A quantitative evaluation method for water invasion degree of gas reservoir type gas storage

Abstract

This invention relates to a method for quantitatively evaluating the degree of water intrusion in a gas reservoir, comprising the following steps: identifying the geological structure and reservoir physical properties of the water-intruded gas reservoir; collecting outcrop samples from the corresponding target reservoir; deploying monitoring sensors at key points of the simulated samples; encapsulating the protective layer and pre-embedding the simulated injection wellbore, as well as prefabricating the gas reservoir injection well and production well; analyzing formation water saturation in the servo pump injection system; simulating gas injection and production under different operating conditions by setting true triaxial geostress conditions; comprehensively evaluating the quantitative assessment of the water edge by monitoring and collecting acoustic velocity, acoustic emission information, and wide-area electromagnetic signals during the gas injection and production process using pre-embedded sensors; and quantitatively evaluating the degree of water intrusion in the gas reservoir under long-term dynamic injection-production alternation using the above data. This invention can be used for the quantitative evaluation of the degree of water intrusion in gas reservoirs under long-term dynamic injection-production alternation, providing technical support for optimizing the injection-production system of depleted gas reservoirs.

Description

Technical Field

[0001] This invention relates to the field of underground gas storage safety inspection technology, specifically to a method for quantitatively evaluating the degree of water intrusion in gas reservoir-type gas storage facilities. Background Technology

[0002] Underground gas storage is one of the most important projects for my country's energy security and people's livelihood. Gas reservoir-type gas storage is the main type of underground gas storage and is currently undergoing rapid development. Gas reservoir-type gas storage is basically converted from depleted gas reservoirs. In the initial stage of production, the formation pressure is low, and edge and bottom water intrudes into the reservoir, resulting in a complex gas-water intermingling distribution and formation seepage conditions. Currently, to address the gas injection loss caused by gas-water intermingling, a multi-cycle injection-production capacity prediction model for water-intrusion-type gas storage has been proposed. To determine the initial injection volume of water-intrusion-type gas storage, a method for determining the injection volume based on the principle of material balance and constrained by the critical flow velocity for stable gas-water interface migration has been established. Based on the binomial production capacity equation, a single-well production potential model for gas storage based on effective permeability has been established. Using suction-dissipation phase permeability evaluation technology and multiple injection-production cycle nuclear magnetic resonance technology, a physical simulation experimental device for water-intrusion-type gas storage has been developed, revealing the microscopic mechanism of gas-water migration during multi-cycle water intrusion. However, existing methods for evaluating the degree of water intrusion in gas reservoirs mainly rely on reservoir numerical simulation and core-scale displacement simulation, lacking technical means and methods for quantitative evaluation of real water intrusion under stress conditions in gas reservoirs. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to provide a quantitative evaluation method for the degree of water intrusion in gas reservoirs, which addresses the shortcomings of the existing technology.

[0004] The technical solution of this invention to solve the above-mentioned technical problems is as follows: A method for quantitatively evaluating the degree of water intrusion in a gas reservoir, comprising the following steps:

[0005] Based on the actual conditions of the water-inundated gas reservoir, physical property parameters are collected, and samples are obtained from downhole based on the physical property parameters.

[0006] Holes were drilled around the sample at the water intrusion front edge in a point array pattern, and different types of sensors were placed in each hole. The sensors on the sample were marked with leads.

[0007] The sample after the lead wire marking is encapsulated. During the encapsulation process, the leads of each sensor are left on the outside. Multiple wells are pre-embedded on the encapsulated sample. The multiple wells include a water injection well, a gas storage injection well, and a gas production well. Each well is equipped with a connection wire connector for sealing.

[0008] An outer cladding layer is fabricated on the sample to obtain a pre-made sample. The connecting wire joints on the gas storage injection well and the gas production well are sealed using a sealing joint. The leads of each sensor are connected to a preset servo pump injection system. Simulated formation water is injected into the sandstone layer of the pre-made sample through the injection well. The data monitored by each sensor is transmitted to the servo pump injection system for formation water saturation analysis to obtain information on the water layer distribution diffusion trend and location. Finally, the leads of each sensor are disconnected from the servo pump injection system.

[0009] The gas injection and gas sampling environment is simulated by a preset test system to obtain test data. During the environmental simulation, each sensor is reconnected to the servo pump injection system. Under the set environment, the data monitored by each sensor is transmitted to the servo pump injection system to perform quantitative evaluation of the water edge. Based on the evaluation information, it is determined whether fingering phenomenon has occurred.

[0010] The test data and evaluation information are used as quantitative information to evaluate the degree of water intrusion in gas reservoirs under long-term dynamic injection-production alternation in injection and production wells.

[0011] The beneficial effects of this invention are as follows: A sample is obtained, different types of sensors are deployed within the sample, and water injection wells, gas storage injection wells, and gas production wells are pre-embedded and encapsulated to obtain a pre-made sample. The pre-made sample is then analyzed for formation water saturation using a servo pump injection system to obtain information on the water layer distribution and diffusion trend and location. Furthermore, a quantitative assessment of the water edge is performed using a pre-set testing system and a servo pump injection system. Based on the test data and assessment information, the degree of water intrusion in the gas storage reservoir under the long-term dynamic alternation of injection and production wells can be quantitatively evaluated, providing technical support for optimizing the injection and production system of depleted gas storage reservoirs.

[0012] Based on the above technical solution, the present invention can be further improved as follows.

[0013] Furthermore, the process of collecting physical property parameters based on the actual conditions of water-inundated gas reservoirs and obtaining samples from downhole based on these parameters specifically involves:

[0014] Based on the actual situation of the water-inundated gas reservoir, physical property parameters are collected from downhole, the target layer is determined based on the physical property parameters, the target layer characteristic parameters are obtained in the target layer, and representative physical model samples are determined based on the target layer characteristic parameters.

[0015] The outcrop sampling layer is determined in the model sample, and the sample is obtained from the outcrop sampling layer according to the set size.

[0016] The beneficial effects of adopting the above-mentioned further scheme are: it is possible to determine the target layer, determine a representative model sample from the target layer, determine the outcrop sampling layer from the model sample, and take samples to obtain the specimen.

[0017] Furthermore, the physical property parameters include downhole core columnar sections, continuous logging data, imaging logging, and drilling and completion data;

[0018] The target stratum characteristic parameters include porosity, permeability, acoustic velocity, and fracture development data.

[0019] Furthermore, determining the outcrop sampling layer in the sample model to be analyzed specifically involves:

[0020] The core sample in the model sample to be analyzed is tested, and the test data is compared with the known sampling reference data to determine the outcrop sampling layer. The comparison data between the test data and the sampling reference data includes parameters such as compressive strength, tensile strength, elastic modulus, Poisson's ratio, porosity, and permeability.

[0021] The beneficial effect of adopting the above-mentioned further scheme is that the sampling location can be accurately determined through various physical property characteristics and characteristic parameters, thus obtaining the sample and laying the foundation for subsequent data analysis.

[0022] Furthermore, the sample after lead marking is encapsulated, with the leads of each sensor left externally during encapsulation. Multiple wells are pre-embedded in the encapsulated sample. Specifically:

[0023] Colorless and transparent epoxy resin material is used as a protective coating agent for encapsulation, and the leads of each sensor are left on the outside during the encapsulation process.

[0024] A diamond drill bit was used to drill holes in the pre-embedded sample. Soluble salt was filled into the bottom of the drilled hole, and putty was used to separate the filling salt. Water injection well, gas storage injection well and gas production well were pre-embedded in the sealed sample. Epoxy resin was used to seal the annulus between each well and the drilled hole of the sample.

[0025] After the epoxy resin has cured, use a long syringe to puncture the clay and repeatedly inject water to dissolve and remove the salt at the bottom, forming a bare-eye section.

[0026] The beneficial effects of adopting the above-mentioned further scheme are: the water injection well, gas storage injection well, and gas production well of the sample are pre-embedded and sealed with epoxy resin to ensure the sealing of the entire simulated well and improve the accuracy of subsequent tests.

[0027] Furthermore, the process of fabricating an outer coating on the sample to obtain a pre-fabricated sample specifically involves:

[0028] A cube mold is made with a set side length, the set side length being greater than the side length of the sample. Cement mortar is used as the sealing material for the sample. The mortar is mixed and stirred according to a set ratio, and then cement slurry is poured into the cube mold.

[0029] The sample is slowly placed into the cubic mold using a crane, centered with the end containing the well shaft facing upwards. The pre-reserved connection connectors of the water injection well shaft, gas injection well shaft, and gas production well shaft, as well as the leads of each sensor, are led out to the outside. Cement mortar is poured around the sample and vibrated. The upper surface of the sample is then sealed with cement mortar to obtain the pre-made sample.

[0030] The advantages of adopting the above-mentioned further scheme are: simulating the test environment, making an outer coating for the sample to obtain a pre-made sample, and leading the lead wire to the outside for easy connection to the servo pump injection system.

[0031] Furthermore, the environmental simulation of the gas injection and gas extraction environment using a preset testing system specifically includes:

[0032] The pre-fabricated sample is placed in a preset true triaxial physical model testing machine, and the preset testing system is turned on. The leads of each sensor are reconnected to the servo pumping system. Information is collected synchronously through each sensor. The required geostress value is applied using the true triaxial physical model testing machine and kept constant. According to the reservoir pore water pressure parameters, the servo pumping system sets a constant pressure value. During the gas injection and production process, water will flow back from the simulated reservoir to the servo pumping system due to the action of gas-driven water. The total amount of returned liquid is monitored by a sensor used to collect liquid flow data.

[0033] Environmental simulations were conducted under different injection and production rates and cycles, based on the established injection and production simulation conditions.

[0034] The beneficial effect of adopting the above-mentioned further scheme is that by using a true triaxial physical model testing machine to conduct environmental simulations under different injection and production rates and different injection and production cycles according to the set injection and production simulation conditions, the authenticity and accuracy of the test are improved.

[0035] Furthermore, the gas injection and gas sampling environment is simulated using a preset testing system. During the simulation, each sensor is reconnected to the servo pumping system. Under the set environment, the data monitored by each sensor is transmitted to the servo pumping system for quantitative assessment of the water edge. Based on the assessment information, it is determined whether fingering has occurred. Specifically:

[0036] During the environmental simulation of gas injection, the acoustic velocity and acoustic emission testing system and the wide-area electromagnetic resistance testing system are activated simultaneously. When the rock saturated water inside the simulated geological body is affected by gas drive, the corresponding penetrating acoustic velocity and waveform are different. The test information of whether the simulated reservoir is water saturated or gas saturated is analyzed by wavelet transform.

[0037] By measuring the resistivity change of the penetrating body using the wide-area electromagnetic method, test information on the water-bearing and gas-bearing characteristics of the simulated reservoir interior can be obtained.

[0038] The degree of damage to the precast sample is monitored by an acoustic emission probe during multiple displacement processes to obtain test information on the damage to the precast sample. If the test produces obvious acoustic emission impacts or events, it indicates that the sample has suffered relatively serious damage, and subsequent tests are stopped.

[0039] Reconnect each of the sensors to the servo pumping system and transmit the data monitored by each of the sensors to the servo pumping system. Obtain the drainage volume during the gas injection process through the servo pumping system. Quantitatively calculate the range value reached by the gas based on the drainage volume. Quantitatively evaluate the water edge based on the range value and various test information. Determine whether fingering phenomenon has occurred based on the evaluation information.

[0040] The beneficial effects of adopting the above-mentioned further scheme are: by simulating the scenario of saturated water in the rocks inside the geological body being affected by gas drive through the acoustic velocity and acoustic emission test system and the wide-area electromagnetic resistance test system, the test information of whether the simulated reservoir is water-saturated or gas-saturated, as well as the test information of water-bearing and gas-bearing characteristics inside the simulated reservoir and the test information of damage to pre-made samples, and by quantitatively assessing the water edge through the servo pump injection system, it can be determined whether fingering phenomenon has occurred. Attached Figure Description

[0041] Figure 1 This is a schematic flowchart illustrating the method for quantitatively evaluating the degree of water intrusion in a gas reservoir provided in this embodiment of the invention. Detailed Implementation

[0042] The principles and features of the present invention are described below with reference to the accompanying drawings. The examples given are only for explaining the present invention and are not intended to limit the scope of the present invention.

[0043] Example 1:

[0044] Figure 1 This is a schematic flowchart illustrating the method for quantitatively evaluating the degree of water intrusion in a gas reservoir provided in this embodiment of the invention.

[0045] like Figure 1 As shown, a method for quantitatively evaluating the degree of water intrusion in a gas reservoir includes the following steps:

[0046] S1. Collect physical property parameters based on the actual situation of the water-invaded gas reservoir, and obtain samples from downhole based on the physical property parameters;

[0047] S2. Holes are drilled around the sample at the position of the water intrusion front edge in a point array manner, and different types of sensors are arranged in each hole, and the lead wires of each sensor on the sample are marked.

[0048] S3. The sample marked with lead wires is encapsulated. During the encapsulation process, the lead wires of each sensor are left on the outside. Multiple wells are pre-embedded on the encapsulated sample. The multiple wells include a water injection well, a gas storage injection well, and a gas production well. Each well is provided with a connection wire connector for sealing.

[0049] S4. The sample is coated to obtain a pre-made sample. The connection wire joints on the gas storage injection well and the gas production well are sealed by a sealing joint. The leads of each sensor are connected to a preset servo pump injection system. Simulated formation water is injected into the sandstone layer of the pre-made sample through the injection well. The data monitored by each sensor is transmitted to the servo pump injection system for formation water saturation analysis to obtain information on the water layer distribution diffusion trend and location. The leads of each sensor are then disconnected from the servo pump injection system.

[0050] S5. The gas injection and gas sampling environment is simulated by a preset test system to obtain test data. During the environmental simulation, each sensor is reconnected to the servo pumping system. Under the set environment, the data monitored by each sensor is transmitted to the servo pumping system to perform quantitative evaluation of the water edge. Based on the evaluation information, it is determined whether fingering phenomenon has occurred.

[0051] S6. The test data and evaluation information are used as quantitative information to evaluate the degree of water intrusion in the gas reservoir under the long-term dynamic injection and production alternation of injection and production wells.

[0052] In the above embodiments, samples are obtained, different types of sensors are deployed within the samples, and water injection wells, gas storage injection wells, and gas production wells are pre-embedded and sealed to obtain pre-made samples. Formation water saturation analysis is performed on the pre-made samples using a servo pump injection system to obtain information on the water layer distribution and diffusion trend and location. A pre-set testing system and servo pump injection system are used to quantitatively assess the water edge. The test data and assessment information can quantitatively evaluate the degree of water intrusion in gas storage reservoirs under long-term dynamic injection-production alternation. This invention can be used for the quantitative evaluation of the degree of water intrusion in gas storage reservoirs under long-term dynamic injection-production alternation, providing technical support for optimizing the injection-production system of depleted gas storage reservoirs.

[0053] Based on Example 1, Example 2:

[0054] The process of collecting physical property parameters based on the actual conditions of water-inundated gas reservoirs and obtaining samples from downhole based on these parameters specifically involves:

[0055] Based on the actual situation of the water-inundated gas reservoir, physical property parameters are collected from downhole, the target layer is determined based on the physical property parameters, the target layer characteristic parameters are obtained in the target layer, and representative physical model samples are determined based on the target layer characteristic parameters.

[0056] The outcrop sampling layer is determined in the model sample, and the sample is obtained from the outcrop sampling layer according to the set size.

[0057] In the above embodiments, a target layer can be determined, a representative model sample can be determined from the target layer, an outcrop sampling layer can be determined from the model sample, and a sample can be obtained.

[0058] Specifically, the physical property parameters include downhole core columnar sections, continuous logging data, imaging logging, and drilling and completion data;

[0059] The target stratum characteristic parameters include porosity, permeability, acoustic velocity, and fracture development data.

[0060] Based on Example 1, Example 3:

[0061] The step of determining the outcrop sampling layer in the sample to be analyzed specifically involves:

[0062] The core sample in the model sample to be analyzed is tested, and the test data is compared with the known sampling reference data to determine the outcrop sampling layer. The comparison data between the test data and the sampling reference data includes parameters such as compressive strength, tensile strength, elastic modulus, Poisson's ratio, porosity, and permeability.

[0063] Specifically, by comprehensively analyzing seismic exploration data, seismic inversion, and outcrop surface characteristics (i.e., known sampling reference data), small-scale rock mechanics and porosity / permeability test core samples were collected and tested. The rock mechanics (compressive and tensile strength, elastic modulus, Poisson's ratio) porosity and permeability parameters of the samples were compared with those of actual downhole core samples to determine the specific outcrop sampling layer. Samples with dimensions greater than 400 mm on each side were obtained for subsequent simulation tests to quantitatively evaluate water intrusion in the target reservoir of the gas storage facility.

[0064] In the above embodiments, the sampling location can be accurately determined and the sample obtained through various physical property characteristics and characteristic parameters, laying the foundation for subsequent data analysis.

[0065] Based on Example 1, Example 4:

[0066] The sample after lead marking is encapsulated, with the leads of each sensor left external during encapsulation. Multiple wells are pre-embedded in the encapsulated sample. Specifically:

[0067] Colorless and transparent epoxy resin is used as a protective coating agent for encapsulation. During encapsulation, the leads of each sensor are left external. The marked leads facilitate subsequent connection to the servo pumping system.

[0068] A diamond drill bit was used to drill holes in the pre-embedded sample. Soluble salt was filled into the bottom of the drilled holes, and putty was used to separate the filling salt. Water injection wells, gas storage injection wells, and gas production wells were pre-embedded in the sealed sample. Epoxy resin was used to seal the annulus between each well and the drilled hole of the sample to ensure the airtightness of the entire simulated well.

[0069] After the epoxy resin has cured, a long syringe is used to puncture the putty, and water is repeatedly injected to dissolve and remove the lower salt, forming an open hole section, thus completing the preparation of the water injection well, gas injection well, and gas production well casing containing the geological body.

[0070] Specifically, small holes are drilled on the periphery of a 400mm cubic sample in a point array pattern to accommodate acoustic wave probes, acoustic emission probes, and wide-area apparent resistance test probes (not limited to these sensors). Then, the leads of various types of sensors are marked and protected to quantitatively measure the signal response at water saturation and different gas injection and production stages, and to analyze the location of the water front.

[0071] The simulated target geological body model is a 400mm×400mm×400m cube. High-strength colorless and transparent epoxy resin material is used as the protective coating agent. After that, the water injection well, gas storage injection well, and gas production well are pre-embedded.

[0072] Specifically, a 200mm deep hole was drilled using a 6mm diameter diamond drill bit. Soluble salt was filled into the lower 170-200mm of the hole. A soft putty or similar material was used to separate the salt filling. A 170mm long steel pipe was then lowered to simulate a wellbore. High-strength epoxy resin was used to seal the space between the simulated wellbore and the annulus of the borehole, ensuring the overall airtightness of the simulated wellbore. After the epoxy resin cured, a long syringe was used to puncture the putty, and water was repeatedly injected to dissolve and remove the lower salt, forming an open-hole section. This completed the preparation of the wellbore for the water injection well, gas injection well, and gas production well in the geological body.

[0073] In the above embodiments, the sample water injection well, gas storage injection well, and gas production well are pre-embedded and sealed with epoxy resin to ensure the airtightness of the entire simulated well and improve the accuracy of subsequent tests.

[0074] Based on Example 1, Example 5:

[0075] The process of fabricating an outer coating layer on the sample to obtain a pre-fabricated sample specifically involves:

[0076] A cube mold is made with a set side length, the set side length being greater than the side length of the sample. Cement mortar is used as the sealing material for the sample. The mortar is mixed and stirred according to a set ratio, and then cement slurry is poured into the cube mold.

[0077] The sample was slowly placed into the cubic mold using a crane, centered with the end containing the well casing facing upwards. The pre-installed connectors for the water injection well casing, gas injection well casing, and gas production well casing, as well as the leads of each sensor, were led to the outside. Cement mortar was poured around the sample and vibrated to ensure compaction. The upper surface of the sample was then sealed with cement mortar using the same method to obtain the pre-cast sample.

[0078] Specifically, a 500mm cube mold was fabricated. Cement mortar was used as the sealing material for the sample, and the mixture was stirred according to a specific ratio. A 50mm thick layer of cement slurry was then poured into the assembled mold and allowed to solidify. A 400mm cube precast sample was then slowly placed into the mold using a crane, centered with the end containing the simulated well shaft facing upwards. The pre-installed connection lines for the water injection well, gas injection well, and gas production well shafts, as well as the leads for various types of sensors, were led out. Cement mortar was slowly poured around the sample, and then the sample was thoroughly vibrated to ensure compaction. The upper surface of the sample was sealed with cement mortar using the same method, completing the outer layer of the sample. The sample was then cured according to concrete curing specifications to ensure the strength of the cement layer.

[0079] To simulate the water saturation characteristics of the samples, after preparing samples from the simulated injection wells, gas injection wells, and gas production wells, sealing joints were used to seal the joints on the injection and production well shafts, leaving only the injection wells intact. The injection wells were then connected to a servo pump injection system, and pre-embedded monitoring sensors were connected to the monitoring system. Simulated formation water was slowly injected into the sandstone layer through the injection well shaft at a pressure of 0.5MPa-1.0MPa. The monitoring system analyzed the distribution and diffusion trends and location information of the water layer to complete the entire saturation process, after which all sensors and connecting cables were disassembled.

[0080] In the above embodiments, a simulated test environment is used to fabricate an outer coating on the sample to obtain a pre-fabricated sample, and the leads are led out to the outside for easy connection to the servo pump injection system.

[0081] Based on Example 1, Example 6:

[0082] The environmental simulation of gas injection and gas extraction environment through a preset testing system is specifically as follows:

[0083] The pre-fabricated sample is placed in a preset true triaxial physical model testing machine, and the preset testing system is turned on. The leads of each sensor are reconnected to the servo pumping system. Information is collected synchronously through each sensor. The required geostress value is applied using the true triaxial physical model testing machine and kept constant. According to the reservoir pore water pressure parameters, the servo pumping system sets a constant pressure value. During the gas injection and production process, water will flow back from the simulated reservoir to the servo pumping system due to the action of gas-driven water. The total amount of returned liquid is monitored by a sensor used to collect liquid flow data.

[0084] Environmental simulations were conducted under different injection and production rates and cycles, based on the established injection and production simulation conditions.

[0085] Specifically, based on the actual reservoir depth and gas injection / production operation conditions of the depleted gas reservoir, the triaxial in-situ stress conditions for loading are determined. The prepared samples are placed in a true triaxial loading chamber, and the hydraulic servo pump injection system and the pipelines connecting the injection and production wells are reconnected to the gas servo control system. Simultaneously, the leads of various sensors embedded within the geological body are connected to the corresponding data acquisition systems and debugged. Then, a large-scale true triaxial physical model testing machine is used to load the required in-situ stress value, maintaining a constant pressure. Based on the reservoir pore water pressure parameters, a constant pressure value is set by the hydraulic servo pump injection system. During the gas injection / production process, water is driven by gas, causing it to flow back from the simulated reservoir to the servo unit. The total volume of returned liquid is monitored by a flow sensor. Simulations are conducted under different injection / production rates and cycles according to the set injection / production simulation conditions, with information collected synchronously by deployed sensors.

[0086] It should be understood that a true triaxial loading device is a testing device that can simulate and provide the geostress conditions of the sample, and can achieve stress loading in both vertical and horizontal directions.

[0087] In the above embodiments, a true triaxial physical model testing machine is used to simulate the environment under different injection and production rates and cycles according to the set injection and production simulation conditions, thereby improving the realism and accuracy of the test.

[0088] Based on Examples 1 to 6, Example 7:

[0089] The gas injection and gas sampling environment is simulated using a preset testing system. During the simulation, each sensor is reconnected to the servo pumping system. Under the set environment, the data monitored by each sensor is transmitted to the servo pumping system for quantitative assessment of the water edge. Based on the assessment information, it is determined whether fingering has occurred. Specifically:

[0090] During the environmental simulation of gas injection, the acoustic velocity and acoustic emission testing system and the wide-area electromagnetic resistance testing system are activated simultaneously. When the saturated water in the simulated geological body is affected by gas drive, the corresponding penetrating acoustic velocity and waveform differ. Wavelet transform is used to analyze the test information of whether the simulated reservoir is saturated with water or gas. It should be understood that wavelet transform is a set of acoustic signal solving techniques with corresponding theoretical formulas. This method is used to calculate the position of fluids and the amount of saturated water in the reservoir.

[0091] By testing the resistivity change of the penetrating body using the wide-area electromagnetic method, test information on the water-bearing and gas-bearing characteristics of the simulated reservoir is obtained. It should be understood that the wide-area electromagnetic method is a technical means of measuring the resistivity change in the rock mass, and it is a newly emerging geodetic surveying technique. It is applied to this embodiment.

[0092] The precast sample is monitored for damage during multiple displacement processes using an acoustic emission probe to obtain test information on the precast sample damage. If the test produces obvious acoustic emission impacts or events, it indicates that the sample has suffered relatively serious damage, and subsequent tests are stopped. At the same time, each of the sensors is reconnected to the servo pumping system, and the data monitored by each of the sensors is transmitted to the servo pumping system. The servo pumping system obtains the displacement during the gas injection process, and the range value of the gas reaching is quantitatively calculated based on the displacement value. The water edge is quantitatively evaluated based on the range value and the test information, and it is determined whether fingering phenomenon has occurred based on the evaluation information.

[0093] In the above embodiments, the acoustic velocity and acoustic emission testing system and the wide-area electromagnetic resistance testing system are used to simulate the scenario where saturated water in the rocks inside the geological body is affected by gas drive. This allows for the analysis of test information on whether the simulated reservoir is water-saturated or gas-saturated, as well as test information on the water-bearing and gas-bearing characteristics inside the simulated reservoir and test information on damage to pre-made samples. Furthermore, a servo pumping system is used to quantitatively assess the water edge, thereby determining whether fingering has occurred.

[0094] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0095] Those skilled in the art will understand that, for the sake of convenience and brevity, the specific working process of the system described above can be referred to the corresponding process in the foregoing method embodiments, and will not be repeated here.

[0096] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for quantitatively evaluating the degree of water intrusion in a gas reservoir, characterized in that, Includes the following steps: Based on the actual conditions of the water-inundated gas reservoir, physical property parameters are collected, and samples are obtained from downhole based on the physical property parameters. Holes were drilled around the sample at the water intrusion front edge in a point array pattern, and different types of sensors were placed in each hole. The sensors on the sample were marked with leads. The sample after the lead wire marking is encapsulated. During the encapsulation process, the leads of each sensor are left on the outside. Multiple wells are pre-embedded on the encapsulated sample. The multiple wells include a water injection well, a gas storage injection well, and a gas production well. Each well is equipped with a connection wire connector for sealing. An outer cladding layer is fabricated on the sample to obtain a pre-made sample. The connecting wire joints on the gas storage injection well and the gas production well are sealed using a sealing joint. The leads of each sensor are connected to a preset servo pump injection system. Simulated formation water is injected into the sandstone layer of the pre-made sample through the injection well. The data monitored by each sensor is transmitted to the servo pump injection system for formation water saturation analysis to obtain information on the water layer distribution diffusion trend and location. Finally, the leads of each sensor are disconnected from the servo pump injection system. The gas injection and gas sampling environment is simulated by a preset test system to obtain test data. During the environmental simulation, each sensor is reconnected to the servo pump injection system. Under the set environment, the data monitored by each sensor is transmitted to the servo pump injection system to perform quantitative evaluation of the water edge. Based on the evaluation information, it is determined whether fingering phenomenon has occurred. The test data and evaluation information are used as quantitative information to evaluate the degree of water intrusion in the gas reservoir under the long-term dynamic injection and production alternation of injection and production wells; The sample after lead marking is encapsulated, with the leads of each sensor left externally during encapsulation. Multiple wells are pre-embedded in the encapsulated sample. Specifically: Colorless and transparent epoxy resin material is used as a protective coating agent for encapsulation, and the leads of each sensor are left on the outside during the encapsulation process. A diamond drill bit was used to drill holes in the pre-embedded sample. Soluble salt was filled into the bottom of the drilled hole, and putty was used to separate the filling salt. Water injection well, gas storage injection well and gas production well were pre-embedded in the sealed sample. Epoxy resin was used to seal the annulus between each well and the drilled hole of the sample. After the epoxy resin has cured, use a syringe to puncture the clay and repeatedly inject water to dissolve and remove the salt at the bottom, forming a bare-eye section. The process of fabricating an outer coating layer on the sample to obtain a pre-fabricated sample specifically involves: A cube mold is made with a set side length, the set side length being greater than the side length of the sample. Cement mortar is used as the sealing material for the sample. The mortar is mixed and stirred according to a set ratio, and then cement slurry is poured into the cube mold. The sample is slowly placed into the cubic mold using a crane, centered with the end containing the well shaft facing upwards. The pre-reserved connection connectors of the water injection well shaft, gas injection well shaft, and gas production well shaft, as well as the leads of each sensor, are led out to the outside. Cement mortar is poured around the sample and vibrated. The upper surface of the sample is then sealed with cement mortar to obtain the pre-made sample.

2. The method for quantitatively evaluating the degree of water intrusion in a gas reservoir-type gas storage facility according to claim 1, characterized in that, The process of collecting physical property parameters based on the actual conditions of water-inundated gas reservoirs and obtaining samples from downhole based on these parameters specifically involves: Based on the actual situation of the water-inundated gas reservoir, physical property parameters are collected from downhole, the target layer is determined based on the physical property parameters, the target layer characteristic parameters are obtained in the target layer, and representative physical model samples are determined based on the target layer characteristic parameters. The outcrop sampling layer is determined in the physical model sample, and the sample is obtained from the outcrop sampling layer according to the set size.

3. The method for quantitatively evaluating the degree of water intrusion in a gas reservoir-type gas storage facility according to claim 2, characterized in that, The physical property parameters include downhole core columnar sections, continuous logging data, imaging logging data, and drilling and completion data. The target stratum characteristic parameters include porosity, permeability, acoustic velocity, and fracture development data.

4. The method for quantitatively evaluating the degree of water intrusion in a gas reservoir-type gas storage facility according to claim 2, characterized in that, The determination of the outcrop sampling layer in the model sample specifically involves: The core sample in the model sample is tested, and the test data is compared with the known sampling reference data to determine the outcrop sampling layer. The comparison data between the test data and the sampling reference data includes parameters such as compressive strength, tensile strength, elastic modulus, Poisson's ratio, porosity, and permeability.

5. The method for quantitatively evaluating the degree of water intrusion in a gas reservoir-type gas storage facility according to claim 1, characterized in that, The environmental simulation of gas injection and gas extraction environment through a preset testing system is specifically as follows: The pre-fabricated sample is placed in a preset true triaxial physical model testing machine, and the preset testing system is turned on. The leads of each sensor are reconnected to the servo pumping system. Information is collected synchronously through each sensor. The required geostress value is applied using the true triaxial physical model testing machine and kept constant. According to the reservoir pore water pressure parameters, the servo pumping system sets a constant pressure value. During the gas injection and production process, water will flow back from the simulated reservoir to the servo pumping system due to the action of gas-driven water. The total amount of returned liquid is monitored by a sensor used to collect liquid flow data. Environmental simulations were conducted under different injection and production rates and cycles, based on the established injection and production simulation conditions.

6. The method for quantitatively evaluating the degree of water intrusion in a gas reservoir-type gas storage facility according to any one of claims 1 to 5, characterized in that, The gas injection and gas sampling environment is simulated using a preset testing system. During the simulation, each sensor is reconnected to the servo pumping system. Under the set environment, the data monitored by each sensor is transmitted to the servo pumping system for quantitative assessment of the water edge. Based on the assessment information, it is determined whether fingering has occurred. Specifically: During the environmental simulation of gas injection, the acoustic velocity and acoustic emission testing system and the wide-area electromagnetic resistance testing system are activated simultaneously. When the rock saturated water inside the simulated geological body is affected by gas drive, the corresponding penetrating acoustic velocity and waveform are different. The test information of whether the simulated reservoir is water saturated or gas saturated is analyzed by wavelet transform. By measuring the resistivity change of the penetrating body using the wide-area electromagnetic method, test information on the water-bearing and gas-bearing characteristics of the simulated reservoir interior can be obtained. The degree of damage to the prefabricated sample during multiple displacement processes is monitored by an acoustic emission probe to obtain test information on the damage to the prefabricated sample. Reconnect each of the sensors to the servo pumping system and transmit the data monitored by each of the sensors to the servo pumping system. Obtain the drainage volume during the gas injection process through the servo pumping system. Quantitatively calculate the range value reached by the gas based on the drainage volume. Quantitatively evaluate the water edge based on the range value and various test information. Determine whether fingering phenomenon has occurred based on the evaluation information.

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