Anisotropy and ground stress evaluation method based on leakage longitudinal waves and related equipment

Abstract

The invention belongs to the field of petroleum geological exploration reservoir evaluation, and discloses a leakage longitudinal wave-based anisotropy and ground stress evaluation method and related equipment.The method is mainly applied to a slow stratum, and comprises the following steps: firstly, extracting a leakage longitudinal wave, and obtaining a fast wave and a slow wave through four-component waveform data of the leakage longitudinal wave; then obtaining an auxiliary fast wave time sequence, an auxiliary slow wave time sequence and an auxiliary fast and slow wave waveform according to the fast wave and the slow wave, carrying out fast and slow wave matching processing based on a waveform matching method to obtain fast wave slowness and slow wave slowness, and finally obtaining leakage longitudinal wave anisotropy according to the fast wave slowness and the slow wave slowness. Anisotropy and ground stress evaluation is realized; according to the method, the cross dipole leakage longitudinal waves which are easy to extract are acquired, and based on the similarity of the waveforms of the fast and slow waves in the longitudinal waves, a waveform inversion method is used, and combined superposition of array sound wave data is fully utilized to suppress noise, so that the calculation precision and stability are improved, and accurate and reliable stratum anisotropy and ground stress evaluation is realized.

Description

Anisotropy of Leaked P-waves and Geostress Evaluation Methods and Related Equipment Technical Field

[0001] This invention belongs to the field of reservoir evaluation in petroleum geological exploration, and particularly relates to a method and related equipment for evaluating anisotropy and geostress based on leakage longitudinal waves. Background Technology

[0002] Cross-dipole logging can accurately evaluate formation anisotropy and has wide applications in formation fracture studies (fracture orientation, fracture strength) and geostress assessment. In fast formations, the shear wave serves as the first wave, providing a strong signal that is easy to extract, resulting in accurate and reliable anisotropy and geostress direction assessments.

[0003] Currently, most methods for analyzing and evaluating anisotropy and geostress employ shear wave extraction. For example, Chinese Patent No. CN111736218B discloses a method, equipment, and readable storage medium for quantitative analysis of the formation anisotropy. This method preprocesses waveform data, extracts fast and slow shear waves, performs dispersion processing and fitting, and analyzes their relative positions to determine the magnitude of anisotropy caused by formation fractures or geostress. However, the above methods are mostly applied to fast formations where bending waves can be effectively excited, and the acoustic signal is dominated by bending wave trains, making shear wave velocity extraction accurate and reliable. In shallow mudstone formations, i.e., when the formation is slow-moving, the bending waves received by the wellbore are subsequent wave trains. The bending waves are strongly interfered with by the first wave and the subsequent wave, which has a significant impact on the waveform analysis and velocity extraction of bending waves, resulting in the inability to accurately obtain important information such as formation anisotropy and geostress direction.

[0004] Therefore, for slow-velocity strata, due to the weak cross-dipole shear wave signal, the existing analysis methods cannot effectively extract the shear wave, thus making it impossible to accurately perform anisotropy and geostress analysis and evaluation. Summary of the Invention

[0005] The purpose of this invention is to provide a method and related equipment for evaluating anisotropy and geostress based on leaked P-waves, in order to solve the technical problem that for slow-velocity strata, due to the weak cross-dipole shear wave signal, existing analysis methods cannot effectively extract shear waves, thus making it impossible to accurately perform anisotropy and geostress analysis and evaluation.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: a method for evaluating anisotropy and geostress based on leaked P-waves, comprising: acquiring fast and slow waves based on four-component waveform data of leaked P-waves; wherein the leaked P-wave is a cross-dipole array acoustic wave; obtaining auxiliary fast wave time series, auxiliary slow wave time series, and auxiliary fast and slow wave waveforms based on the fast and slow waves; performing fast and slow wave matching processing on the auxiliary wave time series, auxiliary slow main wave time series, and auxiliary fast and slow wave waveforms based on waveform matching method to obtain fast wave slowness and slow wave slowness; obtaining the anisotropy of leaked P-waves based on the fast wave slowness and slow wave slowness, so as to realize the evaluation of formation anisotropy and geostress based on the anisotropy of leaked P-waves.

[0007] Furthermore, the steps for obtaining fast and slow waves based on the four-component waveform data of the leaked longitudinal wave are as follows: Fast and slow wave waveforms are derived from the four-component waveform data of the cross-dipole array acoustic wave, resulting in the fast and slow waves, as shown in the following formula:

[0008] In the formula: XX, XY, YX, YY represent four-component waveform data; FP(t) represents fast wave; SP(t) represents slow wave; θ represents the angle between the X direction and the polarization direction of the fast transverse wave.

[0009] Furthermore, the specific steps for obtaining the auxiliary fast wave time series, auxiliary slow wave time series, and auxiliary fast and slow wave waveforms based on the fast and slow waves are as follows: The derivatives of the angles between the fast wave and the slow wave in the X-direction and the polarization direction of the fast transverse wave are calculated to obtain the auxiliary fast wave time series, auxiliary slow wave time series, and auxiliary fast and slow wave waveforms. The specific formulas are as follows:

[0010] In the formula, Indicates the auxiliary fast wave time series; This represents an auxiliary slow-wave time series.

[0011] Furthermore, the specific steps for performing fast-slow wave matching processing on the auxiliary wave time series, auxiliary slow main wave time series, and auxiliary fast-slow wave waveforms based on the waveform matching method are as follows: Based on the linear propagation theory and waveform similarity theory of waveforms, the auxiliary fast wave time series, auxiliary slow wave time series, and auxiliary fast-slow wave waveforms are matched using the waveform matching method to achieve inversion calculation, obtaining the fast wave slowness and slow wave slowness, as shown in the following formulas:

[0012] In the formula, This represents the difference between the slowness of slow waves and the slowness of fast waves; Indicates the speed of a fast wave; Indicates the slowness of slow waves; Indicates the receiver spacing subscript; , Indicates the receiver serial number; This represents the distance between the sound source and the m-th receiver in the receiver array.

[0013] Furthermore, during the inversion calculation, the auxiliary wave waveform and the actual wave waveform are treated equally to ensure that they have the same weight; specifically, the inversion objective function is: .

[0014] Furthermore, the anisotropy of the leaked P-wave is obtained based on the difference between the fast wave slowness and the slow wave slowness, and the average of the fast wave slowness and the slow wave slowness, as shown in the following formula:

[0015] In the formula, This indicates the leakage of longitudinal wave anisotropy; Indicates the speed of a fast wave; This indicates the slowness of a slow wave.

[0016] Furthermore, the obtained anisotropy and geostress magnitude, direction, and rock mechanics parameters are used to create an anisotropy and geostress evaluation result map. Based on the anisotropy and geostress evaluation result map, the anisotropy and geostress of the formation are evaluated.

[0017] An anisotropy and geostress evaluation system based on leaked P-waves includes: a fast and slow wave derivation module for acquiring fast and slow waves based on four-component waveform data of leaked P-waves; wherein the leaked P-wave is a cross-dipole array acoustic wave; an auxiliary wave calculation module for obtaining auxiliary fast wave time series, auxiliary slow wave time series, and auxiliary fast and slow wave waveforms based on the fast and slow waves; a fast and slow wave matching processing module for performing fast and slow wave matching processing on the auxiliary wave time series, auxiliary slow main wave time series, and auxiliary fast and slow wave waveforms based on waveform matching method to obtain fast wave slowness and slow wave slowness; and an anisotropy calculation module for obtaining the anisotropy of the leaked P-wave based on the fast wave slowness and slow wave slowness, so as to realize the formation anisotropy and geostress evaluation based on the anisotropy of the leaked P-waves.

[0018] An apparatus includes: a memory for storing a computer program; and a processor for executing the computer program to implement the steps of the above-described method for evaluating anisotropy and geostress based on leaked longitudinal waves.

[0019] A computer-readable storage medium storing a computer program, which, when executed by a processor, is used to implement the steps of the above-described method for evaluating anisotropy and geostress based on leaked longitudinal waves.

[0020] Compared with existing technologies, the present invention has the following advantages: The present invention provides a method for evaluating anisotropy and geostress based on leaked P-waves. This method is mainly applied to shallow mudstone formations, i.e., slow-velocity formations with large Poisson ratios. First, leaked P-waves are extracted, and fast and slow waves are obtained from the four-component waveform data of the leaked P-waves. Then, auxiliary fast wave time series, auxiliary slow wave time series, and auxiliary fast and slow wave waveforms are obtained based on the fast and slow waves. Next, fast and slow wave matching processing is performed based on the waveform matching method to obtain the fast wave slowness and slow wave slowness. Finally, the anisotropy of the leaked P-waves is obtained based on the fast wave slowness and slow wave slowness, thus achieving anisotropy and geostress evaluation. This method obtains easily extractable cross-dipole leaked P-waves and, based on the similarity of the fast and slow wave waveforms in the P-waves, uses a waveform inversion method to fully utilize the combination and superposition of array acoustic wave data to suppress noise, improving calculation accuracy and stability. This achieves accurate and reliable evaluation of formation anisotropy and geostress, providing important technical support for geological exploration and oil and gas development.

[0021] Preferably, in this invention, the derivatives of the angles between the fast wave and the slow wave in the X direction and the polarization direction of the fast transverse wave are calculated to obtain auxiliary fast wave time series, auxiliary slow wave time series, and auxiliary fast and slow wave waveforms. The above steps improve the accuracy and sensitivity of the method and provide strong support for subsequent fast and slow wave matching processing.

[0022] Preferably, in this invention, the auxiliary wave time series and auxiliary fast and slow wave waveforms are processed by the waveform matching method. This step is the key to realizing the inversion calculation. The fast wave slowness and slow wave slowness can be obtained by the waveform matching method, which provides basic data for subsequent anisotropy and geostress evaluation.

[0023] Preferably, in this invention, during the inversion calculation process, the auxiliary wave waveform and the actual wave waveform are treated equally, so that they have the same weight; this allows the leakage wave azimuth and anisotropy magnitude to be inverted simultaneously. This approach improves the accuracy and reliability of the inversion calculation and avoids errors caused by improper weight settings.

[0024] Preferably, in this invention, the anisotropy of the leaked longitudinal wave is calculated using the same method as that of the transverse wave, which simplifies the calculation process and ensures the accuracy and precision of the calculation.

[0025] Preferably, in this invention, the obtained anisotropy and the acquired geostress magnitude, direction, rock mechanical parameters, etc., are plotted into an anisotropy and geostress evaluation result diagram. This makes the evaluation results more intuitive and easier to understand, providing strong support for decision-making in fields such as geological exploration and oil and gas development. At the same time, the evaluation result diagram can be used to accurately evaluate the anisotropy and geostress of the formation, providing an important reference for subsequent engineering design and construction. Attached Figure Description

[0026] Figure 1 is a schematic diagram of STC processing under weak filtering conditions provided in an embodiment of the present invention; wherein, (a) is a simulation diagram; (b) is a waveform diagram; Figure 2 is a schematic diagram of STC processing under strong filtering conditions provided in an embodiment of the present invention; wherein, (a) is a simulation diagram; (b) is a waveform diagram; Figure 3 is a diagram of anisotropy and geostress evaluation results based on bending waves provided in an embodiment of the present invention; Figure 4 is a diagram of the time difference extraction results of STC for slow formation leakage P-waves and S-waves provided in an embodiment of the present invention; Figure 5 is a flowchart of an anisotropy and geostress evaluation method based on leakage P-waves provided in an embodiment of the present invention; Figure 6 is a diagram of anisotropy and geostress evaluation results based on P-waves for well S025-32 provided in an embodiment of the present invention; Figure 7 is a diagram of anisotropy and geostress evaluation results based on P-waves for well S025-30 provided in an embodiment of the present invention; Figure 8 is a flowchart of an anisotropy and geostress evaluation method based on leakage P-waves provided in the present invention; Figure 9 is a schematic diagram of the structure of an anisotropy and geostress evaluation system based on leakage P-waves provided in the present invention. Detailed Implementation

[0027] Example 1 As described in the background art, currently, most methods for analyzing and evaluating anisotropy and geostress use shear wave extraction. At that time, this method was primarily applied to fast-moving formations, where bending waves could be effectively excited, the acoustic signal was dominated by bending wave trains, and the shear wave velocity extraction was accurate and reliable. However, in shallow mudstone formations, i.e., when the formation is slow-moving, the bending waves received by the wellbore are subsequent wave trains. These bending waves are strongly interfered with by the first wave and the subsequent wave, significantly impacting the waveform analysis and velocity extraction of the bending waves. This results in the inability to accurately obtain important information such as formation anisotropy and geostress direction. Specifically, as shown in Figures 1(a) and 1(b), the dipole waveform is weakly... Filtering fails to effectively observe obvious transverse waves. As shown in Figures 2(a) and 2(b), under strong filtering conditions, after filtering out relatively high-frequency longitudinal waves, transverse waves gradually appear. Although the leakage longitudinal waves are effectively suppressed, the transverse wave signal is inevitably weakened. At this time, the transverse wave signal is extremely unstable, the signal quality is relatively poor, and the extraction of transverse wave correlation is also poor. As shown in Figure 3, due to the low accuracy of transverse wave time difference extraction and the poor quality of the transverse wave waveform itself, the anisotropic processing effect is also poor. The waveform inversion results based on the curved wave show that the amplitude of fast and slow curved waves is weak within the waveform comparison window. There are still interference signals that cannot be filtered out before the comparison window, and the original anisotropic orientation of the inverted waveform is also unstable, making it difficult to accurately determine the orientation of the fast wave.

[0028] To achieve the above objectives, this invention provides an anisotropy and geostress evaluation method based on leaked P-waves. This method solves the problems in the prior art where, for soft strata, the cross-dipole shear wave signal is weak, making it impossible to effectively extract the shear wave and thus impossible to accurately calculate anisotropy and geostress.

[0029] As shown in Figure 5, this embodiment provides an anisotropy and geostress evaluation method based on leaked P-waves, including: First, extracting leaked P-waves: As shown in Figure 4, the study found that in fast-moving strata, bending waves can be effectively excited, and the acoustic signal is dominated by bending wave trains, making the extraction of shear wave velocity accurate and reliable. However, in shallow mudstone strata, i.e., slow-moving strata with a large Poisson ratio, leaked P-waves become the dominant wave, with the "P-wave" as the first wave in the entire wave train, and bending waves as the subsequent wave trains. Bending waves are strongly affected by the continuation of leaked P-waves, making bending wave extraction difficult, or even impossible to extract shear waves. Therefore, in this embodiment, leaked P-waves are extracted, reducing the extraction difficulty and ensuring the accuracy and reliability of subsequent strata evaluation.

[0030] The second step is to obtain the fast and slow waves based on the four-component waveform data of the leaked longitudinal wave: In this embodiment, the fast and slow waves, as well as their waveforms, are derived from the four-component waveform data of the cross-dipole array acoustic wave: The specific formulas are as follows:

[0031] In the formula: XX, XY, YX, YY represent four-component waveform data; FP(t) represents fast wave; SP(t) represents slow wave; θ represents the angle between the X direction and the polarization direction of the fast transverse wave.

[0032] The third step involves obtaining auxiliary fast wave time series, auxiliary slow wave time series, and auxiliary fast and slow wave waveforms based on the fast and slow waves: Differentiating the fast and slow waves with respect to θ yields two auxiliary fast and slow curved wave time series and auxiliary fast and slow wave waveforms, as shown in the following formulas:

[0033] In the formula, Indicates the auxiliary fast wave time series; This represents an auxiliary slow-wave time series.

[0034] The fourth step involves performing fast-slow wave matching processing on the auxiliary wave time series, the auxiliary slow main wave time series, and the auxiliary fast and slow wave waveforms based on the waveform matching method, to obtain the fast wave slowness and the slow wave slowness: Let the slowness of the fast and slow waves be respectively... and Based on the linear propagation theory and waveform similarity theory of waveforms, the fast and slow waves are processed using the waveform matching method. The expression for waveform matching after matching the fast and slow waves is as follows:

[0035] In the formula, This represents the difference between the slowness of slow waves and the slowness of fast waves; Indicates the speed of a fast wave; Indicates the slowness of slow waves; Indicates the receiver spacing subscript; , Indicates the receiver serial number; This represents the distance between the sound source and the m-th receiver in the receiver array.

[0036] in,

[0037] Step 5, Inversion Calculation: In this embodiment, (5) during the inversion calculation, the auxiliary main waveform (controlled by azimuth angle) and the actual main waveform (controlled by anisotropy) are treated equally, so that they have the same weight in the inversion process, and the azimuth of the leakage wave and the magnitude of anisotropy can be inverted simultaneously. The objective function of the inversion is: .

[0038] The integral in the above formula is applied over the entire time window T, within which waveform matching processing is performed. The summation in the formula includes all possible combinations of fast and slow waves in an array of N receivers. By using this data combination or data superposition method, the incoherent noise in the waveform data is greatly suppressed or eliminated, thereby enabling the reliable extraction of anisotropic effects of a smaller magnitude.

[0039] Step 6: Solving for the anisotropy of leaked P-waves: In well logging, the anisotropy of shear waves is defined as the ratio of the slowness difference between fast and slow waves in the formation to the average slowness of the fast and slow waves. The same method is used for leaked P-waves, i.e.:

[0040] In the formula, This indicates the leakage of longitudinal wave anisotropy; Indicates the speed of a fast wave; This indicates the slow wave slowness; here, the fast wave slowness and slow wave slowness are also called the fast leakage P-wave time difference and the slow leakage P-wave time difference.

[0041] This embodiment provides a method for evaluating anisotropy and geostress based on leaked P-waves. This method targets slow-velocity formations, using cross-dipole array acoustic logging to extract leaked P-waves, deriving fast and slow wave waveforms from the leaked P-waves, and calculating formation anisotropy and geostress. The beneficial effects of this method are as follows: This method mainly addresses the problems of weak cross-dipole shear wave signals in soft formations, making it difficult to effectively extract shear waves and thus accurately calculate anisotropy and geostress. It uses leaked P-waves excited by a dipole acoustic source to accurately and reliably perform anisotropy analysis and geostress direction evaluation. This method provides a new research approach for evaluating anisotropy and geostress using cross-dipole array acoustic logging, and can serve as an important supplement and improvement to geostress evaluation methods based on shear wave anisotropy theory. Furthermore, this method has achieved good application results in slow-velocity formations in the Liaohe Gas Storage Facility; as of February 2024, it has been applied in 7 wells, demonstrating good reference value and application prospects for similar formations.

[0042] The anisotropy and geostress evaluation method based on leakage P-waves provided in this embodiment is implemented under actual working conditions, as follows: Since gas storage facilities operate under alternating stress conditions, the requirements for wellbore integrity and gas storage sealing are strict. Therefore, gas storage projects generally use array acoustic logging for both the caprock and reservoir sections to obtain the magnitude, direction, and rock mechanical parameters of geostress, providing a basis for gas storage integrity evaluation and operating pressure design. This method takes the shallow mudstone soft formation of the Liaohe Oilfield gas storage facility as an example to illustrate the anisotropy analysis and geostress direction extraction method based on cross-dipole leakage P-waves and its actual effects.

[0043] Case study well overview: Wells S025-32 and S025-30 are located in the northern part of a fault anticline zone in the western depression of the Liaohe Depression in the Bohai Bay Basin. They are gas storage injection and production wells deployed for XLT reservoirs. The 1600-1700m well sections of both wells are typical shallow, slow-velocity formations, which are the capping layers of the gas storage. The drill bit diameter of this well is 311.1mm, which is a large-diameter wellbore.

[0044] As shown in Figures 6 and 7, using the aforementioned theory and analysis methods, anisotropy and stress direction analysis results were obtained using leaked longitudinal waves. The results show that there is significant acoustic wave splitting within the waveform matching window of the layer, indicating obvious acoustic anisotropy, with anisotropy values ​​around 8%. The fast wave azimuth remains stable at approximately 80 degrees even with instrument rotation, indicating the stability of the stress direction. Comparison with analysis results from other wells in the region shows that the maximum horizontal principal stress azimuth in this area is near east-west, thus confirming the good accuracy and reliability of the evaluation method provided in this embodiment.

[0045] Example 2, as shown in Figure 8, provides a method for evaluating anisotropy and geostress based on leaked P-waves, including the following steps: S1: Obtaining fast and slow waves based on the four-component waveform data of the leaked P-wave; wherein, the leaked P-wave is a cross-dipole array acoustic wave; wherein, the steps for obtaining fast and slow waves based on the four-component waveform data of the leaked P-wave are as follows: The fast and slow wave waveforms are derived from the four-component waveform data of the cross-dipole array acoustic wave, and the specific formulas are as follows:

[0046] In the formula: XX, XY, YX, YY represent four-component waveform data; FP(t) represents fast wave; SP(t) represents slow wave; θ represents the angle between the X direction and the polarization direction of the fast transverse wave.

[0047] S2: Obtaining auxiliary fast wave time series, auxiliary slow wave time series, and auxiliary fast and slow wave waveforms based on fast and slow waves; the specific steps for obtaining the auxiliary fast wave time series, auxiliary slow wave time series, and auxiliary fast and slow wave waveforms based on fast and slow waves are as follows: Solve for the derivatives of the angles between the fast wave and the slow wave in the X direction and the polarization direction of the fast transverse wave, respectively, to obtain the auxiliary fast wave time series, auxiliary slow wave time series, and auxiliary fast and slow wave waveforms. The specific formulas are as follows:

[0048] In the formula, Indicates the auxiliary fast wave time series; This represents an auxiliary slow-wave time series.

[0049] S3: Based on the waveform matching method, fast and slow wave matching processing is performed on the auxiliary wave time series, the auxiliary slow main wave time series, and the auxiliary fast and slow wave waveforms to obtain the fast wave slowness and slow wave slowness. The specific steps for this process are as follows: Based on the linear propagation theory and waveform similarity theory of waveforms, the waveform matching method is used to perform fast and slow wave matching processing on the auxiliary fast wave time series, the auxiliary slow wave time series, and the auxiliary fast and slow wave waveforms to achieve inversion calculation, obtaining the fast wave slowness and slow wave slowness. The specific formulas are as follows:

[0050] In the formula, This represents the difference between the slowness of slow waves and the slowness of fast waves; Indicates the speed of a fast wave; Indicates the slowness of slow waves; Indicates the receiver spacing subscript; , Indicates the receiver serial number; This represents the distance between the sound source and the m-th receiver in the receiver array.

[0051] In the inversion calculation process, the auxiliary wave waveform and the actual wave waveform are treated equally to ensure that they have the same weight; the specific inversion objective function is as follows: .

[0052] Here, the anisotropy of the leaked P-wave is obtained based on the difference between the fast wave slowness and the slow wave slowness, and the average of the fast wave slowness and the slow wave slowness. The specific formula is as follows:

[0053] In the formula, This indicates the leakage of longitudinal wave anisotropy; Indicates the speed of a fast wave; This indicates the slow wave slowness; here, the fast wave slowness and slow wave slowness are also called the fast leakage P-wave time difference and the slow leakage P-wave time difference.

[0054] S4: Draw an anisotropy and geostress evaluation result map based on the obtained anisotropy and geostress magnitude, direction, and rock mechanics parameters, and evaluate the stratigraphic anisotropy and geostress based on the anisotropy and geostress evaluation result map.

[0055] As shown in Figure 9, this embodiment also provides an anisotropy and geostress evaluation system based on leaked P-waves, including: a fast and slow wave derivation module for obtaining fast and slow waves based on the four-component waveform data of leaked P-waves; wherein the leaked P-wave is a cross-dipole array acoustic wave; an auxiliary wave calculation module for obtaining auxiliary fast wave time series, auxiliary slow wave time series, and auxiliary fast and slow wave waveforms based on fast and slow waves; a fast and slow wave matching processing module for performing fast and slow wave matching processing on the auxiliary wave time series, auxiliary slow main wave time series, and auxiliary fast and slow wave waveforms based on waveform matching method to obtain fast wave slowness and slow wave slowness; and an anisotropy calculation module for obtaining the anisotropy of leaked P-waves based on fast wave slowness and slow wave slowness, so as to realize the evaluation of formation anisotropy and geostress based on the anisotropy of leaked P-waves.

[0056] The present invention also provides an apparatus comprising: a memory for storing a computer program; and a processor for executing the computer program to implement the steps of the method for evaluating anisotropy and geostress based on leaked longitudinal waves.

[0057] When the processor executes the computer program, it implements the above-mentioned steps for evaluating anisotropy and geostress based on leaked P-waves. For example: acquiring fast and slow waves based on the four-component waveform data of the leaked P-wave; wherein the leaked P-wave is a cross-dipole array acoustic wave; obtaining auxiliary fast wave time series, auxiliary slow wave time series, and auxiliary fast and slow wave waveforms based on the fast and slow waves; performing fast and slow wave matching processing on the auxiliary wave time series, auxiliary slow main wave time series, and auxiliary fast and slow wave waveforms based on the waveform matching method to obtain the fast wave slowness and slow wave slowness; obtaining the anisotropy of the leaked P-wave based on the fast wave slowness and slow wave slowness, so as to realize the evaluation of formation anisotropy and geostress based on the anisotropy of the leaked P-wave.

[0058] Alternatively, when the processor executes the computer program, it implements the functions of each module in the above system, such as: a fast and slow wave derivation module, used to obtain fast and slow waves based on the four-component waveform data of the leaked P-wave; wherein the leaked P-wave is a cross-dipole array acoustic wave; an auxiliary wave calculation module, used to obtain auxiliary fast wave time series and auxiliary slow wave time series and auxiliary fast and slow wave waveforms based on the fast and slow waves; a fast and slow wave matching processing module, used to perform fast and slow wave matching processing on the auxiliary wave time series, auxiliary slow main wave time series and auxiliary fast and slow wave waveforms based on the waveform matching method to obtain the fast wave slowness and slow wave slowness; and an anisotropy calculation module, used to obtain the anisotropy of the leaked P-wave based on the fast wave slowness and slow wave slowness, so as to realize the evaluation of formation anisotropy and geostress based on the anisotropy of the leaked P-wave.

[0059] For example, the computer program may be divided into one or more modules / units, which are stored in the memory and executed by the processor to complete the present invention. The one or more modules / units may be a series of computer program instruction segments capable of performing preset functions, the instruction segments describing the execution process of the computer program in the anisotropy and geostress evaluation device based on leaked longitudinal waves. For example, the computer program can be divided into a fast and slow wave derivation module, an auxiliary wave calculation module, a fast and slow wave matching processing module, and an anisotropy calculation module; the specific functions of each module are as follows: the fast and slow wave derivation module is used to obtain fast and slow waves based on the four-component waveform data of the leaked P-wave; wherein, the leaked P-wave is a cross-dipole array acoustic wave; the auxiliary wave calculation module is used to obtain auxiliary fast wave time series and auxiliary slow wave time series, as well as auxiliary fast and slow wave waveforms based on the fast and slow waves; the fast and slow wave matching processing module is used to perform fast and slow wave matching processing on the auxiliary wave time series, auxiliary slow main wave time series, and auxiliary fast and slow wave waveforms based on the waveform matching method to obtain the fast wave slowness and slow wave slowness; the anisotropy calculation module is used to obtain the anisotropy of the leaked P-wave based on the fast wave slowness and slow wave slowness, so as to realize the evaluation of formation anisotropy and geostress based on the anisotropy of the leaked P-wave.

[0060] The anisotropy and geostress evaluation device based on leaked P-waves can be a computing device such as a desktop computer, laptop, handheld computer, or cloud server. The device may include, but is not limited to, processors and memory. Those skilled in the art will understand that the above examples of anisotropy and geostress evaluation devices based on leaked P-waves do not constitute a limitation on such devices. The device may include more components than described above, or combine certain components, or use different components. For example, the device may also include input / output devices, network access devices, buses, etc.

[0061] The processor can be a Central Processing Unit (CPU), or other general-purpose processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. The general-purpose processor can be a microprocessor, or any conventional processor. The processor is the control center for the anisotropy and ground stress evaluation based on leaked P-waves, connecting various parts of the entire anisotropy and ground stress evaluation equipment using various interfaces and lines.

[0062] The memory can be used to store the computer program and / or modules. The processor realizes various functions of the anisotropy and geostress evaluation device based on leaked longitudinal waves by running or executing the computer program and / or modules stored in the memory and calling the data stored in the memory.

[0063] The memory may primarily include a program storage area and a data storage area. The program storage area may store the operating system and at least one application program required for a function (such as sound playback, image playback, etc.). The data storage area may store data created based on the use of the mobile phone (such as audio data, phonebook, etc.). Furthermore, the memory may include high-speed random access memory and non-volatile memory, such as hard disks, RAM, plug-in hard disks, smart media cards (SMC), secure digital cards (SD cards), flash cards, at least one disk storage device, flash memory device, or other volatile solid-state storage devices.

[0064] The present invention also provides a computer-readable storage medium storing a computer program that, when executed by a processor, implements the steps of the method for evaluating anisotropy and geostress based on leaked longitudinal waves.

[0065] If the modules / units integrated by the leakage longitudinal wave-based anisotropy and geostress evaluation system are implemented as software functional units and sold or used as independent products, they can be stored in a computer-readable storage medium.

[0066] Based on this understanding, the present invention can implement all or part of the processes in the above-mentioned anisotropy and geostress evaluation method based on leaked P-waves. This can also be accomplished by a computer program instructing related hardware. The computer program can be stored in a computer-readable storage medium. When executed by a processor, the computer program can implement the steps of the above-mentioned anisotropy and geostress evaluation method based on leaked P-waves. The computer program includes computer program code, which can be in the form of source code, object code, executable file, or a preset intermediate form, etc.

[0067] The computer-readable storage medium may include: any entity or device capable of carrying the computer program code, recording media, USB flash drive, portable hard drive, magnetic disk, optical disk, computer memory, read-only memory (ROM), random access memory (RAM), electrical carrier signal, telecommunication signal, and software distribution medium, etc.

[0068] It should be noted that the content contained in the computer-readable storage medium may be appropriately increased or decreased according to the requirements of legislation and patent practice in the jurisdiction. For example, in some jurisdictions, according to legislation and patent practice, the computer-readable storage medium does not include electrical carrier signals and telecommunication signals.

[0069] In summary, this invention provides a method for evaluating anisotropy and geostress based on leaked P-waves. Compared with existing evaluation methods, it has the following advantages: This method effectively extracts fast and slow waves from the four-component waveform data of leaked P-waves, providing accurate basic data for subsequent waveform analysis; furthermore, the auxiliary wave calculation module utilizes this fast and slow wave information to generate auxiliary fast wave time series, slow wave time series, and auxiliary fast and slow wave waveforms, which not only enriches the dimensions of the waveform data but also provides more references for fast and slow wave matching processing; the fast and slow wave matching processing module... The block employs a waveform matching method to perform fine matching between the auxiliary wave time series and waveform, thereby accurately determining the slowness of fast and slow waves. This step significantly improves the extraction accuracy of fast and slow wave characteristic parameters. Finally, the anisotropy calculation module calculates the anisotropy of the leaked P-wave based on the slowness of fast and slow waves, providing a scientific and reliable basis for evaluating formation anisotropy and geostress. Overall, this method solves the problem of difficult extraction of shear waves in slow-velocity formations, achieving high-precision evaluation of formation characteristics, which is of great significance for practical applications in oil and gas exploration and other fields.

[0070] The above embodiments are merely one of the implementation methods for achieving the technical solution of the present invention. The scope of protection claimed by the present invention is not limited to this embodiment, but also includes any variations, substitutions and other implementation methods that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention.

Claims

1. A method for evaluating anisotropy and geostress based on leaked P-waves, characterized in that, include: Fast and slow waves are obtained from four-component waveform data of the leaked longitudinal wave; wherein the leaked longitudinal wave is a cross-dipole array acoustic wave. Based on fast and slow waves, auxiliary fast wave time series, auxiliary slow wave time series, and auxiliary fast and slow wave waveforms are obtained; based on waveform matching method, fast and slow wave matching processing is performed on the auxiliary wave time series, auxiliary slow main wave time series, and auxiliary fast and slow wave waveforms to obtain fast wave slowness and slow wave slowness; based on fast wave slowness and slow wave slowness, the anisotropy of the leaked P-wave is obtained, so as to realize the evaluation of formation anisotropy and geostress based on the anisotropy of the leaked P-wave.

2. The method for evaluating anisotropy and geostress based on leaked P-waves according to claim 1, characterized in that, The steps for obtaining fast and slow waves based on the four-component waveform data of the leaked longitudinal wave are as follows: Fast and slow wave waveforms are derived from the four-component waveform data of the cross-dipole array acoustic wave, and the specific formulas are as follows: In the formula: XX, XY, YX, YY represent four-component waveform data; FP(t) represents fast wave; SP(t) represents slow wave; θ represents the angle between the X direction and the polarization direction of the fast transverse wave.

3. The anisotropy and geostress evaluation method based on leaked P-waves according to claim 2, characterized in that, The specific steps for obtaining the auxiliary fast wave time series, auxiliary slow wave time series, and auxiliary fast and slow wave waveforms based on fast and slow waves are as follows: The derivatives of the angles between the fast wave and the slow wave in the X-direction and the polarization direction of the fast transverse wave are calculated to obtain the auxiliary fast wave time series, auxiliary slow wave time series, and auxiliary fast and slow wave waveforms. The specific formulas are as follows: In the formula, Indicates the auxiliary fast wave time series; This represents an auxiliary slow-wave time series.

4. The anisotropy and geostress evaluation method based on leaked P-waves according to claim 3, characterized in that, The specific steps for performing fast-slow wave matching processing on the auxiliary wave time series, auxiliary slow main wave time series, and auxiliary fast-slow wave waveforms based on the waveform matching method are as follows: Based on the linear propagation theory and waveform similarity theory of waveforms, the auxiliary fast wave time series, auxiliary slow wave time series, and auxiliary fast-slow wave waveforms are matched using the waveform matching method to achieve inversion calculation, obtaining the fast wave slowness and slow wave slowness. The specific formulas are as follows: In the formula, This represents the difference between the slowness of slow waves and the slowness of fast waves; Indicates the speed of a fast wave; Indicates the slowness of slow waves; Indicates the receiver spacing subscript; 、 Indicates the receiver serial number; This represents the distance between the sound source and the m-th receiver in the receiver array.

5. The anisotropy and geostress evaluation method based on leaked P-waves according to claim 4, characterized in that, In the inversion calculation process, the auxiliary wave waveform and the actual wave waveform are treated equally so that they have the same weight; the specific inversion objective function is as follows: 。 6. The method for evaluating anisotropy and geostress based on leaked P-waves according to claim 1, characterized in that, The anisotropy of leaked P-waves is obtained based on the difference between the fast wave slowness and the slow wave slowness, and the average of the fast wave slowness and the slow wave slowness. The specific formula is as follows: In the formula, This indicates the leakage of longitudinal wave anisotropy; Indicates the speed of a fast wave; Indicates the slowness of a slow wave.

7. The method for evaluating anisotropy and geostress based on leaked P-waves according to claim 1, characterized in that, The obtained anisotropy and geostress magnitude, direction, and rock mechanics parameters are used to create an anisotropy and geostress evaluation result map. Based on the anisotropy and geostress evaluation result map, the anisotropy and geostress of the formation are evaluated.

8. An anisotropy and geostress evaluation system based on leaked longitudinal waves, characterized in that, include: The fast and slow wave derivation module is used to obtain fast and slow waves based on the four-component waveform data of the leaked longitudinal wave; wherein, the leaked longitudinal wave is a cross dipole array acoustic wave; The auxiliary wave calculation module is used to obtain auxiliary fast wave time series, auxiliary slow wave time series, and auxiliary fast and slow wave waveforms based on fast and slow waves. The fast and slow wave matching processing module is used to perform fast and slow wave matching processing on the auxiliary wave time series, auxiliary slow main wave time series, and auxiliary fast and slow wave waveforms based on the waveform matching method to obtain the fast wave slowness and slow wave slowness. The anisotropy calculation module is used to obtain the anisotropy of the leaked P-wave based on the fast wave slowness and slow wave slowness, so as to realize the evaluation of formation anisotropy and geostress based on the anisotropy of the leaked P-wave.

9. A device, characterized in that, include: Memory, used to store computer programs; A processor, configured to execute the computer program to implement the steps of the anisotropy and geostress evaluation method based on leaked longitudinal waves as described in any one of claims 1-7.

10. A computer-readable storage medium storing a computer program, characterized in that, When the computer program is executed by the processor, it is used to implement the steps of the anisotropy and geostress evaluation method based on leaked longitudinal waves as described in any one of claims 1-7.

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