding x values in the medium and long distance channels, calculate the average values of coefficients a and b through the above formula, and find the average coefficient value c to obtain the average value of the azimuthal anisotropy factor.

[0140] 3. Predicting fractures in the target layer according to the value of the azimuthal anisotropy factor in each azimuth to obtain a prediction result;

[0141] First, the calculated values of the azimuthal anisotropy factor for each orientation are compared and sorted; the value of the maximum azimuthal anisotropy factor and the value of the minimum azimuthal anisotropy factor are obtained; the crack strength information is obtained based on the value of the maximum azimuthal anisotropy factor, and the crack development direction information is obtained based on the value of the minimum azimuthal anisotropy factor.

[0142] Specifically, it is the average value of the calculated azimuthal anisotropy factor for each orientation.

[0143] In the embodiment of the present invention, the prediction process is specifically as follows:

[0144] According to the size of the azimuth angle, the azimuthal anisotropy factor value in each azimuth is solved in sequence from small to large.

[0145] Compare the azimuthal anisotropy factor values in all directions to determine the maximum and minimum azimuthal anisotropy factor values. The maximum azimuthal anisotropy factor value represents the degree of fracture development in the target layer's heterogeneous fracture formation at the physical point on the ground where the angle gather is located. This provides the degree of fracture development, or fracture strength, to be determined.

[0146] The azimuth with the maximum azimuth anisotropy factor value is perpendicular to the crack strike, and the azimuth with the minimum azimuth anisotropy factor value is parallel to the crack strike. Thus, the azimuth with the minimum azimuth anisotropy factor value is the crack development direction of the heterogeneous fracture formation in the target layer at the ground physical point where the angle gather is located, thereby obtaining the crack development direction, i.e., the crack direction.

[0147] like Figure 2 As shown, a preferred embodiment of the present invention further includes a step of verifying the prediction results.

[0148] 4. Verify the prediction results after the prediction is completed

[0149] Specifically, the prediction results obtained in step 3 are compared with the geological development laws;

[0150] If the prediction results are contrary to the geological development laws, it means that there are deviations in the parameters selected for prediction. It is necessary to adjust the parameters of the azimuth gather data and then re-predict the fractures until the results meet the geological development laws.

[0151] The parameters to be adjusted mainly include common parameters such as the incident angle, azimuth, and analysis time window. Specific parameter adjustments are based on the geological structure development patterns within the region and existing geological knowledge (multiple fault systems have developed within the region, primarily in northwest, northeast, and near north-south directions, forming a network of interlaced fault systems within the region). By selecting a plane location point with a known fracture direction, the key parameters are continuously adjusted until the predicted fracture direction is consistent with the known fracture direction. This completes the parameter adjustment.

[0152] The present invention also provides a three-dimensional pre-stack crack prediction system based on azimuthal anisotropy factor, comprising:

[0153] Data statistics module, used to obtain gather data of each azimuth angle of the target layer;

[0154] A calculation module, used for calculating the value of the azimuthal anisotropy factor of each azimuth according to the gather data of each azimuth angle;

[0155] The prediction module is used to predict the fractures of the target layer according to the value of the azimuthal anisotropy factor in each azimuth and obtain the prediction result.

[0156] The verification module is used to verify the prediction result according to the geological development law, and to adjust the parameters of the various azimuth gather data when the prediction result is contrary to the geological development law.

[0157] The data statistics module includes:

[0158] Acquisition unit, used to obtain CRP gather data at every direction in the entire work area;

[0159] The data processing unit is used to process the CRP gather data to obtain seismic data with high signal-to-noise ratio and high resolution, that is, to obtain the angular gather data at every azimuth in the entire work area;

[0160] A truncation unit is used to perform truncation processing on the angle gather data at each azimuth of the entire work area to obtain the angle gather data of each sub-azimuth of the target layer segment;

[0161] The data processing includes low-frequency noise removal processing and high-resolution sequence stratigraphic processing; the data processing unit includes a low-frequency noise removal processing subunit for removing low-frequency noise in the CRP gather data to improve the signal-to-noise ratio of the seismic data;

[0162] The high-resolution sequence stratigraphic processing subunit is used to perform high-resolution sequence stratigraphic processing on the CRP gather data to improve the resolution of the seismic data.

[0163] The prediction module includes:

[0164] A sorting unit is used to compare and sort the values of the azimuthal anisotropy factor of each orientation;

[0165] The analysis unit is used to obtain the value of the maximum azimuthal anisotropy factor and the value of the minimum azimuthal anisotropy factor, obtain crack strength information according to the value of the maximum azimuthal anisotropy factor, and obtain crack development direction information according to the value of the minimum azimuthal anisotropy factor.

[0166] The verification module includes:

[0167] Comparison unit, used to compare the prediction results with geological development laws;

[0168] A judgment unit is used to judge whether the prediction result is contrary to the geological development law based on the comparison result of the comparison unit;

[0169] The parameter adjustment unit is used to adjust the parameters of the various azimuth gather data when it is determined that the prediction result is contrary to the geological development law.

[0170] The present invention further provides a machine-readable storage medium having machine-executable instructions stored thereon. When the machine-executable instructions are executed by one or more processors, the crack prediction method of the present invention is implemented.

[0171] The present invention also provides a data processing device, comprising a processor and a machine-readable storage medium, wherein the machine-readable storage medium stores machine-executable instructions, and when the processor executes the machine-executable instructions, the crack prediction method of the present invention is implemented.

[0172] Specifically, the azimuthal anisotropy factor-based 3D prestack crack prediction system of the present invention can also be implemented based on the hardware structure of a computer or mobile terminal. The hardware structure includes a processor and a machine-readable storage medium, directly or indirectly electrically connected, to enable data transmission or interaction. The various modules and units in the azimuthal anisotropy factor-based 3D prestack crack prediction system can be stored as executable program modules in a machine-readable storage medium. The processor executes the program modules stored in the machine-readable storage medium to implement the corresponding functions.

[0173] In a specific embodiment of the present invention, taking a tight sandstone fracture reservoir as an example, fracture prediction is implemented using the data processing device of the present invention. The specific operation steps are as follows:

[0174] Step 1: Merge the original single azimuth CRP gather files

[0175] The entire work area is divided into six directions, and the CRP gather data at each direction are divided into several small disk files for recording. Figure 6 The following table shows the gather directories and disk files for the CRP gather data at six locations in this example. Before conducting prestack fracture prediction work, all CRP gather files at each location must be merged to form a complete CRP gather data volume for that location. This yields angular gather data for each location.

[0176] Step 2: Acquire the original single-direction CRP low-frequency information and remove low-frequency noise

[0177] The low-frequency information data of each merged single-azimuth original CRP gather is obtained, and the low-frequency information irrelevant to the seismic response of tight sandstone microfractures is removed, such as low-frequency background noise, low-frequency linear interference, inhomogeneous stratum diffraction wave field, low-frequency converted wave field, etc.

[0178] Step 3: High-resolution sequence stratigraphic processing of the merged single-azimuth CRP gathers

[0179] Perform high-resolution sequence stratigraphic processing on each merged single-azimuth CRP gather (the result of step 1) to improve the resolution of the CRP gather data.

[0180] The gathers processed by high-resolution sequence stratigraphy have a high resolution and are pure dry formation resonance high-frequency responses with no noise or very low noise. They can effectively eliminate the interference of non-fracture formation responses and improve their ability to identify formation microfractures.

[0181] like Figure 7 The following figures show spectrum analysis of the INLine510 high-resolution sequence stratigraphic processing CRP gather at 165 degrees and the INLine510CDP673 high-resolution sequence stratigraphic processing CRP gather at 165 degrees. As can be seen, these gathers have high resolution and are pure dry formation resonance high-frequency responses with no or very low noise. They effectively eliminate interference from non-fractured formation responses and improve their ability to identify microfractures in formations.

[0182] Step 4: Load the layer velocity or RMS velocity in HANDVEL format

[0183] Collect the root mean square velocity in HANDVEL format for this work area. The HANDVEL format velocity is a velocity recorded in the form of a text file. The root mean square velocity is used to generate subsequent angle gathers.

[0184] Step 5: Generate angular gathers for high-resolution sequence stratigraphy processing in a single azimuth after merging

[0185] High-resolution sequence stratigraphic processing angle gathers are obtained by converting the corresponding merged single azimuth high-resolution sequence stratigraphic processing CRP gathers using root mean square velocity.

[0186] Figure 8 is the root mean square velocity in the HANDVEL format in this embodiment, Figure 9 Based on Figure 8 The INLine510 high-resolution sequence stratigraphic processing angle gathers of the 165-degree azimuth main survey line are obtained by converting the HANDVEL format root mean square velocity.

[0187] Step 6: Truncation of the angular gathers after merging the high-resolution sequence stratigraphic processing of the single azimuth target layer

[0188] Since fracture prediction is performed for a specific target layer, only the angle gather data of the target layer segment needs to be intercepted to carry out the work. The benefits of this are that it can reduce the amount of data, save disk space, increase processing speed, improve work efficiency, and accelerate project progress.

[0189] After merging, each high-resolution sequence stratigraphic processing angle gather is truncated, so that several high-resolution sequence stratigraphic processing angle gathers with truncated azimuths are obtained.

[0190] Will Figure 9 The angular gather data in is truncated to obtain Figure 10 The INLine510 high-resolution sequence stratigraphic processing truncated angle gather for the 165-degree azimuth main survey line is shown.

[0191] Step 7: Process the merged and truncated high-resolution sequence stratigraphic data into a single azimuth gather (SGY) output.

[0192] Each single azimuthally truncated high-resolution sequence stratigraphic processed angle gather after merging is exported in the "SGY IBM32float" format for use in subsequent modules.

[0193] Step 8: Generate a single azimuth gather database file by processing the merged and truncated high-resolution sequence stratigraphic layers

[0194] The format of each database file is the same. A single azimuth gather database file includes the main survey line number, the connecting survey line number, the starting channel number, the ending channel number and the total number of channels in this gather.

[0195] like Figure 11 These are database files for processing azimuth gathers for high-resolution sequence stratigraphy in the 0-30_180-210 degree azimuths. Other azimuths are similar and not listed here. The format of each database file is as follows: the first two columns are the main and contact line numbers, the third and fourth columns are the starting and ending trace numbers, and the fifth column is the total number of traces in the gather. These database files are generated for processing individual azimuth gathers from the merged, truncated high-resolution sequence stratigraphy output of SGY. This allows for efficient management of the corresponding prestack angular gather data and improves the efficiency of subsequent modules.

[0196] Step 9: Generate azimuth supergathers from the merged truncated high-resolution sequence stratigraphic processing angle gathers

[0197] like Figure 12 The figure shows the azimuth supergather of the INLine510 high-resolution sequence stratigraphic processing angular gather for the main survey line. This refers to the truncated single azimuth gather for high-resolution sequence stratigraphic processing after merging. It is an azimuth supergather generated by merging all azimuth gathers at the same position with the same INLINE line number and the same XLINE line number to form the high-resolution sequence stratigraphic processing angular gather. Figure 12 What is shown in the figure are 6 azimuth angle gathers at the same common reflection point. The data contains azimuth information, incident angle information, and time information. The three constitute three-dimensional spatial data, and the three-dimensional pre-stack data is used for fracture prediction.

[0198] Step 10: Modify the header of the merged truncated high-resolution sequence stratigraphy angle gather and azimuth super gather

[0199] Modify the SEG-Y header of the truncated high-resolution sequence stratigraphic processing angle gather and azimuth supergather after merging so that the prediction module can use this data correctly.

[0200] Step 11: Generate the azimuth supergather database file of the merged truncated high-resolution sequence stratigraphic processing angle gathers

[0201] Generate high-resolution sequence stratigraphic processing angle gather azimuth super gather database files to effectively manage the corresponding pre-stack angle gather azimuth super gather data and improve the operating efficiency of the subsequent corresponding prediction modules. Figure 13 The azimuth super gather database file is processed for high-resolution sequence stratigraphy. The total number of gathers is the sum of the number of all six azimuth gathers previously divided.

[0202] Step 12: Seismic layer file processing

[0203] Pre-stack fracture prediction is performed for the target layer. The horizon of the target layer is interpreted using the pre-stack time migration data volume, which serves as the target constraint file for the subsequent pre-stack fracture program to instruct and guide the program to carry out the stack fracture prediction work.

[0204] Seismic layer file processing includes: ① conventional synthetic record calibration; ② seismic layer interpretation; ③ layer format conversion.

[0205] Layer format conversion example: Figure 14 This is the target constraint layer file for pre-stack fracture prediction. The first and second columns are the main survey line number and the connecting survey line number, respectively. The third and fourth columns are the normal two-way reflection time of the top interface of the target layer and the normal two-way reflection time of the bottom interface of the target layer, respectively. It is used to constrain the target layer so that pre-stack fracture prediction is only performed on the target layer.

[0206] Step 13: Pre-stack fracture prediction parameter analysis and optimization

[0207] ①、Parameter acquisition

[0208] Obtain parameters such as incident angle, azimuth, and coverage times from the angle gather seismic data header to prepare for subsequent parameter analysis.

[0209] like Figure 15 The file of incidence angle and azimuth angle, in which the first and second columns are the main survey line number and the connecting survey line number respectively, the third column is the internal track number of the track gather, the fourth and fifth columns are the incidence angle, and the sixth column is the azimuth angle.

[0210] Figure 16 It is a coverage number file, in which the first and second columns are the main survey line number and the contact survey line number respectively, and the third column is the coverage number.

[0211] ②. Find the parameter range

[0212] Obtain the maximum and minimum values of relevant parameters such as incident angle and azimuth angle to analyze their distribution range. In this embodiment, the effective incident angle range of the angle gather is 6° to 42°, and the azimuth angle range is 15° to 165°.

[0213] ③ Parameter analysis

[0214] Analyze the azimuth distribution characteristics of the angle gather data to obtain high-resolution sequence stratigraphic processing angle gather azimuth super gather and high-resolution sequence stratigraphic processing angle gather azimuth super gather azimuth-azimuth coverage analysis diagrams.

[0215] In this embodiment, see Figure 17 Processing of angular gathers and azimuth super gathers for high-resolution sequence stratigraphy, Figure 18 The azimuth-azimuth coverage analysis diagram of the angular gathers and azimuth supergathers for high-resolution sequence stratigraphy shows the following data distribution characteristics: ① The data is evenly spaced at fixed azimuths, with 15 traces per azimuth at six fixed azimuths: 15°, 45°, 75°, 105°, 135°, and 165°. ② The data coverage is omnidirectional. ③ The data distribution ranges from azimuths of 15° to 165°, and the angle of incidence ranges from 0° to 42°.

[0216] Prestack fracture prediction is performed on the area with the highest coverage in the center of the work area. Unstable and unreliable data at the work area boundary, caused by low coverage, inaccurate velocity analysis, and offset arcing, is excluded from the work area. At the same time, gathers with sufficient data in areas with insufficient coverage that meet the requirements of the prestack fracture prediction algorithm should be included as much as possible in the final prestack fracture prediction process. In this example, the entire work area is fully covered by the angle gathers, covering an area of approximately 105.44 square kilometers, with no areas of abnormal coverage. Therefore, prestack fracture prediction should be performed on the entire work area.

[0217] Step 14: Prediction of cracks before target stacking

[0218] Based on the parameter analysis, the pre-stack fracture prediction work of the target layer in the whole work area is carried out, thereby completing the pre-stack fracture prediction work of the target layer in the whole work area / the entire work area.

[0219] Obtain planar maps of the predicted fracture strength of the upper and lower sweet spots. Also obtain tectonic stress direction and strain analysis diagrams for the upper and lower sweet spots. This serves as a reference for regional geological structural development patterns. Based on existing geological knowledge, the region has multiple fault systems, primarily trending northwest, northeast, and near north-south, forming a network of interlaced fault systems within the region, enabling verification of the prediction results.

[0220] The pre-stack fracture prediction result finally obtained according to this embodiment is consistent with the regional structural law, that is, the pre-stack fracture prediction result conforms to the structural development law of this region; the prediction result is: the degree of fracture development in the target layer increases from weak to strong from the top to the bottom, and the lower the formation is, the more broken the formation is and the more developed the fractures are.

[0221] The crack prediction method of the present invention has crack prediction results that better reflect the development of structural cracks and the development law of cracks in the area. The prediction results are accurate and reliable, indicating that the method is reliable and has good prediction effect.

[0222] Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A crack prediction method, characterized in that: The following steps are involved: Obtain gather data of each azimuth angle of the target layer; Calculating the value of the azimuthal anisotropy factor in each azimuth according to the gather data of each azimuth angle; Predicting fractures in the target layer according to the value of the azimuthal anisotropy factor in each azimuth to obtain a prediction result; The azimuthal anisotropy factor The calculation formula is: in, is the azimuth; ε x is the ε Thomson parameter parallel to the crack surface; ε y is the ε Thomson parameter perpendicular to the crack surface; δ x is the delta Thomson parameter parallel to the crack surface; y is the delta Thomson parameter perpendicular to the crack surface, and Δ represents the difference between physical quantities.

2. The crack prediction method according to claim 1, characterized in that: The step of verifying the prediction result is also included: comparing the predicted results with geological development laws; Determine whether the predicted result is contrary to the geological development law according to the comparison result; When it is determined that the prediction result is contrary to the geological development law, parameters of the various azimuth gather data are adjusted.

3. The crack prediction method according to claim 1, characterized in that: The method of obtaining the angular gather data of each azimuth of the target layer segment comprises the following steps: Obtain CRP gather data at every direction in the entire work area; Processing the CRP gather data to obtain angle gather data at each azimuth of the entire work area; The angular gather data at each azimuth of the entire work area are truncated.

4. The crack prediction method according to claim 3, characterized in that: The data processing of the CRP gather data comprises the following steps: Remove low-frequency noise processing; High-resolution sequence stratigraphic processing.

5. The crack prediction method according to claim 1, characterized in that: The steps of predicting fractures in the target layer according to the value of the azimuthal anisotropy factor in each azimuth are as follows: Compare and sort the values of the azimuthal anisotropy factor in each orientation; Obtain the value of the maximum azimuthal anisotropy factor and the value of the minimum azimuthal anisotropy factor; The crack strength information is obtained according to the value of the maximum azimuthal anisotropy factor, and the crack development direction information is obtained according to the value of the minimum azimuthal anisotropy factor.

6. The crack prediction method according to claim 1, characterized in that: The angle gather data includes incident angle, azimuth angle and number of coverages.

7. A crack prediction system, characterized in that: include: Data statistics module, used to obtain gather data of each azimuth angle of the target layer; A calculation module, used for calculating the value of the azimuthal anisotropy factor of each azimuth according to the gather data of each azimuth angle; The azimuthal anisotropy factor The calculation formula is: in, is the azimuth; ε x is the ε Thomson parameter parallel to the crack surface; ε y is the ε Thomson parameter perpendicular to the crack surface; δ x is the delta Thomson parameter parallel to the crack surface; y is the delta Thomson parameter perpendicular to the crack surface, Δ represents the difference between physical quantities; The prediction module is used to predict the fractures of the target layer according to the value of the azimuthal anisotropy factor in each azimuth and obtain the prediction result.

8. The crack prediction system according to claim 7, characterized in that: The data statistics module includes: Acquisition unit, used to obtain CRP gather data at every direction in the entire work area; A data processing unit, configured to process the CRP gather data to obtain angle gather data at each azimuth of the entire work area; The truncation unit is used to truncate the angle gather data at each azimuth of the entire work area to obtain the angle gather data of each azimuth of the target layer segment.

9. The crack prediction system according to claim 8, characterized in that: The data processing unit includes: A low-frequency noise removal processing subunit, configured to remove low-frequency noise from the CRP gather data to improve the signal-to-noise ratio of the seismic data; The high-resolution sequence stratigraphic processing subunit is used to perform high-resolution sequence stratigraphic processing on the CRP gather data to improve the resolution of the seismic data.

10. The crack prediction system according to claim 7, characterized in that: The prediction module includes: A sorting unit is used to compare and sort the values of the azimuthal anisotropy factor of each orientation; The analysis unit is used to obtain the value of the maximum azimuthal anisotropy factor and the value of the minimum azimuthal anisotropy factor, and obtain crack strength information according to the value of the maximum azimuthal anisotropy factor, and obtain crack development direction information according to the value of the minimum azimuthal anisotropy factor.

11. The crack prediction system according to any one of claims 7 to 10, characterized in that: It also includes a verification module for verifying the prediction result according to the geological development law, and adjusting the parameters of the various azimuth gather data when the prediction result is contrary to the geological development law.

12. The crack prediction system according to claim 11, characterized in that: The verification module includes: Comparison unit, used to compare the prediction results with geological development laws; A judgment unit is used to judge whether the prediction result is contrary to the geological development law based on the comparison result of the comparison unit; The parameter adjustment unit is used to adjust the parameters of the various azimuth gather data when it is determined that the prediction result is contrary to the geological development law.

13. A machine-readable storage medium having machine-executable instructions stored thereon, wherein the machine-executable instructions, when executed by one or more processors, implement the crack prediction method according to any one of claims 1 to 6.

14. A data processing device comprising a processor and a machine-readable storage medium, wherein the machine-readable storage medium stores machine-executable instructions, and when the machine-executable instructions are executed by the processor, the crack prediction method according to any one of claims 1 to 6 is implemented.

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