3D printing-based three-dimensional fractured-vug type reservoir acid fracturing flow simulation method and system

Abstract

The application provides a three-dimensional fracture-vug type oil reservoir acid fracturing flow simulation method and system based on 3D printing, the method establishes a three-dimensional rock sample digital model by scanning and reconstructing a solid rock sample, sets printing process parameters according to the characteristics of the rock sample, and uses a printing device to print and fuse layer by layer to form a three-dimensional fracture-vug body test piece; mechanical property testing is performed to determine the test pieces that meet the quality matching condition to realize batch printing to obtain a test sample set, acid fracturing process simulation is carried out based on the test sample, the fracture-vug body connectivity after pressure is analyzed and determined, and stress distribution and deformation distribution information is extracted to evaluate the acid fracturing effect of the fracture-vug type oil reservoir under different conditions. The method prints the fracture-vug body rock sample based on the set parameters, overcomes the problems of high uncertainty of the sample preparation in the prior art and difficulty in considering the geometric and mechanical consistency, and realizes acid fracturing simulation based on the test sample of the application, can solve the difficulty in characterizing the stress distribution and fracture morphology after pressure, and realizes accurate and efficient acid fracturing simulation of the fracture-vug type oil reservoir.

Description

Technical Field

[0001] This invention relates to the field of oilfield development and testing technology, and in particular to a method and system for simulating acid fracturing flow in three-dimensional fractured reservoirs based on 3D printing. Background Technology

[0002] The main methods for studying the macroscopic mechanical properties, failure characteristics, and fracture mechanical behavior of complex rock masses containing fractures and karst caves include three categories: in-situ monitoring methods, numerical simulation methods, and indoor physical experimental simulation methods. Among them, indoor physical experimental methods are convenient for observing the three-dimensional spatial distribution of artificial fractures, and can intuitively reflect how the expansion of artificial fractures in the rock mass is affected by pre-existing fractures or karst caves. They can realistically simulate the flow process of oil, gas, and water three-phase fluids in fractured and karst caves and the spatial distribution of remaining oil. At the same time, they can also obtain typical bottom hole flowing pressure history curves during fracturing or production. Therefore, they are one of the important means to study acid fracturing and development scheme optimization for complex fractured and karst cave reservoirs.

[0003] One of the core technologies for indoor physical testing methods is the manufacturing and processing technology of test samples that can be repeated, indiscriminately produced, and mass-produced. For a long time, indoor rock mass test samples have mostly been taken from the target reservoir rock mass. Due to the heterogeneity of natural rock masses, it is necessary to conduct similar tests multiple times. Statistical methods are used to mitigate the uncertainty brought by natural samples taken from the target reservoir to some extent. However, existing methods have not been able to properly solve the problem of accuracy in indoor tests of rock mechanics containing complex structural planes.

[0004] 3D printing technology has advantages such as automation, intelligence, and high manufacturing precision, and can quickly and efficiently manufacture test samples similar to the target reservoir rock mass. However, existing 3D printing technologies mainly have the following two problems in preparing fractured-vuggy media containing caverns and fractures:

[0005] (1) The prepared rock samples are difficult to be consistent with real fractured carbonate rocks in terms of both mechanics and chemistry.

[0006] Existing 3D printing technologies either only consider the mechanical similarity of the prepared rock samples or only consider the similarity of the geometric morphology of the printed specimens' cavities and fractures. How to preserve the geometric morphology of fractures and cavities while ensuring the similarity of the mechanical and chemical characteristics of carbonate rocks, so as to obtain 3D printed specimens suitable for exploring acid fracturing and fracturing stimulation of fractured-vuggy carbonate reservoirs, is one of the problems that deserve attention and solutions.

[0007] (2) It is difficult to characterize the stress distribution and crack morphology of the prepared rock samples after dynamic acid pressure test.

[0008] The greatest advantage of 3D printing technology is its ability to repeatedly produce specimens with nearly identical geometry and mechanics using the same printing materials and processes. This avoids the uncertainties associated with using natural rock samples in related experiments, making it suitable for conducting numerous repetitive or comparative tests. However, current 3D printing technology faces significant challenges in conveniently extracting the stress state of fractured and cavitary rock masses in real time. Characterizing fractures typically relies on directly opening rock samples after fracturing to observe, sketch, and reconstruct hydraulic fractures, natural fractures, and karst caves. Therefore, there is a need to develop 3D printing technologies that can easily extract stress distribution and the morphology of fractures and karst caves from conventional fracturing or acid fracturing.

[0009] The information disclosed in the background section of this invention is intended only to enhance the understanding of the general background of this invention, and should not be construed as an admission or in any way implying that such information constitutes prior art known to those skilled in the art. Summary of the Invention

[0010] To address the aforementioned problems, this invention provides a three-dimensional acid fracturing flow simulation method for fractured-vuggy reservoirs based on 3D printing. This method effectively overcomes the problems of high uncertainty in sample preparation and difficulty in achieving geometric and mechanical consistency in existing technologies. Furthermore, acid fracturing simulation based on samples from this invention can overcome the difficulties in characterizing post-compression stress distribution and fracture morphology, achieving accurate and efficient acid fracturing simulation of fractured-vuggy reservoirs. Preferably, in one embodiment, the method includes:

[0011] Steps for preparing outcrop protolith samples: Collect outcrop samples of fractured-cavity carbonate rocks, and cut and prepare outcrop protolith samples with dimensions that meet the set standards based on the collected samples, as typical fractured-cavity rock samples;

[0012] Steps for constructing a digital model of a fractured cavity: By performing three-dimensional scanning and three-dimensional reconstruction on typical fractured cavity rock samples, a corresponding three-dimensional digital model of the rock sample is established;

[0013] Printing path determination steps: According to the requirements of the printing equipment, the three-dimensional rock sample digital model is processed into multiple printing slices by layering, and the printing slice information is used to determine the computer-recognizable layer-by-layer printing path.

[0014] Printing parameter configuration steps: Set different printing process parameters to match different printing slice layers according to the characteristics of the current typical fractured rock sample, including printing resolution, density, specimen size, structural material, filling rate and layer thickness parameters;

[0015] Specimen printing steps: Using printing equipment, print layer by layer based on printing slice information and printing process parameters, and then fuse the layers to form a three-dimensional slit specimen;

[0016] Specimen processing and testing steps: After removing the support material of the specimen, polishing and coloring are performed, and the specimen is cured. Then, the mechanical properties of the specimen are tested, and the quality matching of the specimen is determined according to the test results. If the quality matching of the current specimen meets the set conditions, the subsequent sample printing steps are executed; otherwise, the printing parameter configuration steps, specimen printing steps, and specimen processing and testing steps are executed again.

[0017] Sample batch printing steps: Based on the current three-dimensional rock sample digital model, printing path and printing process parameters, batch printing is carried out to obtain a sample set for fracturing simulation test;

[0018] Acid Fragmentation Simulation Steps: Based on the printed sample, the acid fragmentation process is simulated under true triaxial load according to the set acid fragmentation simulation conditions;

[0019] Simulation information acquisition and analysis steps: Acquire images of the evolution of fractured-vuggy samples during acid fracturing, construct a three-dimensional geometric distribution model of fractured-vuggy bodies based on these images, analyze and determine the post-fracturing connectivity of fractured-vuggy bodies, and extract stress distribution and deformation distribution information based on photoelastic fringes and stress analysis algorithms. Based on the acquired deformation distribution information and fractured-vuggy body connectivity information, evaluate the acid fracturing effect of fractured-vuggy reservoirs under different conditions.

[0020] In one embodiment, in the printing parameter configuration step, setting the structural materials includes selecting and setting the printing material ratio for the matrix, cracks, and cavities. The matrix material is a mixture of fractured carbonate rock powder and liquid photosensitive resin. The material is Vero White Plus, a white opaque material, which contains filling material for the cracks and cavities. Paraffin wax is used as a temporary support molding material for unfilled cavities. A mesh support material is used as a support material for preparing unfilled cracks.

[0021] Optionally, in one embodiment, a matrix is ​​prepared by mixing fractured carbonate rock powder with liquid photosensitive resin at a volume ratio of 1:5; and unfilled fractures are prepared using Fullcure 705 mesh support material.

[0022] Furthermore, in one embodiment, the specimen processing and testing steps include the following operations:

[0023] The printed specimen is uniformly cured by laser irradiation and seamlessly fused with carbonate rock powder material;

[0024] By heating the material, the paraffin wax supporting the cave structure is gradually melted and removed, ultimately forming a three-dimensional rock-like specimen that includes a matrix, filled cracks and caves, and specimens without filled cracks and caves.

[0025] Specifically, in an optional embodiment, in the specimen processing and testing steps, the processed specimens are subjected to conventional mechanical and fracture mechanical property tests, and the macroscopic mechanical parameters, strain field evolution law and three-dimensional failure characteristics of the specimens are analyzed to determine whether they meet the requirements.

[0026] Preferably, in one embodiment, in the acid pressure simulation step, multiple single variable factors are set according to the test requirements to realize the acid pressure simulation test. The single variable factors include acid injection rate, injection location and distribution conditions of the cavity.

[0027] Furthermore, in one embodiment, in the simulation information acquisition and analysis step, images of the evolution of the fractured sample during the acid fracturing process are acquired by a fast camera, and a corresponding three-dimensional geometric distribution model of the fractured body is constructed based on machine learning. The corresponding fractured body connectivity information is analyzed and obtained. The optical properties of Vera Clear transparent photoelastic matrix material and the stress-freezing properties under temperature load are utilized to extract the full-field stress distribution and deformation distribution information through photoelastic fringes and stress analysis algorithms.

[0028] Specifically, in an optional embodiment, the process of evaluating the acid fracturing effect of fractured-vuggy reservoirs under different conditions based on the acquired deformation distribution information and fracture-vuggy body connectivity information includes:

[0029] Based on the deformation distribution information, the aperture distribution information of each fracture is calculated, the fracture size information is determined, and then the acid fracturing effect of fractured-vuggy reservoirs under different conditions is evaluated based on the obtained fracture width, fracture length, and fracture-vuggy body connectivity information.

[0030] Based on other aspects of the methods described in any one or more of the foregoing embodiments, the present invention also provides a storage medium storing program code that can implement the methods described in any one or more of the foregoing embodiments.

[0031] Based on the application aspects of the methods described in any one or more of the above embodiments, the present invention also provides a three-dimensional fractured reservoir acid fracturing flow simulation system based on 3D printing, which performs the methods described in any one or more of the above embodiments.

[0032] Compared with the closest prior art, the present invention also has the following beneficial effects:

[0033] This invention provides a method and system for simulating acid fracturing flow in three-dimensional fractured-vuggy reservoirs based on 3D printing. The method establishes a three-dimensional digital model of the rock sample by performing three-dimensional solid CT scanning and three-dimensional reconstruction on the fractured-vuggy rock sample. Then, the three-dimensional digital model is layered to form multiple printing slices. The computer printing path is determined, and the three-dimensional digital model is imported into a printing device. The printing device prints and fuses the slices layer by layer based on the printing slice information and printing process parameters to form a three-dimensional fractured-vuggy specimen. This method can accurately obtain samples with geometric and mechanical properties similar to the fractured-vuggy rock sample. It reliably characterizes the properties of complex fractured-vuggy rock masses, enabling the required simulation experiments. It also facilitates batch preparation, and the different samples obtained do not exhibit uncertainties. This fundamentally ensures the stability and accuracy of the test substrate, improving the authenticity of the test data.

[0034] Furthermore, the prepared specimens undergo post-printing processing. After removing the supporting material, they are polished, colored, and cured. Based on the mechanical property test results, it is determined whether the consistency between the current specimen and the real rock mass sample meets the requirements. If not, optimization and adjustment are performed before batch preparation. This avoids waste of preparation materials and redundant operations, and improves the timeliness of specimen preparation while ensuring the quality of the specimens.

[0035] Furthermore, based on the printed samples, acid fracturing simulation was conducted under true triaxial load conditions according to the set acid fracturing simulation conditions. Evolution images of the fractured-vuggy body samples during the acid fracturing process were acquired, and a three-dimensional geometric distribution model of the fractured-vuggy body was constructed based on these images. The post-fracturing connectivity of the fractured-vuggy body was analyzed and determined, and stress and deformation distribution information was extracted. Based on the acquired deformation distribution information and fractured-vuggy body connectivity information, the acid fracturing effect on fractured-vuggy reservoirs under different conditions was evaluated. The 3D-printed fractured-vuggy body samples accurately reflect the acid fracturing evolution data and effectively extract the fractured-vuggy body connectivity, stress distribution information, and deformation distribution information of the samples after the acid fracturing test. Based on this, the acid fracturing effect of the samples corresponding to typical fractured-vuggy rock masses can be accurately analyzed. This not only provides effective support for the multiphase flow law, residual oil distribution law, and acid fracturing stimulation effect of fractured-vuggy carbonate reservoirs, but also provides a theoretical basis for better guiding the targeted acid fracturing reservoir stimulation and efficient oil and gas development of fractured-vuggy carbonate reservoirs, providing technical and theoretical support for improving the quality and efficiency of oil and gas reservoir development and stabilizing and increasing production.

[0036] Other features and advantages of the invention will be set forth in the description which follows, and will be apparent in part from the description, or may be learned by practicing the invention. The objects and other advantages of the invention may be realized and obtained by means of the structures particularly pointed out in the description, claims, and drawings. Attached Figure Description

[0037] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used in conjunction with the embodiments of the invention to explain the invention and do not constitute a limitation thereof. In the drawings:

[0038] Figure 1 This is a schematic flowchart of a three-dimensional fractured reservoir acid fracturing flow simulation method based on 3D printing provided in an embodiment of the present invention;

[0039] Figure 2 This is a schematic diagram of the sample printing process for the three-dimensional fractured reservoir acid pressure flow simulation method based on 3D printing provided in the embodiments of the present invention;

[0040] Figure 3 This is an example diagram of the printing equipment for the three-dimensional fractured reservoir acid fracturing flow simulation method based on 3D printing provided in the embodiments of the present invention;

[0041] Figure 4 This is a schematic diagram of the unfilled cavity printing effect of the three-dimensional fractured reservoir acid pressure flow simulation method based on 3D printing provided in an embodiment of the present invention;

[0042] Figure 5 This is a schematic diagram of the printing effect of the fractured cavity medium sample in the three-dimensional fractured cavity reservoir acid pressure flow simulation method based on 3D printing provided in the embodiments of the present invention;

[0043] Figure 6 This is an example diagram of the oil and gas saturation distribution in the injection and production experiment of the three-dimensional fractured-vuggy reservoir acid fracturing flow simulation method based on 3D printing provided in an embodiment of the present invention;

[0044] Figure 7 This is an example diagram of the statistical efficiency of gas injection displacement for the three-dimensional fractured reservoir acid fracturing flow simulation method based on 3D printing provided in the embodiments of the present invention.

[0045] Figure 8 This is a schematic diagram of the structure of a three-dimensional fractured reservoir acid pressure flow simulation system based on 3D printing, provided in another embodiment of the present invention. Detailed Implementation

[0046] The embodiments of the present invention will be described in detail below with reference to the accompanying drawings and examples. Those skilled in the art will then fully understand how the present invention uses technical means to solve technical problems and achieve technical effects, and will be able to implement the present invention specifically based on the above-described implementation process. It should be noted that, as long as there is no conflict, the various embodiments and features of the present invention can be combined with each other, and the resulting technical solutions are all within the protection scope of the present invention.

[0047] Although the flowchart describes the operations as sequential processes, many of these operations can be performed in parallel, concurrently, or simultaneously. The order of the operations can be rearranged. A process can terminate when its operation is complete, but it may also have additional steps not included in the diagram. A process can correspond to a method, function, procedure, subroutine, subroutine, etc.

[0048] Computer equipment includes user equipment and network equipment. User equipment or clients include, but are not limited to, computers, smartphones, and PDAs (Personal Digital Assistants); network equipment includes, but is not limited to, a single network server, a server group consisting of multiple network servers, or a cloud based on cloud computing consisting of a large number of computers or network servers. Computer equipment can operate independently to implement this invention, or it can connect to a network and implement this invention through interaction with other computer devices within the network. The network in which the computer equipment resides includes, but is not limited to, the Internet, wide area networks (WANs), metropolitan area networks (MANs), local area networks (LANs), and VPN networks.

[0049] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments. Unless the context clearly indicates otherwise, the singular forms “a” and “an” as used herein are also intended to include the plural. It should also be understood that the terms “comprising” and / or “including” as used herein specify the presence of the stated features, integers, steps, operations, units, and / or components, without excluding the presence or addition of one or more other features, integers, steps, operations, units, components, and / or combinations thereof.

[0050] In the field of oilfield development, it is of great significance to study the macroscopic mechanical properties, failure characteristics, and fracture mechanical behavior of complex rock masses containing fractures and karst caves. Existing research methods mainly include three categories: in-situ monitoring, numerical simulation, and indoor physical experiment simulation. Among them, indoor physical experiment simulation is convenient for observing the three-dimensional spatial distribution of artificial fractures, and can intuitively reflect how the expansion of artificial fractures in the rock mass is affected by pre-existing fractures or karst caves. It can realistically simulate the flow process of oil, gas, and water three-phase fluids in fractured and karst caves and the spatial distribution of remaining oil. At the same time, it can also obtain typical bottom hole flowing pressure history curves during fracturing or production. Therefore, it is one of the important means to study acid fracturing and development scheme optimization of complex fractured and karst cave reservoirs.

[0051] One of the core technologies for indoor physical testing methods is the manufacturing and processing technology of test samples that can be repeated, indiscriminately produced, and mass-produced. For a long time, indoor rock mass test samples have mostly been taken from the target reservoir rock mass. Due to the heterogeneity of natural rock masses, it is necessary to conduct similar tests multiple times. Statistical methods are used to mitigate the uncertainty brought by natural samples taken from the target reservoir to some extent. However, existing methods have not been able to properly solve the problem of accuracy in indoor tests of rock mechanics containing complex structural planes.

[0052] Subsequently, concrete casting sample processing technology was applied to study the influence of specific structural surfaces on the mechanical behavior of rock masses. This method has solved the problem of customized processing of rock mass structural surfaces to a certain extent. However, a series of challenges have been encountered in how to select appropriate casting materials to construct casting samples with highly similar characteristics to the original rock in terms of porosity, permeability, mechanical parameters, and fracture parameters (including the matching of aggregates and cement, aggregate particle size distribution and roundness, particle mineral composition and physicochemical properties, etc.), which greatly restricts the research on concrete casting sample processing in rock mass mechanical tests of different types of oil and gas reservoirs.

[0053] 3D printing technology (or additive manufacturing technology), which has experienced rapid development in recent years, boasts advantages such as automation, intelligence, and high precision. Primarily based on three-dimensional digital models and employing mechanical equipment for mechanical deposition, it can quickly and efficiently manufacture test samples similar to the target reservoir rock mass. Currently, the main 3D printing technologies include photopolymerization, fused deposition modeling, and selective sintering. Common printing materials include magnetic powder, quartz sand, gypsum, photosensitive and thermosetting resins, ceramics, PMMA (polymethyl methacrylate), SR20 acrylic copolymer, carbon fiber, and tough plastics. Among these, materials commonly used for rock-like printing include PMMA, magnetic powder, quartz sand, rock powder, gypsum, resin, concrete, and mixtures of various materials.

[0054] For example, Ishutov et al. printed specimens using plastic materials and demonstrated, through X-ray computed tomography, that the specimens exhibited good consistency with the internal pore characteristics of sandstone; Jiang Quan and Song Leibo used powdered gypsum as the printing material to prefabricate rock samples containing porous and fractured structures, preliminarily demonstrating that 3D-printed samples showed good consistency in simulating the mechanical properties and failure modes of real rock samples; Jiang et al. used a mixture of polymer PLA and gypsum powder as the 3D printing material and, through a series of conventional mechanical and fracture mechanics tests, found that the mixture material used was similar to the real rock samples in terms of mechanical properties and failure modes; Ju Yang et al. used the transparent photopolymer material Vero... Clear and Fullcure mesh support materials were used to prepare specimens for 3D printing, achieving the same geometric and distribution characteristics as natural coal and rock fracture structures. Tensile and compressive tests on the specimens showed that the overall mechanical properties of the hybrid material were close to those of natural fractured coal and rock. Li Zhengwei et al. used a mixture of magnetite powder, quartz powder, cement, and gypsum as 3D printing raw materials to prepare thin-layered rock-like specimens. Uniaxial compression tests and non-contact strain observations showed that this method can construct artificial specimens with mechanical properties and failure modes similar to real thin-layered rocks. Song et al. used gypsum powder, silica powder, and stone... Using Ying sand as raw material for 3D printing, the printed specimens have properties similar to natural specimens and can be used to simulate sandstone with high porosity and high permeability. Wang et al. prepared a matrix using natural carbonate rock powder and epoxy resin, used thin silicone rubber to simulate secondary pores, and polypropylene particles of different diameters to simulate spherical pores, thus artificially constructing carbonate rock specimens containing matrix, micropores and macropores. Zhou et al. used concrete casting to prefabricate cubic fracturing specimens with sides of 300 mm containing cracks and caves, and used true triaxial fracturing equipment to carry out the interaction of hydraulic cracks in the fracture caves with pre-existing natural cracks and caves.

[0055] Although 3D printing technology has been introduced into rock mechanics experimental research and widely used to prepare homogeneous or layered rock samples and rock samples containing different fractures and pores (filled or unfilled), it has achieved rapid development in terms of control precision, forming speed, and preparation quality. However, existing 3D printing technologies mainly have the following two problems in preparing fractured and cracked media:

[0056] (1) The prepared rock samples are difficult to be consistent with real fractured carbonate rocks in terms of both mechanics and chemistry.

[0057] Existing 3D printing technologies either only consider the mechanical similarity of the prepared rock samples or only consider the similarity of the geometric morphology of the printed specimens' cavities and fractures. How to preserve the geometric morphology of fractures and cavities while ensuring the similarity of the mechanical and chemical characteristics of carbonate rocks, so as to obtain 3D printed specimens suitable for exploring acid fracturing and fracturing stimulation of fractured-vuggy carbonate reservoirs, is one of the problems that deserve attention and solutions.

[0058] (2) It is difficult to characterize the stress distribution and crack morphology of the prepared rock samples after dynamic acid pressure test.

[0059] The greatest advantage of 3D printing technology is its ability to repeatedly produce specimens with nearly identical geometry and mechanics using the same printing materials and processes. This avoids the uncertainties associated with using natural rock samples in related experiments, making it suitable for conducting numerous repetitive or comparative tests. However, current 3D printing technology faces significant challenges in conveniently extracting the stress state of fractured and cavitary rock masses in real time. Characterizing fractures typically relies on directly opening rock samples after fracturing to observe, sketch, and reconstruct hydraulic fractures, natural fractures, and karst caves. Therefore, there is a need to develop 3D printing technologies that can easily extract stress distribution and the morphology of fractures and karst caves from conventional fracturing or acid fracturing.

[0060] To address the current limitations of 3D printing technology in achieving synchronous and consistent mechanical and chemical properties with real fractured and cavernous complex media, and the difficulty in extracting and analyzing stress distribution and fractured / cavrnous geometry information after fracturing simulation tests, this invention establishes a 3D-printed method and system for simulating acid fracturing flow in fractured / cavrnous reservoirs. This method can achieve 3D printing of carbonate fractured / cavrnous media systems, accurately reproducing the spatial geometry of fractured / cavrnous bodies, and ensuring the similarity of the specimen's mechanical and chemical properties to those of real fractured / cavrnous complex media. It also facilitates the extraction of post-test stress distribution and fractured / cavrnous morphology information, demonstrating high practical value. This invention provides technical support for studying the seepage patterns of fractured / cavrnous media, tapping remaining oil potential, acid fracturing stimulation mechanisms, and acid fracturing scheme design based on the 3D printing of complex carbonate fractured / cavrnous media.

[0061] The following describes the detailed flow of the method according to an embodiment of the present invention with reference to the accompanying drawings, the steps of which can be executed in a computer system containing, for example, a set of computer-executable instructions. Although the logical order of the steps is shown in the flowchart, in some cases, the steps shown or described may be performed in a different order than that shown here.

[0062] Example 1:

[0063] Figure 1 This diagram illustrates a flow chart of the three-dimensional fractured-vuggy reservoir acid fracturing flow simulation method based on 3D printing provided in Embodiment 1 of the present invention. (Refer to...)Figure 1 As can be seen, the method includes the following steps.

[0064] Steps for preparing outcrop protolith samples: Collect outcrop samples of fractured-cavity carbonate rocks, and cut and prepare outcrop protolith samples with dimensions that meet the set standards based on the collected samples, as typical fractured-cavity rock samples;

[0065] Steps for constructing a digital model of a fractured cavity: By performing three-dimensional solid CT scanning and three-dimensional reconstruction on typical fractured cavity rock samples, a corresponding three-dimensional digital model of the rock sample is established.

[0066] Printing path determination steps: According to the requirements of the printing equipment, the three-dimensional rock sample digital model is processed into multiple printing slices by layering, and the printing path is determined by computer recognition based on the printing slice information.

[0067] Printing parameter configuration steps: Set appropriate printing process parameters according to the characteristics of typical fractured rock samples, including printing resolution, density, specimen size, structural material, filling rate and layer thickness parameters for different layers;

[0068] Specimen printing steps: The three-dimensional rock sample digital model is imported into the printing equipment, and the printing equipment prints layer by layer based on the printing slice information and printing process parameters, and then the layers are fused together to form a three-dimensional fractured specimen;

[0069] Specimen processing and testing steps: After removing the support material of the specimen, polishing and coloring are performed, and the specimen is cured. Then, the mechanical properties of the specimen are tested, and the quality matching of the specimen is determined according to the test results. If the quality matching of the current specimen meets the set conditions, the subsequent sample printing steps are executed; otherwise, the printing parameter configuration steps, specimen printing steps, and specimen processing and testing steps are executed again.

[0070] Sample batch printing steps: Based on the current three-dimensional rock sample digital model, printing path and printing process parameters, batch printing is carried out to obtain a sample set for fracturing simulation test;

[0071] Acid Fragmentation Simulation Steps: Based on the printed sample, the acid fragmentation process is simulated under true triaxial load according to the set acid fragmentation simulation conditions;

[0072] Simulation information acquisition and analysis steps: Acquire images of the evolution of fractured-vuggy samples during acid fracturing, construct a three-dimensional geometric distribution model of fractured-vuggy bodies based on these images, analyze and determine the post-fracturing connectivity of fractured-vuggy bodies, and extract stress distribution and deformation distribution information based on photoelastic fringes and stress analysis algorithms. Based on the acquired deformation distribution information and fractured-vuggy body connectivity information, evaluate the acid fracturing effect of fractured-vuggy reservoirs under different conditions.

[0073] The solution adopted in this embodiment of the invention provides effective 3D printing guidance for fractured-cavity carbonate rock media systems and operational guidance for simulating acid fracturing processes based on 3D printed models. It can prepare samples with mechanical and chemical properties similar to real fractured-cavity carbonate rock media, and the acid fracturing simulation test based on the sample facilitates the extraction of stress distribution and fracture geometry information after the test.

[0074] Figure 2 This diagram illustrates a flow chart of a typical fractured rock mass sample 3D printing method according to an embodiment of the present invention. Figure 2 As shown, this method uses different matrix materials, simulated fracture materials, and cave support materials to print fractured cave rock samples. It can provide an effective technical means for studying the multiphase flow law, residual oil distribution law, and acid fracturing effect of carbonate fractured cave systems. At the same time, it can better guide the targeted acid fracturing reservoir stimulation and efficient oil and gas development of fractured cave type carbonate rocks.

[0075] In summary, this invention provides a method for preparing fractured-cavity rock mass samples to characterize complex porous media systems of fractured-cavity carbonate rocks using 3D printing. The 3D printing process for these samples mainly includes the preparation of outcrop samples and the construction of a three-dimensional digital model of the fractured-cavity rock mass; setting relevant printing paths according to sample preparation requirements; determining the ratio of printing materials between the matrix, fractures, and cavities; setting detailed printing parameters; and curing the printed specimens. Based on this, the consistency between the printed specimens and the field outcrop specimens is confirmed by testing mechanical and flow properties. If necessary, the material ratio and printing parameters are adjusted until the requirements are met before batch printing. This method effectively ensures the quality stability of batch-printed specimens and avoids wasting time, costs, and material resources.

[0076] In practical applications, the digital model construction step of the fractured cavity body involves performing three-dimensional solid CT scanning and three-dimensional reconstruction on typical fractured cavity body rock samples prepared by cutting, and then establishing a three-dimensional digital model of the printed sample (such as constructing a three-dimensional data model STL file).

[0077] Then, the three-dimensional digital model is layered and "sliced" according to the set method to complete the planning of the computer's layer-by-layer printing path; that is, the printing path determination step is executed, and the three-dimensional rock sample digital model is processed into multiple printing slices according to the requirements of the printing equipment. The layer-by-layer printing path recognized by the computer is determined based on the printing slice information.

[0078] Further, the printing parameter configuration step is performed, and appropriate printing process parameters are set according to the characteristics of the current typical fractured rock sample, including the printing resolution, density, specimen size, structural material, filling rate and layer thickness parameters of different layers.

[0079] In practical applications, appropriate printing process parameters (such as printing resolution, density, specimen size, filling rate, layer thickness, etc.) are selected according to the characteristics of the fractured rock sample. The three-dimensional digital model is imported into the 3D printing equipment (such as the Object Connex 500 printing equipment developed by Stratasys in the United States). The printer reads the "slice" information and prints layer by layer with liquid, powder, or sheet materials, and fuses the corresponding interfaces of each layer in a set manner to construct a three-dimensional solid specimen. Preferably, the corresponding interfaces of each layer can be fused together by laser irradiation to construct a three-dimensional solid specimen.

[0080] Preferably, in one embodiment, in the printing parameter configuration step, setting the structural materials includes selecting and setting the printing material ratio for the matrix, cracks and cavities, using fractured carbonate rock grinding powder and liquid photosensitive resin as the matrix material, using white opaque material Vero White Plus as the material for the cracks and cavities containing filling material, using paraffin wax as the temporary support molding material for the unfilled cavities, and using a mesh support material as the support material for preparing the unfilled cracks.

[0081] Specifically, in an optional embodiment, a matrix is ​​prepared by mixing fractured carbonate rock powder with liquid photosensitive resin at a volume ratio of 1:5; and unfilled fractures are prepared using Fullcure 705 mesh support material.

[0082] In this invention, the fractured carbonate rock grinding powder material and liquid photosensitive resin (VeraClear) are used as the matrix material (mixed at a volume ratio of carbonate rock powder to resin of 1:5). Vero White Plus, a white opaque material, is used as the filling material for the fractures and cavities. Paraffin wax is used as the temporary support material for the unfilled cavities, and Fullcure 705 is used as the mesh support material to prepare the unfilled cracks. This design ensures the geometric, mechanical, and chemical consistency between the printed specimen and the real fractured carbonate rock mass, while also facilitating the extraction of stress evolution and fracture geometry information.

[0083] The next step is to print the specimen. The three-dimensional rock sample digital model is imported into the printing equipment, which then prints layer by layer based on the printing slice information and printing process parameters. The layers are then fused together to form a three-dimensional fractured specimen. An example diagram of the printing equipment can be found in the appendix. Figure 3 ;

[0084] Further specimen processing and testing steps are performed. After removing the supporting material, the specimen is polished and colored, and then cured. Mechanical property tests are then conducted on the specimen, and the quality matching of the specimen is determined based on the test results. If the quality matching of the current specimen meets the set conditions, the subsequent sample printing step is executed; otherwise, the printing parameter configuration step, specimen printing step, and specimen processing and testing step are repeated. The method of curing the specimen can be set according to the actual specimen requirements. For example, the formed three-dimensional slit specimen can be left to stand at room temperature for a set time to complete the curing process. Optionally, the set time is usually not less than 2 hours.

[0085] The specimen handling and testing procedures include the following operations:

[0086] The printed specimen is uniformly cured by laser irradiation and seamlessly fused with carbonate rock powder material;

[0087] By heating the material, paraffin wax, the supporting material for the karst cave, is gradually melted and removed. The melted wax flows out automatically under gravity, ultimately forming three-dimensional rock-like specimens that include a matrix, filled cracks and karst caves, and specimens without filled cracks and karst caves. An example image of a 3D-printed specimen without filled karst caves is shown below. Figure 4 As shown in the image, an example of a 3D-printed specimen with a complex overall slit-like structure is presented. Figure 5 As shown.

[0088] In the specimen processing and testing steps, a three-dimensional rock-like specimen is ultimately formed, consisting of a matrix, filled cracks and cavities, and unfilled cracks and cavities. The processed specimens are then subjected to conventional mechanical and fracture mechanics tests to analyze their macroscopic mechanical parameters, strain field evolution, and three-dimensional failure characteristics. The consistency between the printed specimen and typical fractured-cavity rock samples prepared from field outcrops is confirmed by testing mechanical and flow properties. If the consistency between the current specimen and the typical fractured-cavity rock sample does not meet the set requirements, the printing parameter configuration step, specimen printing step, and specimen processing and testing step are repeated, adjusting the material ratio and printing parameters until the requirements are met before batch printing. This effectively ensures the quality stability of batch-printed samples and avoids redundant operations and resource waste.

[0089] After determining that the consistency between the current specimen and the typical fractured rock sample does not meet the set requirements, the sample batch printing step is executed. Based on the current three-dimensional rock sample digital model, printing path and printing process parameters, batch printing is performed to obtain a sample set for fracturing simulation test.

[0090] Based on this, an acid stress simulation step is performed. Based on the printed sample, the acid stress process is simulated under true triaxial load based on the set acid stress simulation conditions.

[0091] Preferably, in one embodiment, in the acid pressure simulation step, multiple single variable factors are set according to the test requirements to realize the acid pressure simulation test. The single variable factors include acid injection rate, injection location and distribution conditions of the cavity.

[0092] In practical applications, considering that the acid fracturing effect of fractured-vuggy reservoirs is mainly determined by the depth of the etched fractures, the self-supporting opening of the etched fractures, and the degree of connectivity between the etched fractures and discrete cavities, this invention sets up an acid fracturing simulation test process based on 3D-printed cavities to analyze fracture spatial morphology, dynamic fracture width distribution, and rock mass stress extraction. After obtaining a 3D-printed sample with a certain fracture-cavity distribution that is geometrically, dynamically, and mechanically similar to a real typical fracture-cavity rock sample, acid fracturing process simulations are carried out under true triaxial loads with different acid injection rates, different injection locations, and different fracture-cavity distributions.

[0093] The information on the distribution of cavities and fissures includes the size and connectivity of the cavities and fissures, which is set before the printing operation. In actual operation, the cavities and fissures are printed according to the pre-set distribution information before the acid pressure test is performed.

[0094] Next, the simulation information acquisition and analysis steps are performed. Images of the evolution of fractured and cavernous samples during acid fracturing are acquired. Based on these images, a three-dimensional geometric distribution model of the fractured and cavernous samples is constructed. The post-fracturing connectivity of the fractured and cavernous samples is analyzed and determined. Stress distribution and deformation distribution information are extracted based on photoelastic fringes and stress analysis algorithms. Based on the obtained deformation distribution information and fractured and cavernous sample connectivity information, the acid fracturing effect of fractured and cavernous reservoirs under different conditions is evaluated.

[0095] In a preferred embodiment, in the simulation information acquisition and analysis step, images of the fractured sample evolution during acid fracturing are acquired using a fast camera, and a corresponding three-dimensional fractured geometric distribution model is constructed based on machine learning. The corresponding fractured connectivity information is analyzed and obtained. Furthermore, the optical properties of the Vera Clear transparent photoelastic matrix material and the stress-freezing properties under temperature load are utilized to extract the full-field stress distribution and deformation distribution information through photoelastic fringes and stress analysis algorithms.

[0096] Furthermore, in one embodiment, the process of evaluating the acid fracturing effect of fractured-vuggy reservoirs under different conditions based on the acquired deformation distribution information and fracture-vuggy body connectivity information includes:

[0097] Based on the deformation distribution information, the aperture distribution information of each fracture is calculated, the fracture size information is determined, and then the acid fracturing effect of fractured-vuggy reservoirs under different conditions is evaluated based on the obtained fracture width, fracture size, and fracture cavity connectivity information.

[0098] Based on the mineral composition, three-dimensional fracture-cavity structure, and mechanical properties of carbonate rock fracture-cavity media, this invention designs a 3D printing method for complex fracture-cavity media samples. This solves the problems of strong randomness in fracture-cavity distribution and difficulty in sample preparation in fracture-cavity rock media. Furthermore, the test results readily reflect real fluid flow and acid-etched fracture propagation patterns, forming a systematic real-time extraction technology for stress distribution and propagating fracture geometry. This technology can be used to guide acid fracturing and fracturing stimulation of fracture-cavity carbonate reservoirs and tapping the remaining oil potential of fracture-cavity reservoirs. On the other hand, by simply adjusting the material ratio according to the different properties of carbonate rocks to reflect the corresponding rock mass characteristics, this method can be applied to the printing and acid fracturing parameter analysis of carbonate rock fracture-cavity media samples of different regions and types. It is highly practical and easy to widely apply and promote.

[0099] The present invention will be further described below with reference to specific embodiments. The scope of the present invention is not limited to the embodiments, but is defined in the claims.

[0100] Using the method of this invention, a typical well profile of a fractured-vuggy reservoir (i.e., the S67 fractured-vuggy unit TK625-TK666-TK602-TK644CH in the southern part of the Tahe Sixth Block of the Tahe Oilfield) was selected for fractured-vuggy structure characterization. A 3D-printed digital model was constructed based on similarity criteria, and then a physical model of the well group was prepared using an Object Connex 500 3D printer. Employing a "high injection, low production" strategy, gas injection flooding experiments were conducted based on the printed physical model of the well group and the results of acid fracturing flow simulation analysis.

[0101] When the gas injection rate LCN is -6, -5, and -3.56, the oil and gas saturation distribution at gas injection breakthrough and injection-production balance are shown in the figure. Figure 6 As shown in the diagram (where the transparent portion represents the oil phase and the green portion represents the gas phase), the transparent portion in the model represents the oil phase and the green portion represents the gas phase. With increasing injection rate, the swept volume efficiency can increase by nearly 20%. The principle behind increasing the injection rate to improve oil and gas recovery includes two aspects: first, rapid injection to some extent avoids the formation of local dominant channels, making it easier to form a more dispersed diversion system, thereby increasing the injected swept volume; second, rapid injection will create turbulence locally, and the formation of turbulent patterns is conducive to maximizing the exploitation of remaining oil in local dead zones, thereby improving the final recovery rate.

[0102] Figure 7The study presents a comparison of oil displacement sweep efficiency at the gas injection breakthrough and when injection-production balance is achieved. The results show that the method of this invention can be used to print scaled-down physical models that closely resemble actual fractured-vuggy systems. Based on similarity criteria, different injection-production rates and wellbore sizes can be set to simulate the oil displacement sweep volume, residual oil distribution patterns, and corresponding recovery rates under different injection rate conditions and injection-production schemes. Therefore, this invention provides an efficient and reliable research method for designing and optimizing injection-production schemes, exploring residual oil distribution patterns, and improving oil and gas recovery rates. Optimization of injection-production schemes can increase oil and gas recovery rates by approximately 20%, resulting in significant economic benefits.

[0103] For the foregoing method embodiments, in order to simplify the description, they are all described as a series of actions. However, those skilled in the art should understand that the present invention is not limited to the described order of actions, because according to the present invention, some steps can be performed in other orders or simultaneously. Furthermore, those skilled in the art should also understand that the embodiments described in the specification are preferred embodiments, and the actions and modules involved are not necessarily essential to the present invention.

[0104] It should be noted that, in other embodiments of the present invention, the method can also combine one or more of the above embodiments to obtain a new 3D printing-based three-dimensional fractured-vuggy reservoir acid fracturing flow simulation method, so as to achieve efficient and accurate fracturing simulation research on fractured-vuggy reservoirs.

[0105] It should be noted that, based on the methods in any one or more embodiments of the present invention described above, the present invention also provides a storage medium storing program code that can implement the methods described in any one or more embodiments. When the program code is executed by the operating system, it can implement the three-dimensional fractured reservoir acid pressure flow simulation method based on 3D printing as described above.

[0106] Example 2:

[0107] The methods described in the above-disclosed embodiments of the present invention are detailed. These methods can be implemented using various devices or systems. Therefore, based on other aspects of the methods described in any one or more of the above embodiments, the present invention also provides a 3D-printed three-dimensional fractured-vuggy reservoir acid fracturing flow simulation system. This system is used to execute the 3D-printed three-dimensional fractured-vuggy reservoir acid fracturing flow simulation method described in any one or more of the above embodiments. Specific embodiments are given below for detailed description.

[0108] Specifically, Figure 8 The diagram shows a schematic representation of the structure of a 3D-printed, three-dimensional fractured reservoir acid fracturing flow simulation system provided in an embodiment of the present invention. Figure 8 As shown, the system includes:

[0109] The outcrop sample preparation module is configured to collect fracture-cavity carbonate outcrop samples, and cut and prepare outcrop samples with dimensions that meet the set standards based on the collected samples, as typical fracture-cavity samples.

[0110] The module for constructing digital models of fractured cavern bodies is configured to establish corresponding three-dimensional digital models of rock samples by performing three-dimensional scanning and three-dimensional reconstruction on typical fractured cavern body rock samples.

[0111] The printing path determination module is configured to perform layered processing on the three-dimensional rock sample digital model to form multiple printing slices according to the requirements of the printing equipment, and determine a computer-recognizable layer-by-layer printing path based on the printing slice information.

[0112] The printing parameter configuration module allows you to set different printing process parameters for different printing slice layers based on the characteristics of typical fractured rock samples. These parameters include printing resolution, density, specimen size, structural material, filling rate, and layer thickness.

[0113] The specimen printing module is configured to use a printing device to print layer by layer based on the printing slice information and printing process parameters, and then fuse the layers to form a three-dimensional slit specimen;

[0114] The specimen processing and testing module is configured to remove the support material from the specimen, perform polishing and coloring, cure the specimen, and then conduct mechanical property tests on the specimen. The quality matching of the specimen is determined based on the test results. If the quality matching of the current specimen meets the set conditions, the subsequent sample printing module is started; otherwise, the printing parameter configuration module, specimen printing module, and specimen processing and testing module are restarted.

[0115] The sample batch printing module is configured to batch print samples based on the current three-dimensional rock sample digital model, printing path and printing process parameters to obtain a sample set for fracturing simulation test.

[0116] The acid stress simulation module is configured to simulate the acid stress process under true triaxial load based on the printed sample and the set acid stress simulation conditions.

[0117] The simulation information acquisition and analysis module is configured to acquire images of the evolution of fractured and cavernous samples during acid fracturing, construct a three-dimensional geometric distribution model of the fractured and cavernous samples based on these images, analyze and determine the post-fracturing connectivity of the fractured and cavernous samples, extract stress distribution and deformation distribution information based on photoelastic fringes and stress analysis algorithms, and evaluate the acid fracturing effect of fractured and cavernous reservoirs under different conditions based on the acquired deformation distribution information and fractured and cavernous connectivity information.

[0118] In one embodiment, the printing parameter configuration module is used to set the structural materials, including selecting and setting the printing material ratio of the matrix, cracks and cavities. The matrix material is a mixture of fractured carbonate rock powder and liquid photosensitive resin. The material is Vero White Plus, a white opaque material, which is used as the material for the cracks and cavities containing filling material. Paraffin wax is used as the temporary support molding material for the unfilled cavities. A mesh support material is used as the support material for preparing the unfilled cracks.

[0119] Optionally, in one embodiment, the printing parameter configuration module uses a 1:5 volume ratio of ground powder material of fractured carbonate rock to liquid photosensitive resin to prepare a matrix; and uses Fullcure 705 mesh support material to prepare unfilled cracks.

[0120] Furthermore, in one embodiment, the specimen processing and testing module is configured to perform the following operations:

[0121] The printed specimen is uniformly cured by laser irradiation and seamlessly fused with carbonate rock powder material;

[0122] By heating the material, the paraffin wax supporting the cave structure is gradually melted and removed, ultimately forming a three-dimensional rock-like specimen that includes a matrix, filled cracks and caves, and specimens without filled cracks and caves.

[0123] Specifically, in an optional embodiment, the specimen processing and testing module performs conventional mechanical and fracture mechanics performance tests on the processed specimens, analyzes the macroscopic mechanical parameters, strain field evolution law and three-dimensional failure characteristics of the specimens, and determines whether the requirements are met.

[0124] Preferably, in one embodiment, the acid pressure simulation module is configured to set multiple single variable factors to realize the acid pressure simulation test according to the test requirements. The single variable factors include acid injection rate, injection location and distribution conditions of the cavity.

[0125] Furthermore, in one embodiment, the simulation information acquisition and analysis module acquires images of the evolution of the fractured sample during the acid fracturing process using a fast camera, constructs a corresponding three-dimensional geometric distribution model of the fractured body based on machine learning, analyzes and obtains the corresponding fractured body connectivity information, and utilizes the optical properties of the Vera Clear transparent photoelastic matrix material and the stress-freezing properties under temperature load to extract the full-field stress distribution and deformation distribution information through photoelastic fringes and stress analysis algorithms.

[0126] Specifically, in an optional embodiment, the process by which the simulation information acquisition and analysis module evaluates the acid fracturing effect of fractured-vuggy reservoirs under different conditions based on the acquired deformation distribution information and fracture-vuggy body connectivity information includes:

[0127] Based on the deformation distribution information, the aperture distribution information of each fracture is calculated, the fracture size information is determined, and then the acid fracturing effect of fractured-vuggy reservoirs under different conditions is evaluated based on the obtained fracture width, fracture length, and fracture-vuggy body connectivity information.

[0128] In the three-dimensional fractured reservoir acid pressure flow simulation system based on 3D printing provided in this embodiment of the invention, each module or unit structure can operate independently or in combination according to actual printing configuration requirements and simulation test data processing requirements to achieve the corresponding technical effects.

[0129] It should be understood that the embodiments disclosed herein are not limited to the specific structures, processing steps, or materials disclosed herein, but should be extended to equivalent substitutions of these features as understood by those skilled in the art. It should also be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting.

[0130] The phrase "an embodiment" in the specification means that a specific feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the invention. Therefore, the phrase "an embodiment" appearing in various places throughout the specification does not necessarily refer to the same embodiment.

[0131] While the embodiments disclosed in this invention are as described above, the content is merely for the purpose of facilitating understanding of the invention and is not intended to limit the invention. Any person skilled in the art to which this invention pertains may make any modifications and variations in form and detail of the implementation without departing from the spirit and scope disclosed herein; however, the scope of patent protection for this invention shall still be determined by the scope defined in the appended claims.

Claims

1. A method for simulating acid fracturing flow in three-dimensional fractured-vuggy reservoirs based on 3D printing, characterized in that, The method includes: Steps for preparing outcrop protolith samples: Collect outcrop samples of fractured-cavity carbonate rocks, and cut and prepare outcrop protolith samples with dimensions that meet the set standards based on the collected samples, as typical fractured-cavity rock samples; Steps for constructing a digital model of a fractured cavity: By performing three-dimensional scanning and three-dimensional reconstruction on typical fractured cavity rock samples, a corresponding three-dimensional digital model of the rock sample is established; Printing path determination steps: According to the requirements of the printing equipment, the three-dimensional rock sample digital model is processed into multiple printing slices by layering, and the printing slice information is used to determine the computer-recognizable layer-by-layer printing path. Printing parameter configuration steps: Set different printing process parameters to match different printing slice layers according to the characteristics of the current typical fractured rock sample, including printing resolution, density, specimen size, structural material, filling rate and layer thickness parameters; Specimen printing steps: Using printing equipment, print layer by layer based on printing slice information and printing process parameters, and then fuse the layers to form a three-dimensional slit specimen; Specimen processing and testing steps: After removing the support material of the specimen, polishing and coloring are performed, and the specimen is cured. Then, the mechanical properties of the specimen are tested, and the quality matching of the specimen is determined according to the test results. If the quality matching of the current specimen meets the set conditions, the subsequent sample printing steps are executed; otherwise, the printing parameter configuration steps, specimen printing steps, and specimen processing and testing steps are executed again. Sample batch printing steps: Based on the current three-dimensional rock sample digital model, printing path and printing process parameters, batch printing is carried out to obtain a sample set for fracturing simulation test; Acid Fragmentation Simulation Steps: Based on the printed sample, the acid fragmentation process is simulated under true triaxial load according to the set acid fragmentation simulation conditions; Simulation information acquisition and analysis steps: Acquire images of the evolution of fractured and cavernous samples during acid fracturing, construct a three-dimensional geometric distribution model of fractured and cavernous samples based on the images, analyze and determine the post-fracturing connectivity of fractured and cavernous samples, and extract stress distribution and deformation distribution information based on photoelastic fringes and stress analysis algorithms. Based on the obtained deformation distribution information and fractured and cavernous sample connectivity information, evaluate the acid fracturing effect of fractured and cavernous reservoirs under different conditions. Among them, images of the evolution of the fractured specimens during the acid pressing process were acquired by a fast camera, and a corresponding three-dimensional geometric distribution model of the fractured specimens was constructed based on machine learning. The corresponding connection information of the fractured specimens was analyzed and obtained. The optical properties and stress-freezing properties of the Vera Clear transparent photoelastic matrix material under temperature load were used to extract the full-field stress distribution and deformation distribution information through photoelastic fringes and stress analysis algorithms.

2. The method according to claim 1, characterized in that, In the printing parameter configuration step, setting the structural materials includes selecting and setting the printing material ratio for the matrix, cracks, and karst bodies. The matrix material is a mixture of ground carbonate rock powder and liquid photosensitive resin. The white opaque material Vero White Plus is used as the material for cracks and karst bodies containing filling material. Paraffin wax is used as the temporary support molding material for unfilled karst bodies. A mesh support material is used as the support material for preparing unfilled cracks.

3. The method according to claim 2, characterized in that, A matrix was prepared by mixing fractured carbonate rock powder with liquid photosensitive resin at a volume ratio of 1:5; unfilled fractures were prepared using Fullcure 705 mesh support material.

4. The method according to claim 1, characterized in that, The specimen handling and testing procedures include the following operations: The printed specimen is uniformly cured by laser irradiation and seamlessly fused with carbonate rock powder material; By heating the material, the paraffin wax supporting the cave structure is gradually melted and removed, ultimately forming a three-dimensional rock-like specimen that includes a matrix, filled cracks and caves, and specimens without filled cracks and caves.

5. The method according to claim 1, characterized in that, In the specimen processing and testing steps, the processed specimens are subjected to conventional mechanical and fracture mechanics tests. The macroscopic mechanical parameters, strain field evolution law and three-dimensional failure characteristics of the specimens are analyzed to determine whether they meet the requirements.

6. The method according to claim 1, characterized in that, In the acid pressure simulation step, multiple single variable factors are set according to the test requirements to realize the acid pressure simulation test. The single variable factors include acid injection rate, injection location and distribution conditions of the cavity.

7. The method according to claim 1, characterized in that, The process of evaluating the acid fracturing effect on fractured-vuggy reservoirs under different conditions based on the acquired deformation distribution information and fracture-vuggy body connectivity information includes: Based on the deformation distribution information, the aperture distribution information of each fracture is calculated, the fracture size information is determined, and then the acid fracturing effect of fractured-vuggy reservoirs under different conditions is evaluated based on the obtained fracture width, fracture length, and fracture-vuggy body connectivity information.

8. A storage medium, characterized in that, The storage medium stores program code capable of implementing the method as described in any one of claims 1 to 7.

9. A three-dimensional fractured-vuggy reservoir acid fracturing flow simulation system based on 3D printing, characterized in that, The system performs the method as described in any one of claims 1 to 7.

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