Crack feature inversion method and system, storage medium and electronic equipment

Abstract

The invention belongs to the technical field of geophysics, and provides a fracture feature inversion method and system, a storage medium and electronic equipment, and the method comprises the steps: simulating the filling process of hydrocarbon fluid based on a digital core sample, and obtaining the distribution condition and saturation of the hydrocarbon fluid in the filling process; on the basis of the digital core sample, crack models with different inclination angles are constructed, and the hydrocarbon fluid filling process of each crack model is simulated in combination with the distribution condition and saturation of the hydrocarbon fluid in the filling process; acquiring acoustic parameters and electrical parameters of each fracture model in the hydrocarbon fluid charging process, and generating an inversion model according to the acoustic parameters and the electrical parameters corresponding to all the fracture models; and based on the inversion model, inverting actual fracture characteristics and reservoir physical parameters, and obtaining a fracture characteristic inversion result. And by taking the digital core sample as input, establishing an acoustic and electrical inversion template for the non-uniform medium containing the hydrocarbon fluid, and accurately inverting fracture characteristics and reservoir physical property parameters.

Description

Technical Field

[0001] This disclosure belongs to the field of geophysical technology, and in particular relates to a method, system, storage medium and electronic device for fracture feature inversion. Background Technology

[0002] Fractures are prevalent in unconventional energy reservoirs, providing crucial pathways for the storage and circulation of oil and gas. Therefore, the quantitative prediction and accurate evaluation of reservoir fracture parameters are of paramount importance in the exploration and development of unconventional oil and gas reservoirs.

[0003] The presence of fractures significantly enhances the permeability and diffusion efficiency of hydrocarbon fluids, enabling them to enter and fill reservoirs more rapidly. However, in areas with few or no fractures, the fluid injection process is relatively slow. These complex geological features often lead to uneven fluid distribution within the reservoir, and even localized blockages in some areas, further increasing the difficulty of oil and gas exploration and development. In the exploration and development of oil and gas resources, a deep understanding and accurate prediction of key parameters such as fracture characteristics are crucial for optimizing extraction strategies and improving oil and gas recovery rates.

[0004] The distribution of hydrocarbon fluids has a significant impact on the acoustic and electrical properties of rocks. Firstly, the distribution of hydrocarbon fluids greatly affects the acoustic properties of rocks. Hydrocarbon fluids have low density and compressibility; their presence alters the velocity of sound in the rock, influencing sound wave propagation and attenuation. Therefore, the influence of hydrocarbon fluids must be considered in elastic wave exploration to accurately identify subsurface structures. Secondly, the presence of hydrocarbon fluids also affects the resistivity and conductivity of rocks. Since hydrocarbon fluids are generally poor conductors of electricity, their presence reduces rock resistivity and increases conductivity. This effect is particularly important in oil and gas exploration, as changes in resistivity are a crucial indicator for identifying oil and gas reservoirs.

[0005] Acoustic-electric inversion of rock cores involves measuring the acoustic and electrical properties of core samples to obtain physical parameters of the rock, including but not limited to acoustic velocity and resistivity. Mathematical methods are then used to invert and derive a physical parameter model of the core. Existing inversion models assume a homogeneous medium, resulting in low accuracy for complex, heterogeneous media and hydrocarbon-filled reservoirs. Most existing models also assume isotropic media, failing to account for the influence of anisotropic media. In research on anisotropic models, the electromagnetic geophysics team at Chang'an University, focusing on the electrical anisotropy of fractured rocks, performed tensor-based corrections to classical models such as Archie's theorem and combined them with mechanical tensors to predict fracture morphology and distribution. Han Tongcheng's research at China University of Petroleum (East China) used a combined acoustic-electric method to conduct experimental and theoretical studies on artificial sandstone containing directional fractures, analyzing the correlation between P-wave velocity and electrical conductivity in different directions.

[0006] In summary, existing technologies lack a method for measuring anisotropic media and generating inversion models during hydrocarbon fluid filling. Summary of the Invention

[0007] To address the aforementioned issues, this disclosure provides a fracture feature inversion method, system, storage medium, and electronic device. It utilizes digital core samples to generate fracture models with different tilt angles, simulates the hydrocarbon fluid injection process, and acquires electrical and acoustic parameters during the injection process. These parameters are then used to generate a map, enabling accurate inversion of fracture features and reservoir properties of actual core samples.

[0008] This invention is achieved through the following technical solution:

[0009] In a first aspect, embodiments of this disclosure provide a crack feature inversion method, the method comprising:

[0010] Based on digital core samples, the hydrocarbon fluid filling process was simulated to obtain the distribution and saturation of hydrocarbon fluids during the filling process;

[0011] Based on digital core samples, fracture models with different inclination angles were constructed. The hydrocarbon fluid filling process of each fracture model was simulated by combining the distribution and saturation of hydrocarbon fluids during the filling process.

[0012] Acoustic and electrical parameters of each fracture model during hydrocarbon fluid filling were obtained. Based on the acoustic and electrical parameters of all fracture models, an anisotropic acoustic-electric joint chart was established, and an inversion model was generated.

[0013] Based on the inversion model, combined with the acoustic and electrical parameters of the actual core, fracture characteristics and reservoir physical parameters are inverted to obtain fracture characteristic inversion results.

[0014] Furthermore,

[0015] Based on digital core samples, core pore models, dominant channel models, and non-dominant channel models are generated. The core pore model includes natural fractures, the dominant channel model includes fractures extending away from the direction of hydrocarbon fluids, and the non-dominant channel model includes fractures extending in the direction of hydrocarbon fluids.

[0016] The hydrocarbon fluid filling process was simulated using the core pore model, the dominant channel model, and the non-dominant channel model, respectively.

[0017] Obtain the distribution and saturation of hydrocarbon fluid during the filling process of the dominant channel model; obtain the distribution and saturation of hydrocarbon fluid during the filling process of the non-dominant channel model.

[0018] Furthermore,

[0019] Based on digital core samples, fracture models with no tilt angle, 30° tilt angle, 45° tilt angle, 60° tilt angle, and 90° tilt angle were constructed respectively. Each fracture model is a three-dimensional model.

[0020] Based on the distribution and saturation of hydrocarbon fluids during the filling process, the hydrocarbon fluid filling process was simulated using fracture models with no tilt angle, a 30° tilt angle, a 45° tilt angle, a 60° tilt angle, and a 90° tilt angle.

[0021] Furthermore,

[0022] Obtain the longitudinal wave velocity variation curve, transverse wave velocity variation curve, and resistivity variation curve of the fracture model during hydrocarbon fluid filling process;

[0023] Based on the longitudinal wave velocity variation curve and transverse wave velocity variation curve of the fracture model during hydrocarbon fluid filling process, and combined with the distribution and saturation of hydrocarbon fluid during filling process, an acoustic velocity-saturation line graph is generated.

[0024] Based on the longitudinal wave velocity variation curves, transverse wave velocity variation curves, acoustic velocity-saturation line graphs, and resistivity variation curves of all fracture models during hydrocarbon fluid filling, an anisotropic acoustic-electric joint chart is established, and an inversion model is generated.

[0025] Furthermore,

[0026] During the injection of hydrocarbon fluid, the fracture model simulates the process by applying acoustic excitation at the boundary of the fracture model, recording the longitudinal wave waveform and the transverse wave waveform, calculating the longitudinal wave velocity and the transverse wave velocity, and generating the longitudinal wave velocity variation curve and the transverse wave velocity variation curve.

[0027] In simulating hydrocarbon fluid injection, the crack model applies electrical excitation at the boundary of the crack model to obtain the electric field strength and current density. Based on the electric field strength and current density, the resistivity tensor value is determined, and the resistivity change curve is generated.

[0028] Furthermore,

[0029] Based on the resistivity change curves of all fracture models during hydrocarbon fluid filling, and combined with the distribution and saturation of hydrocarbon fluid during filling, a resistivity-fracture inclination angle-saturation line graph is generated.

[0030] By combining the longitudinal wave velocity variation curves, transverse wave velocity variation curves, resistivity variation curves, acoustic velocity-saturation line graphs, and resistivity-crack inclination angle-saturation line graphs of all crack models during hydrocarbon fluid filling, an anisotropic acoustic-electric joint chart is established, and an inversion model is generated.

[0031] Furthermore,

[0032] At the boundary of the crack model, three electrical excitations are applied in different directions.

[0033] Secondly, based on the same inventive concept, this disclosure also provides a crack feature inversion system, the system comprising: a first simulated filling module, a crack simulated filling module, an inversion model generation module, and an inversion module;

[0034] The first simulated filling module is used to simulate the filling process of hydrocarbon fluids based on digital core samples, and to obtain the distribution and saturation of hydrocarbon fluids during the filling process;

[0035] The fracture simulation and filling module is used to construct fracture models with different inclination angles based on digital core samples. It combines the distribution and saturation of hydrocarbon fluids during the filling process to simulate the hydrocarbon fluid filling process of each fracture model.

[0036] The inversion model generation module is used to obtain the acoustic and electrical parameters of each fracture model during the hydrocarbon fluid filling process, and to establish an anisotropic acoustic-electric joint chart based on the acoustic and electrical parameters of all fracture models, and generate the inversion model.

[0037] The inversion module is used to invert fracture characteristics and reservoir physical parameters based on the inversion model and the acoustic and electrical parameters of the actual core, and obtain fracture characteristic inversion results.

[0038] Thirdly, based on the same inventive concept, the present disclosure also provides a computer-readable storage medium storing one or more programs, which, when executed, can implement the aforementioned crack feature inversion method.

[0039] Fourthly, based on the same inventive concept, embodiments of this disclosure also provide an electronic device, including a processor, a communication interface, a memory, and a communication bus. The processor, communication interface, and memory communicate with each other via the communication bus. The processor is used to execute a program stored in the aforementioned computer-readable storage medium.

[0040] Compared with the prior art, this disclosure has the following advantages:

[0041] 1. Establish acoustic and electrical inversion templates for heterogeneous media containing hydrocarbon fluids to simultaneously invert fracture characteristics and reservoir physical parameters, providing a basis for oil reservoir development engineering and practice.

[0042] 2. Establish a complete and unified physical field (acoustic and electrical) upscaling theory system, and use digital core samples as input to achieve joint upscaling of acoustic, electrical and fluid saturation, and accurately invert fracture characteristics and reservoir physical parameters.

[0043] Other features and advantages of this disclosure will be set forth in the following description and will be apparent in part from the description or may be learned by practicing the disclosure. The objects and other advantages of this disclosure may be realized and obtained by means of the structures pointed out in the description, claims and drawings. Attached Figure Description

[0044] To more clearly illustrate the technical solutions in the embodiments of this disclosure or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this disclosure. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0045] Figure 1 A flowchart of a crack feature inversion method provided in this embodiment of the present disclosure;

[0046] Figure 2 This is a schematic diagram of hydrocarbon fluid filling provided in an embodiment of the present disclosure;

[0047] Figure 3 A line graph showing the relationship between charge time and saturation provided in this embodiment of the disclosure;

[0048] Figure 4A schematic diagram of a crack model provided in an embodiment of this disclosure;

[0049] Figure 5 A schematic diagram of shear wave velocity and longitudinal wave velocity during the filling process provided in this embodiment of the present disclosure;

[0050] Figure 6 This is a schematic diagram of the transverse and longitudinal wave velocities of another filling process provided in an embodiment of the present disclosure;

[0051] Figure 7 A sound wave velocity-saturation line graph provided in this embodiment of the disclosure;

[0052] Figure 8 Another acoustic velocity-saturation line graph provided in this embodiment of the disclosure;

[0053] Figure 9 A resistivity-crack inclination angle-saturation line graph provided for embodiments of this disclosure;

[0054] Figure 10 This is a schematic diagram of another crack model provided in an embodiment of the present disclosure;

[0055] Figure 11 Another resistivity-crack inclination angle-saturation line graph provided for embodiments of this disclosure;

[0056] Figure 12 A schematic diagram of an actual crack inversion pattern provided in this embodiment of the present disclosure;

[0057] Figure 13 A block diagram of a crack feature inversion system provided in this disclosure embodiment;

[0058] Figure 14 This is a schematic diagram of an electronic device structure provided in an embodiment of the present disclosure. Detailed Implementation

[0059] To make the objectives, technical solutions, and advantages of the embodiments of this disclosure clearer, the technical solutions of the embodiments of this disclosure will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this disclosure, and not all embodiments. Based on the embodiments of this disclosure, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this disclosure.

[0060] Firstly, Figure 1 A flowchart of a crack feature inversion method provided in this disclosure is shown below. Figure 1 As shown, this disclosure provides a crack feature inversion method, including:

[0061] S1: Based on digital core samples, simulate the hydrocarbon fluid filling process to obtain the distribution and saturation of hydrocarbon fluid during the filling process.

[0062] S2: Based on digital core samples, fracture models with different tilt angles are constructed. The hydrocarbon fluid distribution and saturation during the filling process are combined to simulate the hydrocarbon fluid filling process of each fracture model.

[0063] S3: Obtain the acoustic and electrical parameters of each fracture model during the hydrocarbon fluid filling process, and based on the acoustic and electrical parameters of all fracture models, establish an anisotropic acoustic-electric joint chart and generate an inversion model.

[0064] S4: Based on the inversion model, combined with the acoustic and electrical parameters of the actual core, the fracture characteristics and reservoir physical parameters are inverted to obtain the fracture characteristic inversion results.

[0065] In this embodiment, the distribution and characteristics of fractures often exhibit strong heterogeneity. To accurately invert fracture features such as angle and porosity, it is necessary to acquire multiple fracture models with different tilt angles, perform hydrocarbon fluid filling, and obtain acoustic and electrical parameters during the hydrocarbon fluid filling process. This generates an anisotropic acoustic-electric joint map containing information on the acoustic and electrical parameters corresponding to fracture models with different tilt angles. This map is used to generate an inversion model, which inverts fracture features such as angle and porosity. When inverting fracture features such as angle and porosity, a map of actual fracture core samples is created. Based on the inversion model, an optimal root-finding algorithm is used to invert fracture features such as angle and porosity, and the fracture feature inversion results are obtained.

[0066] In some examples, based on digital core samples, the hydrocarbon fluid charging process is simulated to obtain the distribution and saturation of the hydrocarbon fluid during the charging process, specifically including:

[0067] S11: Based on digital core samples, generate core pore models, dominant channel models, and non-dominant channel models; wherein, the core pore model includes natural fractures, the dominant channel model includes fractures extending away from the direction of hydrocarbon fluids, and the non-dominant channel model includes fractures extending in the direction of hydrocarbon fluids.

[0068] Specifically, based on digital core samples, a core pore model including natural fractures is generated; a dominant channel model including fractures extending away from the hydrocarbon fluid direction is generated, where fractures extending away from the hydrocarbon fluid direction can be understood as fractures almost perpendicular to the ground, with the bottom of the fractures connected to the hydrocarbon fluid; a non-dominant channel model including fractures extending along the hydrocarbon fluid direction is generated, where fractures extending along the hydrocarbon fluid direction can be understood as fractures almost parallel to the ground, with the bottom of the fractures not connected to the hydrocarbon fluid; in this embodiment of the disclosure, the pixel size of the core pore model, the dominant channel model, and the non-dominant channel model is 100×100, and the physical size is 1mm×1mm.

[0069] It is important to understand that the cracks do not extend in a straight line; the vertical, parallel, and tilt angles described here, as well as those described later, are all approximations.

[0070] S12: Simulates the hydrocarbon fluid filling process of the core pore model, the hydrocarbon fluid filling process of the dominant channel model, and the hydrocarbon fluid filling process of the non-dominant channel model, respectively.

[0071] In this embodiment of the disclosure, the duration of the simulated hydrocarbon fluid filling process is 2 seconds.

[0072] S13: Obtain the distribution and saturation of hydrocarbon fluid during the hydrocarbon fluid filling process in the dominant channel model; obtain the distribution and saturation of hydrocarbon fluid during the hydrocarbon fluid filling process in the non-dominant channel model.

[0073] Specifically, in a core pore model without cracks, during hydrocarbon filling, the oil (hydrocarbon fluid) saturation in the core pores continuously increases while the water saturation gradually decreases, resulting in a more uniform filling process. When cracks are present, the hydrocarbon fluid is mainly filled along the crack direction, and the oil (hydrocarbon fluid) and water saturation in the cracks and pores reach a stable value after a certain filling time.

[0074] In some examples, based on digital core samples, fracture models with different inclination angles were constructed. Combining the distribution and saturation of hydrocarbon fluids during the filling process, the hydrocarbon fluid filling process of each fracture model was simulated, specifically including:

[0075] S21: Based on digital core samples, fracture models with no tilt angle, 30° tilt angle, 45° tilt angle, 60° tilt angle, and 90° tilt angle were constructed respectively. Each fracture model is a three-dimensional model.

[0076] Specifically, the fracture model without tilt angle includes fractures extending away from the hydrocarbon fluid direction, with the fracture tilt angle considered as 0°; the fracture model with a 90° tilt angle includes fractures extending along the hydrocarbon fluid direction, with the fracture tilt angle considered as 90°; and the fracture models with 30°, 45°, and 60° tilt angles include fractures tilted relative to the direction perpendicular to the hydrocarbon fluid direction. All fracture models are three-dimensional models, such as cubic models, and are much smaller than the core structure scale of actual oil reservoirs. Using the fracture feature inversion method disclosed in this disclosure, accurate upscaling inversion of fracture features and reservoir physical parameters can be achieved.

[0077] S22: Based on the distribution and saturation of hydrocarbon fluids during the filling process, simulate the hydrocarbon fluid filling process of fracture models with no tilt angle, 30° tilt angle, 45° tilt angle, 60° tilt angle, and 90° tilt angle respectively.

[0078] In some examples, the acoustic and electrical parameters of each fracture model during the hydrocarbon fluid filling process are obtained separately. Based on the acoustic and electrical parameters corresponding to all fracture models, an anisotropic acoustic-electric joint chart is established, and an inversion model is generated, specifically including:

[0079] S31: Obtain the longitudinal wave velocity change curve, transverse wave velocity change curve, and resistivity change curve of the fracture model during hydrocarbon fluid filling.

[0080] S32: Based on the longitudinal wave velocity variation curve and transverse wave velocity variation curve of the fracture model during hydrocarbon fluid filling process, and combined with the distribution and saturation of hydrocarbon fluid during filling process, generate a sound wave velocity-saturation line graph.

[0081] Specifically, the sound wave velocity-saturation line graph has the horizontal axis representing the saturation of the hydrocarbon-containing fluid and the vertical axis representing the transverse or longitudinal wave velocity.

[0082] S33: Based on the longitudinal wave velocity variation curves, transverse wave velocity variation curves, acoustic velocity-saturation line graphs, and resistivity variation curves of all fracture models during hydrocarbon fluid filling, an anisotropic acoustic-electric joint plot is established, and an inversion model is generated.

[0083] In some examples, the changes in P-wave velocity, S-wave velocity, and resistivity of the fracture model during hydrocarbon fluid filling are obtained, specifically including:

[0084] S311: During the simulation of hydrocarbon fluid injection using the crack model, acoustic excitation is applied to the boundary of the crack model, the longitudinal wave waveform and transverse wave waveform are recorded, the longitudinal wave velocity and transverse wave velocity are calculated, and the longitudinal wave velocity variation curve and transverse wave velocity variation curve are generated.

[0085] Specifically, as elastic waves, the propagation, attenuation, and reflection of sound waves in rock cores are affected by various factors such as pore structure, mineral composition, formation pressure, and fluid distribution. In the fracture model simulating hydrocarbon fluid injection, sound wave excitation is applied to the fracture model boundary, and the P-wave and S-wave waveforms are recorded. The P-wave and S-wave velocities are calculated, generating curves showing the variation of P-wave and S-wave velocities.

[0086] Furthermore, to calculate the transverse and longitudinal wave velocities, it is necessary to determine the jump point time t. The jump point time t represents the point at which the sound wave waveform begins to significantly deviate from the baseline, typically corresponding to the initial rising edge of the sound wave waveform. Simultaneously, it is also necessary to determine the distance L between the sound wave excitation point and the sound wave receiving point. The specific formula for calculating the wave velocity is as follows:

[0087]

[0088] Where V (m / s) is the wave speed (which can be the transverse wave velocity V) s or longitudinal wave velocity V p L is the distance between the sound wave excitation point and the sound wave receiving point, and t is the start-up time, which usually corresponds to the initial rising edge of the sound wave waveform.

[0089] It should be noted that acoustic parameters can be calculated and P-wave velocities and S-wave velocities, as well as the curves showing the variation of P-wave velocities and S-wave velocities, can be obtained through finite element numerical simulation. No further limitations are imposed here.

[0090] S312: In simulating hydrocarbon fluid injection, the crack model applies electrical excitation at the boundary of the crack model to obtain the electric field strength and current density. Based on the electric field strength and current density, the resistivity tensor value is determined, and the resistivity change curve is generated.

[0091] Specifically, the crack model is a cubic structure. The crack size in the crack model may be unequal in different directions, exhibiting strong anisotropy. A three-dimensional Cartesian coordinate system is established with one vertex of the crack model as the origin. Three electrical excitations are applied from three directions, namely the X-axis, Y-axis, and Z-axis. The electrical excitations can be radio frequency signals. The electric field intensity and current density are obtained three times respectively, generating the electric field intensity matrix and the current density matrix. The resistivity tensor value is calculated using the electric field intensity matrix and the current density matrix.

[0092] Based on classical electromagnetic theory, constitutive equations are established between electric field strength and electric displacement, and between electric field strength and current density, as shown in equations (1) and (2):

[0093]

[0094]

[0095] in, The electric field strength is expressed in V / m. Represents current density [A / m] 2 ], Represents electric displacement field [C / m] 2 ], where σ is the conductivity [Sm] and ε is the dielectric constant [F / m].

[0096] Furthermore, in conjunction with the embodiments of this disclosure, a three-dimensional rectangular coordinate system is established with one vertex of the crack model as the origin. Three electrical excitations are applied from three directions, namely the X-axis, Y-axis and Z-axis, and nine resistivity component values ​​can be extracted.

[0097] The electric field intensity and current density are obtained three times respectively, generating the electric field intensity matrix and current density matrix, and the resistivity tensor value is calculated. The specific formula is as follows:

[0098]

[0099] in, Represents the electric field intensity matrix. Represents the current density matrix. This represents the resistivity tensor value.

[0100] In some examples, based on the corresponding P-wave velocity variation curves, S-wave velocity variation curves, acoustic velocity-saturation line graphs, and resistivity variation curves of all fracture models during hydrocarbon fluid filling, an anisotropic acoustic-electric joint plot is established, and an inversion model is generated, including:

[0101] S331: Based on the resistivity change curves of all fracture models during hydrocarbon fluid filling, and combined with the distribution and saturation of hydrocarbon fluid during filling, a resistivity-fracture inclination angle-saturation line graph is generated.

[0102] Specifically, the horizontal axis of the resistivity-crack inclination angle-saturation line graph represents the saturation of hydrocarbon-containing fluids, and the vertical axis represents resistivity. The relationship curves between the saturation of hydrocarbon-containing fluids and resistivity corresponding to all crack models with different inclination angles are placed in the resistivity-crack inclination angle-saturation line graph.

[0103] S332: By combining the longitudinal wave velocity variation curves, transverse wave velocity variation curves, resistivity variation curves, acoustic velocity-saturation line graphs, and resistivity-crack inclination angle-saturation line graphs of all crack models during hydrocarbon fluid filling, an anisotropic acoustic-electric joint chart is established, and an inversion model is generated.

[0104] Example 1:

[0105] like Figure 2 As shown, based on digital core samples, a core pore model including natural fractures is generated; a dominant channel model including fractures extending away from the direction of hydrocarbon fluids is generated, where fractures extending away from the direction of hydrocarbon fluids can be understood as fractures almost perpendicular to the ground, with the bottom of the fractures connected to the hydrocarbon fluids; and a non-dominant channel model including fractures extending along the direction of hydrocarbon fluids is generated, where fractures extending along the direction of hydrocarbon fluids can be understood as fractures almost parallel to the ground, with the bottom of the fractures not connected to the hydrocarbon fluids. The pixel size of the core pore model, dominant channel model, and non-dominant channel model is 100×100, and the physical size is 1mm×1mm.

[0106] It is important to understand that the cracks do not extend in a straight line; the vertical, parallel, and tilt angles described here, as well as those described later, are all approximations.

[0107] The hydrocarbon fluid charging process was simulated in three models: a core pore model, a dominant channel model, and a model without a dominant channel. The simulation duration was 2 seconds. The distribution and saturation of hydrocarbon fluid were obtained during the charging process in the dominant channel model and the model without a dominant channel.

[0108] like Figure 3 As shown, in the core pore model without cracks, during hydrocarbon filling, the oil (hydrocarbon fluid) saturation of the core pores continuously increases while the water saturation gradually decreases, resulting in a more uniform filling process. When cracks are present, the hydrocarbon fluid is mainly filled along the crack direction, and the oil (hydrocarbon fluid) and water saturation of the cracks and pores reach a stable value after a certain filling time.

[0109] like Figure 4 As shown, based on digital core samples, fracture models with no tilt angle, 30° tilt angle, 45° tilt angle, 60° tilt angle, and 90° tilt angle were constructed respectively.

[0110] Among them, the crack model without tilt angle includes cracks extending away from the direction of hydrocarbon fluid, and the crack tilt angle is regarded as 0°; the crack model with a 90° tilt angle includes cracks extending along the direction of hydrocarbon fluid, and the crack tilt angle is regarded as 90°; the crack models with a 30° tilt angle, a 45° tilt angle, and a 60° tilt angle include cracks tilted relative to the direction perpendicular to the direction of hydrocarbon fluid.

[0111] Based on the distribution and saturation of hydrocarbon fluids during the filling process, the hydrocarbon fluid filling process was simulated using fracture models with no tilt angle, a 30° tilt angle, a 45° tilt angle, a 60° tilt angle, and a 90° tilt angle.

[0112] In the crack model simulation of hydrocarbon fluid injection, acoustic excitation is applied to the crack model boundary, and the P-wave and S-wave waveforms are recorded. The P-wave and S-wave velocities are calculated, generating P-wave and S-wave velocity variation curves. Acoustic parameters can be calculated using the finite element method (FEM) to obtain the P-wave and S-wave velocities, as well as their variation curves; no further limitations are imposed here. Figure 5 , 6 As shown, Figure 5 The transverse and longitudinal wave velocities during hydrocarbon fluid filling process corresponding to a crack model without tilt angle. Figure 6 The transverse and longitudinal wave velocities during hydrocarbon fluid filling process corresponding to a crack model with a 90° tilt angle are given. Figure 5 and Figure 6 V in p V represents the longitudinal wave velocity. s This represents the transverse wave velocity. Multiple time points can be defined to calculate the transverse and longitudinal wave velocities during hydrocarbon fluid filling in the fracture model.

[0113] Furthermore, the specific formula for calculating wave speed is as follows:

[0114]

[0115] Where V (m / s) is the wave speed (which can be the transverse wave velocity V) s or longitudinal wave velocity V p L is the distance between the sound wave excitation point and the sound wave receiving point, and t is the start-up time, which usually corresponds to the initial rising edge of the sound wave waveform.

[0116] In simulating hydrocarbon fluid injection, the crack model applies electrical excitation at the boundary of the crack model to obtain the electric field strength and current density. Based on the electric field strength and current density, the resistivity tensor value is determined, and the resistivity change curve is generated.

[0117] A three-dimensional Cartesian coordinate system is established with one vertex of the crack model as the origin. Three electrical excitations are applied from three directions, namely the X-axis, Y-axis and Z-axis. The electrical excitations can be radio frequency signals. The electric field intensity and current density are obtained three times respectively, and the electric field intensity matrix and current density matrix are generated. The resistivity tensor value is calculated using the electric field intensity matrix and current density matrix.

[0118] Based on classical electromagnetic theory, constitutive equations are established between electric field strength and electric displacement, and between electric field strength and current density, as shown in equations (1) and (2):

[0119]

[0120]

[0121] in, The electric field strength is expressed in V / m. Represents current density [A / m] 2 ], Represents electric displacement field [C / m] 2 ], where σ is the conductivity [Sm] and ε is the dielectric constant [F / m].

[0122] Furthermore, in conjunction with the embodiments of this disclosure, a three-dimensional rectangular coordinate system is established with one vertex of the crack model as the origin. Three electrical excitations are applied from three directions, namely the X-axis, Y-axis and Z-axis, and nine resistivity component values ​​can be extracted.

[0123] The electric field intensity and current density are obtained three times respectively, generating the electric field intensity matrix and current density matrix, and the resistivity tensor value is calculated. The specific formula is as follows:

[0124]

[0125] in, Represents the electric field intensity matrix. Represents the current density matrix. This represents the resistivity tensor value.

[0126] like Figure 7 , 8 As shown, based on the longitudinal wave velocity and transverse wave velocity variation curves of the fracture model during hydrocarbon fluid charging, and combined with the distribution and saturation of the hydrocarbon fluid during charging, an acoustic velocity-saturation line graph is generated. The horizontal axis of the acoustic velocity-saturation line graph represents the oil (hydrocarbon fluid) saturation, and the vertical axis represents the transverse wave velocity (V). s or longitudinal wave velocity (V) p ).

[0127] like Figure 9 As shown, Figure 9 The horizontal axis represents the saturation of the hydrocarbon fluid, and the vertical axis represents resistivity. Based on the resistivity change curves of all fracture models during hydrocarbon fluid charging, combined with the distribution and saturation of the hydrocarbon fluid during charging, a resistivity-fracture inclination angle-saturation line graph is generated. The horizontal axis of the resistivity-fracture inclination angle-saturation line graph represents the hydrocarbon fluid saturation, and the vertical axis represents resistivity. The relationship curves between hydrocarbon fluid saturation and resistivity for all fracture models at different inclination angles are placed on the resistivity-fracture inclination angle-saturation line graph.

[0128] like Figure 10 As shown, in order to verify the accuracy of the resistivity-fracture inclination angle-saturation line graph, two fracture models were set up for verification based on the core data samples. A fracture model with a 55° inclination angle and a fracture model with a 75° inclination angle were established to simulate the hydrocarbon fluid injection process in the fracture model.

[0129] In simulating hydrocarbon fluid injection, an electrical excitation is applied to the boundary of the fracture model. The electric field strength and current density are acquired, and the resistivity tensor value is determined based on these values, generating a resistivity change curve. Combining the distribution and saturation of the hydrocarbon fluid during the injection process, the relationship curves between hydrocarbon fluid saturation and resistivity for fracture models with 55° and 75° inclination angles are added to the resistivity-fracture inclination angle-saturation line graph, as shown below. Figure 11 As shown, the relationship curve between saturation and resistivity of hydrocarbon-containing fluids corresponding to the crack model with a 75° tilt angle lies between the relationship curves corresponding to the crack models with a 90° tilt angle and a 60° tilt angle; similarly, the relationship curve between saturation and resistivity of hydrocarbon-containing fluids corresponding to the crack model with a 55° tilt angle lies between the relationship curves corresponding to the crack models with a 45° tilt angle and a 60° tilt angle. In this case, the resistivity-crack tilt angle-saturation line graph is accurate, and the corresponding resistivity change curve is also accurate, which can be used to generate anisotropic acoustic-electric joint plots.

[0130] By combining the longitudinal wave velocity variation curves, transverse wave velocity variation curves, resistivity variation curves, acoustic velocity-saturation line graphs, and resistivity-crack inclination angle-saturation line graphs of all fracture models during hydrocarbon fluid filling, an anisotropic acoustic-electric joint chart is established, and an inversion model is generated.

[0131] Based on the inversion model, combined with the acoustic and electrical parameters of actual core samples, fracture characteristics and reservoir physical parameters are inverted to obtain fracture characteristic inversion results. For example... Figure 12As shown, Figure 12 This is a schematic diagram of an actual fracture inversion chart provided in an embodiment of this disclosure, wherein the red lines represent measured data. Using the fracture feature inversion method provided in this disclosure, fracture features such as oil saturation and fracture angle, as well as reservoir physical parameters, are inverted to finally obtain the fracture feature inversion results.

[0132] Secondly, Figure 13 A block diagram of a crack feature inversion system provided in this disclosure embodiment is shown below. Figure 3 As shown, based on the same inventive concept, this disclosure also provides a crack feature inversion system, the system including: a first simulated filling module, a crack simulated filling module, an inversion model generation module, and an inversion module;

[0133] The first simulated charging module is used to simulate the charging process of hydrocarbon fluids based on digital core samples, and to obtain the distribution and saturation of hydrocarbon fluids during the charging process;

[0134] The fracture simulation and filling module is used to construct fracture models with different inclination angles based on digital core samples. It combines the distribution and saturation of hydrocarbon fluids during the filling process to simulate the hydrocarbon fluid filling process of each fracture model.

[0135] The inversion model generation module is used to obtain the acoustic and electrical parameters of each fracture model during the hydrocarbon fluid filling process, and to establish an anisotropic acoustic-electric joint chart based on the acoustic and electrical parameters of all fracture models, and generate the inversion model.

[0136] The inversion module is used to invert fracture characteristics and reservoir physical parameters based on the inversion model and the acoustic and electrical parameters of the actual core, and to obtain fracture characteristic inversion results.

[0137] Thirdly, based on the same inventive concept, the present disclosure also provides a computer-readable storage medium storing one or more programs, which, when executed, can implement the aforementioned crack feature inversion method.

[0138] Fourthly, based on the same inventive concept, such as Figure 14 As shown in the illustration, this disclosure also provides an electronic device, including a processor, a communication interface, the aforementioned computer-readable storage medium, and a communication bus. The processor, communication interface, and computer-readable storage medium communicate with each other via the communication bus. The processor is used to execute a program stored in the aforementioned computer-readable storage medium.

[0139] It should be noted that the electrical connection between the above-mentioned units does not necessarily mean the connection between lines. The indirect connection method can be applied to the embodiments of this disclosure as long as it achieves the purpose of this disclosure.

[0140] Although the present disclosure has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and such modifications or substitutions 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 disclosure.

Claims

1. A method for inverting crack features, characterized in that, The method includes: Based on digital core samples, the hydrocarbon fluid filling process was simulated to obtain the distribution and saturation of hydrocarbon fluids during the filling process; Based on the digital core samples, fracture models with different tilt angles were constructed. The hydrocarbon fluid filling process of each fracture model was simulated by combining the distribution and saturation of hydrocarbon fluid during the filling process. Acoustic and electrical parameters of each fracture model during hydrocarbon fluid filling were obtained. Based on the acoustic and electrical parameters of all fracture models, an anisotropic acoustic-electric joint chart was established, and an inversion model was generated. Based on the inversion model, combined with the acoustic and electrical parameters of the actual core, fracture characteristics and reservoir physical parameters are inverted to obtain fracture characteristic inversion results.

2. The method according to claim 1, characterized in that, The process of simulating hydrocarbon fluid charging based on digital core samples to obtain the distribution and saturation of hydrocarbon fluid during the charging process includes: Based on the digital core samples, a core pore model, a dominant channel model, and a non-dominant channel model are generated; wherein, the core pore model includes natural fractures, the dominant channel model includes fractures extending away from the direction of hydrocarbon fluid, and the non-dominant channel model includes fractures extending in the direction of hydrocarbon fluid. The hydrocarbon fluid filling process of the core pore model, the hydrocarbon fluid filling process of the dominant channel model, and the hydrocarbon fluid filling process of the non-dominant channel model were simulated respectively. The distribution and saturation of hydrocarbon fluid during the hydrocarbon fluid filling process of the dominant channel model are obtained; the distribution and saturation of hydrocarbon fluid during the hydrocarbon fluid filling process of the non-dominant channel model are obtained.

3. The method according to claim 1, characterized in that, Based on digital core samples, fracture models with different inclination angles are constructed. Combining the distribution and saturation of hydrocarbon fluids during the filling process, the hydrocarbon fluid filling process of each fracture model is simulated, including: Based on the digital core samples, fracture models with no tilt angle, 30° tilt angle, 45° tilt angle, 60° tilt angle, and 90° tilt angle were constructed respectively, and each fracture model was a three-dimensional model. Based on the distribution and saturation of hydrocarbon fluids during the filling process, the hydrocarbon fluid filling process was simulated using fracture models with no tilt angle, a 30° tilt angle, a 45° tilt angle, a 60° tilt angle, and a 90° tilt angle.

4. The method according to claim 1, characterized in that, The process involves acquiring the acoustic and electrical parameters of each fracture model during the hydrocarbon fluid filling process, establishing an anisotropic acoustic-electric joint chart based on the acoustic and electrical parameters corresponding to all fracture models, and generating an inversion model, including: Obtain the longitudinal wave velocity variation curve, transverse wave velocity variation curve, and resistivity variation curve of the fracture model during hydrocarbon fluid filling process; Based on the longitudinal wave velocity variation curve and the transverse wave velocity variation curve corresponding to the fracture model during hydrocarbon fluid filling process, and combined with the distribution and saturation of hydrocarbon fluid during the filling process, an acoustic velocity-saturation line graph is generated. Based on the longitudinal wave velocity variation curves, transverse wave velocity variation curves, acoustic velocity-saturation line graphs, and resistivity variation curves of all fracture models during hydrocarbon fluid filling, the anisotropic acoustic-electric joint chart is established, and the inversion model is generated.

5. The method according to claim 4, characterized in that, The acquisition of the fracture model during hydrocarbon fluid filling includes the following: longitudinal wave velocity variation curves, transverse wave velocity variation curves, and resistivity variation curves. During the injection of hydrocarbon fluid using a fracture model, acoustic excitation is applied to the boundary of the fracture model, and the longitudinal wave waveform and transverse wave waveform are recorded. The longitudinal wave velocity and transverse wave velocity are calculated, and the longitudinal wave velocity variation curve and the transverse wave velocity variation curve are generated. In simulating hydrocarbon fluid injection, the crack model applies electrical excitation at the boundary of the crack model to obtain the electric field strength and current density. Based on the electric field strength and current density, the resistivity tensor value is determined, and the resistivity change curve is generated.

6. The method according to claim 4, characterized in that, Based on the longitudinal wave velocity variation curves, transverse wave velocity variation curves, acoustic velocity-saturation line graphs, and resistivity variation curves of all fracture models during hydrocarbon fluid filling, an anisotropic acoustic-electric joint chart is established, and an inversion model is generated, including: Based on the resistivity change curves of all fracture models during hydrocarbon fluid filling, and combined with the distribution and saturation of hydrocarbon fluid during filling, a resistivity-fracture inclination angle-saturation line graph is generated. By combining the longitudinal wave velocity variation curves, transverse wave velocity variation curves, resistivity variation curves, acoustic velocity-saturation line graphs, and resistivity-crack inclination angle-saturation line graphs of all crack models during hydrocarbon fluid filling, an anisotropic acoustic-electric joint chart is established, and an inversion model is generated.

7. The method according to claim 5, characterized in that, At the boundary of the crack model, three electrical excitations are applied in different directions.

8. A crack feature inversion system, characterized in that, The system includes: a first simulation filling module, a fracture simulation filling module, an inversion model generation module, and an inversion module; The first simulated filling module is used to simulate the filling process of hydrocarbon fluids based on digital core samples, and to obtain the distribution and saturation of hydrocarbon fluids during the filling process; The fracture simulation and filling module is used to construct fracture models with different tilt angles based on the digital core samples, and to simulate the hydrocarbon fluid filling process of each fracture model by combining the distribution and saturation of hydrocarbon fluids during the filling process. The inversion model generation module is used to obtain the acoustic and electrical parameters of each fracture model during the hydrocarbon fluid filling process, and to establish an anisotropic acoustic-electric joint chart based on the acoustic and electrical parameters of all fracture models, and generate an inversion model. The inversion module is used to invert fracture characteristics and reservoir physical parameters based on the inversion model and in combination with the acoustic and electrical parameters of the actual core, and to obtain fracture characteristic inversion results.

9. A computer-readable storage medium storing one or more programs, characterized in that, When one or more of these programs are executed, the crack feature inversion method described in any one of claims 1-7 can be implemented.

10. An electronic device, comprising a processor, a communication interface, a computer-readable storage medium as described in claim 9, and a communication bus; wherein, The processor, communication interface, and computer-readable storage medium communicate with each other via a communication bus; Its features are, The processor is used to execute programs stored in a computer-readable storage medium.

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