Quantitative evaluation method of organic acid corrosion effect and organic acid corrosion system

Abstract

The embodiment of the invention provides a quantitative evaluation method for an organic acid corrosion effect and an organic acid corrosion system. The method comprises the following steps: selecting a typical reservoir sample; performing pore structure analysis on the typical reservoir sample to obtain a pore structure of the typical reservoir sample; carrying out an organic acid corrosion experiment on the typical reservoir sample; performing pore structure analysis on the typical reservoir sample corroded by the organic acid to obtain a pore structure of the typical reservoir sample corroded by the organic acid; and comparing the pore structure of the typical reservoir sample with the pore structure of the typical reservoir sample subjected to organic acid corrosion, and quantitatively evaluating the influence of the organic acid corrosion effect on the pore structure of the compact sandstone reservoir. In the embodiment of the invention, the change of the pore structure of the compact sandstone reservoir under the corrosion action of the organic acid can be quantitatively analyzed, and the corrosion mechanism of the organic acid in the compact sandstone reservoir is researched; and a favorable support is provided for researching the pore structure change of the tight sandstone reservoir under different geological conditions under the action of organic acid corrosion and predicting a favorable enrichment area of tight oil and gas.

Description

Technical Field

[0001] The present application relates to the technical field of unconventional oil and gas resource evaluation, and specifically to a quantitative evaluation method for organic acid dissolution and an organic acid dissolution system. Background Art

[0002] With the development of oil and gas exploration, tight oil and gas has become one of the most important areas for increasing production in unconventional resources. my country's tight oil and gas has a wide distribution range and many types, with broad exploration prospects. Tight sandstone oil and gas is the most common tight oil and gas in my country. The thermal evolution of organic matter in source rocks can release a large amount of organic acid and strongly dissolve aluminosilicate and carbonate minerals, thereby forming large-scale secondary pores and improving the pore structure of tight sandstone reservoirs.

[0003] At present, the research on the impact of organic acid dissolution on tight sandstone reservoirs tends to focus on changes in mineral content and macroscopic physical properties of reservoirs. Studies have shown that organic acid dissolution has a great contribution to the secondary pores of reservoirs and will increase the porosity of reservoirs. Some scholars have calculated the porosity or surface area increment that can be produced by organic acid dissolution in specific areas.

[0004] However, most of the current research focuses on the changes in macroscopic physical properties of reservoirs and the mechanism of mineral dissolution, and does not characterize the changes in reservoir pore structure caused by organic acid dissolution. As a result, it is impossible to determine the changes in the pore structure of tight sandstone reservoirs under organic acid dissolution.

[0005] It should be pointed out that the information disclosed in the background technology section of this application is only intended to deepen the understanding of the general background technology of this application, and should not be regarded as an admission or suggestion in any form that the information constitutes prior art already known to those skilled in the art. Summary of the invention

[0006] In view of this, the present application provides a quantitative evaluation method for organic acid dissolution and an organic acid dissolution system, so as to solve the problem that the prior art fails to characterize the changes in the reservoir pore structure caused by organic acid dissolution, and thus cannot determine the changes in the pore structure of the tight sandstone reservoir under organic acid dissolution.

[0007] In a first aspect, the present application provides a quantitative evaluation method for organic acid dissolution, comprising:

[0008] According to the petrological characteristics and geological background of the tight sandstone reservoir in the study area, typical reservoir samples were selected;

[0009] Performing pore structure analysis on the typical reservoir sample to obtain the pore structure of the typical reservoir sample;

[0010] Conducting an organic acid dissolution experiment on the typical reservoir sample;

[0011] Performing pore structure analysis on typical reservoir samples after organic acid dissolution to obtain the pore structure of the typical reservoir samples after organic acid dissolution;

[0012] The pore structure of the typical reservoir sample and the pore structure of the typical reservoir sample after organic acid dissolution are compared to quantitatively evaluate the effect of the organic acid dissolution on the pore structure of the tight sandstone reservoir.

[0013] In a possible implementation, the petrological characteristics and geological background of the tight sandstone reservoir in the study area include:

[0014] Mineral composition, mineral grain size and pore type of tight sandstone reservoirs in the study area.

[0015] In a possible implementation, the pore structure analysis includes:

[0016] Physical property measurement, micron CT scanning and high-pressure mercury injection experiment.

[0017] In a possible implementation, the measurement parameters of the physical property measurement include: permeability and porosity.

[0018] In a possible implementation, the measurement parameters of the micron CT scan include: micron pore radius distribution, micron throat radius distribution and coordination number.

[0019] In a possible implementation, the measurement parameters of the high-pressure mercury injection experiment include: micro-nano pore throat radius distribution and pore throat ratio.

[0020] In a possible implementation, the performing of an organic acid dissolution experiment on the typical reservoir sample includes:

[0021] Determine the experimental conditions according to the geological conditions of the tight sandstone reservoir in the study area;

[0022] An organic acid dissolution experiment was carried out on the typical reservoir sample under the experimental conditions.

[0023] In a possible implementation, the experimental conditions include:

[0024] The type and concentration of organic acid used in the experiment, the experimental pressure and experimental temperature, and the type and mineralization of formation water used in the experiment.

[0025] In a possible implementation, the performing of an organic acid dissolution experiment on the typical reservoir sample includes:

[0026] An organic acid dissolution experiment was carried out on the typical reservoir samples by adopting an open system dynamic charging method.

[0027] In a possible implementation, the comparing the pore structure of the typical reservoir sample and the pore structure of the typical reservoir sample after being dissolved by organic acid includes:

[0028] Compare the permeability, porosity, micron pore radius distribution, micron throat radius distribution, coordination number, micro-nano pore throat radius distribution and / or pore throat ratio in the pore structure of the typical reservoir sample and the pore structure of the typical reservoir sample after organic acid dissolution.

[0029] In a second aspect, an embodiment of the present application provides an organic acid dissolution system, comprising:

[0030] A dissolution device, used to carry a typical reservoir sample to be dissolved;

[0031] An organic acid filling device, used for filling the dissolution device with organic acid, so that the typical reservoir sample in the dissolution device is dissolved under the action of the organic acid;

[0032] A solution collecting device, used to collect the dissolved solution discharged from the dissolution device;

[0033] A temperature control device, used to control the experimental temperature in the dissolution device;

[0034] A ring pressure device, used to control the experimental pressure in the dissolution device;

[0035] A control device is used to control the organic acid filling device, the temperature control device and the ring pressing device.

[0036] In the embodiments of the present application, the pore structure changes of tight sandstone reservoirs under the action of organic acid dissolution can be quantitatively analyzed, and the organic acid dissolution mechanism in tight sandstone reservoirs can be studied, which provides favorable support for studying the pore structure changes of tight sandstone reservoirs under different geological conditions under the action of organic acid dissolution and predicting favorable tight oil and gas enrichment areas, and has broad application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0038] Figure 1 A schematic flow chart of a quantitative evaluation method for organic acid dissolution provided in an embodiment of the present application;

[0039] Figure 2 An electron microscope image of a dense sandstone sample before organic acid dissolution provided in an embodiment of the present application;

[0040] Figure 3 A pore throat radius distribution diagram of a dense sandstone sample before organic acid dissolution provided in an embodiment of the present application;

[0041] Figure 4 A pore throat radius distribution diagram of a dense sandstone sample after organic acid dissolution provided in an embodiment of the present application;

[0042] Figure 5 A distribution diagram of micron pore radius before and after organic acid dissolution provided in an embodiment of the present application;

[0043] Figure 6 A distribution diagram of the micron throat radius before and after organic acid dissolution provided in an embodiment of the present application;

[0044] Figure 7 A structural block diagram of an organic acid dissolution system provided in an embodiment of the present application. DETAILED DESCRIPTION

[0045] In order to better understand the technical solution of the present application, the embodiments of the present application are described in detail below with reference to the accompanying drawings.

[0046] It should be clear that the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in the field without creative work are within the scope of protection of the present application.

[0047] The terms used in the embodiments of the present application are only for the purpose of describing specific embodiments, and are not intended to limit the present application. The singular forms "a", "said" and "the" used in the embodiments of the present application and the appended claims are also intended to include plural forms, unless the context clearly indicates other meanings.

[0048] It should be understood that the term "and / or" used in this article is only a description of the association relationship of associated objects, indicating that there can be three relationships. 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 this article generally indicates that the associated objects before and after are in an "or" relationship.

[0049] In view of the problem that the prior art does not characterize the changes in the reservoir pore structure caused by organic acid dissolution, and thus cannot determine the changes in the pore structure of the tight sandstone reservoir under the action of organic acid dissolution, the embodiment of the present application provides a quantitative evaluation method for organic acid dissolution, which can quantitatively analyze the changes in the pore structure of the tight sandstone reservoir under the action of organic acid dissolution, study the organic acid dissolution mechanism in the tight sandstone reservoir, and provide favorable support for studying the changes in the pore structure of the tight sandstone reservoir under different geological conditions under the action of organic acid dissolution and predicting the favorable enrichment area of ​​tight oil and gas, and has broad application prospects. It is described in detail below in conjunction with the specific implementation method.

[0050] See also Figure 1 , is a schematic diagram of a quantitative evaluation method for organic acid dissolution provided in an embodiment of the present application. Figure 1 As shown, it mainly includes the following steps.

[0051] Step S101: Select typical reservoir samples according to the petrological characteristics and geological background of the tight sandstone reservoir in the study area.

[0052] In a possible implementation, the petrological characteristics and geological background of the tight sandstone reservoir in the study area include: the mineral composition, mineral grain size and pore type of the tight sandstone reservoir in the study area.

[0053] Step S102: Perform pore structure analysis on typical reservoir samples to obtain the pore structure of the typical reservoir samples.

[0054] In a possible implementation, pore structure analysis includes: physical property measurement, micron CT scanning and high-pressure mercury injection experiment.

[0055] In a specific implementation, before executing step S102, the typical reservoir sample may be first washed with oil, and then subjected to physical property measurement, micron CT scanning, and high-pressure mercury injection testing. Part of the sample (i.e., the typical reservoir sample) is prepared as a plunger sample with a diameter of 2 cm and a length of 5 cm; the other part is prepared as a crushed sample.

[0056] In a possible implementation, the test method for measuring physical properties is a gas test method, and the sample required is a plunger sample with a diameter of 2 cm and a length of 5 cm. The measured physical property parameters include permeability and porosity.

[0057] In a possible implementation, the sample selected for micron CT scanning is the same plunger sample with a diameter of 2 cm and a length of 5 cm. The experiment is based on GB / T38531-2020 (microbeam analysis of compact rock micro-nanoscale pore structure computer tomography (CT) analysis method), and the measurement parameters include: micron pore radius distribution, micron throat radius distribution and coordination number.

[0058] In a possible implementation, the high-pressure mercury injection test is based on GB / T 21650.1-2008 (Mercury injection and gas adsorption method for pore size distribution and porosity of solid materials Part 1: Mercury injection method), the experimental sample is a crushed sample, and the measurement parameters include: micro-nano pore throat radius distribution and pore throat ratio.

[0059] Step S103: performing an organic acid dissolution experiment on a typical reservoir sample.

[0060] In one possible implementation, the experimental conditions can be first determined according to the geological conditions of the tight sandstone reservoir in the study area; then, the organic acid dissolution experiment can be carried out on typical reservoir samples under the experimental conditions. It can be understood that the continuous flow dissolution experiment of organic acid on tight sandstone reservoir under actual temperature and pressure conditions can be more consistent with the transformation effect of organic acid on the pore structure of tight sandstone reservoir under actual conditions.

[0061] In the specific implementation, the experimental conditions include: the type and concentration of organic acid used in the experiment, the experimental pressure and experimental temperature, and the type and salinity of formation water used in the experiment. In addition, the plunger sample in this step is the same plunger sample with a diameter of 2 cm and a length of 5 cm, and is saturated with formation water before the organic acid dissolution experiment.

[0062] In a specific implementation, an organic acid dissolution experiment can be carried out by using the organic acid dissolution system provided in the embodiment of the present application. The organic acid dissolution system is described in detail below.

[0063] Step S104: performing pore structure analysis on the typical reservoir sample after organic acid dissolution to obtain the pore structure of the typical reservoir sample after organic acid dissolution.

[0064] In a specific implementation, the typical reservoir sample after organic acid dissolution is subjected to the same type of pore structure analysis as step S102, and the pore structure analysis includes physical property measurement, micrometer CT scanning and high-pressure mercury injection experiment. The specific content can be found in the description of step S102, and will not be repeated here for the sake of brevity.

[0065] Step S105: Compare the pore structure of the typical reservoir sample with the pore structure of the typical reservoir sample after organic acid dissolution, and quantitatively evaluate the effect of organic acid dissolution on the pore structure of the tight sandstone reservoir.

[0066] In a specific implementation, the permeability, porosity, micron pore radius distribution, micron throat radius distribution, coordination number, micro-nano pore throat radius distribution and / or pore throat ratio of the pore structure of typical reservoir samples and the pore structure of typical reservoir samples after organic acid dissolution can be compared, thereby quantitatively evaluating the effect of organic acid dissolution on the pore structure of tight sandstone reservoirs.

[0067] In the embodiments of the present application, the pore structure changes of tight sandstone reservoirs under the action of organic acid dissolution can be quantitatively analyzed, and the organic acid dissolution mechanism in tight sandstone reservoirs can be studied, which provides favorable support for studying the pore structure changes of tight sandstone reservoirs under different geological conditions under the action of organic acid dissolution and predicting favorable tight oil and gas enrichment areas, and has broad application prospects.

[0068] For ease of understanding, the technical solution provided in the embodiment of the present application is described in detail below by taking a certain dense sandstone as the research object, which specifically includes the following steps.

[0069] Step S201: Analyze the petrological characteristics and geological background of the tight sandstone reservoir in the experimental area, and select typical reservoir samples based on the petrological characteristics and geological background of the tight sandstone reservoir. The petrological characteristics and geological background include parameters such as mineral composition, mineral particle size, pore type, etc. The microscopic characteristics of the tight sandstone sample before organic acid dissolution are as follows: Figure 2 shown.

[0070] Specifically, according to the exploration practice of tight sandstone reservoirs, samples were selected for mineral composition analysis. The results of the mineral composition analysis are shown in Table 1.

[0071] Table 1:

[0072]

[0073] The samples were selected for mineral particle size analysis. The results of mineral particle size analysis are shown in Table 2.

[0074] Table 2:

[0075] Rock Type Average value φ Standard Deviation Skewness Kurtosis Sorting coefficient Lithic feldspathic sandstone 3.61 1.79 2.73 11.74 1.52

[0076] Samples were selected for pore type analysis. The pore type of the samples was mainly porous type. The pores were distributed in a network pattern locally. Intergranular pores and intercrystalline pores were mainly developed. The minerals were mainly in linear contact and compacted tightly.

[0077] Step S202: Perform pore structure analysis on the typical reservoir sample selected in step S201, wherein the pore structure analysis includes: physical property measurement, micrometer CT scanning and high-pressure mercury injection experiment.

[0078] Specifically, typical reservoir samples were prepared into plug samples with a diameter of 2 cm and a length of 5 cm, and the physical properties of the samples were measured by gas measurement. Micron CT scanning was then performed, and finally 30 g of the same sample was selected for high-pressure mercury injection testing.

[0079] The physical property test results show that the porosity of the dense sandstone sample is 9.65%, and the permeability is 0.19×10 -3 μm 2. The results of high-pressure mercury injection experiments show that the pore throat radius distribution range of dense sandstone samples is 0.006-1μm, the average pore throat radius is 0.308μm, the sorting coefficient is 2.965, and the pore throat volume ratio is 1.78. The micron CT scanning results show that the micron-level pore radius distribution range of dense sandstone samples is 1-11μm, the micron-level throat radius distribution range is 1-8μm, and the coordination number is 1.031.

[0080] Step S203: Use the plunger sample for physical property measurement in step S202 to conduct an organic acid dissolution experiment. According to the actual geological conditions and laboratory conditions, the organic acid is selected as a 0.5 mol / L acetic acid solution (prepared by pure acetic acid reagent and deionized water), the formation water type is CaCl2 type, and the mineralization is 63.9 g / L. The experimental temperature is set to 100°C, the experimental pressure is set to 10 MPa, and the experimental time is 20 hours. The experiment adopts a continuous flow open system and rock internal dissolution mode, and the flow rate is constant at 0.5 mL / min.

[0081] Step S204: Perform pore structure analysis on the plug sample after organic acid dissolution in step S203, wherein the pore structure analysis includes: physical property measurement, micrometer CT scanning and high-pressure mercury injection experiment.

[0082] The results of physical property tests show that the porosity of the dense sandstone sample is 12.69% and the permeability is 24.38×10 -3 μm 2 . The results of high-pressure mercury injection experiments show that the pore throat radius distribution range of dense sandstone samples is 0.004-16μm, the average pore throat radius is 4.438μm, the sorting coefficient is 4.495, and the pore throat volume ratio is 2.58. The micron CT scanning results show that the micron-level pore radius distribution range of dense sandstone samples is 1-12μm, the micron-level throat radius distribution range is 1-9μm, and the coordination number is 1.865.

[0083] Step S205: Compare the test results in step S202 and step S204 to quantitatively evaluate the effect of organic acid dissolution on the pore structure of the tight sandstone reservoir. The comparison of micro-nano pore structure before and after organic acid dissolution is shown in Table 3.

[0084] Table 3:

[0085]

[0086]

[0087] Since the pore structure of tight sandstone reservoirs changes complexly after organic acid dissolution, the commonly used pore structure parameters cannot fully characterize the pore structure of the samples. Therefore, the pore throat radius distribution diagram of tight sandstone samples before organic acid dissolution, the pore throat radius distribution diagram of tight sandstone samples after organic acid dissolution, the micron pore radius distribution diagram before and after organic acid dissolution, and the micron throat radius distribution diagram before and after organic acid dissolution can be drawn to intuitively express the changes in the pore structure of tight sandstone reservoirs caused by organic acid dissolution.

[0088] In this example, the organic acid dissolution experiment on tight sandstone was conducted to analyze the improvement effect of organic acid dissolution on the pore structure of tight sandstone reservoir. The results show that:

[0089] (1) The effect of organic acid dissolution on physical properties is very obvious. Under the influence of organic acid dissolution, the reservoir porosity increased by 3.04% and the reservoir permeability increased by 128 times, which greatly improved the physical properties of the tight sandstone reservoir and was conducive to the migration and accumulation of oil and gas.

[0090] (2) The effect of organic acid dissolution on the pore throat radius is very obvious. Before organic acid dissolution, the reservoir pore throat radius ranged from 0.006 to 1 μm, with an average value of 0.308 μm. After organic acid dissolution, the reservoir pore throat radius distribution range was 0.004 to 16 μm, with an average value of 4.438 μm. The average pore throat radius expanded by 14 times. The distribution of pore throat radius before organic acid dissolution is shown in Figure 2. Figure 3 As shown in Figure 1, the reservoir pore throat radius is mainly distributed between 0.01 and 1 μm, and the permeability contribution mainly comes from the pore throats of 0.2 to 1 μm. The distribution of pore throat radius after organic acid dissolution is shown in Figure 1. Figure 4 As shown in the figure, the number of pore throats with a radius in the range of 1 to 15 μm increases, and the pore throat radius that mainly contributes to the permeability is in the range of 5 to 15 μm. The pore throats in the range of 0.2 μm to 1 μm no longer contribute to the permeability, and the minimum value of the pore throat radius decreases to 0.004 μm.

[0091] (3) Micron CT results show that under the dissolution of organic acids, the distribution range of micron-scale pore radius in tight sandstone reservoirs varies only to a limited extent, e.g. Figure 5 As shown in Figure 1, the overall distribution is in the range of 1 to 10 μm, but the number of pores in the range of 1 to 5 μm has decreased significantly, the number of pores in the range of 5 to 10 μm has increased, and the average pore radius has increased from 1.63 μm to 4.26 μm. The distribution range of the micron-scale throat radius in tight sandstone reservoirs has limited changes, such as Figure 6 As shown, the overall distribution is in the range of 1 to 8 μm, but the number of throats in the range of 1 to 2 μm is greatly reduced, the number of pores in the range of 2 to 8 μm is increased, and the average throat radius increases from 1.24 μm to 2.54 μm.

[0092] Corresponding to the above embodiment, the embodiment of the present application also provides an organic acid dissolution system.

[0093] See also Figure 7 , is a structural block diagram of an organic acid dissolution system provided in an embodiment of the present application. Figure 7 As shown, the organic acid dissolution system is mainly composed of the following devices.

[0094] A dissolution device, used to carry a typical reservoir sample to be dissolved;

[0095] An organic acid filling device, used for filling the dissolution device with organic acid, so that the typical reservoir sample in the dissolution device is dissolved under the action of the organic acid;

[0096] A solution collecting device, used to collect the dissolved solution discharged from the dissolution device;

[0097] A temperature control device, used to control the experimental temperature in the dissolution device;

[0098] A ring pressure device, used to control the experimental pressure in the dissolution device;

[0099] A control device is used to control the organic acid filling device, the temperature control device and the ring pressing device.

[0100] Among them, the organic acid filling device and the dissolution device, as well as the dissolution device and the solution collecting device can be connected by pipelines for inputting or outputting solutions; the control device is electrically connected to the temperature control device, the organic acid filling device, and the ring pressing device to send control signals to the temperature control device, the organic acid filling device, and the ring pressing device, thereby causing the temperature control device, the organic acid filling device, and the ring pressing device to perform corresponding operations.

[0101] In a possible implementation, the temperature control device can also control the overall ambient temperature of the organic acid filling device, the ring pressing device, the dissolution device and the solution collecting device.

[0102] It should be pointed out that the specific contents involved in the embodiments of the present application can be found in the description of the above method embodiments, and for the sake of brevity, they will not be repeated here.

[0103] In the embodiments of the present application, "at least one" refers to one or more, and "plurality" refers to two or more. "And / or" describes the association relationship of associated objects, indicating that three relationships may exist. For example, A and / or B can represent the existence of A alone, the existence of A and B at the same time, and the existence of B alone. Among them, A and B can be singular or plural. The character " / " generally indicates that the previous and subsequent associated objects are in an "or" relationship. "At least one of the following" and similar expressions refer to any combination of these items, including any combination of single or plural items. For example, at least one of a, b and c can be represented by: a, b, c, ab, ac, bc, or abc, where a, b, c can be single or multiple.

[0104] Those of ordinary skill in the art will appreciate that the various units and algorithm steps described in the embodiments disclosed herein can be implemented in a combination of electronic hardware, computer software, and electronic hardware. 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 be beyond the scope of this application.

[0105] 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.

[0106] In several embodiments provided in the present application, any function can be stored in a computer-readable storage medium if it is implemented in the form of a software functional unit and sold or used as an independent product. Based on this understanding, the technical solution of the present application can be essentially or partly embodied in the form of a software product that contributes to the prior art. The computer software product is stored in a storage medium, including several instructions for 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 the present application. The aforementioned storage medium includes: U disk, mobile hard disk, read-only memory (ROM), random access memory (RAM), disk or optical disk, etc., and other media that can store program codes.

[0107] The above is only a specific implementation of the present application. Any person skilled in the art can easily think of changes or substitutions within the technical scope disclosed in the present application, which should be included in the protection scope of the present application. The protection scope of the present application should be based on the protection scope of the claims.

Claims

1. A quantitative evaluation method for organic acid dissolution, characterized in that: include: According to the petrological characteristics and geological background of the tight sandstone reservoir in the study area, typical reservoir samples were selected; Performing pore structure analysis on the typical reservoir sample to obtain the pore structure of the typical reservoir sample; Conducting an organic acid dissolution experiment on the typical reservoir sample; Performing pore structure analysis on typical reservoir samples after organic acid dissolution to obtain the pore structure of the typical reservoir samples after organic acid dissolution; The pore structure of the typical reservoir sample and the pore structure of the typical reservoir sample after organic acid dissolution are compared to quantitatively evaluate the effect of the organic acid dissolution on the pore structure of the tight sandstone reservoir.

2. The method according to claim 1, characterized in that The petrological characteristics and geological background of the tight sandstone reservoir in the study area include: Mineral composition, mineral grain size and pore type of tight sandstone reservoirs in the study area.

3. The method according to claim 1, characterized in that The pore structure analysis comprises: Physical property measurement, micron CT scanning and high-pressure mercury injection experiment.

4. The method according to claim 3, characterized in that The measurement parameters of the physical property measurement include: permeability and porosity.

5. The method according to claim 3, characterized in that: The measurement parameters of the micron CT scan include: micron pore radius distribution, micron throat radius distribution and coordination number.

6. The method according to claim 3, characterized in that The measurement parameters of the high-pressure mercury injection experiment include: micro-nano pore throat radius distribution and pore throat ratio.

7. The method according to claim 1, characterized in that The organic acid dissolution experiment on the typical reservoir sample comprises: Determine the experimental conditions according to the geological conditions of the tight sandstone reservoir in the study area; An organic acid dissolution experiment was carried out on the typical reservoir sample under the experimental conditions.

8. The method according to claim 7, characterized in that The experimental conditions include: The type and concentration of organic acid used in the experiment, the experimental pressure and experimental temperature, the type and mineralization of formation water used in the experiment.

9. The method according to claim 1, characterized in that: The organic acid dissolution experiment on the typical reservoir sample comprises: An organic acid dissolution experiment was carried out on the typical reservoir samples by adopting an open system dynamic charging method.

10. The method according to claim 1, characterized in that The comparison of the pore structure of the typical reservoir sample and the pore structure of the typical reservoir sample after organic acid dissolution includes: Compare the permeability, porosity, micron pore radius distribution, micron throat radius distribution, coordination number, micro-nano pore throat radius distribution and / or pore throat ratio in the pore structure of the typical reservoir sample and the pore structure of the typical reservoir sample after organic acid dissolution.

11. An organic acid dissolution system, characterized in that: include: A dissolution device, used to carry a typical reservoir sample to be dissolved; An organic acid filling device, used for filling the dissolution device with organic acid, so that the typical reservoir sample in the dissolution device is dissolved under the action of the organic acid; A solution collecting device, used to collect the dissolved solution discharged from the dissolution device; A temperature control device, used to control the experimental temperature in the dissolution device; A ring pressure device, used to control the experimental pressure in the dissolution device; A control device is used to control the organic acid filling device, the temperature control device and the ring pressing device.

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