Fractured tight sandstone gas reservoir water drive recovery rate evaluation method and system

Abstract

The invention discloses a fractured tight sandstone gas reservoir water drive recovery rate evaluation method and system. The method comprises the steps that artificial fracture forming is conducted on different forms of reservoir plunger cores; carrying out bound water making experiment on the rock core after fracture making, so that the rock core reaches a saturated gas state; injecting water into the rock core with bound water and then scanning to obtain a scanning image; and after the scanning image is processed, the water content of the scanning crack is counted through the processed image, and the water drive recovery ratio is calculated. According to the method, the microscopic percolation mechanism of the fractured low-hole sandstone reservoir is studied through artificial fracture forming of a real rock core, an experiment of bound water making of the rock core and a water flooding collaborative micron CT scanning experiment, the displacement efficiency under different types of fracture development conditions is calculated, and a basis is provided for making a technical countermeasure for improving the recovery efficiency of the fractured tight sandstone gas reservoir.

Description

Technical Field

[0001] This invention relates to the field of oil and gas development, and in particular to a method and system for evaluating the water drive recovery rate of fractured tight sandstone gas reservoirs. Background Technology

[0002] Numerous microfractures, matrix pores, and artificial fractures formed during development within fractured tight sandstone gas reservoirs constitute a complex seepage system that controls the gas-water distribution and influences the reservoir's development effectiveness. Research on the microscopic seepage of fractured tight sandstone gas reservoirs is limited. In particular, current traditional testing methods can only perform analysis and simulation at a large scale, failing to precisely describe the two-phase flow characteristics at the pore scale. Specifically, quantitative descriptions of the microscopic gas-water distribution and displacement efficiency under different reservoir fracture conditions are still lacking. Summary of the Invention

[0003] The purpose of this invention is to provide a method and system for evaluating the water drive recovery rate of fractured tight sandstone gas reservoirs, in order to solve the problem that traditional testing methods can only perform analysis and simulation on a large scale and cannot accurately describe the two-phase flow characteristics at the pore scale.

[0004] To achieve the above objectives, the present invention adopts the following technical solution:

[0005] In a first aspect, the present invention provides a method for evaluating the waterflood recovery rate of fractured tight sandstone gas reservoirs, comprising:

[0006] Artificial fracture creation was carried out on reservoir cores with different morphologies using plungers.

[0007] After fracture formation, a water-binding experiment was conducted on the core sample to bring it to a saturated gas state.

[0008] The core sample containing bound water was scanned after water injection to obtain the scanned image;

[0009] After processing the scanned images, the water drive recovery rate is calculated by statistically analyzing the water content of the scanned fractures in the processed images.

[0010] Furthermore, artificial fractures were created in reservoir cores with different morphologies, including:

[0011] Triaxial stress was used to artificially create fractures in real rock cores. External forces were applied to different surfaces of different rock cores to cause them to crack longitudinally or laterally, forming longitudinal through fractures, transverse through fractures, and conjugate through fractures.

[0012] Furthermore, water-binding experiments were conducted on the core samples after fracture formation, including:

[0013] The fractured core was washed with oil, dried, vacuumed, and saturated with brine. Most of the movable water was removed by centrifugation at maximum speed, and then methane gas was used to displace the remaining water phase in the core, so that the core reached a saturated gas state.

[0014] Furthermore, methane gas is used to displace the residual aqueous phase in the core, including:

[0015] First, the core was weighed and then placed in a holder. The confining pressure was set to 15 MPa, the temperature to 90℃, and the inlet pressure was adjusted to 10 MPa. Methane was injected from top to bottom to displace the residual water in the core for 1 hour, so that the core reached a saturated gas state. Then, the core was CT scanned to obtain the distribution characteristics of bound water in pores and fractures, and the core was weighed after gas driving.

[0016] Furthermore, the core samples containing bound water were scanned after water injection to obtain scanned images, including:

[0017] An aqueous solution containing a developer was injected into the core containing bound water. Before injection, the core was divided into upper and lower sections for CT scanning. The injection volume was measured at the core inlet. Aqueous solutions with different pore volumes were injected. After each injection, the core was divided into upper and lower sections for scanning. After standing, the core was scanned again in both sections before the next volume multiple was injected.

[0018] Further image processing includes:

[0019] The scanned images are reconstructed, filtered, and denoised, and the three phases of gas, water, and rock skeleton are segmented into three phases.

[0020] Furthermore, the waterflood recovery rate is calculated by statistically scanning the fracture water content using the processed images, including:

[0021] By statistically analyzing the fracture water content after displacement and the fracture water content after stabilization, the difference between the two is the amount of water entering the matrix. By calculating the ratio of the amount of water in the fracture to the amount of water entering the matrix pores and the pore volume occupied by gas before water injection, the displacement efficiency curve is obtained, which is the water-drive recovery rate.

[0022] Secondly, the present invention provides a waterflood recovery assessment system for fractured tight sandstone gas reservoirs, comprising:

[0023] The fracture-making module is used to artificially create fractures in reservoir cores of different shapes.

[0024] The water-binding module is used to conduct water-binding experiments on the core after fracture formation, so that the core reaches a saturated gas state.

[0025] The scanning module is used to scan core samples containing bound water after water injection to obtain scanned images.

[0026] The calculation output module is used to process the scanned image and calculate the water drive recovery rate by statistically analyzing the water content of the scanned fracture in the processed image.

[0027] Thirdly, the present invention provides a computer device, including a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the computer program to implement the steps of a method for evaluating the water drive recovery rate of fractured tight sandstone gas reservoirs.

[0028] Fourthly, the present invention provides a computer-readable storage medium storing a computer program that, when executed by a processor, implements the steps of a method for evaluating the waterflood recovery rate of fractured tight sandstone gas reservoirs.

[0029] Compared with the prior art, the present invention has the following technical effects:

[0030] This invention investigates the microscopic seepage mechanism of fractured low-porosity sandstone reservoirs through artificial fracture creation in real rock cores, core-based bound water creation experiments, and water-drive combined with micron-CT scanning experiments. It also calculates the displacement efficiency under different fracture development conditions, providing a basis for formulating enhanced oil recovery technology strategies for fractured tight sandstone gas reservoirs.

[0031] This invention proposes a method for calculating waterflood recovery by combining artificial fracture creation with waterflooding and micron-level CT scanning experiments using real core samples. This method observes changes in the pore-throat structure, fluid saturation, and displacement efficiency of the matrix and fractures in tight sandstone reservoirs during displacement, replacing traditional core analysis experiments. On the one hand, it compensates for the shortcomings of physical experimental methods; on the other hand, it promotes the development of numerical simulation of gas reservoirs. It overcomes the limitations of traditional methods that cannot accurately describe the characteristics of two-phase flow at the pore scale, allowing observation of gas-water displacement characteristics in three-dimensional space based on real core experiments. Furthermore, it proposes a novel method for calculating the recovery rate of fractured gas reservoirs. This method, through combined gas-water displacement scanning after core fracture creation, obtains CT scan displacement efficiency curves, providing reliable parameters for numerical simulation studies of fractured tight sandstone gas reservoirs. Attached Figure Description

[0032] Figure 1 Images a through f are CT scans of rock cores with different morphologies of artificially fractured rock.

[0033] Figure 2 This is a diagram of a displacement-coordinated micron-CT scanning device.

[0034] Figure 3 This is a gas-water distribution map of different displacement nodes in sample No. 4.

[0035] Figure 4 This is a diagram showing the water saturation of cracks at different displacement nodes in sample No. 4.

[0036] Figure 5 This is the water-drive recovery curve for sample No. 4.

[0037] Figure 6 This is a composite graph of the water drive recovery curves of 6 samples.

[0038] Figure 7 This is a flowchart of the present invention. Detailed Implementation

[0039] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0040] In the description of this invention, it should be understood that the terms "comprising" and "including" indicate the presence of the described features, integrals, steps, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, integrals, steps, operations, elements, components and / or collections thereof.

[0041] It should also be understood that the terminology used in this specification is for the purpose of describing particular embodiments only and is not intended to limit the invention. As used in this specification and the appended claims, the singular forms “a,” “an,” and “the” are intended to include the plural forms unless the context clearly indicates otherwise.

[0042] It should also be further understood that the term "and / or" as used in this specification and the appended claims refers to any combination and all possible combinations of one or more of the associated listed items, and includes such combinations. For example, A and / or B can represent three cases: A alone, A and B simultaneously, and B alone. Additionally, the character " / " in this invention generally indicates that the preceding and following objects have an "or" relationship.

[0043] It should be understood that although terms such as first, second, third, etc., may be used in the embodiments of the present invention to describe the preset range, these preset ranges should not be limited to these terms. These terms are only used to distinguish the preset ranges from one another. For example, without departing from the scope of the embodiments of the present invention, the first preset range may also be referred to as the second preset range, and similarly, the second preset range may also be referred to as the first preset range.

[0044] Depending on the context, the word "if" as used here can be interpreted as "when," "when," "in response to determination," or "in response to detection." Similarly, depending on the context, the phrase "if determination" or "if detection (of the stated condition or event)" can be interpreted as "when determination," "in response to determination," "when detection (of the stated condition or event)," or "in response to detection (of the stated condition or event)."

[0045] The accompanying drawings illustrate various structural schematic diagrams according to embodiments disclosed in this invention. These drawings are not to scale, and some details have been enlarged for clarity, and some details may have been omitted. The shapes of the various regions and layers shown in the drawings, as well as their relative sizes and positional relationships, are merely exemplary and may deviate from reality due to manufacturing tolerances or technical limitations. Furthermore, those skilled in the art can design regions / layers with different shapes, sizes, and relative positions as needed.

[0046] This invention provides a method for evaluating the waterflood recovery rate of fractured tight sandstone gas reservoirs.

[0047] Please see Figure 1 A method for evaluating the waterflood recovery rate of fractured tight sandstone gas reservoirs includes the following steps:

[0048] Artificial fracture creation was carried out on reservoir cores with different morphologies using plungers.

[0049] After fracture formation, a water-binding experiment was conducted on the core sample to bring it to a saturated gas state.

[0050] The core sample containing bound water was scanned after water injection to obtain the scanned image;

[0051] After processing the scanned images, the water drive recovery rate is calculated by statistically analyzing the water content of the scanned fractures in the processed images.

[0052] Specifically:

[0053] Triaxial stress was used to artificially create fractures in real rock cores. External forces were applied to different surfaces of different rock cores to cause them to crack longitudinally or laterally, forming longitudinal through fractures, transverse through fractures, and conjugate through fractures.

[0054] The fractured core was washed with oil, dried, vacuumed, and saturated with brine. Most of the movable water was removed by centrifugation at maximum speed, and then methane gas was used to displace the remaining water phase in the core, so that the core reached a saturated gas state.

[0055] An aqueous solution containing a developer was injected into the core containing bound water. Before injection, the core was divided into upper and lower sections for CT scanning. The injection volume was measured at the core inlet. Aqueous solutions with different pore volumes were injected. After each injection, the core was divided into upper and lower sections for scanning. After standing for 12 hours, the core was scanned again. Then, the next volume multiple was injected.

[0056] After reconstructing, filtering, and denoising the CT scan images, the three phases of gas, water, and rock skeleton are segmented.

[0057] By statistically analyzing the fracture water content after displacement and the fracture water content after stabilization, the difference between the two is the amount of water entering the matrix. By calculating the ratio of the amount of water in the fracture to the amount of water entering the matrix pores and the pore volume occupied by gas before water injection, the CT scan displacement efficiency curve is obtained, which is the water drive recovery rate.

[0058] In another embodiment of the present invention, a waterflood recovery rate assessment system for fractured tight sandstone gas reservoirs is provided. This system can be used to implement the aforementioned waterflood recovery rate assessment method for fractured tight sandstone gas reservoirs. Specifically, the system includes:

[0059] The fracture-making module is used to artificially create fractures in reservoir cores of different shapes.

[0060] The water-binding module is used to conduct water-binding experiments on the core after fracture formation, so that the core reaches a saturated gas state.

[0061] The scanning module is used to scan core samples containing bound water after water injection to obtain scanned images.

[0062] The calculation output module is used to process the scanned image and calculate the water drive recovery rate by statistically analyzing the water content of the scanned fracture in the processed image.

[0063] In another embodiment of the present invention, a terminal device is provided, comprising a processor and a memory. The memory stores a computer program, which includes program instructions. The processor executes the program instructions stored in the computer storage medium. The processor may be a Central Processing Unit (CPU), or other general-purpose processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. It is the computing and control core of the terminal, suitable for implementing one or more instructions, specifically suitable for loading and executing one or more instructions to achieve a corresponding method flow or corresponding function. The processor described in this embodiment of the present invention can be used in the operation of a waterflood recovery rate assessment method for fractured tight sandstone gas reservoirs.

[0064] Example:

[0065] Step 1: As Figure 1 As shown, taking six plunger core samples from the Keshen gas field in the Kuqa depression of the Tarim Basin as an example, triaxial stress extrusion was used to artificially create fractures in the six real core samples. External forces were applied to different surfaces of different core samples to cause them to crack longitudinally or laterally, forming longitudinal through fractures, transverse through fractures, and conjugate through fractures, respectively.

[0066] Step 2: Core Sample Binding Water Experiment. First, the fractured core sample is washed with oil, dried, vacuumed, and treated with saturated brine. Then, it is dehydrated by centrifugation at different speeds. Even after centrifugation, the artificial core still contains a certain amount of water. Therefore, a gas purging method is used to create bound water. The specific steps are as follows:

[0067] First, the core was weighed and then placed in a holder. The confining pressure was set to 15 MPa, the temperature to 90℃, and the inlet pressure was adjusted to 10 MPa. Methane was injected from top to bottom to displace the residual water in the core for 1 hour, so that the core reached a saturated gas state. Then, the core was CT scanned to obtain the distribution characteristics of bound water in pores and fractures, and the core was weighed after gas driving.

[0068] The bound water saturation of the core was calculated by taking into account the difference in core mass before and after the formation of bound water, the core's apparent volume, nuclear magnetic porosity, and pore volume.

[0069] Step 3: Conduct water-drive synergistic micron-CT scanning experiments on core samples after water confinement. The experimental setup is shown in [link to experimental setup]. Figure 2 First, the core sample from the water-binding experiment was placed in a holder, with a confining pressure of 15 MPa, an outlet pressure of 12 MPa, and a temperature of 90℃. Next, an aqueous solution containing a developer was injected from bottom to top at a water-drive injection rate of 0.005 ml / min. Before injection, the core was divided into upper and lower sections and CT scanned with a precision of 16 micrometers. The injection volume was measured at the core inlet, with pore volume aqueous solutions of 0.15 PV, 0.3 PV, 0.5 PV, 0.75 PV, 1 PV, and 2 PV (cumulative volume) injected respectively. After each injection, the core was scanned in both upper and lower sections. After standing for 12 hours, the upper and lower sections were scanned again, followed by the injection of the next volume multiple of aqueous solution. Finally, a CT scan of the entire displacement node was obtained.

[0070] Step 4: After completing the displacement-coordinated micron-CT scan through the above steps, the CT scan image is reconstructed, filtered, and denoised. Then, the three phases of gas, water, and rock skeleton are segmented to obtain gas-water distribution maps at different displacement nodes, such as... Figure 3 As shown in the figure, for longitudinal through-cracks, water will enter the crack at the beginning of water injection (0.15PV) and slowly fill the crack. During the settling process after water injection, the water in the crack will decrease and enter the core matrix.

[0071] Due to the resolution limitations of CT scans, the stromal pores are too small to be visible. Therefore, what CT observes can be considered the water phase within the fractures. Statistical analysis of the water content in the fractures yields the following results: Figure 4 During core injection, water mainly enters the fracture channels (over 90%). During the stabilization process, water in the fractures enters the matrix pores through infiltration. The matrix pores absorb the most water during the stabilization process after 0.15 PV of water injection (reaching 32.71%). As the injection volume increases, the amount of water entering the matrix gradually decreases. At an injection volume of 0.75 PV, the water saturation of the core exceeds 90%, and the water absorption of the matrix pores drops to 5.51%. The injected water mainly flows out of the core outlet through the fracture channels. After further increasing the injection volume, the amount of water entering the matrix is ​​very limited.

[0072] Step 5: The water drive efficiency is the ratio of the sum of water volume in the fractures and water volume entering the matrix pores to the pore volume occupied by gas before water injection. The decrease in water volume in the fractures during the water injection stabilization process can be considered as water entering the matrix pores through percolation. By statistically calculating the fracture water content after displacement and the fracture water content after stabilization, the difference between the two is the amount of water entering the matrix. The water drive efficiency curve can then be calculated. (See...) Figure 5This shows that before the injection point of 0.5 PV (i.e., before the fractures are filled with water), the water drive recovery rate increases linearly with the increase of the injection volume; at the 0.5 PV point (i.e., after the fractures are filled with water), the water drive recovery rate reaches an inflection point, and further increasing the injection volume to 2.0 PV increases the recovery rate by less than 10%, ultimately reaching a water drive recovery rate of 66.44%. Therefore, the period before 0.5 PV injection is the main stage of water drive gas production. Furthermore, the water drive recovery rate curves from the six rock samples show that... Figure 6 High-angle longitudinal penetration fractures and conjugate penetration fractures are more effective in improving gas-driven water recovery efficiency. The simpler the fracture morphology or the more longitudinal fractures are close to the producing layer, the larger the fracture width, and the more obvious the effect of improving gas-driven water recovery. Transverse penetration fractures are the least effective in improving gas-driven water recovery efficiency.

[0073] In another embodiment of the present invention, a storage medium is also provided, specifically a computer-readable storage medium (memory). This computer-readable storage medium is a memory device in a terminal device used to store programs and data. It is understood that the computer-readable storage medium here can include both the built-in storage medium in the terminal device and extended storage media supported by the terminal device. The computer-readable storage medium provides storage space that stores the terminal's operating system. Furthermore, this storage space also stores one or more instructions suitable for loading and execution by a processor. These instructions can be one or more computer programs (including program code). It should be noted that the computer-readable storage medium here can be high-speed RAM or non-volatile memory, such as at least one disk storage device.

[0074] One or more instructions stored in a computer-readable storage medium can be loaded and executed by a processor to implement the corresponding steps of the above embodiments regarding a method for evaluating the water drive recovery rate of a fractured tight sandstone gas reservoir.

[0075] Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the above-described division of functional units and modules is merely an example. In practical applications, the above functions can be assigned to different functional units and modules as needed, that is, the internal structure of the device can be divided into different functional units or modules to complete all or part of the functions described above. The functional units and modules in the embodiments 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. Furthermore, the specific names of the functional units and modules are only for easy differentiation and are not intended to limit the scope of protection of this application. The specific working process of the units and modules in the above system can be referred to the corresponding process in the foregoing method embodiments, and will not be repeated here.

[0076] In the above embodiments, the descriptions of each embodiment have different focuses. For parts that are not described in detail or recorded in a certain embodiment, please refer to the relevant descriptions of other embodiments.

[0077] 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 invention can be implemented in electronic hardware, or a combination of computer software and electronic hardware. 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 implementations should not be considered beyond the scope of this invention.

[0078] In the embodiments provided by this invention, it should be understood that the disclosed devices / terminals and methods can be implemented in other ways. For example, the device / terminal embodiments described above are merely illustrative. For instance, the division of modules or 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 coupling or direct coupling or communication connection shown or discussed may be through some interfaces; the indirect coupling or communication connection between devices or units may be electrical, mechanical, or other forms.

[0079] 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 this embodiment according to actual needs.

[0080] Furthermore, the functional units in the various embodiments of the present invention 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.

[0081] If the integrated module / 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, all or part of the processes in the methods of the above embodiments can also be implemented by a computer program instructing related hardware. The computer program can be stored in a computer-readable storage medium, and when executed by a processor, it can implement the steps of the various method embodiments described above. The computer program includes computer program code, which can be in the form of source code, object code, executable files, or certain intermediate forms. The computer-readable medium can include: any entity or device capable of carrying the computer program code, recording media, USB flash drives, portable hard drives, magnetic disks, optical disks, computer memory, read-only memory (ROM), random-access memory (RAM), electrical carrier signals, telecommunication signals, and software distribution media, etc. It should be noted that the content included in the computer-readable medium can be appropriately added or removed according to the requirements of legislation and patent practice in the jurisdiction. For example, in some jurisdictions, according to legislation and patent practice, computer-readable media do not include electrical carrier signals and telecommunication signals.

[0082] This application is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of this application. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart... Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0083] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0084] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0085] The above content is only for illustrating the technical concept of the present invention and should not be construed as limiting the scope of protection of the present invention. Any modifications made to the technical solution based on the technical concept proposed in this invention shall fall within the scope of protection of the claims of this invention.

Claims

1. A method for evaluating the waterflood recovery rate of fractured tight sandstone gas reservoirs, characterized in that, include: Artificial fracture creation was carried out on reservoir cores with different morphologies using plungers. After fracture formation, a water-binding experiment was conducted on the core sample to bring it to a saturated gas state. The core sample containing bound water was scanned after water injection to obtain the scanned image; After processing the scanned images, the water drive recovery rate is calculated by statistically analyzing the water content of the scanned fractures in the processed images.

2. The method for evaluating waterflood recovery rate in fractured tight sandstone gas reservoirs according to claim 1, characterized in that, Artificial fracture creation was performed on reservoir cores with different morphologies, including: Triaxial stress was used to artificially create fractures in real rock cores. External forces were applied to different surfaces of different rock cores to cause them to crack longitudinally or laterally, forming longitudinal through fractures, transverse through fractures, and conjugate through fractures.

3. The method for evaluating waterflood recovery rate in fractured tight sandstone gas reservoirs according to claim 1, characterized in that, Experiments were conducted on the fractured core samples to create bound water, including: The fractured core was washed with oil, dried, vacuumed, and saturated with brine. Most of the movable water was removed by centrifugation at maximum speed, and then methane gas was used to displace the remaining water phase in the core, so that the core reached a saturated gas state.

4. The method for evaluating waterflood recovery rate in fractured tight sandstone gas reservoirs according to claim 3, characterized in that, Displacement of residual aqueous phase in core samples using methane gas, including: First, the core was weighed and then placed in a holder. The confining pressure was set to 15 MPa, the temperature to 90℃, and the inlet pressure was adjusted to 10 MPa. Methane was injected from top to bottom to displace the residual water in the core for 1 hour, so that the core reached a saturated gas state. Then, the core was CT scanned to obtain the distribution characteristics of bound water in pores and fractures, and the core was weighed after gas driving.

5. The method for evaluating waterflood recovery rate in fractured tight sandstone gas reservoirs according to claim 1, characterized in that, Scanning was performed on the core sample containing bound water after water injection, yielding scanned images, including: An aqueous solution containing a developer was injected into the core containing bound water. Before injection, the core was divided into upper and lower sections for CT scanning. The injection volume was measured at the core inlet. Aqueous solutions with different pore volumes were injected. After each injection, the core was divided into upper and lower sections for scanning. After standing, the core was scanned again in both sections before the next volume multiple was injected.

6. The method for evaluating waterflood recovery rate in fractured tight sandstone gas reservoirs according to claim 1, characterized in that, Image processing, including: The scanned images are reconstructed, filtered, and denoised, and the three phases of gas, water, and rock skeleton are segmented into three phases.

7. The method for evaluating waterflood recovery rate in fractured tight sandstone gas reservoirs according to claim 1, characterized in that, Waterflood recovery rate is calculated by statistically scanning fracture water content using processed images, including: By statistically analyzing the fracture water content after displacement and the fracture water content after stabilization, the difference between the two is the amount of water entering the matrix. By calculating the ratio of the amount of water in the fracture to the amount of water entering the matrix pores and the pore volume occupied by gas before water injection, the displacement efficiency curve is obtained, which is the water-drive recovery rate.

8. A system for evaluating the waterflood recovery rate of fractured tight sandstone gas reservoirs, characterized in that, include: The fracture-making module is used to artificially create fractures in reservoir cores of different shapes. The water-binding module is used to conduct water-binding experiments on the core after fracture formation, so that the core reaches a saturated gas state. The scanning module is used to scan core samples containing bound water after water injection to obtain scanned images. The calculation output module is used to process the scanned image and calculate the water drive recovery rate by statistically analyzing the water content of the scanned fracture in the processed image.

9. 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 steps of the method for evaluating the water drive recovery rate of a fractured tight sandstone gas reservoir as described in any one of claims 1 to 7.

10. A computer-readable storage medium storing a computer program, characterized in that, When the computer program is executed by the processor, it implements the steps of the method for evaluating the water drive recovery rate of a fractured tight sandstone gas reservoir as described in any one of claims 1 to 7.

Images