Method and device for evaluating pore throat structure of tight sandstone before and after water-rock reaction

Abstract

The embodiment of the invention provides a method and a device for evaluating a pore throat structure of tight sandstone before and after a water-rock reaction. The method comprises the following steps: drilling two identical rock core samples from sandstone; simulated formation water is prepared according to water sample analysis of an oil field; the method comprises the following steps: placing a first rock core sample in a container containing simulated formation water, and vacuumizing the container to saturate the first rock core sample; injecting carbon dioxide gas into the vacuumized container, and simulating a water-rock reaction; and analyzing the first rock core sample and the pollution-free second rock core sample according to various different types of analysis methods to obtain pore throat size distribution, pore throat topology network structure, pore throat structure fractal characteristics and pore throat connectivity corresponding to the tight sandstone before and after the water-rock reaction. According to the embodiment of the invention, the pore throat structure of the sandstone before and after the water-rock reaction can be more accurately evaluated.

Description

Technical Field

[0001] The embodiments of this specification relate to the field of rock pores, and in particular, to a method and device for evaluating the pore throat structure of dense sandstone before and after water-rock reaction. Background Art

[0002] With the continuous increase in oil and gas consumption, the development of tight sandstone reservoirs has received more and more attention. The storage and seepage space of tight sandstone matrix includes pores and throats. The pores in the form of residual intergranular pores and dissolution pores are the main storage space for oil and gas, contributing to the main porosity of the rock; the throat is the channel connecting the pores and determines the permeability of the rock. The pore and throat structure characteristics such as the type, size distribution, and connectivity of pores and throats are the key to affecting the storage and seepage capacity of the reservoir, and directly determine the seepage law and development effect of tight sandstone oil and gas.

[0003] Water-rock reaction refers to the chemical reaction process that occurs when the surface of a rock comes into contact with water. This reaction can convert minerals on the surface of the rock into another mineral and may produce dissolved minerals. The process of water-rock reaction is completed by the chemical reaction of ions in water on the surface of the rock. Water-rock reaction is of great significance in geology because it can change the properties of rocks and affect the geological morphology. For example, water-rock reaction can soften rocks, making them easier to erode. Water-rock reaction can also produce new rocks, such as hydrated iron ore and sulfate rocks. The significance of studying water-rock reaction is that it helps us understand the evolution of rocks and can provide us with important information about the evolution of the earth's crust. It also helps us understand the chemical composition of the earth's crust and the properties of rocks, and thus provides us with information about geological processes and geological environments.

[0004] Therefore, there is an urgent need for a method to evaluate the pore throat structure of dense sandstone before and after water-rock reaction, which can more accurately evaluate the pore throat structure of sandstone before and after water-rock reaction. Summary of the invention

[0005] The purpose of the embodiments of this specification is to provide a method and device for evaluating the pore throat structure of dense sandstone before and after water-rock reaction, so as to more accurately evaluate the pore throat structure of sandstone before and after water-rock reaction.

[0006] To achieve the above objectives, on the one hand, the embodiments of this specification provide a method for evaluating the pore throat structure of dense sandstone before and after water-rock reaction, comprising:

[0007] Two identical core samples were drilled from the sandstone;

[0008] According to the water sample analysis of the oil field, simulated formation water is configured;

[0009] placing the first core sample in a container containing simulated formation water, and evacuating the container to saturate the first core sample;

[0010] injecting carbon dioxide gas into the vacuumized container to simulate water-rock reaction;

[0011] The first core sample and the uncontaminated second core sample are analyzed according to a variety of different types of analysis methods to obtain the pore throat size distribution, pore throat topological network structure, pore throat structure fractal characteristics and pore throat connectivity of the dense sandstone before and after water-rock reaction.

[0012] Preferably, the first core sample and the uncontaminated second core sample are analyzed respectively according to a plurality of different types of analysis methods to obtain the pore throat size distribution, pore throat topological network structure, pore throat structure fractal characteristics and pore throat connectivity of the dense sandstone before and after the water-rock reaction, respectively, further comprising:

[0013] Collect images of the first core sample and the second core sample to obtain image features of the two;

[0014] According to the image features of the two, the pore-throat network topological structure and pore-throat structure fractal features of the tight sandstone before and after the water-rock reaction are analyzed;

[0015] Obtaining indirect values ​​associated with the first core sample and the second core sample using an indirect method;

[0016] In coordination with the indirect numerical value, the pore throat size distribution of the tight sandstone before and after the water-rock reaction is obtained by inversion;

[0017] By comparing the core pore resistance of the first core sample before and after the simulated water-rock reaction, the pore throat connectivity of the dense sandstone before and after the water-rock reaction is obtained.

[0018] Preferably, the image acquisition method comprises: at least one of a casting thin section acquisition method, a scanning electron microscopy method, a field emission scanning electron microscopy method, a focused ion beam scanning electron microscopy method and an X-CT scanning method.

[0019] Preferably, the image features include two-dimensional image features and three-dimensional image features.

[0020] Preferably, the indirect method comprises at least one of constant pressure mercury injection, constant rate mercury injection, gas adsorption, gas desorption and nuclear magnetic resonance.

[0021] Preferably, the indirect values ​​include: T2 spectrum distribution obtained by nuclear magnetic resonance method, and pore throat size distribution characteristics obtained by constant pressure mercury injection method;

[0022] The inverse method of obtaining the pore throat size distribution of the tight sandstone before and after the water-rock reaction in coordination with the indirect numerical value further includes:

[0023] Draw a first curve between the T2 spectrum distribution and water saturation of the first core sample and a second curve between the pore throat size distribution characteristics and water saturation in a set coordinate system;

[0024] Selecting the first curve and the second curve respectively corresponding to the same set water saturation, fitting the relationship between the two curves with a linear function, and converting the first curve into the pore throat size distribution corresponding to the first core sample;

[0025] Draw a third curve between the T2 spectrum distribution and water saturation of the second core sample and a fourth curve between the pore throat size distribution characteristics and water saturation in a set coordinate system;

[0026] The third curve and the fourth curve corresponding to the same set water saturation are selected, and the relationship between the two curves is fitted with a linear function, so as to convert the third curve into the pore throat size distribution corresponding to the second core sample.

[0027] Preferably, comparing the core pore resistivity of the first core sample before and after the simulated water-rock reaction to obtain the pore throat connectivity of the tight sandstone before and after the water-rock reaction further includes:

[0028] If the core pore resistance of the first core sample before the simulated water-rock reaction is greater than the core pore resistance after the simulated water-rock reaction, it is determined that the tight sandstone has lower core permeability after the water-rock reaction than before the water-rock reaction, thereby blocking pore throat connectivity;

[0029] If the core pore resistance of the first core sample before the simulated water-rock reaction is less than the core pore resistance after the simulated water-rock reaction, it is determined that the core permeability of the dense sandstone increases after the water-rock reaction compared with before the water-rock reaction, thereby improving the pore throat connectivity.

[0030] Preferably, the process of evacuating the container to saturate the first core sample and analyzing according to a plurality of different types of analysis methods is cyclically performed.

[0031] On the other hand, an embodiment of this specification provides a device for evaluating the pore throat structure of dense sandstone before and after water-rock reaction, the device comprising:

[0032] Drilling module for drilling two identical core samples from sandstone;

[0033] Configuration module, used to configure simulated formation water according to the water sample analysis of the oil field;

[0034] A vacuum saturation module is used to place the first core sample in a container containing simulated formation water, and vacuum the container to saturate the first core sample;

[0035] A simulation reaction module, used for injecting carbon dioxide gas into the vacuumized container to simulate a water-rock reaction;

[0036] The analysis module is used to analyze the first core sample and the uncontaminated second core sample according to a plurality of different types of analysis methods, so as to obtain the pore throat size distribution, pore throat topological network structure, pore throat structure fractal characteristics and pore throat connectivity of the dense sandstone before and after the water-rock reaction.

[0037] On the other hand, an embodiment of the present specification further provides a computer device, including a memory, a processor, and a computer program stored in the memory, wherein when the computer program is executed by the processor, the instructions according to any one of the methods described above are executed.

[0038] On the other hand, an embodiment of the present specification further provides a computer-readable storage medium having a computer program stored thereon, wherein when the computer program is executed by a processor of a computer device, the computer program executes instructions according to any one of the methods described above.

[0039] It can be seen from the technical solutions provided in the above embodiments of this specification that, through the embodiments of this specification, a first core sample and a second core sample are set for comparison, wherein the first core sample is used to simulate the water-rock reaction, and the second core sample is preserved without pollution. According to a variety of different types of analysis methods, it is possible to perform all-round and multi-level analysis, and more accurately obtain the pore throat structures of dense sandstone before and after the water-rock reaction, which helps us understand the evolution process of rocks, and can provide us with important information about the evolution of the earth's crust. It also helps us understand the chemical composition of the earth's crust and the properties of rocks, and then provides us with information about geological processes and geological environments.

[0040] In order to make the above and other purposes, features and advantages of the present specification more obvious and easy to understand, the following specifically cites preferred embodiments and describes them in detail with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] In order to more clearly illustrate the embodiments of this specification or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this specification. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0042] Figure 1 A schematic flow chart of a method for evaluating the pore throat structure of dense sandstone before and after water-rock reaction provided in an embodiment of this specification is shown;

[0043] Figure 2 A schematic diagram of a process for analyzing a first core sample and a second non-contaminated core sample according to a plurality of different types of analysis methods provided in an embodiment of this specification is shown;

[0044] Figure 3 A schematic diagram of the process of inverting the pore throat size distribution of tight sandstone before and after water-rock reaction by using the coordinated indirect numerical value provided in the embodiment of this specification is shown;

[0045] Figure 4 A schematic diagram of the module structure of a device for evaluating the pore throat structure of dense sandstone before and after water-rock reaction provided in an embodiment of this specification is shown;

[0046] Figure 5 A schematic diagram of the structure of a computer device provided in an embodiment of this specification is shown.

[0047] Description of the accompanying symbols:

[0048] 100. Drilling module;

[0049] 200, configuration module;

[0050] 300. Vacuum saturation module;

[0051] 400, simulation reaction module;

[0052] 500, analysis module;

[0053] 502. Computer equipment;

[0054] 504, processor;

[0055] 506. Memory;

[0056] 508, driving mechanism;

[0057] 510, input / output module;

[0058] 512. Input devices;

[0059] 514. Output device;

[0060] 516. Presentation equipment;

[0061] 518. Graphical user interface;

[0062] 520, network interface;

[0063] 522, communication link;

[0064] 524. Communication bus. DETAILED DESCRIPTION

[0065] The following will be combined with the drawings in the embodiments of this specification to clearly and completely describe the technical solutions in the embodiments of this specification. Obviously, the described embodiments are only part of the embodiments of this specification, not all of the embodiments. Based on the embodiments in this specification, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the embodiments of this specification.

[0066] Water-rock reaction refers to the chemical reaction process that occurs when the surface of a rock comes into contact with water. This reaction can convert minerals on the surface of the rock into another mineral and may produce dissolved minerals. The process of water-rock reaction is completed by the chemical reaction of ions in water on the surface of the rock. Water-rock reaction is of great significance in geology because it can change the properties of rocks and affect the geological morphology. For example, water-rock reaction can soften rocks, making them easier to erode. Water-rock reaction can also produce new rocks, such as hydrated iron ore and sulfate rocks. The significance of studying water-rock reaction is that it helps us understand the evolution of rocks and can provide us with important information about the evolution of the earth's crust. It also helps us understand the chemical composition of the earth's crust and the properties of rocks, and thus provides us with information about geological processes and geological environments.

[0067] In order to solve the above problems, the embodiments of this specification provide a method for evaluating the pore throat structure of dense sandstone before and after water-rock reaction. Figure 1 This is a flow chart of a method for evaluating the pore throat structure of dense sandstone before and after water-rock reaction provided in the embodiment of this specification. This specification provides the method operation steps described in the embodiment or flow chart, but based on conventional or non-creative labor, more or fewer operation steps may be included. The order of steps listed in the embodiment is only one way of executing the order of many steps and does not represent the only execution order. When the system or device product is executed in practice, it can be executed in the order of the method shown in the embodiment or the accompanying drawings or in parallel.

[0068] It should be noted that the terms "first", "second", etc. in the description and claims of the embodiments of this specification and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged where appropriate, so that the embodiments of this specification described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions, for example, a process, method, device, product or equipment that includes a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or equipment.

[0069] Reference Figure 1 The embodiment of this specification provides a method for evaluating the pore throat structure of dense sandstone before and after water-rock reaction, including:

[0070] S101: Two identical core samples were drilled from sandstone;

[0071] S102: According to the water sample analysis of the oil field, simulated formation water is configured;

[0072] S103: placing the first core sample in a container containing simulated formation water, and evacuating the container to saturate the first core sample;

[0073] S104: injecting carbon dioxide gas into the vacuumized container to simulate water-rock reaction;

[0074] S105: Analyze the first core sample and the uncontaminated second core sample according to a plurality of different types of analysis methods to obtain the pore throat size distribution, pore throat topological network structure, pore throat structure fractal characteristics and pore throat connectivity of the dense sandstone before and after the water-rock reaction.

[0075] When drilling two identical core samples from sandstone, it is necessary to sample through a sampler and configure simulated formation water. The container used for vacuum saturation can be a reactor, which is performed by the following operations: Wear latex gloves, rinse the inner wall of the reactor with simulated formation water samples, put the first core sample into the high-temperature and high-pressure reactor and fix it, measure 30mL of simulated formation water and pour it into the reactor, tighten and seal the reactor; connect the reactor outlet to the vacuum pump with a latex tube, start the vacuum pump, and vacuum the space in the reactor for 5 minutes, so that the first core sample can be saturated.

[0076] Furthermore, carbon dioxide gas is injected into the vacuum reactor. The specific amount of carbon dioxide gas can be determined according to the actual situation. Carbon dioxide is dissolved in simulated formation water to simulate water-rock reaction. The second core sample only needs to be contaminated and preserved as a control.

[0077] By analyzing the first core sample and the uncontaminated second core sample using a variety of different types of analysis methods, the pore-throat structures of the dense sandstone before and after the water-rock reaction can be obtained. The pore-throat structures specifically include: pore-throat size distribution, pore-throat topological network structure, pore-throat structure fractal characteristics, and pore-throat connectivity.

[0078] In the embodiment of this specification, the process of evacuating the container to saturate the first core sample and analyzing according to a variety of different types of analysis methods can be performed cyclically, that is, steps S103-S105 can be performed cyclically to reduce errors.

[0079] Through the embodiments of this specification, a first core sample and a second core sample are set for comparison, wherein the first core sample is used to simulate the water-rock reaction, and the second core sample is preserved without pollution. According to a variety of different types of analysis methods, it is possible to perform all-round and multi-level analysis, and more accurately obtain the pore throat structures of dense sandstone before and after the water-rock reaction, which helps us understand the evolution of rocks, and can provide us with important information about the evolution of the earth's crust. It also helps us understand the chemical composition of the earth's crust and the properties of rocks, and further provides us with information about geological processes and geological environments.

[0080] In the embodiments of this specification, refer to Figure 2 , the first core sample and the uncontaminated second core sample are analyzed respectively according to a plurality of different types of analysis methods to obtain the pore throat size distribution, pore throat topological network structure, pore throat structure fractal characteristics and pore throat connectivity of the tight sandstone before and after the water-rock reaction, further comprising:

[0081] S201: collecting images of the first core sample and the second core sample to obtain image features of the two;

[0082] S202: Analyze and obtain the pore-throat network topological structure and pore-throat structure fractal characteristics of the tight sandstone before and after the water-rock reaction according to the image features of the two;

[0083] S203: using an indirect method to obtain indirect values ​​associated with the first core sample and the second core sample;

[0084] S204: inverting the pore throat size distribution of the tight sandstone before and after the water-rock reaction according to the indirect numerical value;

[0085] S205: Compare the core pore resistance of the first core sample before and after the simulated water-rock reaction to obtain the pore throat connectivity of the tight sandstone before and after the water-rock reaction.

[0086] Wherein, the image acquisition method includes: at least one of a casting thin section acquisition method, a scanning electron microscope method, a field emission scanning electron microscope method, a focused ion beam scanning electron microscope method and an X-CT scanning method.

[0087] Specifically, cast thin sections are made by pouring dyed resin or liquid glue into the pore throat space of the rock under vacuum, solidifying the resin or liquid glue at a certain temperature and pressure, and then grinding it into rock thin sections, and observing the pore and throat characteristics under a polarizing microscope. The advantage of this technology is that the pore throat space is poured with dyed resin or liquid glue, which can conveniently and directly observe the true morphology and content, type and size distribution. However, after oil washing and pouring, some fine and loose clay matrix between particles may migrate, affecting the understanding of some pore throats. It should be combined with other testing technologies to comprehensively analyze the filling material and pore throat characteristics.

[0088] Specifically, the principle of the scanning electron microscope is that when the focused electron beam scans the surface of the rock sample point by point, it will generate reaction signals such as backscattered electrons, secondary electrons, X-rays, Auger electrons and transmitted electrons. Secondary electrons and backscattered electrons are sensitive to changes in the surface morphology of the sample and can be used as modulation signals of the cathode ray tube to obtain morphological contrast images. Compared with polarizing microscopes, minerals under scanning electron microscopes have the characteristics of three-dimensional images, high resolution and large depth of field. It can not only analyze the three-dimensional morphology of micropores and throats in rocks, pore throat configuration relationships, clay mineral types and their occurrence forms, but also adjust the inclination angle of the sample to obtain a series of microscopic images of the rock surface at different inclination angles, and then obtain a three-dimensional image of the rock surface through image processing technology. Before scanning, a metal film needs to be evaporated on the rock surface to prevent the current generated by the focused electron beam from accumulating on the rock surface. The resulting charging and discharging effect affects the transmission of electronic signals, but the evaporated metal conductive film affects the morphological characteristics of the pore throats.

[0089] Specifically, X-CT scanning refers to X-ray computed tomography, which uses an X-ray beam and a highly sensitive detector to scan the core in sections. The detector receives the attenuated X-ray information passing through the core, and calculates the X-ray absorption coefficient value of each point in the layer. Different data are displayed in different gray levels, thereby reproducing the pore structure. CT scanning does not require complex processing of the core, maintains the internal structure and external morphology of the core, and can quickly observe the physical parameters such as rock pore throat distribution, connectivity, and porosity.

[0090] The image features of the first core sample and the second core sample can be obtained by image acquisition, and the image features include two-dimensional image features and three-dimensional image features. For example, the two-dimensional image features obtained by the casting thin section acquisition method and the three-dimensional image features obtained by the scanning electron microscope method can be combined to obtain the image features of the first core sample and the second core sample. According to the image features of the first core sample and the second core sample, the pore throat network topology and pore throat structure fractal features corresponding to the tight sandstone before and after the water-rock reaction can be analyzed, wherein the first core sample characterizes the pore throat network topology and pore throat structure fractal features corresponding to the water-rock reaction, and the second core sample characterizes the pore throat network topology and pore throat structure fractal features corresponding to the water-rock reaction.

[0091] In the embodiments of this specification, the indirect method includes at least one of constant pressure mercury injection, constant rate mercury injection, gas adsorption, gas desorption and nuclear magnetic resonance. For example, constant pressure mercury injection regards the complex pore throat system as a series of interconnected cylindrical capillary networks. When mercury (non-wetting phase) is injected into porous rocks, the capillary force becomes a resistance to mercury injection, so an injection pressure is required to overcome the capillary force. However, constant pressure mercury injection is shielded by pores and can only give the pore throat volume controlled by a certain level of throat, and cannot distinguish throats from pores.

[0092] Indirect methods can be used to obtain indirect values ​​associated with the first core sample and the second core sample. For example, the indirect values ​​include: T2 spectrum distribution obtained by nuclear magnetic resonance and pore throat size distribution characteristics obtained by constant pressure mercury injection.

[0093] Reference Figure 3 , the inverse method of the indirect numerical value to obtain the corresponding pore throat size distribution of the tight sandstone before and after the water-rock reaction further includes:

[0094] S301: drawing a first curve between T2 spectrum distribution and water saturation of the first core sample and a second curve between the pore throat size distribution characteristics and water saturation in a set coordinate system;

[0095] S302: Selecting a first curve and a second curve respectively corresponding to the same set water saturation, fitting the relationship between the two curves with a linear function, and converting the first curve into a pore throat size distribution corresponding to the first core sample;

[0096] S303: drawing a third curve between T2 spectrum distribution and water saturation of the second core sample and a fourth curve between the pore throat size distribution characteristics and water saturation in a set coordinate system;

[0097] S304: Select the third curve and the fourth curve corresponding to the same set water saturation, fit the relationship between the two curves with a linear function, and convert the third curve into the pore throat size distribution corresponding to the second core sample.

[0098] Nuclear magnetic resonance T2 spectrum is often used to study the pore structure of cores, cement or other porous materials, and is widely used in fields such as petroleum geology and geotechnical materials. The principle of T2 spectrum is: the relaxation of fluid includes free relaxation, surface relaxation and diffusion relaxation; the fluid in large pores is weakly affected by surface relaxation, so the T2 time is longer; the fluid in small pores is strongly affected by surface relaxation, so the T2 time is shorter. Since the pore size distribution changes continuously, the relaxation time of the pore fluid also changes continuously, which forms the so-called T2 spectrum.

[0099] When inversion is performed in coordination with indirect numerical values, the above steps S301-S304 show the T2 spectrum distribution obtained by the coordinated nuclear magnetic resonance method and the pore throat size distribution characteristics obtained by the constant pressure mercury injection method. Other indirect numerical values, such as resistivity index, saturation, and high-pressure mercury injection can also be used for inversion.

[0100] Through the above steps S301-S304, the pore throat size distributions corresponding to the first core sample and the second core sample can be obtained respectively. The first core sample is the pore throat size distribution corresponding to the water-rock reaction, and the second core sample is the pore throat size distribution corresponding to the water-rock reaction.

[0101] In the embodiment of this specification, the comparison of the core pore resistance of the first core sample before and after the simulated water-rock reaction to obtain the pore throat connectivity of the tight sandstone before and after the water-rock reaction further includes:

[0102] If the core pore resistance of the first core sample before the simulated water-rock reaction is greater than the core pore resistance after the simulated water-rock reaction, it is determined that the tight sandstone has lower core permeability after the water-rock reaction than before the water-rock reaction, thereby blocking pore throat connectivity;

[0103] If the core pore resistance of the first core sample before the simulated water-rock reaction is less than the core pore resistance after the simulated water-rock reaction, it is determined that the core permeability of the dense sandstone increases after the water-rock reaction compared with before the water-rock reaction, thereby improving the pore throat connectivity.

[0104] In the embodiment of this specification, formation water is simulated through step S104, the core pore resistance of the first core sample is measured once before step S104, and the core pore resistance of the first core sample is measured again after step S104, or the core pore resistance of the first core sample can be continuously measured since before step S104, for example, from step S103.

[0105] Based on the above-mentioned method for evaluating the pore throat structure of dense sandstone before and after water-rock reaction, the embodiment of this specification also provides a corresponding device for evaluating the pore throat structure of dense sandstone before and after water-rock reaction. The device may include a system (including a distributed system), software (application), module, component, server, client, etc. using the method described in the embodiment of this specification and a device combined with necessary implementation hardware. Based on the same innovative concept, the device in one or more embodiments provided in the embodiment of this specification is as described in the following embodiment. Since the implementation scheme and method of the device to solve the problem are similar, the implementation of the specific device in the embodiment of this specification can refer to the implementation of the aforementioned method, and the repetitions will not be repeated. As used below, the term "unit" or "module" can implement a combination of software and / or hardware of predetermined functions. Although the device described in the following embodiments is preferably implemented in software, the implementation of hardware, or a combination of software and hardware, is also possible and conceived.

[0106] Specifically, Figure 4 This is a schematic diagram of the module structure of an embodiment of a device for evaluating the pore throat structure of dense sandstone before and after water-rock reaction provided in the embodiment of this specification, with reference to Figure 4 As shown, a device for evaluating the pore throat structure of dense sandstone before and after water-rock reaction provided in an embodiment of this specification includes: a drilling module 100, a configuration module 200, a vacuum saturation module 300, a simulation reaction module 400 and an analysis module 500.

[0107] A drilling module 100 is used to drill two identical core samples from sandstone;

[0108] Configuration module 200, configured to configure simulated formation water according to the water sample analysis of the oil field;

[0109] The vacuum saturation module 300 is used to place the first core sample in a container containing simulated formation water, and vacuum the container to saturate the first core sample;

[0110] A simulation reaction module 400 is used to inject carbon dioxide gas into the vacuumized container to simulate a water-rock reaction;

[0111] The analysis module 500 is used to analyze the first core sample and the uncontaminated second core sample according to a plurality of different types of analysis methods, and obtain the pore throat size distribution, pore throat topological network structure, pore throat structure fractal characteristics and pore throat connectivity of the dense sandstone before and after the water-rock reaction.

[0112] Reference Figure 5As shown, based on the above-mentioned method for evaluating the pore throat structure of dense sandstone before and after water-rock reaction, a computer device 502 is also provided in an embodiment of this specification, wherein the above-mentioned method is run on the computer device 502. The computer device 502 may include one or more processors 504, such as one or more central processing units (CPUs) or graphics processing units (GPUs), and each processing unit may implement one or more hardware threads. The computer device 502 may also include any memory 506, which is used to store any kind of information such as code, settings, data, etc. In a specific embodiment, the computer program on the memory 506 and which can be run on the processor 504, when the computer program is run by the processor 504, can execute instructions according to the above-mentioned method. Non-limitingly, for example, the memory 506 may include any one or more combinations of the following: any type of RAM, any type of ROM, flash memory device, hard disk, optical disk, etc. More generally, any memory may use any technology to store information. Further, any memory may provide volatile or non-volatile retention of information. Further, any memory may represent a fixed or removable component of the computer device 502. In one embodiment, when the processor 504 executes the associated instructions stored in any memory or combination of memories, the computer device 502 can perform any operation of the associated instructions. The computer device 502 also includes one or more drive mechanisms 508 for interacting with any memory, such as a hard disk drive mechanism, an optical disk drive mechanism, etc.

[0113] The computer device 502 may also include an input / output module 510 (I / O) for receiving various inputs (via input devices 512) and for providing various outputs (via output devices 514). A specific output mechanism may include a presentation device 516 and an associated graphical user interface 518 (GUI). In other embodiments, the input / output module 510 (I / O), input device 512, and output device 514 may not be included, and the computer device 502 may be used as a computer device in a network. The computer device 502 may also include one or more network interfaces 520 for exchanging data with other devices via one or more communication links 522. One or more communication buses 524 couple the components described above together.

[0114] The communication link 522 may be implemented in any manner, for example, through a local area network, a wide area network (e.g., the Internet), a point-to-point connection, etc., or any combination thereof. The communication link 522 may include any combination of hardwired links, wireless links, routers, gateway functions, name servers, etc., governed by any protocol or combination of protocols.

[0115] Corresponds to Figure 1-Figure 3The method in the embodiment of the present specification also provides a computer-readable storage medium, on which a computer program is stored, and when the computer program is executed by a processor, the steps of the above method are executed.

[0116] The embodiment of the present specification also provides a computer-readable instruction, wherein when the processor executes the instruction, the program therein causes the processor to execute the following Figures 1 to 3 The method shown.

[0117] It should be understood that in the various embodiments of this specification, the size of the serial numbers of the above-mentioned processes does not mean the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of this specification.

[0118] It should also be understood that in the embodiments of this specification, the term "and / or" is only a description of the association relationship of the associated objects, indicating that three relationships can exist. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. In addition, the character " / " in the embodiments of this specification generally indicates that the associated objects before and after are in an "or" relationship.

[0119] Those of ordinary skill in the art will appreciate that the units and algorithm steps of each example described in conjunction with the embodiments disclosed in the embodiments of this specification can be implemented with electronic hardware, computer software, or a combination of the two. In order to clearly illustrate the interchangeability of hardware and software, the composition and steps of each example have been generally described in terms of function in the above description. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Professional and technical personnel can use different methods to implement the described functions for each specific application, but such implementation should not be considered to exceed the scope of the embodiments of this specification.

[0120] Those skilled in the art can clearly understand that, for the convenience and brevity of description, the specific working processes of the systems, devices and units described above can refer to the corresponding processes in the aforementioned method embodiments and will not be repeated here.

[0121] In the several embodiments provided in this specification, it should be understood that the disclosed systems, devices and methods can be implemented in other ways. For example, the device embodiments described above are only schematic. For example, the division of the units is only a logical function division. There may be other division methods in actual implementation, such as multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. In addition, the mutual coupling or direct coupling or communication connection shown or discussed can be an indirect coupling or communication connection through some interfaces, devices or units, or it can be an electrical, mechanical or other form of connection.

[0122] The units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed on multiple network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the embodiments of this specification.

[0123] In addition, each functional unit in each embodiment of this specification may be integrated into one processing unit, or each unit may exist physically separately, or two or more units may be integrated into one unit. The above integrated unit may be implemented in the form of hardware or in the form of software functional units.

[0124] If the integrated unit is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the embodiment of this specification is essentially or the part that contributes to the prior art, or all or part of the technical solution can be embodied in the form of a software product, and the computer software product is stored in a storage medium, including a number of instructions to enable a computer device (which can be a personal computer, a server, or a network device, etc.) to perform all or part of the steps of the method described in each embodiment of this specification. The aforementioned storage medium includes: U disk, mobile hard disk, read-only memory (ROM, Read-Only Memory), random access memory (RAM, Random Access Memory), disk or optical disk and other media that can store program code.

[0125] Specific embodiments are used in this specification to illustrate the principles and implementation methods of the embodiments of this specification. The description of the above embodiments is only used to help understand the methods and core ideas of the embodiments of this specification. At the same time, for those skilled in the art, according to the ideas of the embodiments of this specification, there will be changes in the specific implementation methods and application scopes. In summary, the content of this specification should not be understood as a limitation on the embodiments of this specification.

Claims

1. A method for evaluating the pore throat structure of dense sandstone before and after water-rock reaction, characterized in that: include: Two identical core samples were drilled from the sandstone; According to the water sample analysis of the oil field, simulated formation water is configured; placing the first core sample in a container containing simulated formation water, and evacuating the container to saturate the first core sample; injecting carbon dioxide gas into the vacuumized container to simulate water-rock reaction; The first core sample and the uncontaminated second core sample are analyzed according to a variety of different types of analysis methods to obtain the pore throat size distribution, pore throat topological network structure, pore throat structure fractal characteristics and pore throat connectivity of the dense sandstone before and after water-rock reaction.

2. The method for evaluating the pore throat structure of dense sandstone before and after water-rock reaction according to claim 1, characterized in that: The first core sample and the uncontaminated second core sample are analyzed respectively according to a plurality of different types of analysis methods to obtain the pore throat size distribution, pore throat topological network structure, pore throat structure fractal characteristics and pore throat connectivity of the tight sandstone before and after the water-rock reaction, respectively, further comprising: Collect images of the first core sample and the second core sample to obtain image features of the two; According to the image features of the two, the pore-throat network topological structure and pore-throat structure fractal features of the tight sandstone before and after the water-rock reaction are analyzed; Obtaining indirect values ​​associated with the first core sample and the second core sample using an indirect method; In coordination with the indirect numerical value, the pore throat size distribution of the tight sandstone before and after the water-rock reaction is obtained by inversion; By comparing the core pore resistance of the first core sample before and after the simulated water-rock reaction, the pore throat connectivity of the dense sandstone before and after the water-rock reaction is obtained.

3. The method for evaluating the pore throat structure of dense sandstone before and after water-rock reaction according to claim 2, characterized in that: The image acquisition method includes: at least one of a casting thin section acquisition method, a scanning electron microscope method, a field emission scanning electron microscope method, a focused ion beam scanning electron microscope method and an X-CT scanning method.

4. The method for evaluating the pore throat structure of dense sandstone before and after water-rock reaction according to claim 3, characterized in that: The image features include two-dimensional image features and three-dimensional image features.

5. The method for evaluating the pore throat structure of dense sandstone before and after water-rock reaction according to claim 2, characterized in that: The indirect method includes at least one of a constant pressure mercury injection method, a constant rate mercury injection method, a gas adsorption method, a gas desorption method and a nuclear magnetic resonance method.

6. The method for evaluating the pore throat structure of dense sandstone before and after water-rock reaction according to claim 5, characterized in that: The indirect values ​​include: T2 spectrum distribution obtained by nuclear magnetic resonance method, and pore throat size distribution characteristics obtained by constant pressure mercury injection method; The inverse method of obtaining the pore throat size distribution of the tight sandstone before and after the water-rock reaction in coordination with the indirect numerical value further includes: Draw a first curve between the T2 spectrum distribution and water saturation of the first core sample and a second curve between the pore throat size distribution characteristics and water saturation in a set coordinate system; Selecting the first curve and the second curve respectively corresponding to the same set water saturation, fitting the relationship between the two curves with a linear function, and converting the first curve into the pore throat size distribution corresponding to the first core sample; Draw a third curve between the T2 spectrum distribution and water saturation of the second core sample and a fourth curve between the pore throat size distribution characteristics and water saturation in a set coordinate system; The third curve and the fourth curve corresponding to the same set water saturation are selected, and the relationship between the two curves is fitted with a linear function, so as to convert the third curve into the pore throat size distribution corresponding to the second core sample.

7. The method for evaluating the pore throat structure of dense sandstone before and after water-rock reaction according to claim 2, characterized in that: The comparing the core pore resistance of the first core sample before and after the simulated water-rock reaction to obtain the pore throat connectivity of the tight sandstone before and after the water-rock reaction further includes: If the core pore resistance of the first core sample before the simulated water-rock reaction is greater than the core pore resistance after the simulated water-rock reaction, it is determined that the tight sandstone has lower core permeability after the water-rock reaction than before the water-rock reaction, thereby blocking pore throat connectivity; If the core pore resistance of the first core sample before the simulated water-rock reaction is less than the core pore resistance after the simulated water-rock reaction, it is determined that the core permeability of the dense sandstone increases after the water-rock reaction compared with before the water-rock reaction, thereby improving the pore throat connectivity.

8. The method for evaluating the pore throat structure of dense sandstone before and after water-rock reaction according to claim 1, characterized in that: The process of evacuating the container to saturate the first core sample and then analyzing the sample according to various types of analysis methods is cyclically performed.

9. A device for evaluating the pore throat structure of dense sandstone before and after water-rock reaction, characterized in that: The device comprises: Drilling module for drilling two identical core samples from sandstone; Configuration module, used to configure simulated formation water according to the water sample analysis of the oil field; A vacuum saturation module is used to place the first core sample in a container containing simulated formation water, and vacuum the container to saturate the first core sample; A simulation reaction module, used for injecting carbon dioxide gas into the vacuumized container to simulate a water-rock reaction; The analysis module is used to analyze the first core sample and the uncontaminated second core sample according to a plurality of different types of analysis methods, so as to obtain the pore throat size distribution, pore throat topological network structure, pore throat structure fractal characteristics and pore throat connectivity of the dense sandstone before and after the water-rock reaction.

10. A computer device comprising a memory, a processor, and a computer program stored in the memory, characterized in that: When the computer program is executed by the processor, the computer program executes the instructions of the method according to any one of claims 1 to 8.

11. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor of a computer device, the computer program executes the instructions of the method according to any one of claims 1 to 8.

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