Experimental device and method for proppant embedding depth under action of carbon dioxide
By designing an experimental device to simulate the proppant embedding process under the action of carbon dioxide and shale, the problem of measuring the proppant embedding depth under the carbon dioxide phase in the existing technology was solved, and accurate measurement was achieved in the actual oil and gas extraction environment.
Patent Information
- Application Number
- CN202410862217.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-06-28
- Publication Date
- 2025-12-30
AI Technical Summary
Existing technologies cannot measure the proppant embedding depth in shale in real time while controlling the carbon dioxide phase, and CT scans are complex and expensive, making it impossible to simulate the proppant embedding process under the interaction of carbon dioxide and shale.
Design an experimental device including an experimental sleeve, an extrusion assembly, a gas supply assembly, an insulation assembly, and a loading assembly. By controlling the phase state and stress conditions of carbon dioxide, the embedding depth of the proppant is measured in real time to simulate the actual oil and gas extraction environment.
This invention enables the measurement of proppant embedding depth under controlled carbon dioxide phase, solving the problem of inaccurate evaluation of proppant embedding depth in existing technologies and improving measurement accuracy and economy.
Smart Images
Figure CN121229080A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of oil and gas reservoir fracturing technology, specifically to an experimental apparatus and a method for measuring the proppant embedding depth under the action of carbon dioxide. Background Technology
[0002] In the development of unconventional oil and gas reservoirs, hydraulic fracturing is a key technology for enhancing production. By constructing a large-scale, complex fracture network underground and using proppant to fill the fractures and prevent closure, long-term high and stable production of shale oil and gas wells can be ensured. Carbon dioxide, as a high-performance fracturing fluid, has been applied to the fracturing of shale oil and gas reservoirs. Carbon dioxide reacts with shale, altering its mechanical properties and thus affecting proppant embedding during subsequent fracture closure. Proppant embedding also creates micro-fractures on the shale surface, promoting further interaction between carbon dioxide and shale. The degree of interaction between carbon dioxide and shale is closely related to its phase state. In actual oil and gas extraction, carbon dioxide, as a fracturing fluid, enters the shale in a supercritical state due to reservoir temperature and pressure. Accurately evaluating the degree of proppant embedding under the influence of carbon dioxide is crucial for understanding the effectiveness of carbon dioxide fracturing.
[0003] Current technologies only simulate proppant embedding under closure stress. After the experiment, rock samples are removed, and the proppant embedding depth is determined using methods such as 3D laser scanning, scanning electron microscopy image analysis, and surface inverted film 3D microscopy. However, these technologies cannot provide real-time measurement of the proppant embedding process under the coupled conditions of fluid-rock interaction and closure stress. Another technology uses a CT scanner to achieve real-time measurement of proppant embedding depth in fracture conductivity testing, simultaneously considering the coupled effects of closure stress and fluid-rock interaction. However, CT scanning is complex and expensive, and its accuracy is significantly affected by the CT scanner's energy. Furthermore, the experimental setup in this technology cannot control the carbon dioxide phase, therefore, it cannot test the proppant embedding depth under carbon dioxide-shale interaction.
[0004] Therefore, there is an urgent need for a device that can solve at least one of the above problems. Summary of the Invention
[0005] The purpose of this invention is to provide an experimental apparatus and method for measuring the proppant embedding depth under the action of carbon dioxide, in order to solve the problem in the prior art that the proppant embedding depth cannot be obtained while controlling the phase state of carbon dioxide.
[0006] To achieve the above objectives, the present invention provides an experimental apparatus for propellant embedding depth under the action of carbon dioxide, the experimental apparatus comprising: The experimental sleeve is a cylindrical structure with openings at both ends, and a pair of experimental through holes are symmetrically opened on the cylindrical wall of the experimental sleeve; Two extrusion components are embedded in the two open ends of the experimental sleeve. Each extrusion component includes a rock plate that fits the shape of the inner wall of the experimental sleeve. The two rock plates are movably embedded in the experimental sleeve, and a crack is formed between the two rock plates. A pair of experimental through holes communicate with the crack, and proppant is laid in the crack. The gas supply component is connected to the experimental through hole at one end of the fissure to supply carbon dioxide into the fissure, while the experimental through hole at the other end of the fissure serves as an exhaust hole. A thermal insulation component is installed on the outer wall of the experimental sleeve to regulate the temperature inside the experimental sleeve so as to control the carbon dioxide entering the fissure to always be in a supercritical state. A loading component is used to apply pressure to two extrusion components so that the two extrusion components compress the proppant within the fissure.
[0007] Specifically, the experimental apparatus further includes a vent valve, located at the discharge port, for selectively connecting the crack to the outside of the experimental sleeve.
[0008] Specifically, each extrusion assembly further includes a pressure plate that conforms to the shape of the rock slab, the pressure plate being fixed to the side of the rock slab facing away from the fissure.
[0009] Specifically, each extrusion assembly also includes a sealing ring, which is disposed on the pressure plate and is used to seal the gap between the pressure plate and the inner wall of the experimental sleeve.
[0010] Specifically, the gas supply component includes: a gas source, a pressurization unit, and a phase control unit; The gas source is used to supply carbon dioxide; The pressurization unit is connected to the gas source through a pipeline and is used to liquefy the carbon dioxide supplied by the gas source into liquid carbon dioxide and deliver the liquid carbon dioxide to the phase control unit. The phase control unit is connected to the pressurization unit and the experimental through hole at one end of the cylinder wall of the experimental sleeve. The phase control unit is used to heat liquid carbon dioxide to generate carbon dioxide and send it into the fissure.
[0011] Specifically, the pressurization unit includes: a low-temperature bath, an intermediate container, and a constant-speed, constant-pressure pump; The low-temperature bath is connected to the gas source through a pipeline. The low-temperature bath is used to reduce the temperature of the carbon dioxide supplied by the gas source in order to liquefy the carbon dioxide into liquid carbon dioxide. The intermediate container is connected to the cryogenic bath and the phase control unit and is used to store liquid carbon dioxide; The constant speed and constant pressure pump is used to pump the liquid carbon dioxide in the intermediate container to the phase control unit and to boost the pressure of the liquid carbon dioxide pumped to the phase control unit.
[0012] Specifically, the pressurization unit further includes an insulating heat strip covering the intermediate container to prevent the liquid carbon dioxide from exchanging heat with the outside of the intermediate container.
[0013] Specifically, the phase control unit includes: a heating coil and a heater; The heating coil is connected to an experimental through hole at one end of the wall of the intermediate container and the experimental sleeve, and is used to transport pressurized liquid carbon dioxide and gaseous carbon dioxide. The heater is mounted on the heating coil and is used to heat the pressurized liquid carbon dioxide entering the heating coil into gaseous carbon dioxide.
[0014] Specifically, the heat preservation component includes a heating belt, which is wrapped around the outer wall of the experimental sleeve to regulate the temperature inside the experimental sleeve.
[0015] Specifically, the experimental apparatus further includes a temperature controller, electrically connected to the heating belt and the heater, for controlling the opening and closing of the heating belt and the heater.
[0016] Specifically, the loading component includes a pair of loading modules, each loading module being connected to a corresponding extrusion component, and pressure is applied to the two extrusion components through the pair of loading modules.
[0017] Another aspect of the present invention provides an experimental method for determining the proppant embedding depth under the action of carbon dioxide, implemented based on the experimental apparatus for determining the proppant embedding depth under the action of carbon dioxide as described in any of the preceding claims, the experimental method comprising: S1) Two extrusion components are nested in the experimental sleeve, so that a crack is formed between the rock plates of the two extrusion components. A pair of experimental through holes on the wall of the experimental sleeve are connected to the crack. S2) Propionate is laid in the fracture, and a specified pressure is applied to the two extrusion components by the loading component to pre-compress the proppant in the fracture; S3) Adjust the temperature inside the experimental sleeve to ensure that the carbon dioxide entering the fissure is always in a supercritical state. S4) Carbon dioxide is supplied into the fissure through the experimental through hole at one end of the experimental sleeve until the fissure is completely filled with carbon dioxide. The experimental through hole at the other end is then blocked. Carbon dioxide is continuously supplied into the fissure until the carbon dioxide pressure entering the fissure reaches the target pressure. The experimental through hole at the other end of the fissure serves as a discharge hole. S5) After standing for a specified time, pressure is applied to the two extrusion components through the loading component to the target axial stress, so as to extrude the proppant in the crack, and the displacement value of the loading component in the pressure direction and the stress value corresponding to the displacement value are recorded in real time. S6) Open the discharge port to release the carbon dioxide from the fissure; S7) Calculate the proppant embedding depth based on the real-time recorded displacement value, the stress value corresponding to the displacement value, the elastic modulus of the rock slab, and the height of the rock slab.
[0018] The experimental apparatus for measuring the proppant embedding depth under the action of carbon dioxide provided by this invention comprises two extrusion components movably installed within an experimental sleeve open at both ends. A fissure is formed between the rock plates of the two extrusion components, and the fissure is connected to a pair of experimental through holes on the experimental sleeve. Propane is laid in the fissure, and the rock plates of the two extrusion components simulate shale. A gas supply component delivers carbon dioxide as fracturing fluid into the fissure. The carbon dioxide enters the fissure and reacts with the rock plates, and a loading component applies pressure to the rock plates of the two extrusion components, causing the rock plates of the two extrusion components to compress the proppant laid in the fissure. Under the compression of the rock plates, the proppant embeds into the side of the rock plate in contact with the proppant. In order to simulate the actual working state of the carbon dioxide delivered into the fissure, a heat insulation component is set on the outer wall of the experimental sleeve. The heat insulation component controls the carbon dioxide entering the fissure to a supercritical state, thereby simulating the actual working state of carbon dioxide in shale. The experimental apparatus and method for measuring the proppant embedding depth under the action of carbon dioxide provided by this invention can obtain the proppant embedding depth in the rock slab of the extrusion assembly while controlling the carbon dioxide phase, thus solving the problem in the prior art that the proppant embedding depth cannot be obtained while controlling the carbon dioxide phase.
[0019] Other features and advantages of the embodiments of the present invention will be described in detail in the following detailed description section. Attached Figure Description
[0020] The accompanying drawings are provided to further illustrate embodiments of the present invention and form part of the specification. They are used together with the following detailed description to explain the embodiments of the present invention, but do not constitute a limitation thereof. In the drawings: Figure 1 This is a schematic diagram of an experimental apparatus for measuring the proppant embedding depth under the action of carbon dioxide, according to one embodiment of the present invention. Figure 2 This is a schematic diagram of the assembly of the experimental sleeve and extrusion assembly in the experimental apparatus for measuring the proppant embedding depth under the action of carbon dioxide provided by the present invention.
[0021] Explanation of reference numerals in the attached figures 1-Experimental sleeve; 2-Extrusion assembly; 3-Gas supply assembly; 4-Insulation assembly; 5-Loading assembly; 6-Supporting agent; 11-Experimental through hole; 21-Crack; 210-Rock slab; 211-Pressure plate; 213-Sealing ring; 31-Gas source; 32-Pressure booster unit; 33-Phase control unit; 320-Low temperature bath; 321-Intermediate container; 322-Constant speed and constant pressure pump; 330-Heating coil; 331-Heater; 41-Heating belt; 51-Loading module. Detailed Implementation
[0022] The specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are for illustration and explanation only and are not intended to limit the present invention.
[0023] In embodiments of the present invention, unless otherwise stated, directional terms such as "upper," "lower," "top," and "bottom" are generally used to describe the relative positional relationships of components in relation to the directions shown in the accompanying drawings or in relation to the vertical, perpendicular, or gravitational directions.
[0024] Figure 1 This is a schematic diagram of the experimental setup for propellant embedding depth under the action of carbon dioxide; Figure 2 This is a schematic diagram of the assembly of the experimental sleeve and extrusion assembly in the experimental setup for measuring the proppant embedment depth under the action of carbon dioxide.
[0025] like Figures 1-2 As shown, one aspect of the present invention provides an experimental apparatus for determining the proppant embedding depth under the action of carbon dioxide, the experimental apparatus comprising: The experimental sleeve 1 is a cylindrical structure with openings at both ends, and a pair of experimental through holes 11 are symmetrically opened on the cylindrical wall of the experimental sleeve 1. Two extrusion components 2 are embedded in the two open ends of the experimental sleeve 1. Each extrusion component 2 includes a rock plate 210 that fits the shape of the inner wall of the experimental sleeve 1. The two rock plates 210 are movably embedded in the experimental sleeve 1. A crack 21 is formed between the two rock plates 210. A pair of experimental through holes 11 communicate with the crack 21. The proppant 6 is laid in the crack 21. The gas supply component 3 is connected to the fissure 21 through an experimental through hole 11 at one end, and is used to supply carbon dioxide into the fissure 21. The experimental through hole 11 at the other end of the fissure 21 serves as an exhaust hole. The heat insulation component 4 is disposed on the outer wall of the experimental sleeve 1 and is used to adjust the temperature inside the experimental sleeve 1 to control the carbon dioxide entering the crack 21 to always be in a supercritical state. Loading component 5 is used to apply pressure to the two extrusion components 2 so that the two extrusion components 2 extrude the proppant 6 within the fissure 21.
[0026] The experimental apparatus for determining the proppant embedding depth under the action of carbon dioxide provided by this invention, such as... Figures 1-2 As shown, the experimental sleeve 1 is open at both ends. Two rock plates 210 of the two compression components 2 are respectively embedded into the experimental sleeve 1 through the openings at both ends of the experimental sleeve 3. A crack 21 is formed between the rock plates 210 of the two compression components 2. The crack 21 is also connected to two experimental through holes 11 opened on the experimental sleeve 1. Propane 6 is laid in the crack 21. A specified pressure is applied to the rock plates 210 of the two compression components 2 by the loading component 5 to pre-compress the proppane in the crack 21. The loading component 5 is a rock mechanics instrument. The specified pressure is applied by the loading component 5 to... After the proppant is compacted, the gas source assembly 3 supplies carbon dioxide into the fracture 21 through the experimental through-hole 11 at one end. Once the carbon dioxide has filled the entire fracture 21, the experimental through-hole 11 at the other end is sealed. After a specified settling time, for example, 5 days, the loading assembly 5 continues to apply pressure to the rock slabs 210 of the two compression assemblies 2 to the target axial stress, compressing the proppant with greater pressure. During the process of the loading assembly 5 gradually applying pressure to the rock slabs 210 of the two compression assemblies 2 to the target axial stress, the loading assembly 5 records the pressure in real time. The displacement value in the pressure direction and the stress value corresponding to the displacement value are used to simulate the reaction between carbon dioxide and shale in underground shale during oil and gas extraction. In order to make the simulation environment closer to the real underground environment, a heat insulation component 4 is set on the outer wall of the experimental sleeve 2. The temperature inside the experimental sleeve 1 is controlled at the same temperature as the underground shale by the heat insulation component 4. At this temperature, carbon dioxide is in a supercritical state. After the loading component 5 applies pressure to the target axial stress, the experimental through hole 11 at the other end is opened to discharge the carbon dioxide in the fracture 21. The proppant embedding depth is calculated based on the recorded displacement value and corresponding stress value of the loading component 5, the elastic modulus of the rock plate 210 of the compression component 2, and the total height of the rock plates 210 of the two compression components 2 in the pressure direction. This allows the present application to obtain the proppant embedding depth of the rock plate 210 of the compression component 2 under the control of the carbon dioxide phase state, solving the problem in the prior art that it is impossible to obtain the proppant embedding depth under the control of the carbon dioxide phase state.
[0027] To facilitate the discharge of carbon dioxide from another test through-hole 11, the experimental apparatus further includes a vent valve 7, located at the discharge port, for selectively connecting the slit 21 to the outside of the experimental sleeve 1. When the vent valve 7 is closed, the slit 21 is not connected to the outside, and the carbon dioxide inside the slit 21 cannot be discharged. When the vent valve 7 is open, the slit 21 is connected to the outside, and the carbon dioxide inside the slit 21 can be discharged from the test through-hole 11 at the other end.
[0028] In one embodiment, such as Figure 1As shown in Figure 2, in order to simulate real fracturing conditions, each extrusion assembly 2 further includes a pressure plate 211 that conforms to the shape of the rock slab 210, the pressure plate 211 being fixed to the side of the rock slab 210 facing away from the crack 21.
[0029] Each extrusion assembly 2 also includes a sealing ring 213, which is disposed on the pressure plate 211 and is used to seal the gap between the pressure plate and the inner wall of the experimental sleeve 1.
[0030] The rock slabs 210 of the two extrusion components 2 are arranged opposite each other, and a crack 21 is formed between the two rock slabs 210. The rock slabs 210 simulate shale. The pressure plate 211 of each extrusion component 2 is connected to the loading component 5. The pressure applied by the loading component 5 is transmitted to the proppant 6 through the pressure plate 211 and the rock slab 210, avoiding the loading component 5 from directly transmitting pressure to the rock slab 210, which would cause the rock slab 210 to break. When the loading component 5 applies pressure to the two extrusion components 2, the rock slabs of the two extrusion components 2... 210 gradually approaches the extrusion proppant 6; to prevent carbon dioxide from overflowing from the gap between the extrusion assembly 2 and the experimental sleeve 1 when carbon dioxide is subsequently delivered into the crack 21, an annular sealing ring 213 is set between the pressure plate 211 of the extrusion assembly 2 and the inner wall of the experimental sleeve 1. The sealing ring 213 seals the gap between the pressure plate 211 and the inner wall of the experimental sleeve 1 to prevent carbon dioxide from overflowing. The rock plate 210 and the pressure plate 211 fit the shape of the inner wall of the experimental sleeve 1.
[0031] In one embodiment, such as Figure 1 As shown, in order to stably supply carbon dioxide into the fissure 21, the gas supply assembly 3 includes: a gas source 31, a pressurization unit 32, and a phase control unit 33; The gas source 31 is used to supply carbon dioxide; The pressurization unit 32 is connected to the gas source 31 through a pipeline and is used to liquefy the carbon dioxide supplied by the gas source 31 into liquid carbon dioxide and deliver the liquid carbon dioxide to the phase control unit 33. The phase control unit 33 is connected to the pressurization unit 32 and the experimental through hole 11 at one end of the cylinder wall of the experimental sleeve 1. The phase control unit 33 is used to heat liquid carbon dioxide to generate carbon dioxide and send it into the crack 21.
[0032] The pressurization unit 32 includes: a low-temperature bath 320, an intermediate container 321, and a constant-speed and constant-pressure pump 322; The low-temperature bath 320 is connected to the gas source 31 through a pipeline. The low-temperature bath 320 is used to reduce the temperature of the carbon dioxide supplied by the gas source 31 and liquefy the carbon dioxide into liquid carbon dioxide. The intermediate container 321 is connected to the low-temperature bath 320 and the phase control unit 33 via pipes and is used to store liquid carbon dioxide. The constant speed and constant pressure pump 322 is used to pump the liquid carbon dioxide in the intermediate container 321 to the phase control unit 33 and to boost the pressure of the liquid carbon dioxide pumped to the phase control unit 33.
[0033] The pressurization unit 32 further includes an insulating heat strip covering the intermediate container 321 to prevent the liquid carbon dioxide from exchanging heat with the outside of the intermediate container 321.
[0034] The phase control unit 33 includes: a heating coil 330 and a heater 331; The heating coil 330 is connected to the experimental through hole 11 at one end of the wall of the intermediate container 321 and the experimental sleeve 1, and is used to transport pressurized liquid carbon dioxide and gaseous carbon dioxide. The heater 331 is disposed on the heating coil 330, and the heater 331 is used to heat the pressurized liquid carbon dioxide entering the heating coil 330 into gaseous carbon dioxide.
[0035] The gas source 31 stores gaseous carbon dioxide. To ensure a stable supply of carbon dioxide to the fissure 21, the carbon dioxide in the gas source 31 is cooled in the low-temperature bath 320 and then transported to the intermediate container 321. The carbon dioxide in the intermediate container 321 is pressure-balanced with the carbon dioxide in the gas source 31. The carbon dioxide pressure in the gas source 31 is usually 6 MPa. The temperature in the low-temperature bath 320 is controlled at -4℃, which is conducive to rapid pressurization of carbon dioxide in the later stage. Carbon dioxide flows through a cryogenic bath 320 and is cooled to become liquid carbon dioxide. The liquid carbon dioxide is stored in an intermediate container 321. Then, it is pumped by a constant-speed, constant-pressure pump 322 to the heating coil 330 of the phase control unit 33. The liquid carbon dioxide is then boosted by the constant-speed, constant-pressure pump 322 and pumped into the heating coil 330. When the pressurized liquid carbon dioxide flows through the heating coil 330, it is heated by a heater 331 located outside the heating coil 330. The pressurized liquid carbon dioxide is heated to the critical temperature corresponding to the supercritical carbon dioxide state. The heating temperature of the heater 331 is set to 90°C with reference to the formation temperature. The heated carbon dioxide finally enters the fracture 21 through the experimental through-hole 11 at one end. Liquid carbon dioxide is easy to store and pressurize. When the liquid carbon dioxide is stored in the intermediate container 321, in order to avoid the external temperature from affecting the phase state of the carbon dioxide, the outer wall of the intermediate container 321 is wrapped with insulating heat to prevent the liquid carbon dioxide from absorbing external heat and affecting the phase state of the carbon dioxide.
[0036] In order to adjust the temperature inside the experimental sleeve 1 to be close to the temperature of the underground shale during oil and gas extraction, the heat insulation component 4 includes a heating belt 41, which is wrapped around the outer wall of the experimental sleeve 1 to adjust the temperature inside the experimental sleeve 1. The heating temperature of the heating belt 41 is set to 90°C with reference to the formation temperature conditions.
[0037] The experimental apparatus for measuring the proppant embedding depth under the action of carbon dioxide further includes a temperature controller 8, which is electrically connected to the heating band 41 and the heater 331, and is used to control the opening and closing of the heating band 41 and the heater 331.
[0038] The temperature inside the experimental sleeve 1 is adjusted by heating belt 41 so that the phase state of carbon dioxide entering the fracture 21 is the same as that of carbon dioxide in shale during actual oil and gas extraction, thereby obtaining the actual proppant embedding depth value. In order to facilitate the control of heating belt 41 and heater 331, temperature controller 8 is set to control the opening and closing of heating belt 41 and heater 331.
[0039] like Figures 1-2 As shown, the loading assembly 5 includes a pair of loading modules 51, each loading module 51 being connected to a corresponding extrusion assembly 2. Pressure is applied to the two extrusion assemblies 2 through the pair of loading modules 51. The loading assembly 5 has two loading modules 51, each loading module 51 connected to an extrusion assembly 2, and the two loading modules 51 simultaneously apply pressure to their corresponding extrusion assemblies 2. The two extrusion assemblies 2 move within the experimental sleeve 1, gradually approaching each other, thereby extruding the proppant 6.
[0040] Another aspect of the present invention provides an experimental method for determining the proppant embedding depth under the action of carbon dioxide, implemented based on the experimental apparatus for determining the proppant embedding depth under the action of carbon dioxide as described in any of the preceding claims, the experimental method comprising: S1) Two extrusion components 2 are nested in the experimental sleeve 1, so that a crack 21 is formed between the rock plates 210 of the two extrusion components 2, wherein a pair of experimental through holes 11 on the cylinder wall of the experimental sleeve 1 are connected to the crack 21. S2) Propionate is laid in the fissure 21, and a specified pressure is applied to the two extrusion components 2 by the loading component 5 to pre-compress the proppant in the fissure 21. S3) Adjust the temperature inside the experimental sleeve 1 to control the carbon dioxide entering the fissure 21 to always be in a supercritical state. S4) Carbon dioxide is supplied into the crack 21 through the experimental through hole 11 at one end of the experimental sleeve 1 until the crack 21 is completely filled with carbon dioxide. The experimental through hole 11 at the other end is blocked, and carbon dioxide is continuously supplied into the crack 21 until the carbon dioxide pressure entering the crack 21 reaches the target pressure. The experimental through hole 11 at the other end of the crack 21 serves as a discharge hole. S5) After standing for a specified time, pressure is applied to the two extrusion components 2 through the loading component 5 to the target axial stress, so as to extrude the proppant in the crack 21, and the displacement value of the loading component 5 in the pressure direction and the stress value corresponding to the displacement value are recorded in real time. S6) Open the discharge hole to discharge the carbon dioxide in the fissure 21; S7) Calculate the proppant embedding depth based on the real-time recorded displacement value, the stress value corresponding to the displacement value, the elastic modulus of the rock slab 210, and the height of the rock slab 210.
[0041] The present invention provides an experimental method for determining the embedding depth of proppant under the action of carbon dioxide. First, an experimental sleeve 1 and two extrusion components 2 are assembled. The rock plates 210 of the two extrusion components 2 are embedded into the inner cavity of the experimental sleeve 1 from both ends. During assembly, one rock plate 210 of one extrusion component 2 is first placed into the inner cavity of the experimental sleeve 1 from one open end. Propane 6 is then laid on the rock plate 210 of this extrusion component 2. The proppant 6 is any one or a combination of multiple types of materials, including quartz sand, ceramsite, and coated sand. The particle size of the proppant 6 can be a single particle size or a combination of multiple particle sizes. For example, 40 / 70 mesh ceramsite proppant can be laid on the rock plate 210 at a concentration of 1.5 kg / m³. 2Another extrusion assembly 2's rock plate 210 is inserted into the inner cavity of the experimental sleeve 1 from the other open end of the experimental sleeve 1, with the two extrusion assemblies 2's rock plates 210 positioned opposite each other. Before introducing carbon dioxide into the fracture 21, the temperature inside the experimental sleeve 1 is adjusted so that the carbon dioxide entering the fracture 21 can be maintained in a supercritical state. A specified pressure is simultaneously applied to the rock plates 210 of the two extrusion assemblies 2 by the two loading modules 51 of the loading assembly 5 to pre-compress the proppant. Under the action of the specified pressure, the proppant is compacted by the rock plates 210 of the two extrusion assemblies 2. The specified pressure during pre-compression is 1... The pressure is measured in MPa, and the initial displacement values of the two loading modules 51 of the current loading component 5 in the pressure application direction are recorded. Then, liquid carbon dioxide is pumped to the heating coil 330 by the constant speed and constant pressure pump 322. The liquid carbon dioxide is heated and its phase changes in the heating coil 330, and heated carbon dioxide is supplied into the fissure 21. After the heated carbon dioxide is supplied into the fissure 21 for a period of time until the fissure 21 is completely filled with carbon dioxide, the experimental through hole 11 at the other end is blocked by the vent valve 7, and the constant speed and constant pressure pump 322 continues to supply liquid carbon dioxide into the heating coil 330. After being heated in the heating coil 330, the liquid carbon dioxide continues to enter the fissure 21 until the pressure of the carbon dioxide entering the fissure 21 reaches the target pressure and is higher than the critical pressure corresponding to the supercritical state of carbon dioxide, such as the target pressure being 10. At this point, the carbon dioxide supply is stopped. After a specified settling time, for example, after 5 days, the two loading modules 51 of the loading assembly 5 are activated to continue applying pressure to the extrusion assembly 2 until the pressure reaches the target axial stress, at which point the pressure application is stopped, for example, the target axial stress is 50 MPa. Throughout the process of applying pressure to the target axial stress, the displacement values and corresponding stress values of the two loading modules 51 of the loading assembly 5 are recorded in real time. Then, the vent valve 7 is opened to release the carbon dioxide from the crack 21, and the heating belt 41 and heater 331 are shut off via the temperature controller 8. The depth of proppant embedment in the rock plate 210 is calculated based on the real-time recorded displacement value of the loading assembly 5 in the pressure direction, the corresponding stress value, the elastic modulus of the rock plate 210 of the extrusion assembly 2 in contact with the proppant, and the total height of the rock plates 210 of the two extrusion assemblies in the pressure direction. The formula for calculating the depth of proppant embedment in the rock plate 210 is as follows:
[0042] D For the proppant embedding depth; Displacement values recorded by the rock mechanics instrument; The stress value corresponding to the displacement value is recorded by the rock mechanics instrument in the direction of pressure application; The elastic modulus of the rock slab; The total height of the two rock slabs 210 in the direction of pressure application.
[0043] The experimental apparatus for measuring the proppant embedding depth under the action of carbon dioxide provided by this invention comprises two extrusion components movably installed within an experimental sleeve open at both ends. A fissure is formed between the rock plates of the two extrusion components, and the fissure is connected to a pair of experimental through holes on the experimental sleeve. Propane is laid in the fissure, and the rock plates of the two extrusion components simulate shale. A gas supply component delivers carbon dioxide as fracturing fluid into the fissure. The carbon dioxide enters the fissure and reacts with the rock plates, and a loading component applies pressure to the rock plates of the two extrusion components, causing the rock plates of the two extrusion components to compress the proppant laid in the fissure. Under the compression of the rock plates, the proppant embeds into the side of the rock plate in contact with the proppant. In order to simulate the actual working state of the carbon dioxide delivered into the fissure, a heat insulation component is set on the outer wall of the experimental sleeve. The heat insulation component controls the carbon dioxide entering the fissure to a supercritical state, thereby simulating the actual working state of carbon dioxide in shale. The experimental apparatus and method for measuring the proppant embedding depth under the action of carbon dioxide provided by this invention can obtain the proppant embedding depth in the rock slab of the extrusion assembly while controlling the carbon dioxide phase, thus solving the problem in the prior art that the proppant embedding depth cannot be obtained while controlling the carbon dioxide phase.
[0044] The preferred embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the present invention is not limited to the specific details of the above embodiments. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solution of the present invention, and these simple modifications all fall within the protection scope of the present invention.
[0045] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable way without contradiction. In order to avoid unnecessary repetition, the present invention will not describe the various possible combinations separately.
[0046] Those skilled in the art will understand that all or part of the steps in the methods of the above embodiments can be implemented by a program instructing related hardware. This program is stored in a storage medium and includes several instructions to cause a microcontroller, chip, or processor to execute all or part of the steps of the methods described in the various embodiments of the present invention. The aforementioned storage medium includes various media capable of storing program code, such as a USB flash drive, a portable hard drive, a read-only memory (ROM), a random access memory (RAM), a magnetic disk, or an optical disk.
[0047] Furthermore, various different embodiments of the present invention can be combined in any way, as long as they do not violate the spirit of the embodiments of the present invention, they should also be regarded as the content disclosed by the embodiments of the present invention.
Claims
1. An experimental device for measuring the embedment depth of a proppant under the action of carbon dioxide, characterized in that it comprises: The experimental device comprises: an experimental sleeve (1) in a cylindrical structure with open ends, a pair of experimental through holes (11) being symmetrically arranged on the cylindrical wall of the experimental sleeve (1); two extrusion assemblies (2) being embedded at the two open ends of the experimental sleeve (1), each extrusion assembly (2) comprising a rock plate (210) which is in conformity with the shape of the inner cylindrical wall of the experimental sleeve (1), the two rock plates (210) being movably embedded in the experimental sleeve (1), a fissure (21) being formed between the two rock plates (210), a pair of experimental through holes (11) being communicated with the fissure (21), and proppants (6) being laid in the fissure (21); a gas source supply assembly (3) being communicated with the experimental through hole (11) at one end of the fissure (21) and being used for supplying carbon dioxide into the fissure (21), and the experimental through hole (11) at the other end of the fissure (21) being used as a discharge hole; a heat preservation assembly (4) being arranged on the outer wall of the experimental sleeve (1) and being used for adjusting the temperature in the experimental sleeve (1) to control the carbon dioxide entering the fissure (21) to be always in a supercritical state; a loading assembly (5) being used for applying pressure to the two extrusion assemblies (2) to make the two extrusion assemblies (2) extrude the proppants (6) in the fissure (21).
2. The experimental apparatus for the embedment depth of the proppant under the action of carbon dioxide according to claim 1, characterized in that, The experimental device further comprises a vent valve (7) being arranged at the discharge hole and being used for selectively communicating the fissure (21) with the outside of the experimental sleeve (1).
3. The experimental apparatus for the embedment depth of the proppant under the action of carbon dioxide according to claim 1, characterized in that, Each extrusion assembly (2) further comprises a pressing plate (211) which is in conformity with the shape of the rock plate (210) and is fixed to the side of the rock plate (210) which is away from the fissure (21).
4. The experimental apparatus for the embedment depth of the proppant under the action of carbon dioxide according to claim 3, characterized in that, Each extrusion assembly (2) further comprises a sealing ring (213) which is annularly arranged on the pressing plate (211) and is used for sealing the gap between the pressing plate (211) and the inner cylindrical wall of the experimental sleeve (1).
5. The experimental apparatus for the embedment depth of the proppant under the action of carbon dioxide according to claim 1, characterized in that, The gas source supply assembly (3) comprises a gas source (31), a pressurizing unit (32) and a phase state control unit (33); the gas source (31) is used for supplying carbon dioxide; the pressurizing unit (32) is connected with the gas source (31) through a pipeline and is used for liquefying the carbon dioxide supplied by the gas source (31) into liquid carbon dioxide and delivering the liquid carbon dioxide to the phase state control unit (33); the phase state control unit (33) is connected with the pressurizing unit (32) and the experimental through hole (11) at one end of the cylindrical wall of the experimental sleeve (1), and the phase state control unit (33) is used for heating the liquid carbon dioxide to generate carbon dioxide and send it into the fissure (21).
6. The experimental apparatus for the embedment depth of the proppant under the action of carbon dioxide according to claim 5, characterized in that, The pressurizing unit (32) comprises a low-temperature bath (320), an intermediate container (321) and a constant-speed constant-pressure pump (322); the low-temperature bath (320) is connected with the gas source (31) through a pipeline, and the low-temperature bath (320) is used for lowering the temperature of the carbon dioxide supplied by the gas source (31) to liquefy the carbon dioxide into liquid carbon dioxide; the intermediate container (321) is connected with the low-temperature bath (320) and the phase state control unit (33) and is used for storing the liquid carbon dioxide; The constant-speed constant-pressure pump (322) is used for pumping the liquid carbon dioxide in the intermediate container (321) to the phase state control unit (33) and pressurizing and pumping the liquid carbon dioxide to the phase state control unit (33).
7. The experimental apparatus for the embedment depth of the proppant under the action of carbon dioxide according to claim 6, characterized in that, The pressurizing unit (32) further comprises: a heat insulation belt wrapped on the intermediate container (321) for avoiding heat exchange between the liquid carbon dioxide and the outside of the intermediate container (321).
8. The experimental apparatus for the embedment depth of the proppant under the action of carbon dioxide according to claim 6, characterized in that, The phase state control unit (33) comprises: a heating coil (330) and a heater (331). The heating coil (330) is connected with the intermediate container (321) and the experimental through hole (11) on one end of the barrel wall of the experimental sleeve (1), and is used for conveying the pressurized liquid carbon dioxide and gaseous carbon dioxide. The heater (331) is arranged on the heating coil (330), and the heater (331) is used for heating the pressurized liquid carbon dioxide into gaseous carbon dioxide entering the heating coil (330).
9. The experimental apparatus for the embedment depth of the proppant under the action of carbon dioxide according to claim 8, characterized in that, The heat preservation assembly (4) comprises: a heating belt (41) wound on the outer wall of the experimental sleeve (1) for adjusting the temperature in the experimental sleeve (1).
10. The experimental apparatus for the embedment depth of the proppant under the action of carbon dioxide according to claim 9, characterized in that, The experimental device further comprises: a temperature controller (8) electrically connected with the heating belt (41) and the heater (331) for controlling the opening and closing of the heating belt (41) and the heater (331).
11. The experimental apparatus for the embedment depth of the proppant under the action of carbon dioxide according to claim 9, characterized in that, The loading assembly (5) comprises a pair of loading modules (51), each loading module (51) is connected with one extrusion assembly (2), and a pair of loading modules (51) are used for applying pressure to the two extrusion assemblies (2).
12. An experimental method for the proppant embedment depth under the action of carbon dioxide, implemented based on the experimental device for the proppant embedment depth under the action of carbon dioxide according to any one of claims 1-11, characterized in that, The experimental method comprises: S1) nesting two extrusion assemblies (2) in the experimental sleeve (1) to form a fracture (21) between the rock plates (210) of the two extrusion assemblies (2), wherein a pair of experimental through holes (11) on the barrel wall of the experimental sleeve (1) are communicated with the fracture (21); S2) laying a proppant in the fracture (21), and pre-pressing the proppant in the fracture (21) by applying a specified pressure to the two extrusion assemblies (2) through the loading assembly (5); S3) adjusting the temperature in the experimental sleeve (1) to control the carbon dioxide entering the fracture (21) to be always in a supercritical state; S4) supplying carbon dioxide into the fracture (21) through the experimental through hole (11) arranged at one end of the experimental sleeve (1) until the fracture (21) is filled with carbon dioxide, plugging the experimental through hole (11) at the other end, continuously supplying carbon dioxide into the fracture (21) until the pressure of the carbon dioxide entering the fracture (21) reaches a target pressure, wherein the experimental through hole (11) at the other end of the fracture (21) is used as a discharge hole; S5) after standing for a specified period of time, applying pressure to the two extrusion assemblies (2) to a target axial stress through the loading assembly (5) to extrude the proppant in the fracture (21), and recording the displacement value of the loading assembly (5) in the pressure direction and the stress value corresponding to the displacement value in real time; S6) opening the discharge hole to discharge the carbon dioxide in the fracture (21). S7) calculating the proppant embedment depth according to the real-time recorded displacement value, the stress value corresponding to the displacement value, the elastic modulus of the rock plate (210), and the height of the rock plate (210).