A method and apparatus for evaluating the seepage hysteresis effect in carbonate gas reservoirs

Abstract

This specification relates to the field of carbonate gas reservoir development technology, and provides a method and apparatus for evaluating the seepage lag effect in carbonate gas reservoirs. The method includes: acquiring seismic data of the target reservoir; determining the seismic ant body morphology and outcrop fracture-vuggy development characteristics of the target reservoir based on the seismic data; constructing a digital core simulation model of fracture-vuggy development based on the seismic ant body morphology and outcrop fracture-vuggy development characteristics; performing simulation on the digital core simulation model of fracture-vuggy development, and determining the fluid flow characteristics data of the fracture-vuggy zone and matrix zone in the target reservoir based on the simulation results; and calculating seepage lag characteristic parameters based on the fluid flow characteristic data, wherein the seepage lag characteristic parameters are used to characterize the time difference between the fluid reaching a quasi-steady state in the fracture-vuggy zone and reaching a quasi-steady state in the matrix zone. Through the embodiments of this specification, the seepage lag effect of carbonate reservoirs can be quantitatively evaluated.

Description

Technical Field

[0001] The embodiments in this specification relate to the field of carbonate gas reservoir development technology, and in particular to a method and apparatus for evaluating the seepage hysteresis effect of carbonate gas reservoirs. Background Technology

[0002] Carbonate gas reservoirs refer to geological layers composed of carbonate rocks capable of storing and producing natural gas. Carbonate rocks are mainly composed of minerals such as calcite and dolomite, which readily form various pores and fractures during sedimentation, providing excellent pathways for the accumulation and migration of natural gas. Due to the typically complex pore structure and strong heterogeneity of carbonate reservoirs, high-speed injection and production processes can impede gas flow, causing actual gas seepage velocity or pressure changes to lag behind expected or theoretical changes, resulting in seepage lag. This phenomenon not only affects the efficiency of gas reservoir production but also significantly impacts reservoir evaluation and development strategies, thereby increasing the difficulty of oil and gas exploration and development.

[0003] By evaluating the seepage lag effect, we can gain a more accurate understanding of the reservoir's storage capacity and fluid flow characteristics, thereby optimizing the extraction strategy. However, existing technologies lack methods for evaluating the seepage lag effect in carbonate gas reservoirs during high-speed injection and production. Therefore, there is an urgent need for a quantitative evaluation method for the seepage lag effect in carbonate gas reservoirs. Summary of the Invention

[0004] To address the aforementioned problems in the prior art, the purpose of the embodiments in this specification is to provide a method and apparatus for evaluating the seepage lag effect in carbonate gas reservoirs, so as to quantitatively evaluate the seepage lag effect in carbonate gas reservoirs during high-speed injection and production.

[0005] To solve the above-mentioned technical problems, the specific technical solutions of the embodiments in this specification are as follows:

[0006] On the one hand, the embodiments of this specification provide a method for evaluating the seepage hysteresis effect in carbonate gas reservoirs, the method comprising:

[0007] Acquire seismic data of the target reservoir;

[0008] Based on the earthquake data, determine the seismic ant body morphology and outcrop fracture development characteristics of the target reservoir;

[0009] Based on the morphological characteristics of earthquake ants and the development characteristics of outcrops and cavities, a digital core simulation model of cavity development was constructed.

[0010] The digital core simulation model of fracture and cavity development was used to simulate the fluid flow characteristics of the fracture and cavity zone and the matrix zone in the target reservoir.

[0011] The seepage hysteresis characteristic parameters are calculated based on the fluid flow characteristic data, wherein the seepage hysteresis characteristic parameters are used to characterize the time difference between the fluid reaching a pseudo-steady state in the crevice region and reaching a pseudo-steady state in the matrix region.

[0012] The seepage hysteresis effect of the target reservoir is evaluated based on the seepage hysteresis characteristic parameters.

[0013] Furthermore, the fluid flow characteristic data includes the crossflow coefficient and the storage capacity ratio;

[0014] The determination of fluid flow characteristic data in the fractured-vuggy zone and matrix zone of the target reservoir based on simulation results includes:

[0015] The volume ratios of fractures and voids and matrix in the target reservoir are determined based on the simulation results.

[0016] The reservoir capacity ratio is calculated based on the proportion of fracture and void volume and the proportion of matrix volume in the target reservoir.

[0017] The channeling coefficient of the target reservoir is determined from a pre-constructed ternary map of reservoir channeling coefficients based on the reservoir capacity ratio, wherein the ternary map of reservoir channeling coefficients stores the reservoir capacity ratio and channeling coefficient under different fracture-vuggy and matrix volume ratios.

[0018] Further, the calculation of seepage hysteresis characteristic parameters based on the fluid flow characteristic data includes:

[0019] The seepage hysteresis characteristic parameters are calculated using the following formula:

[0020]

[0021] Among them, W 滞后 The parameters represent seepage hysteresis characteristics, ω represents the reservoir ratio, λ represents the channeling coefficient, a represents the bedrock morphology factor, and r represents the seepage hysteresis characteristic parameter. w Indicates the radius of the bottom of the well.

[0022] Furthermore, the process of constructing the ternary map of the reservoir channeling coefficient includes:

[0023] Several digital core simulation models were constructed, with each model having a different proportion of fracture-cavity volume and matrix volume.

[0024] The corresponding reservoir ratio is calculated based on the proportion of fracture and cavity volume and the proportion of matrix volume in each digital core simulation model;

[0025] Numerical simulations were performed on the aforementioned digital core simulation models to obtain production prediction data for each digital core simulation model.

[0026] Based on the production prediction data, well test interpretation is performed on each digital core simulation model to obtain the crossflow coefficient of each digital core simulation model;

[0027] Based on the aforementioned flow coefficient and reservoir capacity ratio, a ternary graph of reservoir flow coefficient under different fracture and matrix volume ratios is constructed.

[0028] Furthermore, the seepage hysteresis characteristic parameter is in the range of [0,1], and the evaluation of the seepage hysteresis effect of the target reservoir based on the seepage hysteresis characteristic parameter includes:

[0029] The closer the seepage hysteresis characteristic parameter is to 0, the stronger the seepage hysteresis effect of the target reservoir.

[0030] The closer the seepage hysteresis characteristic parameter is to 1, the weaker the seepage hysteresis effect of the target reservoir.

[0031] Furthermore, the digital core simulation model for fracture development includes:

[0032] The digital core simulation model of fracture-cavity development is represented by the following formula:

[0033]

[0034] Where, ε p Porosity is represented by ρ; fluid density is represented by g / cm³. 3 Q m Indicates mass source, unit g / (cm³) 3 •s); u represents velocity vector, unit m / s; p represents pressure, unit MPa; μ represents fluid viscosity, unit mPa·s; κ represents permeability of the matrix, unit mD; F represents force, unit g / (cm²). 2 ·s 2 ); Let represent the partial differential equation coincidence, t represent time, T represent the transpose, and I represent the identity matrix. This represents the Hamiltonian operator.

[0035] On the other hand, the embodiments of this specification provide a device for evaluating the seepage hysteresis effect in carbonate gas reservoirs, the device comprising:

[0036] The acquisition module is used to acquire seismic data of the target reservoir.

[0037] The feature acquisition module is used to determine the morphological characteristics of seismic ant bodies and the development characteristics of outcrop fractures and cavities in the target reservoir based on the seismic data.

[0038] The model building module is used to construct a digital core simulation model of fracture and cavity development based on the morphological characteristics of the earthquake ants and the development characteristics of outcrops and cavities.

[0039] The simulation module is used to simulate the digital core simulation model of fracture and cavity development, and to determine the fluid flow characteristics of the fracture and cavity zone and matrix zone in the target reservoir based on the simulation results.

[0040] The parameter calculation module is used to calculate the seepage hysteresis characteristic parameters based on the fluid flow characteristic data, wherein the seepage hysteresis characteristic parameters are used to characterize the time difference between the fluid reaching a pseudo-steady state in the crevice region and reaching a pseudo-steady state in the matrix region.

[0041] The evaluation module is used to evaluate the seepage hysteresis effect of the target reservoir based on the seepage hysteresis characteristic parameters.

[0042] In another aspect, embodiments of this specification also provide a computer device, including a memory, a processor, and a computer program stored in the memory, wherein the computer program, when executed by the processor, performs instructions of any of the methods described above.

[0043] In another aspect, embodiments of this specification also provide a computer-readable storage medium having a computer program stored thereon, the computer program being executed by a processor of a computer device to perform instructions for any of the methods described above.

[0044] In another aspect, embodiments of this specification also provide a computer program product, which, when run by the processor of a computer device, executes instructions for any of the methods described above.

[0045] Using the above technical solution, the method for evaluating the seepage lag effect of carbonate gas reservoirs provided in this specification first determines the morphological characteristics of seismic ant bodies and the development characteristics of outcrop fractures and cavities in the target reservoir based on seismic data. These characteristics reveal the location, morphology, and development characteristics of fractures and cavities within the target reservoir. Based on these characteristics, a digital core simulation model of fracture and cavity development in the target reservoir can be constructed. By simulating this model, fluid flow characteristics in the fracture and cavity zones and matrix zones of the target reservoir can be determined based on the simulation results. Then, seepage lag characteristic parameters are calculated based on the fluid flow characteristic data. These parameters reflect the time difference between the fluid reaching a quasi-steady state in the high-permeability fracture and cavity zone and in the low-permeability matrix zone, thus enabling a quantitative evaluation of the seepage lag effect of the target reservoir.

[0046] The above description is merely an overview of some embodiments of the technical solutions in this specification. In order to better understand the technical means of some embodiments of this specification and to implement them in accordance with the content of the specification, and to make the above and other objects, features and advantages of the embodiments of this specification more apparent and understandable, preferred embodiments are described below in detail with reference to the accompanying drawings. Attached Figure Description

[0047] To more clearly illustrate the technical solutions in the embodiments or prior art of this specification, the drawings used in the description of the embodiments or prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this specification. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0048] Figure 1 A flowchart illustrating a method for evaluating the seepage hysteresis effect in carbonate gas reservoirs, as described in some embodiments of this specification, is shown.

[0049] Figure 2 This specification shows a schematic diagram of a three-dimensional numerical model of a reservoir with well-developed fracture-vuggy structures and good connectivity in some embodiments.

[0050] Figure 3 This specification shows a schematic diagram of a three-dimensional numerical model of a partially connected reservoir model with fracture-vuggy scale development in some embodiments;

[0051] Figure 4 This specification shows a schematic diagram of a three-dimensional numerical model of a weakly connected reservoir with locally developed fractures and cavities in some embodiments.

[0052] Figure 5 This specification shows a flowchart illustrating the process of determining fluid flow characteristics of fractured and matrix regions in a target reservoir based on simulation results in some embodiments of this specification.

[0053] Figure 6 This specification shows ternary plots of reservoir channeling coefficients under different fracture-matrix ratios in some embodiments;

[0054] Figure 7 This specification shows schematic diagrams of pressure drop in high-permeability fractured cavities and low-permeability matrix formations in some embodiments;

[0055] Figure 8 This specification shows a schematic diagram of the module structure of a carbonate gas reservoir seepage hysteresis effect evaluation device in some embodiments.

[0056] Figure 9 A schematic diagram of the structure of a computer device is shown in this specification.

[0057] Explanation of symbols in the attached drawings:

[0058] 801. Acquisition Module;

[0059] 802. Feature Acquisition Module;

[0060] 803. Model building module;

[0061] 804. Simulation module;

[0062] 805. Parameter Calculation Module;

[0063] 806. Evaluation Module;

[0064] 902. Computer equipment;

[0065] 904, Processor;

[0066] 906. Memory;

[0067] 908. Drive mechanism;

[0068] 910. Input / Output Module;

[0069] 912. Input devices;

[0070] 914. Output devices;

[0071] 916. Presentation equipment;

[0072] 918. Graphical User Interface;

[0073] 920. Network interface;

[0074] 922. Communication link;

[0075] 924. Communication bus. Detailed Implementation

[0076] The technical solutions in the embodiments of this specification will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this specification, and not all embodiments. Based on the embodiments in this specification, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this specification.

[0077] To address the aforementioned issues, this specification provides an embodiment of a method for evaluating the seepage hysteresis effect in carbonate gas reservoirs. Figure 1This is a flowchart illustrating a method for evaluating the seepage hysteresis effect in carbonate gas reservoirs, as provided in the embodiments of this specification. This specification provides the operational steps described in the embodiments or flowcharts, but based on conventional or non-inventive labor, more or fewer operational steps may be included. The order of steps listed in the embodiments is merely one possible execution order among many and does not represent the only possible execution order. In actual system or device products, the methods shown in the embodiments or accompanying drawings can be executed sequentially or in parallel.

[0078] It should be noted that the terms "first," "second," etc., used in this specification, claims, and the foregoing drawings are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover a non-exclusive inclusion; for example, a process, method, apparatus, product, or device that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or devices.

[0079] Reference Figure 1 As shown in the embodiments of this specification, a method for evaluating the seepage hysteresis effect in carbonate gas reservoirs is provided. The method includes:

[0080] S101: Acquire seismic data of the target reservoir.

[0081] S102: Determine the morphological characteristics of seismic ant bodies and the development characteristics of outcrops and cavities in the target reservoir based on the seismic data.

[0082] S103: Based on the morphological characteristics of the earthquake ants and the development characteristics of outcrops and cavities, a digital core simulation model of cavity development is constructed.

[0083] S104: Simulate the digital core simulation model of fracture and cavity development, and determine the fluid flow characteristics of the fracture and cavity zone and matrix zone in the target reservoir based on the simulation results.

[0084] S105: The seepage hysteresis characteristic parameter is calculated based on the fluid flow characteristic data, wherein the seepage hysteresis characteristic parameter is used to characterize the time difference between the fluid reaching a pseudo-steady state in the crevice region and reaching a pseudo-steady state in the matrix region.

[0085] S106: Evaluate the seepage hysteresis effect of the target reservoir based on the seepage hysteresis characteristic parameters.

[0086] The method for evaluating the seepage lag effect of carbonate gas reservoirs provided in this specification uses seepage lag characteristic parameters to characterize the time difference between the fluid reaching a pseudo-steady state in high-permeability fractured-vuggy areas and in low-permeability matrix areas, thereby enabling a quantitative evaluation of the seepage lag effect of the target reservoir based on the seepage lag characteristic parameters.

[0087] In the embodiments of this specification, in step S101, the target reservoir is a fractured-vuggy gas reservoir in a carbonate gas reservoir. In terms of static characteristics, the core of a fractured-vuggy reservoir has a multi-medium medium structure, with small- to medium-scale fractures and cavities predominating. The porosity-permeability relationship includes two distribution characteristics: fracture-type and fracture-vuggy reservoirs. The reservoir matrix is ​​low-porosity and low-permeability, while locally developed fracture sections exhibit high permeability. In terms of dynamic characteristics, the production curves of production wells in fractured-vuggy gas reservoirs show high initial production but a short stable production period. For example, the initial production exceeds 1 million cubic meters per well, but the average stable production period is only 2 years. This indicates that the fractured-vuggy gas reservoir initially extracts gas from the high-permeability areas of the fractures and cavities, but due to the short stable production period, the gas is quickly depleted. When gas is extracted from the low-permeability areas, the flow rate in the low-permeability areas decreases due to untimely gas replenishment. Well test interpretation of production data reveals that fractured-vuggy gas reservoirs exhibit radial flow characteristics of dual media or strong heterogeneity. Specifically, the production process shows a high-permeability fractured-vuggy zone near the wellbore and a low-permeability zone further away, indicating a lag in gas flow within the reservoir. Furthermore, the pressure drop-reserve curve of the fractured-vuggy gas reservoir shows a significant two-stage characteristic; the upward curve in the later stage indicates gas replenishment from the low-permeability zone to the high-permeability zone, further suggesting a seepage lag. Dynamic characteristics show that the high-permeability fractured-vuggy zone provides more fluid flow channels due to its high reservoir permeability and well-developed fractures and vuggies, making fluid flow relatively easy. In contrast, the low-permeability matrix zone has low permeability, high fluid flow resistance, and a dense matrix, making fluid flow difficult. This can lead to differences in the time it takes for fluid pressure to reach a steady state in different areas, resulting in a seepage lag effect.

[0088] To further explore the underlying causes of seepage lag, three-dimensional numerical models of three different fracture-vuggy reservoir development patterns were constructed based on the seismic ant body morphology and outcrop fracture-vuggy development characteristics. Figures 2-4 As shown, Figure 2 It is a model with good connectivity and development of the suture cavity. Figure 3 It is a model of partially connected development of suture-like openings. Figure 4This model represents a partially developed and weakly connected fracture-vuggy reservoir. A model with well-developed fracture-vuggy structures and good connectivity indicates a reservoir with both well-developed fractures and vuggies and good connectivity; wells in this model are generally high-yield wells. A model with partially developed and partially connected fractures and vuggies indicates a reservoir with well-developed fractures and vuggies but slightly poorer connectivity; wells in this model are generally medium-yield wells. A model with partially developed and weakly connected fractures and vuggies indicates a reservoir with moderately developed fractures and vuggies and narrow points between them, significantly affecting fluid flow; wells in this model are relatively low-yield wells. Fracture-vuggy reservoirs exhibit diverse fracture-vuggy development. The three models described above represent different combinations of fracture-vuggy reservoirs. Three digital core models were established based on these three fracture-vuggy styles for numerical simulation. The simulation results yielded microscopic seepage characteristics between high-permeability fractures and vuggies and low-permeability matrix, revealing that fracture-vuggy reservoirs do indeed exhibit seepage hysteresis characteristics at the microscopic level. First, based on the 3D seismic interpretation results, the ant-like bodies of the fracture-vuggy reservoir and the morphology of fractures and cavities developed on outcrops are obtained. Then, the macroscopic fractures and cavities are scaled down proportionally to form a simplified diagram of the central fracture-vuggy pattern, thereby generating a 3D digital core model. The center of the digital core is a miniature fracture-vuggy body, which can then be used for numerical simulation. Figures 2-4 As shown, the three-dimensional numerical models of the above three types of fractured-vuggy reservoirs are characterized based on the fractured-vuggy bodies developed in the reservoirs. To further differentiate connectivity, Figure 2 The model features a through-crack carved in the center of the slit, thus maximizing connectivity. Figure 3 The model only sculpted half of the crack connecting to the boundary, indicating strong connectivity. Figure 4 The model is depicted by the invisible slits on the surface, without any additional sculpted cracks to increase connectivity, thus making this model the least connected.

[0089] Solving the simulation model yields the pressure and velocity of the fluid at any point and time within the fractured cavity and matrix during the 3D digital core simulation, essentially allowing visualization of the fluid flow state within the fractured cavity and matrix. Simulation results reveal a significant convergence of fluid into the fractured cavity system under constant pressure differential. The pressure drop propagates to the fractured cavity boundary, and the matrix cannot replenish the fluid in time, leading to a decrease in outlet flow. Analysis of the simulation results shows that the velocity difference between the fluid in the fractured cavity and the matrix can reach 14-40 times, and the maximum pressure drop rate in the fractured cavity system is 17-35 times that of the matrix, resulting in flow imbalance. Furthermore, the fluid flow exhibits two quasi-steady-state stages: the fluid in the fractured cavity system reaches a quasi-steady state after the pressure drop propagates to the fractured cavity boundary, and the overall flow system finally reaches a quasi-steady state after the pressure is transmitted into the matrix. Therefore, it can be concluded that the untimely replenishment of the low-permeability matrix to the high-permeability fractured cavity leads to seepage lag. Based on field practice and simulation results from the aforementioned digital core model, it is evident that high-speed injection and production conditions lead to significant seepage lag in fractured-vuggy reservoirs. To quantitatively study this phenomenon, this specification defines the seepage lag effect in fractured-vuggy reservoirs as the time difference between the quasi-steady state reached by the high-permeability fractured-vuggy zone and the quasi-steady state reached by the low-permeability matrix zone. The physical meaning of the seepage lag effect is that due to differences in flow regime and velocity in different media, coupled with the diversity of fractured-vuggy combinations, the flow characteristics become discontinuous as pressure drop propagates.

[0090] In the embodiments of this specification, in step S101, the seismic data of the target reservoir can be acquired using seismic exploration instruments. Acquisition parameters include excitation parameters (such as excitation well depth), arrangement parameters (such as minimum shot-receiver distance, maximum shot-receiver distance, cell size, receiver spacing, and offset aperture), and receiving parameters (such as receiver combination distance and combination characteristics). After acquiring the seismic data, it needs to be processed, including denoising, filtering, stacking, and migration steps, to obtain processed seismic data that more clearly reflects the structure and characteristics of the reservoir.

[0091] In the embodiments of this specification, step S102 involves analyzing and processing seismic data to obtain the morphological characteristics of seismic ant bodies and the development characteristics of outcrops in fracture-vuggy reservoirs. These two characteristics reflect the distribution and development features of fractures and cavities within the reservoir. Seismic ant bodies are three-dimensional models or images obtained using ant-tracking technology, reflecting geological structures such as underground fractures and faults. Each data point (or "ant") has certain characteristics (such as data value, gradient, and neighborhood). Outcrop fracture-vuggy development characteristics mainly describe the development of fractures and cavities in surface or shallow rock strata. These fractures and cavities are typically formed by geological processes (such as weathering, erosion, and tectonic movements). Interpreting the seismic data yields the morphological characteristics of seismic ant bodies, i.e., the location and morphology of fracture-vuggy bodies within the strata. Outcrops are the exposed portions of strata on the ground; their development characteristics can be obtained through observation and mapping.

[0092] In this embodiment of the specification, in step S103, firstly, image processing technology is used to identify fracture traces from the ant body. After identifying the fracture traces, tracking algorithms or image processing technology are used to extract these traces. The extracted fracture traces should include information such as the location, direction, length, and width of the fractures. Secondly, based on the extracted fracture traces, a preliminary fracture system is constructed, that is, the fracture traces are converted into fracture surfaces or fracture networks in three-dimensional space. Then, attributes such as fracture aperture, permeability, and porosity are assigned to the fracture system according to the development characteristics of outcrops and cavities. Based on the comparison between the geological model and actual data, the fracture system is optimized, including adjusting the location, direction, length, and width of the fractures, and modifying the attribute values ​​of the fractures, so that the fracture system is more in line with the actual geological conditions, thereby meeting the needs of fluid flow simulation. Then, according to the geometry and size of the target reservoir, the digital core model is divided into grids, the optimized fracture system is embedded into the corresponding positions in the model grid, and the permeability, porosity, and other attributes of the grid are updated. After the model is constructed, it is validated using actual seismic data. Based on the validation results, the digital core model is adjusted and optimized as necessary to ensure that the model can accurately reflect the fracture system and related properties of the reservoir.

[0093] In the embodiments of this specification, step S104 uses the Brinkman model, which can describe multi-scale seepage problems. Considering both the matrix and the fissures, numerical simulation is conducted by modifying the Navier-Stokes equations. The equations used are as follows:

[0094]

[0095]

[0096] The first formula is based on the equation established by the conservation of mass, and the second formula is based on the equation established by the conservation of momentum. εp Porosity is represented by ρ; fluid density is represented by g / cm³. 3 Q m Indicates mass source, unit g / (cm³) 3 •s); u represents velocity vector, unit m / s; p represents pressure, unit MPa; μ represents fluid viscosity, unit mPa·s; κ represents permeability of the matrix, unit mD; F represents force, unit g / (cm²). 2 ·s 2 ); Let represent the partial differential equation coincidence, t represent time, T represent the transpose, and I represent the identity matrix. This represents the Hamiltonian operator.

[0097] Given initial conditions, boundary conditions, and fluid viscosity parameters, the above formula can be simplified. Then, a numerical simulation of the reservoir seepage hysteresis effect can be carried out. The lattice Boltzmann method is used for the solution, and the equations are as follows:

[0098]

[0099]

[0100] Where u represents the velocity vector, ε p ρ represents porosity, p represents fluid density, μ represents fluid viscosity, and κ represents the permeability of the matrix. This indicates that the partial differential equations coincide, and t represents time. Let represent the Hamiltonian operator, and Δ represent the Laplace operator.

[0101] In the embodiments of this specification, in step S104, the fluid flow characteristic data includes the channeling coefficient and the reservoir capacity ratio. The channeling coefficient describes the ease of fluid exchange between fractures and the matrix in a dual-porosity reservoir, reflecting the ability of fluid in the matrix to channel into the fractures. The reservoir capacity ratio is the ratio of the elastic storage capacity of the fracture system to the total elastic storage capacity of the reservoir, describing the relative magnitude of the elastic storage capacity of the fractures and the matrix. (Refer to...) Figure 5 The step of determining the fluid flow characteristic data of the fractured-vuggy zone and matrix zone in the target reservoir based on simulation results includes:

[0102] S501: Determine the volume ratio of fractures and voids and the volume ratio of matrix in the target reservoir based on the simulation results.

[0103] S502: The reservoir capacity ratio is calculated based on the proportion of fracture and cavity volume and the proportion of matrix volume in the target reservoir.

[0104] S503: Determine the crossflow coefficient of the target reservoir from a pre-constructed ternary map of reservoir crossflow coefficients based on the reservoir capacity ratio, wherein the ternary map of reservoir crossflow coefficients stores the reservoir capacity ratio and crossflow coefficient under different fracture-vuggy and matrix volume ratios.

[0105] Specifically, the storage capacity ratio can be calculated using the following formula:

[0106]

[0107] Where φ1 represents the average porosity of the high-permeability fracture-vuggy zone, φ2 represents the average porosity of the low-permeability matrix zone, r1 represents the radius of the high-permeability fracture-vuggy zone, and r2 represents the radius of the low-permeability matrix zone. Based on the reservoir capacity ratio calculated in step S502 and the known fracture-vuggy volume ratio and matrix volume ratio, the corresponding channeling coefficient is found from the pre-constructed ternary reservoir channeling coefficient chart.

[0108] In some embodiments of this specification, the process of constructing the ternary plot of the reservoir channeling coefficient includes:

[0109] Several digital core simulation models were constructed, with each model having a different proportion of fracture-cavity volume and matrix volume.

[0110] The corresponding reservoir ratio is calculated based on the proportion of fracture and cavity volume and the proportion of matrix volume in each digital core simulation model;

[0111] Numerical simulations were performed on the aforementioned digital core simulation models to obtain production prediction data for each digital core simulation model.

[0112] Based on the production prediction data, well test interpretation is performed on each digital core simulation model to obtain the crossflow coefficient of each digital core simulation model;

[0113] Based on the aforementioned flow coefficient and reservoir capacity ratio, a ternary graph of reservoir flow coefficient under different fracture and matrix volume ratios is constructed.

[0114] like Figure 6 As shown, the ternary chart of reservoir channeling coefficient is a graph plotted with matrix, fracture, and vulcanization as the coordinate axes. Each point represents a specific proportion of matrix, fracture, and vulcanization models, corresponding to a reservoir capacity ratio and a channeling coefficient. Using this ternary chart, the channeling coefficient of reservoirs with different proportions of matrix, fracture, and vulcanization can be obtained conveniently and quickly, thereby evaluating the seepage hysteresis effect of reservoirs with different fracture-vulcanization combinations.

[0115] In the embodiments of this specification, the calculation of seepage hysteresis characteristic parameters based on the fluid flow characteristic data includes:

[0116] The seepage hysteresis characteristic parameters are calculated using the following formula:

[0117]

[0118] Among them, W 滞后 The parameters represent seepage hysteresis characteristics, ω represents the reservoir ratio, λ represents the channeling coefficient, a represents the bedrock morphology factor, and r represents the seepage hysteresis characteristic parameter. w Indicates the radius of the bottom of the well.

[0119] This can be understood as follows: based on the above-mentioned digital core simulation and theoretical research results, the seepage hysteresis effect is defined as the time difference between the quasi-steady state reached in the high-permeability fractured cavity zone and the quasi-steady state reached in the low-permeability matrix zone. Therefore, the embodiments in this specification use the seepage hysteresis effect characteristic parameters to quantitatively characterize the seepage hysteresis effect of fluid between the high-permeability fractured cavity zone and the low-permeability matrix. From Figure 7 It can be intuitively seen that the characteristic parameter of the seepage hysteresis effect is the ratio of the time t1 when the seepage in the cavity reaches a pseudo-steady state to the time t2 when the entire flow system reaches a pseudo-steady state after the pressure drop funnel further transfers to the matrix. The expression for the characteristic parameter of the seepage hysteresis effect is derived based on the seepage theory equation. The derivation process is as follows:

[0120]

[0121] Among them, W 滞后 The parameters represent the seepage hysteresis characteristics, where t1 represents the time when the seepage in the fractured cavity reaches a pseudo-steady state, t2 represents the time when the entire flow system reaches a pseudo-steady state after the pressure drop funnel transfers to the matrix, φ1 represents the average porosity of the high-permeability fractured cavity region, φ2 represents the average porosity of the low-permeability matrix region, μ represents the viscosity of the fluid, and C... t R represents the overall compressibility coefficient of the formation, r1 represents the radius of the high-permeability fracture-vuggy zone, r2 represents the radius of the low-permeability matrix zone, K1 represents the average permeability of the high-permeability fracture-vuggy zone, K2 represents the average permeability of the low-permeability matrix zone, ω represents the reservoir ratio, λ represents the channeling coefficient, and a represents the fracture shape factor. w The expression indicates that the seepage hysteresis effect is strongly correlated with the reservoir capacity ratio and channeling coefficient of fractured-vuggy reservoirs. The seepage hysteresis characteristic parameter is in the range [0,1], and when W... 滞后 A value approaching 0 indicates a stronger heterogeneity and a more significant seepage hysteresis effect. 滞后 A value approaching 1 indicates that the reservoir is becoming homogeneous and the seepage hysteresis effect has disappeared.

[0122] It should be noted that the user information (including but not limited to user device information, user personal information, etc.) and data (including but not limited to data used for analysis, stored data, displayed data, etc.) involved in this application are all information and data authorized by the user or fully authorized by all parties. Furthermore, the acquisition, storage, use, and processing of data in the technical solutions described in the embodiments of this application all comply with relevant regulations.

[0123] Based on the aforementioned method for evaluating the seepage lag effect in carbonate gas reservoirs, this specification also provides a corresponding device for evaluating the seepage lag effect in carbonate gas reservoirs. The device may include a system (including a distributed system), software (application), module, component, server, client, etc., using the method described in this specification, combined with necessary implementation hardware. Based on the same innovative concept, the devices in one or more embodiments provided in this specification are as described in the following embodiments. Since the implementation schemes and methods for solving the problem by the device are similar, the implementation of the specific device in this specification can refer to the implementation of the aforementioned method, and repeated details will not be elaborated further. As used below, the terms "unit" or "module" can refer to a combination of software and / or hardware that performs a predetermined function. Although the device described in the following embodiments is preferably implemented in software, hardware implementation, or a combination of software and hardware, is also possible and contemplated.

[0124] Specifically, Figure 8 This is a schematic diagram of the module structure of one embodiment of a carbonate gas reservoir seepage hysteresis effect evaluation device provided in this specification, with reference to... Figure 8 As shown in the embodiments of this specification, a device for evaluating the seepage hysteresis effect in carbonate gas reservoirs includes:

[0125] Module 801 is used to acquire seismic data of the target reservoir;

[0126] Feature acquisition module 802 is used to determine the morphological characteristics of seismic ant bodies and the development characteristics of outcrop fractures and cavities in the target reservoir based on the seismic data;

[0127] The model building module 803 is used to build a digital core simulation model of crevice development based on the morphological characteristics of the earthquake ant body and the development characteristics of outcrop crevice.

[0128] Simulation module 804 is used to simulate the digital core simulation model of fracture and vulcan development, and to determine the fluid flow characteristics data of the fracture and vulcan zone and matrix zone in the target reservoir based on the simulation results.

[0129] The parameter calculation module 805 is used to calculate the seepage hysteresis characteristic parameters based on the fluid flow characteristic data, wherein the seepage hysteresis characteristic parameters are used to characterize the time difference between the fluid reaching a pseudo-steady state in the high-permeability fracture zone and the fluid reaching a pseudo-steady state in the low-permeability matrix zone.

[0130] Evaluation module 806 is used to evaluate the seepage hysteresis effect of the target reservoir based on the seepage hysteresis characteristic parameters.

[0131] The beneficial effects obtained by the apparatus provided in the embodiments of this specification are consistent with the beneficial effects obtained by the methods described above, and will not be repeated here.

[0132] Reference Figure 9 As shown, based on the aforementioned method for evaluating the seepage hysteresis effect in carbonate gas reservoirs, one embodiment of this specification also provides a computer device 902, wherein the above-described method operates on the computer device 902. The computer device 902 may include one or more processors 904, such as one or more central processing units (CPUs), each of which can implement one or more hardware threads. The computer device 902 may also include any memory 906 for storing any kind of information, such as code, settings, data, etc. Non-limitingly, for example, the memory 906 may include any type of RAM, any type of ROM, flash memory, hard disk, optical disk, etc. More generally, any memory can use any technology to store information. Further, any memory can provide volatile or non-volatile retention of information. Further, any memory can represent a fixed or removable component of the computer device 902. In one case, when the processor 904 executes associated instructions stored in any memory or combination of memories, the computer device 902 can perform any operation of the associated instructions. The computer device 902 also includes one or more drive mechanisms 908 for interacting with any memory, such as a hard disk drive mechanism, an optical disk drive mechanism, etc.

[0133] Computer device 902 may also include an input / output module 910 (I / O) for receiving various inputs (via input device 912) and providing various outputs (via output device 914). A specific output mechanism may include a presentation device 916 and an associated graphical user interface (GUI) 918. In other embodiments, the input / output module 910 (I / O), input device 912, and output device 914 may be omitted, and the device may function solely as a computer device within a network. Computer device 902 may also include one or more network interfaces 920 for exchanging data with other devices via one or more communication links 922. One or more communication buses 924 couple the components described above together.

[0134] Communication link 922 can be implemented in any way, such as via a local area network (LAN), a wide area network (WAN) (e.g., the Internet), a point-to-point connection, or any combination thereof. Communication link 922 may include any combination of hardwired links, wireless links, routers, gateway functions, name servers, etc., governed by any protocol or combination of protocols.

[0135] Corresponding to, for example Figure 1 and Figure 5In addition to the method shown, embodiments of this specification also provide a computer-readable storage medium storing a computer program that, when executed by a processor, performs the steps of the above-described method.

[0136] This specification also provides computer-readable instructions, wherein when a processor executes the instructions, the program therein causes the processor to perform the following... Figure 1 and Figure 5 The method shown.

[0137] This specification also provides a computer program product, including at least one instruction or at least one program segment, wherein the at least one instruction or the at least one program segment is loaded and executed by a processor to achieve the following: Figure 1 and Figure 5 The method shown.

[0138] It should be understood that in the various embodiments of this specification, the sequence number of each process does not imply the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of this specification.

[0139] It should also be understood that, in the embodiments of this specification, the term "and / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, and B existing alone. Additionally, the character " / " in this specification generally indicates that the preceding and following related objects have an "or" relationship.

[0140] Those skilled in the art will recognize that the units and algorithm steps of the various examples described in conjunction with the embodiments disclosed in this specification can be implemented in electronic hardware, computer software, or a combination of both. To clearly illustrate the interchangeability of hardware and software, the components and steps of each example have been generally described in terms of functionality in the foregoing description. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of this specification.

[0141] Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the specific working processes of the systems, devices, and units described above can be referred to the corresponding processes in the foregoing method embodiments, and will not be repeated here.

[0142] In the embodiments provided in this specification, it should be understood that the disclosed systems, apparatuses, and methods can be implemented in other ways. For example, the apparatus embodiments described above are merely illustrative; for instance, the division of units is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the couplings or direct couplings or communication connections shown or discussed may be indirect couplings or communication connections through some interfaces, devices, or units, or they may be electrical, mechanical, or other forms of connection.

[0143] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of the embodiments described in this specification, depending on actual needs.

[0144] Furthermore, the functional units in the various embodiments of this specification can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. The integrated unit can be implemented in hardware or as a software functional unit.

[0145] If the integrated unit is implemented as a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of this specification, in essence, or the part that contributes to the prior art, or all or part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of this specification. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0146] This specification uses specific embodiments to illustrate the principles and implementation methods of this specification. The descriptions of the above embodiments are only for the purpose of helping to understand the methods and core ideas of this specification. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of this specification. Therefore, the content of this specification should not be construed as a limitation of this specification.

Claims

1. A method for evaluating the seepage hysteresis effect in carbonate gas reservoirs, characterized in that, The method includes: Acquire seismic data of the target reservoir; Based on the earthquake data, determine the seismic ant body morphology and outcrop fracture development characteristics of the target reservoir; Based on the morphological characteristics of earthquake ants and the development characteristics of outcrops and cavities, a digital core simulation model of cavity development was constructed. The digital core simulation model of fracture and cavity development was used to simulate the fluid flow characteristics of the fracture and cavity zone and the matrix zone in the target reservoir. The seepage hysteresis characteristic parameters are calculated based on the fluid flow characteristic data, wherein the seepage hysteresis characteristic parameters are used to characterize the time difference between the fluid reaching a pseudo-steady state in the crevice region and reaching a pseudo-steady state in the matrix region. The seepage hysteresis effect of the target reservoir is evaluated based on the seepage hysteresis characteristic parameters.

2. The method according to claim 1, characterized in that, The fluid flow characteristic data includes crossflow coefficient and storage capacity ratio; The determination of fluid flow characteristic data in the fractured-vuggy zone and matrix zone of the target reservoir based on simulation results includes: The volume ratios of fractures and voids and matrix in the target reservoir are determined based on the simulation results. The reservoir capacity ratio is calculated based on the proportion of fracture and void volume and the proportion of matrix volume in the target reservoir. The channeling coefficient of the target reservoir is determined from a pre-constructed ternary map of reservoir channeling coefficients based on the reservoir capacity ratio, wherein the ternary map of reservoir channeling coefficients stores the reservoir capacity ratio and channeling coefficient under different fracture-vuggy and matrix volume ratios.

3. The method according to claim 2, characterized in that, The calculation of seepage hysteresis characteristic parameters based on the fluid flow characteristic data includes: The seepage hysteresis characteristic parameters are calculated using the following formula: Among them, W 滞后 The parameters represent seepage hysteresis characteristics, ω represents the reservoir ratio, λ represents the channeling coefficient, a represents the bedrock morphology factor, and r represents the seepage hysteresis characteristic parameter. w Indicates the radius of the bottom of the well.

4. The method according to claim 2, characterized in that, The process of constructing the ternary plot of the reservoir channeling coefficient includes: Several digital core simulation models were constructed, with each model having a different proportion of fracture-cavity volume and matrix volume. The corresponding reservoir ratio is calculated based on the proportion of fracture and cavity volume and the proportion of matrix volume in each digital core simulation model; Numerical simulations were performed on the aforementioned digital core simulation models to obtain production prediction data for each digital core simulation model. Based on the production prediction data, well test interpretation is performed on each digital core simulation model to obtain the crossflow coefficient of each digital core simulation model; Based on the aforementioned flow coefficient and reservoir capacity ratio, a ternary graph of reservoir flow coefficient under different fracture and matrix volume ratios is constructed.

5. The method according to claim 1, characterized in that, The seepage hysteresis characteristic parameter is in the range [0,1]. The evaluation of the seepage hysteresis effect of the target reservoir based on the seepage hysteresis characteristic parameter includes: The closer the seepage hysteresis characteristic parameter is to 0, the stronger the seepage hysteresis effect of the target reservoir. The closer the seepage hysteresis characteristic parameter is to 1, the weaker the seepage hysteresis effect of the target reservoir.

6. The method according to claim 1, characterized in that, The digital core simulation model for fracture development includes: The digital core simulation model of fracture-cavity development is represented by the following formula: Where, ε p Porosity is represented by ρ; fluid density is represented by g / cm³. 3 Q m Indicates mass source, unit g / (cm³) 3 •s); u represents velocity vector, unit m / s; p represents pressure, unit MPa; μ represents fluid viscosity, unit mPa·s; κ represents permeability of the matrix, unit mD; F represents force, unit g / (cm²). 2 ·s 2 ); Let represent partial differential equations, t represent time, T represent transpose, I represent the identity matrix, and ▽ represent the Hamiltonian operator.

7. A device for evaluating the seepage hysteresis effect in carbonate gas reservoirs, characterized in that, The device includes: The acquisition module is used to acquire seismic data of the target reservoir. The feature acquisition module is used to determine the morphological characteristics of seismic ant bodies and the development characteristics of outcrops and cavities in the target reservoir based on the seismic data. The model building module is used to construct a digital core simulation model of fracture and cavity development based on the morphological characteristics of the earthquake ant bodies and the development characteristics of outcrops and cavities. The simulation module is used to simulate the digital core simulation model of fracture and cavity development, and to determine the fluid flow characteristics of the fracture and cavity zone and matrix zone in the target reservoir based on the simulation results. The parameter calculation module is used to calculate the seepage hysteresis characteristic parameters based on the fluid flow characteristic data, wherein the seepage hysteresis characteristic parameters are used to characterize the time difference between the fluid reaching a pseudo-steady state in the crevice region and reaching a pseudo-steady state in the matrix region. The evaluation module is used to evaluate the seepage hysteresis effect of the target reservoir based on the seepage hysteresis characteristic parameters.

8. A computer device, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that, When the processor executes the computer program, it implements the method as described in any one of claims 1 to 6.

9. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores a computer program that, when executed by a processor, implements the method as described in any one of claims 1 to 6.

10. A computer program product, characterized in that, It includes at least one instruction or at least one program segment, said at least one instruction or said at least one program segment being loaded and executed by a processor to implement the method as claimed in any one of claims 1 to 6.

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