Gas storage three-dimensional model and manufacturing method thereof, simulation experiment device and experiment method

Abstract

This invention discloses a three-dimensional model of a gas storage facility and its fabrication method, as well as a simulation experimental device and method. The model includes: a clamping device with a confining pressure cavity inside; a reservoir body to simulate a real reservoir, located within the confining pressure cavity; a surrounding rock simulation layer covering the reservoir body and located within the confining pressure cavity; at least one injection-production simulation well penetrating the clamping device and the surrounding rock simulation layer and communicating with the reservoir body; and at least one monitoring simulation well penetrating the clamping device and extending into the surrounding rock simulation layer. This invention ensures that the stresses of the surrounding rock simulation layer and the reservoir body are mutually restrictive and mutually influential during injection and production, thereby considering the influence of the surrounding rock and achieving a more realistic simulation of the underground gas storage facility. By setting up a monitoring simulation well extending into the surrounding rock simulation layer, pressure monitoring of the surrounding rock simulation layer can be achieved to determine whether leakage has occurred, thus accurately evaluating the sealing performance of the surrounding rock layer during the operation of the gas storage facility.

Description

Technical Field

[0001] This invention relates to the field of oil and gas development technology, and in particular, to a three-dimensional model of a gas storage facility and its fabrication method, as well as a simulation experimental apparatus and experimental method. Background Technology

[0002] This section is intended to provide background or context for the embodiments of the invention set forth in the claims. The description herein is not an admission that it is prior art simply because it is included in this section.

[0003] Natural gas, as a highly efficient and green energy source, plays a crucial role in the energy transition. In recent years, natural gas consumption has experienced rapid double-digit growth, with increasingly pronounced seasonal and regional differences. Underground gas storage facilities, serving as natural gas "granaries" and "energy batteries," have played a significant strategic and practical role in responding to emergencies such as extreme cold weather, ensuring economic development and social stability.

[0004] The construction of gas storage facilities differs significantly from gas reservoir development. The surrounding rock (caprock and underrock) is crucial to the sealing performance of gas storage facilities; therefore, its influence must be considered during construction. Underground reservoirs are strata with high permeability and porosity, capable of storing gas. These are typically depleted oil and gas reservoirs after extraction. The reservoir itself is surrounded by caprock and underrock (surrounding rock), which have extremely low permeability and porosity, preventing gas from passing through and effectively protecting the reservoir. This prevents gas from diffusing into other strata, and leaks are generally avoided during reservoir development. However, during gas storage facility operation, the injection and production rates are much faster than in gas reservoir development. For emergency supply, half of the reservoir's reserves may need to be extracted within three months, a rate 20 to 25 times faster than normal gas reservoir development. Under these highly variable operating conditions, whether the sealing performance of the surrounding rock will fail requires experimental verification.

[0005] While existing simulation devices simulate confining pressure, they do not include surrounding rock. The inventors have discovered that in actual underground environments, the surrounding rock (caprock and bottom support layer) is crucial for evaluating the sealing performance of gas storage facilities. Therefore, existing simulation devices do not consider the impact of real underground surrounding rock on gas storage facilities, resulting in poor simulation performance. Summary of the Invention

[0006] The purpose of this invention is to provide a three-dimensional model of a gas storage facility and its manufacturing method, as well as a three-dimensional simulation experimental device and method for a gas storage facility, in order to solve the technical problem that the existing simulation experimental devices do not consider the influence of the actual underground surrounding rock on the gas storage facility, resulting in poor simulation effects.

[0007] The above-mentioned objectives of the present invention can be achieved by the following technical solutions:

[0008] This invention provides a three-dimensional model of a gas storage facility, comprising: a clamp having a confining pressure cavity inside; a reservoir body for simulating a real reservoir, the reservoir body being located within the confining pressure cavity; a surrounding rock simulation layer covering the reservoir body and located within the confining pressure cavity; at least one injection-production simulation well penetrating the clamp and the surrounding rock simulation layer and communicating with the reservoir body; and at least one monitoring simulation well penetrating the clamp and communicating into the surrounding rock simulation layer.

[0009] In an embodiment of the present invention, the three-dimensional model of the gas storage tank further includes an elastic layer and a confining pressure injection pipe. The elastic layer covers the surrounding rock simulation layer, and one end of the confining pressure injection pipe extends through the clamp to the gap between the elastic layer and the clamp.

[0010] In an embodiment of the present invention, the surrounding rock simulation layer is spherically wrapped around the reservoir, and the clamp is spherically clamped onto the surrounding rock simulation layer.

[0011] In embodiments of the present invention, the number of injection-production simulation wells is multiple, and the injection-production simulation wells are injection-production pipe fittings made of high-temperature and high-pressure materials.

[0012] In embodiments of the present invention, the number of monitoring simulation wells is multiple, and the monitoring simulation wells are monitoring pipe fittings made of high-temperature and high-pressure materials.

[0013] This invention also provides a method for creating a three-dimensional model of a gas storage facility, comprising the following steps: obtaining an artificial reservoir core based on the shape and pore structure of a real reservoir, wherein the artificial reservoir core forms the reservoir mass; or extracting a real reservoir core from the real reservoir, wherein the real reservoir core forms the reservoir mass; obtaining an artificial surrounding rock core on the reservoir mass based on the pore structure of the real surrounding rock layer, and encapsulating the reservoir mass with the artificial surrounding rock core, thereby forming the simulated surrounding rock layer; wherein the... At least one injection-production channel and at least one monitoring channel are reserved on the surrounding rock simulation layer; one end of at least one injection-production pipe is extended from at least one of the injection-production channels to the vicinity of the reservoir to form at least one injection-production simulation well; one end of at least one monitoring pipe is extended from at least one of the monitoring channels into the surrounding rock simulation layer to form at least one monitoring simulation well; the surrounding rock simulation layer containing the reservoir is placed into the confining pressure cavity of the clamp, and the other end of the injection-production pipe and the other end of the monitoring pipe extend from the injection-production hole and monitoring hole provided on the clamp.

[0014] In an embodiment of the present invention, the process of preparing an artificial reservoir core based on the shape and pore structure of a real reservoir includes the following steps: obtaining the shape characteristics of the real reservoir and the distribution characteristics of small fractures and large cavities; determining the shape of the artificial reservoir core based on the shape characteristics of the real reservoir; scanning the pore structure of the real reservoir core extracted from the real reservoir and performing three-dimensional modeling of the pore structure of the real reservoir core to obtain a three-dimensional data volume of the pore structure of the real reservoir core; and, based on the shape of the artificial reservoir core, converting the three-dimensional data volume of the pore structure of the real reservoir core into a three-dimensional data volume of the pore structure of the real reservoir core. The artificial reservoir core is assembled into its shape and enlarged proportionally to obtain a first three-dimensional data volume of the artificial reservoir core. Based on the distribution characteristics of small fractures and karst caves, proportionally reduced three-dimensional data volumes of small fractures and karst caves are inserted into the first three-dimensional data volume of the artificial reservoir core to obtain a second three-dimensional data volume of the artificial reservoir core with a triple medium of pores, cavities, and fractures. Based on the second three-dimensional data volume of the artificial reservoir core, the artificial reservoir core is replicated proportionally using 3D printing, laser engraving, or sandstone cemented artificial core methods, so that the artificial reservoir core forms the reservoir mass.

[0015] In an embodiment of the present invention, the real surrounding rock layer includes a caprock layer covering the real reservoir and a bottom support layer located below the real reservoir; the step of preparing an artificial surrounding rock core on the reservoir based on the pore structure of the real surrounding rock layer includes the following steps: obtaining the distribution characteristics of faults and fractures present in the caprock layer and the bottom support layer; scanning the pore structure of the caprock core and the bottom support core taken from the bottom support layer, performing three-dimensional modeling of the pore structure of the caprock core and the bottom support core, obtaining three-dimensional data volumes of the pore structure of the caprock core and the bottom support core; and then preparing the caprock core. The three-dimensional data volume of the pore structure of the core layer and the three-dimensional data volume of the pore structure of the bottom support core are spliced ​​into a sphere and enlarged proportionally to obtain the first three-dimensional data volume of the artificial surrounding rock core. According to the distribution characteristics of faults and fractures, the three-dimensional data volume of faults and fractures of proportional reduction is inserted into the first three-dimensional data volume of the artificial surrounding rock core to obtain the second three-dimensional data volume of the artificial surrounding rock core. Based on the second three-dimensional data volume of the artificial surrounding rock core, the artificial surrounding rock core is replicated proportionally on the reservoir by means of 3D printing, laser engraving or sandstone cemented artificial core, thereby forming the surrounding rock simulation layer that covers the reservoir.

[0016] The present invention also provides a three-dimensional simulation experimental device for a gas storage facility, comprising: the aforementioned three-dimensional model of the gas storage facility; a constant temperature chamber in which the three-dimensional model of the gas storage facility is placed; an injection and production mechanism, including an injection structure and a production structure connected to the injection and production simulation well; a confining pressure application mechanism connected to the surrounding rock cavity; and a first pressure monitoring structure for monitoring the pressure of the monitoring simulation well.

[0017] In an embodiment of the present invention, the injection structure includes a natural gas tank, a formation water tank, and an injection pump. The injection pump can inject natural gas provided by the natural gas tank and / or water provided by the formation water tank from the injection-production simulation well into the three-dimensional model of the gas storage tank.

[0018] In an embodiment of the present invention, both the injection structure and the production structure are connected to the injection-production simulation well via an injection-production control valve. The production structure includes a first production pipeline, a second production pipeline, and a fluid recovery container. The input end of the first production pipeline is connected to at least one of the injection-production simulation wells, and the output end of the first production pipeline is connected to the fluid recovery container. The input end of the second production pipeline is connected to at least another injection-production simulation well via the injection-production control valve, and the output end of the second production pipeline is connected to the fluid recovery container via the first production pipeline. The injection-production control valve is equipped with a second pressure monitoring structure.

[0019] In embodiments of the present invention, a first mass flow meter is provided between the injection-production control valve and the injection-production simulation well; a second mass flow meter is provided between the first production pipeline and the fluid recovery container; or a third pressure monitoring structure and a back pressure pump are provided between the first production pipeline and the fluid recovery container.

[0020] In an embodiment of the present invention, the confining pressure application mechanism includes a confining pressure pump, which is connected to the confining pressure chamber via a confining pressure injection pipe. The output end of the confining pressure pump is provided with a fourth pressure monitoring structure, which is used to monitor the confining pressure applied by the confining pressure application mechanism.

[0021] This invention also provides a three-dimensional simulation experiment method for a gas storage facility, using the aforementioned three-dimensional simulation experiment device for a gas storage facility. The experiment method includes the following steps: detecting the sealing performance of the three-dimensional simulation experiment device for the gas storage facility; the confining pressure application mechanism slowly pressurizes the pressure in the confining pressure chamber to the formation pressure; the injection structure injects water and natural gas from the injection-production simulation well into the three-dimensional model of the gas storage facility until the three-dimensional model of the gas storage facility reaches the state before the construction of the gas storage facility; the injection-production mechanism performs multiple cycles of gas injection and production, and the first pressure monitoring structure monitors the pressure change of the monitoring simulation well during the gas injection and production period; based on the pressure change of the monitoring simulation well, the parameters of the injection-production mechanism are optimized; wherein, the optimized parameters include one or more of the following: gas injection rate, gas injection pressure, gas production rate, gas production pressure, and injection-production mode.

[0022] The features and advantages of this invention are:

[0023] The three-dimensional model of the gas storage facility of the present invention uses a simulated surrounding rock layer to cover the gas storage mass and place it together in the confining pressure cavity of the clamping device. This allows the gas storage mass to simulate an underground gas reservoir, while the simulated surrounding rock layer simulates a surrounding rock layer that can prevent gas leakage, thus achieving a more realistic simulation of the underground gas storage facility. By setting up a monitoring simulation well extending into the simulated surrounding rock layer, the pressure of the simulated surrounding rock layer can be monitored to determine whether leakage has occurred, thereby accurately evaluating the sealing performance of the surrounding rock layer during the operation of the gas storage facility.

[0024] The method for creating a three-dimensional model of a gas storage facility according to the present invention involves first creating a storage mass, and then directly creating an artificial surrounding rock core on the storage mass based on the pore structure of the real surrounding rock layer. This forms a simulated surrounding rock layer that covers the storage mass, ensuring that the simulated surrounding rock layer and the storage mass are connected as a whole, rather than being two separate parts. This ensures that the stress of the simulated surrounding rock layer and the storage mass is mutually restrictive and mutually influential during the injection and production process, thereby taking into account the influence of the surrounding rock and achieving a more realistic simulation of the underground gas storage facility.

[0025] The three-dimensional simulation experimental device and method for gas storage of the present invention utilize a three-dimensional model of the gas storage for simulation experiments. On the one hand, it can realistically consider the impact of the surrounding rock layer on the gas storage when simulating the injection and production seepage of the gas storage. On the other hand, it can monitor the pressure of the simulated well through the first pressure monitoring structure to determine whether leakage occurs in the simulated surrounding rock layer, thereby evaluating the sealing performance of the gas storage during high-speed injection and production. Furthermore, it can optimize the parameters of the injection mechanism based on the pressure changes of the simulated well during gas injection and production, thereby simulating and obtaining the optimal injection and production gas volume and pressure under the condition that the surrounding rock layer will not leak, providing a theoretical basis for the design of the storage capacity parameters of the gas storage. Attached Figure Description

[0026] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0027] Figure 1 This is a schematic diagram of the three-dimensional model of the gas storage facility in this invention.

[0028] Figure 2 This is a schematic diagram of the structure of a three-dimensional simulation experimental device for a gas storage tank according to an embodiment of the present invention.

[0029] Figure 3 This is a schematic diagram of the structure of a three-dimensional simulation experimental device for a gas storage tank according to another embodiment of the present invention.

[0030] In the picture:

[0031] 100. Three-dimensional model of the gas storage facility; 1. Storage mass; 2. Surrounding rock simulation layer; 3. Elastic layer; 4. Clamping device; 5. Injection-production simulation well; 5'. Injection-production simulation well; 6. Monitoring simulation well; 7. Confining pressure injection pipe;

[0032] 8. Injection pump; 9. Natural gas tank; 10. Formation water tank; 11. Injection and production control valve; 12. First production pipeline;

[0033] 13. Second production pipeline; 14. Fluid recovery container; 15. Back pressure pump; 16. First pressure monitoring structure;

[0034] 17. Second pressure monitoring structure; 18. Third pressure monitoring structure; 19. Fourth pressure monitoring structure; 20. Confining pressure pump; 21. First mass flow meter; 22. Second mass flow meter. Detailed Implementation

[0035] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0036] Implementation Method 1

[0037] like Figure 1As shown, the present invention provides a three-dimensional model 100 of a gas storage facility, comprising: a clamp 4 having a confining pressure cavity inside; a reservoir 1 for simulating a real reservoir, the reservoir 1 being located within the confining pressure cavity; a surrounding rock simulation layer 2 covering the reservoir 1 and located within the confining pressure cavity; at least one injection-production simulation well 5 penetrating the clamp 4 and the surrounding rock simulation layer 2, identical to the reservoir 1; and at least one monitoring simulation well 6 penetrating the clamp 4 and extending into the surrounding rock simulation layer 2.

[0038] The three-dimensional model 100 of the gas storage facility of the present invention uses a surrounding rock simulation layer 2 to cover the storage mass 1 and place them together in the confining pressure cavity of the clamp 4. This allows the storage mass 1 to simulate an underground gas reservoir, and the surrounding rock simulation layer 2 to simulate a surrounding rock layer that can prevent gas leakage, thus achieving a more realistic simulation of the underground gas storage facility. By setting a monitoring simulation well 6 that extends into the surrounding rock simulation layer 2, the pressure of the surrounding rock simulation layer 2 can be monitored to determine whether leakage has occurred, so as to accurately evaluate the sealing performance of the surrounding rock layer during the operation of the gas storage facility.

[0039] Specifically, the shape of reservoir 1 is not specifically limited and can be set according to the shape of the actual reservoir, as long as the shape factor η of the two is similar. The expression for the shape factor η is η = b / a, where b is the height dimension and a is the length dimension. In some embodiments of the present invention, reservoir 1 is generally cubic with a side length of 10cm-30cm. In other embodiments of the present invention, reservoir 1 is generally elliptical. The injection-production simulation well 5 being the same as reservoir 1 means that the bottom of injection-production simulation well 5 is in contact with the surface of reservoir 1 and directly communicates with the pore structure of reservoir 1, or it can directly extend into the interior of reservoir 1.

[0040] The pore structure of reservoir 1 is fabricated based on the pore structure of the actual reservoir. Reservoir 1 can be an artificial reservoir core with the same pore structure as the actual reservoir. This avoids the difficulty of obtaining a real reservoir core with the desired pore structure during actual core sampling, especially for fractured-vuggy reservoirs where large fractures and cavities are unavailable. Furthermore, since cores from real reservoirs are typically cylindrical with a diameter of approximately 5-6 cm, it is impossible to fabricate a large reservoir 1 for experiments. Of course, if the required model size for the experiment is not too large, a real reservoir core taken from the actual reservoir can be used as reservoir 1. The material for the surrounding rock simulation layer 2 is selected based on the properties of the gas storage's capping and bottom layers, including but not limited to gypsum. The pore structure of the surrounding rock simulation layer 2 is fabricated based on the pore structure of the capping and bottom layers. The specific fabrication methods for reservoir 1 and surrounding rock simulation layer 2 are described in Implementation Method Two and will not be detailed here.

[0041] In an embodiment of the present invention, the three-dimensional model 100 of the gas storage tank further includes an elastic layer 3 and a confining pressure injection pipe 7. The elastic layer 3 covers the surrounding rock simulation layer 2, and the confining pressure injection pipe 7 connects the gap between the elastic layer 3 and the clamp 4. Liquid is injected into the gap between the elastic layer 3 and the clamp 4 through the confining pressure injection pipe 7, thereby applying confining pressure to the surrounding rock simulation layer 2 and the storage tank 1 within the confining pressure cavity.

[0042] Specifically, the surrounding rock simulation layer 2 is spherically wrapped around the reservoir 1, and the clamping device 4 is spherically clamped onto the surrounding rock simulation layer 2. By setting the confining pressure simulation layer and the clamping device 4 into spherical shapes, three-dimensional loading of the surrounding rock simulation layer 2 in the confining pressure cavity is achieved, more realistically restoring the formation stress, thereby improving the accuracy of the simulation experiment results. After the surrounding rock simulation layer 2 wraps around the reservoir 1, it is roughly a sphere with a diameter of 1m. The elastic layer 3 is made of a high-temperature and high-pressure resistant elastic material; for example, the elastic layer 3 can be a rubber sleeve.

[0043] In this embodiment of the invention, there are multiple injection-production simulation wells 5, which are injection-production pipe fittings made of high-temperature and high-pressure materials (such as steel). By setting multiple injection-production simulation wells 5, simulations of different injection-production modes such as one injection and one production, simultaneous injection and production, and one injection and multiple production can be achieved. There are multiple monitoring simulation wells 6, which are monitoring pipe fittings made of high-temperature and high-pressure materials (such as steel). By setting multiple monitoring simulation wells 6, the sealing performance at different locations in the surrounding rock simulation layer 2 can be monitored during the injection-production process. Specifically, there are four injection-production simulation wells 5, which are evenly distributed around the reservoir 1 along the circumference of the reservoir 1. The clamp 4 is provided with injection-production holes for the injection-production pipe fittings to extend from the confining pressure chamber. There are four monitoring simulation wells 6. The clamp 4 is provided with monitoring holes for monitoring the pipe fittings to extend from the confining pressure chamber. The injection-production holes and injection-production pipe fittings, as well as the monitoring holes and monitoring pipe fittings, can all be fixed on the clamp 4 by threaded connection.

[0044] Implementation Method 2

[0045] like Figure 1As shown, the present invention also provides a method for fabricating a three-dimensional model 100 of a gas storage facility, comprising the following steps: fabricating an artificial reservoir core based on the shape and pore structure of a real reservoir, the artificial reservoir core forming a reservoir mass 1; or extracting a real reservoir core from a real reservoir, the real reservoir core forming a reservoir mass 1; fabricating an artificial surrounding rock core on the reservoir mass 1 based on the pore structure of the real surrounding rock layer, and having the artificial surrounding rock core cover the reservoir mass 1, thereby forming a simulated surrounding rock layer 2; wherein, At least one injection-production channel and at least one monitoring channel are reserved on the surrounding rock simulation layer 2; one end of at least one injection-production pipe is extended from at least one injection-production channel to the periphery of the reservoir 1 to form at least one injection-production simulation well 5; one end of at least one monitoring pipe is extended from at least one monitoring channel into the surrounding rock simulation layer 2 to form at least one monitoring simulation well 6; the surrounding rock simulation layer 2 containing the reservoir 1 is placed into the confining pressure cavity of the clamp 4, and the other end of the injection-production pipe and the other end of the monitoring pipe extend from the injection-production hole and monitoring hole provided on the clamp 4. The specific structure, working principle and beneficial effects of the gas storage three-dimensional model 100 in this embodiment are the same as those of the gas storage three-dimensional model 100 in Embodiment 1, and will not be repeated here.

[0046] The method for manufacturing a three-dimensional model 100 of a gas storage facility of the present invention involves first creating a storage mass 1, and then directly cementing an artificial surrounding rock core onto the storage mass 1 based on the pore structure of the real surrounding rock layer, thereby forming a surrounding rock simulation layer 2 that covers the storage mass 1. This ensures that the surrounding rock simulation layer 2 and the storage mass 1 are connected as a whole, rather than being two separate parts. This allows the stresses of the surrounding rock simulation layer 2 and the storage mass 1 to mutually restrict and influence each other during the injection and production process, thus taking into account the influence of the surrounding rock and achieving a more realistic simulation of the underground gas storage facility.

[0047] In an embodiment of the present invention, an artificial reservoir core is prepared based on the shape and pore structure of a real reservoir, comprising the following steps: obtaining the shape characteristics of the real reservoir and the distribution characteristics of small fractures and large cavities; determining the shape of the artificial reservoir core based on the shape characteristics of the real reservoir; scanning the pore structure of the real reservoir core extracted from the real reservoir and performing three-dimensional modeling of the pore structure of the real reservoir core to obtain a three-dimensional data volume of the pore structure of the real reservoir core; and processing the three-dimensional data volume of the pore structure of the real reservoir core into a model based on the shape of the artificial reservoir core. The artificial reservoir core is assembled into its shape and enlarged proportionally to obtain the first three-dimensional data volume of the artificial reservoir core. Based on the distribution characteristics of small fractures and karst caves, proportionally reduced three-dimensional data volumes of small fractures and karst caves are inserted into the first three-dimensional data volume of the artificial reservoir core to obtain the second three-dimensional data volume of the artificial reservoir core with pores, cavities, and fractures. Based on the second three-dimensional data volume of the artificial reservoir core, an artificial reservoir core is replicated proportionally using 3D printing, laser engraving, or sandstone cementation, so that the artificial reservoir core forms a reservoir mass 1.

[0048] The shape characteristics of the actual reservoir, as well as the distribution characteristics of small fractures and large karst caves, can be obtained through three-dimensional seismic interpretation of the gas reservoir. Micron-level CT, nano-level CT, and focused ion beam scanning electron microscopy (FIB-SEMCT) can be used to scan the pore structure of the actual reservoir core. Then, a three-dimensional model of the pore structure of the actual reservoir core is created using digital core software or by self-programming, resulting in a three-dimensional data volume of the pore structure of the actual reservoir core. In this embodiment of the invention, the first three-dimensional data volume of the artificial reservoir core is a cubic artificial core three-dimensional data volume with a side length of 10cm-30cm. Furthermore, if the actual reservoir has good physical properties and is relatively homogeneous, fractures and cavities can be disregarded. That is, it is not necessary to insert proportionally scaled-down three-dimensional data volumes of small fractures and karst caves into the first three-dimensional data volume of the artificial reservoir core to obtain the second three-dimensional data volume of the artificial reservoir core. Instead, the artificial reservoir core, i.e., reservoir volume 1, can be directly replicated proportionally based on the first three-dimensional data volume of the artificial reservoir core.

[0049] In an embodiment of the present invention, the real surrounding rock layer includes a caprock layer covering the real reservoir and a bottom support layer located below the real reservoir; an artificial surrounding rock core is prepared on reservoir 1 based on the pore structure of the real surrounding rock layer, including the following steps: obtaining the distribution characteristics of faults and fractures present in the caprock layer and the bottom support layer; scanning the pore structure of the caprock core and the bottom support core taken from the bottom support layer, performing three-dimensional modeling of the pore structure of the caprock core and the bottom support core, obtaining three-dimensional data volumes of the pore structure of the caprock core and the bottom support core; and processing the pore structure of the caprock core. The three-dimensional data volume of the structure and the three-dimensional data volume of the pore structure of the bottom support rock core are spliced ​​into a sphere and enlarged proportionally to obtain the first three-dimensional data volume of the artificial surrounding rock core. According to the distribution characteristics of faults and fractures, the three-dimensional data volumes of faults and fractures of proportional reduction are inserted into the first three-dimensional data volume of the artificial surrounding rock core to obtain the second three-dimensional data volume of the artificial surrounding rock core. Based on the second three-dimensional data volume of the artificial surrounding rock core, the artificial surrounding rock core is replicated proportionally on reservoir 1 by means of 3D printing, laser engraving or sandstone cemented artificial core, thereby forming the surrounding rock simulation layer 2 that covers reservoir 1.

[0050] The distribution characteristics of faults and fractures in the overburden and base layers can be obtained by integrating the results of 3D seismic interpretation and well logging interpretation. Micron-CT, nano-CT, and focused ion beam scanning electron microscopy (FIB-SEMCT) can be used to scan the pore structure of the overburden and base layer cores. Then, 3D models of the pore structure of the overburden and base layer cores can be created using digital core software or by self-programming, resulting in 3D data volumes of the pore structure of both the overburden and base layer cores.

[0051] Implementation Method 3

[0052] like Figure 2 and Figure 3 As shown, the present invention also provides a three-dimensional simulation experimental device for a gas storage facility, comprising: a three-dimensional model 100 of the gas storage facility; a constant temperature chamber in which the three-dimensional model 100 of the gas storage facility is placed; an injection and production mechanism, including an injection structure and a production structure connected to the injection and production simulation well; a confining pressure application mechanism connected to the surrounding rock cavity; and a first pressure monitoring structure 16 for monitoring the pressure of the monitoring simulation well 6. In this embodiment, the three-dimensional model 100 of the gas storage facility has the same specific structure, working principle, and beneficial effects as the three-dimensional model 100 of the gas storage facility in Embodiment 1, and will not be described again here.

[0053] The three-dimensional model 100 of the gas storage tank is used to simulate a gas storage tank with surrounding rock layers; the constant temperature chamber is used to keep the three-dimensional model 100 of the gas storage tank at a high temperature to simulate the high temperature state of the real strata; the confining pressure application mechanism is used to inject liquid into the confining pressure cavity, thereby applying confining pressure around the surrounding rock simulation layer 2, and realistically simulating the impact of the surrounding rock confining pressure on the reservoir; the injection structure and the production structure are connected to the injection-production simulation well 5 and / or the injection-production simulation well 5', thereby performing injection-production simulation on the three-dimensional model 100 of the gas storage tank; the pressure of the monitoring simulation well 6 is monitored by the first pressure monitoring structure 16 to realize the pressure monitoring of the surrounding rock simulation layer 2; the pressure in the injection-production simulation well 5 is monitored by the second pressure monitoring structure 17 to realize the pressure monitoring of the reservoir 1.

[0054] The three-dimensional simulation experimental device for gas storage of the present invention uses a three-dimensional model 100 of the gas storage for simulation experiments. On the one hand, it can realistically consider the impact of the surrounding rock layer on the gas storage when simulating the injection and production seepage of the gas storage. On the other hand, it can monitor the pressure of the simulated well 6 through the first pressure monitoring structure 16 to determine whether the surrounding rock simulated layer 2 has leaked, thereby evaluating the sealing performance of the gas storage during high-speed injection and production. Furthermore, it can optimize the parameters of the injection and production mechanism based on the pressure changes of the simulated well 6 and the injection and production simulated well 5 during the gas injection and production period. This allows for the simulation to obtain the optimal injection and production rate and pressure under the condition that the surrounding rock layer will not leak, providing a theoretical basis for the design of the storage capacity parameters of the gas storage.

[0055] In embodiments of the present invention, the injection and production mechanism includes multiple control valves installed on multiple injection and production pipe fittings to control multiple injection and production simulation wells 5 and 5' to combine into different injection and production modes. Taking the four injection and production simulation wells in this embodiment as an example, the injection and production modes include simultaneous injection and production, one injection and one production, two injections and two productions, three injections and one production, and one injection and three productions.

[0056] The injection structure includes a natural gas tank, a formation water tank 10, and an injection pump 8. The injection pump 8 injects natural gas from the natural gas tank and / or water from the formation water tank 10 into the three-dimensional model 100 of the gas storage facility from the injection-production simulation well 5. The injection structure is connected to the injection-production simulation well 5 via an injection-production control valve 11. The production structure includes a first production pipeline 12, a second production pipeline 13, and a fluid recovery container 14. The input end of the first production pipeline 12 is connected to at least one injection-production simulation well 5', and the output end of the first production pipeline 12 is connected to the fluid recovery container 14. The input end of the second production pipeline 13 is connected to at least another injection-production simulation well 5 via the injection-production control valve 11, and the output end of the second production pipeline 13 is connected to the fluid recovery container 14 via the first production pipeline 12. The injection-production control valve 11 is equipped with a second pressure monitoring structure 17. Natural gas is injected into the gas storage 3D model 100 by connecting natural gas tank 9 to injection-production simulation well 5 via injection-production control valve 11. Similarly, formation water tank 10 is connected to injection-production simulation well 5 via injection-production control valve 11, allowing water to be injected into the gas storage 3D model 100. A fluid recovery container 14 is used to recover fluid flowing out of the first production pipeline 12 during the injection-production process. Injection-production pressure is monitored by a second pressure monitoring structure 17.

[0057] Specifically, injection pump 8 is connected to natural gas tank 9 and formation water tank 10, respectively. Natural gas tank 9 and formation water tank 10 are connected to two ports of injection-production control valve 11 via pipelines. Injection-production control valve 11 also has two other ports connected to injection-production simulation well 5 and the second production pipeline 13, respectively. During single-injection-one-production or multiple-injection-multiple-production operations, one or more injection-production simulation wells 5 are connected to the injection structure via injection-production control valve 11 to form one or more injection wells, and another one or more injection-production simulation wells 5' are connected to the first production pipeline 12 to form one or more production wells. During simultaneous injection and production, during injection, one injection-production simulation well 5 is connected to the injection structure via injection-production control valve 11; during production, the same injection-production simulation well 5 is connected to the second production pipeline 13 via injection-production control valve 11.

[0058] In addition, a first mass flow meter 21 is provided between the injection-production control valve 11 and the injection-production simulation well 5 to control the injection speed of the injection structure. In one embodiment of the present invention, a second mass flow meter 22 is provided between the first production pipeline 12 and the fluid recovery container 14 to control the production speed. By controlling the gas production speed, the purpose of constant-speed gas production can be achieved, and the production speed can also be changed at any time. In another embodiment of the present invention, a third pressure monitoring structure 18 and a back pressure pump 15 are provided between the first production pipeline 12 and the fluid recovery container 14 to form a preset pressure at the production end, thereby controlling the gas production pressure to achieve the purpose of constant-pressure gas production, and the production pressure can also be changed at any time.

[0059] In an embodiment of the present invention, the confining pressure application mechanism includes a confining pressure pump 20, which is connected to the confining pressure chamber via a confining pressure injection pipe 7. The output end of the confining pressure pump 20 is provided with a fourth pressure monitoring structure 19, which is used to monitor the confining pressure applied by the confining pressure application mechanism.

[0060] The first pressure monitoring structure 16 includes multiple first pressure gauges installed on multiple monitoring pipe fittings. The second pressure monitoring structure 17 includes a second pressure gauge installed on the injection-production control valve 11. The third pressure monitoring structure 18 includes a third pressure gauge installed between the back pressure pump 15 and the first production pipeline 12. The fourth pressure monitoring structure 19 includes a fourth pressure gauge installed on the confining pressure injection pipe 7. Furthermore, the three-dimensional simulation experimental device for the gas storage also includes a fifth pressure monitoring structure, which includes multiple fifth pressure gauges installed on multiple injection-production pipe fittings. This allows for pressure monitoring of different locations within the gas storage unit 1 by monitoring the pressure of different injection-production pipe fittings. All the first, second, third, fourth, and fifth pressure gauges are electrically connected to a processing terminal. The processing terminal processes the pressure monitoring signals obtained from the first, second, third, fourth, and fifth pressure gauges to generate pressure information.

[0061] Implementation Method 4

[0062] like Figure 2 and Figure 3 As shown, the present invention also provides a three-dimensional simulation experiment method for gas storage, which uses a three-dimensional simulation experiment device for gas storage. The specific structure, working principle and beneficial effects of the three-dimensional simulation experiment device for gas storage in this embodiment are the same as those in embodiment three, and will not be repeated here.

[0063] The three-dimensional simulation experimental method for gas storage tanks of the present invention includes the following steps:

[0064] Step S1: Check the airtightness of the three-dimensional simulation experimental device for the gas storage tank.

[0065] Specifically, the purpose of checking the sealing performance is to verify whether the 3D model 100 of the gas storage facility and the injection / production mechanism are properly connected and whether there are any leaks. Preferably, the sealing performance testing method is as follows: First, pressurize the 3D model 100 of the gas storage facility to a first preset pressure. Then, inject gas at a second preset pressure into each connecting pipeline of the injection / production mechanism and the 3D model 100 of the gas storage facility. After the pressure balances, close the injection / production control valve 11 and observe whether the pressure of each pressure gauge changes. If it changes, it indicates a leak. Check the sealing performance of each part one by one and correct it. The first preset pressure should be 2-3 MPa higher than the second preset pressure; for example, the first preset pressure could be 5 MPa and the second preset pressure could be 3 MPa.

[0066] Step S2: The confining pressure application mechanism slowly increases the pressure in the confining pressure chamber to the formation pressure.

[0067] Specifically, a confining pressure pump 20 is used to inject liquid (such as water) into the three-dimensional model 100 of the gas storage and pressurize it to the formation pressure, such as 20 MPa. Its function is to simulate the original pressure of the formation at the far end of the gas storage.

[0068] Step S3: The injection structure injects formation water and natural gas from injection-production simulation well 5 into reservoir 1 until reservoir 1 reaches the state before the gas storage facility is built.

[0069] Specifically, water and natural gas are injected to bring the 3D model 100 of the gas storage facility to the state before the construction of the gas reservoir in the later stages of development. The purpose is that before construction, the gas storage facility is generally a depleted oil and gas reservoir. If it is a gas reservoir, there will be remaining natural gas and formation water. Therefore, to restore the initial state before gas injection and production, natural gas and water need to be injected. The method to determine whether the 3D model 100 of the gas storage facility has reached the state before the construction of the gas reservoir in the later stages of development is as follows: First, water is injected to saturate the water in the reservoir 1. Gas is injected using a one-inject-one-production method until no water is produced. Gas injection continues until the pressure is consistent with the pressure of the oil and gas reservoir before construction, which is generally 2MPa-3MPa. Gas injection is stopped after the pressure stabilizes.

[0070] Step S4: The injection and production structures perform multiple cycles of gas injection and production. The first pressure monitoring structure 16 monitors the pressure changes of the injection and production simulation well 5 during the gas injection and production period.

[0071] The specific gas injection method is as follows: the natural gas tank 9 and a simulated injection well 5 are connected through the injection-production control valve 11, so that the simulated injection well 5 is used as the injection well. Then, natural gas is injected into the reservoir 1 using the injection pump 8. Constant pressure injection or constant injection speed controlled by the first mass flow meter 21 is selected until the injection reaches 2MPa-3MPa lower than the original formation pressure and then the injection stops. The pressure changes at the wellhead of the simulated injection well 5 and the wellheads of the other simulated injection wells 5' are monitored. When the gas diffuses through the reservoir 1 to the wellheads of the other simulated injection wells 5', that is, the pressure at the wellhead of the simulated injection well 5 decreases while the pressure at the wellheads of the other simulated injection wells 5' increases, the injection continues until the pressure of the entire reservoir 1 stabilizes.

[0072] If the injection and extraction are carried out simultaneously, during gas extraction, the injection and extraction simulation well 5 and the second extraction pipeline 13 are connected through the injection and extraction control valve 11, so that the gas is extracted from the injection and extraction simulation well 5 through the second extraction pipeline 13, and the back pressure pump 15 is used to extract gas at a constant pressure, or the extraction speed is controlled by the second mass flow meter 22. If the injection and extraction are carried out one injection at a time, during gas extraction, the control valve on the injection and extraction simulation well 5' connected by the first extraction pipeline 12 is opened to extract gas. In addition, during the injection and extraction, the pressure of the confining pressure simulation layer is monitored in real time by the first pressure monitoring structure 16, and the injection speed and injection volume are monitored in real time by the first mass flow meter 21, and the extraction speed and extraction volume are monitored by the second mass flow meter 22.

[0073] Step S5: Optimize the parameters of the injection-production mechanism based on the pressure changes in the simulated well 6. The optimized parameters include one or more of the following: injection rate, injection pressure, production rate, production pressure, and injection-production mode.

[0074] Specific parameter optimizations are shown in the following examples:

[0075] In one embodiment, the optimized parameters are the gas injection rate and the gas injection pressure: using the first mass flow meter 21, different gas injection rates and pressures are designed for experiments, and the pressure values ​​of the injection and production simulation wells 5 around the reservoir 1 are recorded. If the pressure value does not exceed the original formation pressure and the monitoring simulation well 6 does not detect the sealing failure of the surrounding rock simulation layer 2, the optimal gas injection rate and pressure are selected to quickly fill the gas reservoir.

[0076] In another embodiment, the optimized parameters are gas extraction rate and gas extraction pressure: experiments are conducted at different gas extraction rates and / or gas extraction pressures to select the optimal gas extraction rate and gas extraction pressure, which can ensure a long stable production time for the gas storage facility and meet a large gas production demand.

[0077] In another embodiment, the optimized parameter is the injection-production mode: different injection-production simulation wells 5 and 5' are combined for gas injection and production, and the mode that can achieve rapid injection and production effect is selected. In the embodiment of the present invention, the three-dimensional model 100 of the gas storage has four injection-production simulation wells, which are subjected to different injection-production modes, such as one injection and one production, two injections and two productions, one injection and three productions, and simultaneous injection and simultaneous production, etc., and the mode that can achieve rapid injection and production effect is selected.

[0078] like Figure 2 As shown, in this embodiment, it aims to achieve constant-rate injection and extraction by controlling the injection and extraction speed. For example... Figure 3As shown, in another embodiment, constant pressure injection and production is achieved by controlling the injection and production pressure. Specifically, when the control valve on the injection and production simulation well 5' connected to the first production pipeline 12 is opened, and the second production pipeline 13 is disconnected from the injection and production control valve 11, it is an injection and production mode of one injection and one production; when the control valve on the injection and production simulation well 5' connected to the first production pipeline 12 is closed, and the second production pipeline 13 is connected to the injection and production control valve 11, and gas is produced from the second production pipeline 13, it is an injection and production mode of simultaneous injection and production.

[0079] The above descriptions are merely a few embodiments of the present invention. Those skilled in the art can make various modifications or variations to the embodiments of the present invention based on the content disclosed in the application documents without departing from the spirit and scope of the present invention.

Claims

1. A method for creating a three-dimensional model of a gas storage facility, characterized in that, The three-dimensional model of the gas storage facility includes: The clamp has an internal pressure chamber; A reservoir mass is used to simulate a real reservoir, and the reservoir mass is located within the confining pressure cavity; The surrounding rock simulation layer covers the reservoir and is located within the confining pressure cavity; At least one injection-production simulation well penetrates the clamp and the surrounding rock simulation layer and communicates with the reservoir; At least one monitoring simulation well extends through the clamp into the surrounding rock simulation layer; The method for creating the three-dimensional model of the gas storage facility includes the following steps: Artificial reservoir cores are prepared based on the shape and pore structure of the real reservoir, and the artificial reservoir cores form the reservoir mass; or a real reservoir core is taken from the real reservoir, and the real reservoir core forms the reservoir mass. Based on the pore structure of the real surrounding rock layer, an artificial surrounding rock core is prepared on the reservoir, and the artificial surrounding rock core is used to cover the reservoir to form the surrounding rock simulation layer; wherein, at least one injection-production channel and at least one monitoring channel are reserved on the surrounding rock simulation layer. One end of at least one injection / production pipe is extended from at least one of the injection / production channels to the vicinity of the reservoir to form at least one injection / production simulation well; One end of at least one monitoring pipe is extended from at least one of the monitoring channels into the surrounding rock simulation layer to form at least one monitoring simulation well; The simulated surrounding rock layer containing the reservoir is placed into the confining pressure cavity of the clamp, and the other end of the injection-production pipe and the other end of the monitoring pipe extend out from the injection-production hole and monitoring hole provided on the clamp.

2. The method for creating a three-dimensional model of a gas storage facility according to claim 1, characterized in that, The three-dimensional model of the gas storage facility also includes an elastic layer and a confining pressure injection pipe. The elastic layer covers the surrounding rock simulation layer, and one end of the confining pressure injection pipe extends through the clamp to the gap between the elastic layer and the clamp.

3. The method for creating a three-dimensional model of a gas storage facility according to claim 1, characterized in that, The surrounding rock simulation layer is spherically wrapped around the reservoir, and the clamp is spherically clamped onto the surrounding rock simulation layer.

4. The method for creating a three-dimensional model of a gas storage facility according to claim 1, characterized in that, The number of injection-production simulation wells is multiple, and the injection-production simulation wells are injection-production pipe fittings made of high-temperature and high-pressure materials.

5. The method for creating a three-dimensional model of a gas storage facility according to claim 1, characterized in that, The number of monitoring simulation wells is multiple, and the monitoring simulation wells are monitoring pipe fittings made of high-temperature and high-pressure materials.

6. The method for creating a three-dimensional model of a gas storage facility according to claim 1, characterized in that, The process of preparing artificial reservoir cores based on the shape and pore structure of real reservoirs includes the following steps: The shape characteristics of the actual reservoir and the distribution characteristics of small fractures and large caverns were obtained; The shape of the artificial reservoir core is determined based on the shape characteristics of the real reservoir. The pore structure of the real reservoir core extracted from the real reservoir is scanned, and a three-dimensional model of the pore structure of the real reservoir core is performed to obtain a three-dimensional data volume of the pore structure of the real reservoir core. Based on the shape of the artificial reservoir core, the three-dimensional data volume of the pore structure of the real reservoir core is stitched together to form the shape of the artificial reservoir core and enlarged proportionally to obtain the first three-dimensional data volume of the artificial reservoir core; Based on the distribution characteristics of small fractures and karst caves, proportionally scaled-down three-dimensional data volumes of small fractures and karst caves are inserted into the first three-dimensional data volume of the artificial reservoir core to obtain the second three-dimensional data volume of the artificial reservoir core with a triple medium of pores, cavities, and fractures. Based on the second three-dimensional data volume of the artificial reservoir core, the artificial reservoir core is replicated in proportion by means of 3D printing, laser engraving or sandstone cementation, so that the artificial reservoir core forms the reservoir mass.

7. The method for creating a three-dimensional model of a gas storage facility according to claim 1, characterized in that, The actual surrounding rock layer includes a cover layer overlying the actual reservoir and a bottom support layer located below the actual reservoir; The process of preparing an artificial surrounding rock core on the reservoir based on the pore structure of the real surrounding rock includes the following steps: The distribution characteristics of faults and cracks in the covering layer and the base layer are obtained; The pore structure of the overburden core and the bottom support core extracted from the bottom support layer are scanned, and the pore structure of the overburden core and the bottom support core are modeled in three dimensions to obtain the three-dimensional data volume of the pore structure of the overburden core and the three-dimensional data volume of the pore structure of the bottom support core. The three-dimensional data volume of the pore structure of the overburden core and the three-dimensional data volume of the pore structure of the bottom support core are spliced ​​into a sphere and enlarged proportionally to obtain the first three-dimensional data volume of the artificial surrounding rock core. Based on the distribution characteristics of faults and fractures, a proportionally scaled-down three-dimensional data volume of faults and fractures is inserted into the first three-dimensional data volume of the artificial surrounding rock core, thereby obtaining the second three-dimensional data volume of the artificial surrounding rock core. Based on the second three-dimensional data volume of the artificial surrounding rock core, the artificial surrounding rock core is replicated on the reservoir in proportion by means of 3D printing, laser engraving or sandstone cemented artificial core, thereby forming the surrounding rock simulation layer that covers the reservoir.

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