Carbon dioxide phase transition fracturing test system and test method

Abstract

The present application belongs to the technical field of rock mass blasting, and discloses a carbon dioxide phase change fracturing test system and a test method. The carbon dioxide phase change fracturing test system comprises a loading pipe, a phase change pipe, a detection assembly and a hydraulic fracturing simulation device. The loading pipe is used for containing fracturing fluid. A plurality of phase change pipes are sequentially connected to the loading pipe along the length direction of the loading pipe. The phase change pipe is used for phase change expansion of carbon dioxide. A plurality of detection assemblies are sequentially arranged along the length direction of the loading pipe. The detection assembly comprises a pressure sensor and a temperature sensor. The loading pipe has a pressure release port. At least one detection assembly is arranged at the pressure release port. The hydraulic fracturing simulation device is connected to the pressure release port and is used for simulating lithological material. The carbon dioxide phase change fracturing test system can accurately analyze and determine the excitation time between different phase change pipes, so as to generate stronger blasting capacity through the superposition of carbon dioxide phase change pressure in the plurality of phase change pipes.

Description

Technical Field

[0001] This invention relates to the field of rock blasting technology, and in particular to a carbon dioxide phase transformation fracturing test system and test method. Background Technology

[0002] In fields such as rock mining and oil and gas well drilling, effective rock fracturing is a key step. With increasing demands for safe production and environmental protection, carbon dioxide phase change fracturing technology has emerged and is gradually replacing traditional explosive blasting as the most common method for rock blasting.

[0003] The core principle of carbon dioxide phase change fracturing technology is that liquid carbon dioxide rapidly vaporizes and expands in volume upon heating, generating a powerful impact force to induce fracturing. However, current carbon dioxide phase change fracturing methods still suffer from limitations such as a single phase change loading method and a lack of coordinated operation of multiple phase change tubes, hindering further improvements in rock-breaking efficiency. Therefore, exploring more efficient carbon dioxide phase change loading methods has become an important development direction for current carbon dioxide phase change fracturing technology. Summary of the Invention

[0004] The purpose of this invention is to provide a carbon dioxide phase change fracturing test system and test method, which can accurately analyze and determine the excitation time between different phase change tubes, so as to generate a stronger bursting capability through the superposition of carbon dioxide phase change pressure in multiple phase change tubes.

[0005] To achieve this objective, the present invention adopts the following technical solution:

[0006] The carbon dioxide phase change fracturing test system includes:

[0007] Loading tube, the loading tube being used to contain fracturing fluid;

[0008] Multiple phase change tubes are connected sequentially to the loading tube along the length of the loading tube. The phase change tubes are used to perform phase change expansion of carbon dioxide.

[0009] Multiple detection components are arranged sequentially along the length of the loading tube. Each detection component includes a pressure sensor and a temperature sensor. The pressure sensor is used to detect the pressure of the fracturing fluid in the loading tube, and the temperature sensor is used to detect the temperature of the fracturing fluid in the loading tube. The loading tube has a pressure relief port, and at least one set of the detection components is arranged at the pressure relief port.

[0010] A hydraulic fracturing simulation device is connected to the pressure release port, and the hydraulic fracturing simulation device is used to simulate lithological materials.

[0011] Preferably, the loading tube includes a main body and a release tube connected to each other, and the pressure relief port is opened in the release tube;

[0012] The multiple detection components on the main body are evenly spaced.

[0013] Preferably, the phase change tube has a gas outlet on its sidewall, the phase change tube is rotatably connected to the loading tube, and the gas outlet is located inside the loading tube.

[0014] The carbon dioxide phase change fracturing test method, using the aforementioned carbon dioxide phase change fracturing test system, includes the following steps:

[0015] S1. Fill the loading tube with the fracturing fluid, fill all the phase change tubes with carbon dioxide, and connect the hydraulic fracturing simulation device to the pressure release port of the loading tube.

[0016] S2. The designated phase change tubes are activated sequentially according to the set time intervals;

[0017] S3. Record the detection data of all the detection components, and plot the pressure change curve and temperature change curve respectively;

[0018] S4. Change the time interval in step S2 and repeat steps S1 to S3 to obtain the time interval corresponding to the maximum burst pressure, where the burst pressure is the pressure of the fracturing fluid at the pressure release port. Preferably,

[0019] Preferably, the amount of carbon dioxide filling in the phase change tube is changed, and steps S1 to S4 are repeated.

[0020] Preferably, the spacing of the phase change tubes is changed, and steps S1 to S4 are repeated.

[0021] Preferably, the excitation sequence of the different phase change transistors is changed, and steps S1 to S4 are repeated.

[0022] Preferably, the direction of the gas outlet located in the loading tube on the phase change tube is changed, and steps S1 to S4 are repeated.

[0023] The beneficial effects of this invention are as follows:

[0024] The carbon dioxide phase change fracturing test system provided by this invention includes a loading tube, multiple phase change tubes, and multiple detection components. The loading tube contains fracturing fluid. Since multiple detection components, including pressure sensors and temperature sensors, are arranged along the length of the loading tube, the system can obtain temperature and pressure data of the fracturing fluid at various points in the loading tube during the test, thereby understanding the time-varying patterns of temperature and pressure during the carbon dioxide phase change process. Because multiple phase change tubes are connected to the loading tube and are arranged sequentially along its length, all used for phase change expansion of carbon dioxide, this test system can detect the temperature and pressure changes of the fracturing fluid in the multiple phase change tubes. By employing a pressure superposition resonance method, the pressure limitation of a single phase change tube is overcome, thereby generating a more powerful blasting capability under the same conditions, which greatly improves rock breaking and fracturing efficiency. In addition, by individually controlling and intermittently activating carbon dioxide in different phase change tubes, and by monitoring the pressure and temperature changes of the fracturing fluid at the loading pipe and pressure release port, the optimal activation time of different phase change tubes can be accurately analyzed and determined to ensure that the maximum blasting pressure is obtained at the pressure release port. This allows the test system to flexibly adapt to various complex rock conditions and engineering requirements by adjusting various parameters, which has important practical significance for improving rock breaking efficiency and accelerating construction progress.

[0025] The carbon dioxide phase change fracturing test method provided by this invention uses the aforementioned carbon dioxide phase change fracturing test system. By setting multiple phase change tubes on the loading tube, the pressure of carbon dioxide phase change expansion in the multiple phase change tubes is superimposed in the loading tube, thereby obtaining a better blasting effect. Subsequently, by sequentially activating multiple phase change tubes and adjusting the activation time interval, the optimal activation time of different phase change tubes can be determined, thereby providing data support and reference for actual rock breaking operations. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of the carbon dioxide phase change fracturing test system provided in a specific embodiment of the present invention;

[0027] Figure 2 This is a schematic diagram of the loading tube and phase change tube provided in a specific embodiment of the present invention.

[0028] In the picture:

[0029] 1-Loading tube; 11-Main body; 12-Release tube;

[0030] 2-Phase changer;

[0031] 3-Detection component; 31-Pressure sensor; 32-Temperature sensor;

[0032] 4-Hydraulic fracturing simulation device. Detailed Implementation

[0033] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and not intended to limit it. Furthermore, it should be noted that, for ease of description, the accompanying drawings show only the parts relevant to the present invention, and not all of the structures.

[0034] In the description of this invention, unless otherwise explicitly specified and limited, the terms "connected," "linked," and "fixed" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0035] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0036] In the description of this embodiment, the terms "upper," "lower," "right," and "left," etc., refer to the orientation or positional relationship shown in the accompanying drawings. They are used only for ease of description and simplification of operation, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the present invention. In addition, the terms "first" and "second" are used only for distinction in description and have no special meaning.

[0037] like Figures 1 to 2As shown, the present invention provides a carbon dioxide phase change fracturing test system, which includes a loading tube 1, multiple phase change tubes 2, multiple detection components 3, and a hydraulic fracturing simulation device 4. The loading tube 1 is used to contain fracturing fluid; the multiple phase change tubes 2 are sequentially connected to the loading tube 1 along its length, and the phase change tubes 2 are used to perform phase change expansion of carbon dioxide; the multiple detection components 3 are sequentially arranged along the length of the loading tube 1, and the detection components 3 include a pressure sensor 31 and a temperature sensor 32. The pressure sensor 31 is used to detect the pressure of the fracturing fluid in the loading tube 1, and the temperature sensor 32 is used to detect the temperature of the fracturing fluid in the loading tube 1. The loading tube 1 has a pressure release port, and at least one set of detection components 3 is set at the pressure release port; the hydraulic fracturing simulation device 4 is connected to the pressure release port and is used to simulate lithological materials. Specifically, since multiple detection components 3 are arranged along the length of the loading pipe 1, including pressure sensors 31 and temperature sensors 32, the temperature and pressure data of the fracturing fluid in the loading pipe 1 at various points during the test can be obtained, thereby understanding the changes in temperature and pressure along the path and over time during the carbon dioxide phase change process. Because multiple phase change tubes 2 are connected to the loading pipe 1, and these multiple phase change tubes 2 are arranged sequentially along the length of the loading pipe 1 and are all used for phase change expansion of carbon dioxide, this test system can overcome the limitations of a single phase change tube 2 through the pressure superposition and resonance of multiple phase change tubes 2. The pressure limitation allows for a stronger blasting capability under the same conditions, thus greatly improving rock breaking and fracturing efficiency. Furthermore, by individually controlling and intermittently activating carbon dioxide in different phase change tubes 2, and by monitoring the pressure and temperature changes of the fracturing fluid at the loading tube 1 and the pressure release port, the optimal activation time for different phase change tubes 2 can be accurately analyzed and determined to ensure maximum blasting pressure at the pressure release port. This allows the experimental system to flexibly adapt to various complex rock conditions and engineering requirements by adjusting various parameters, which is of significant practical importance for improving rock breaking efficiency and accelerating construction progress.

[0038] In this embodiment, both the loading tube 1 and the phase change tube 2 are commonly used carbon dioxide phase change generating devices in the art. The phase change tube 2 is equipped with a heating device and a rupture disc. Before the test begins, the operator fills it with a certain amount of liquid carbon dioxide. After the test begins, the operator activates the heating device, which causes the liquid carbon dioxide to undergo phase change and expansion. When the internal pressure of the phase change tube 2 reaches a certain value, the rupture disc breaks, and the gaseous carbon dioxide in the phase change tube 2 enters the loading tube 1, thereby releasing pressure on the fracturing fluid in the loading tube 1. In this embodiment, the loading tube 1 is made of P110 steel with excellent compressive strength and is filled with water to serve as the medium for pressure transmission. When the gas carbon dioxide in the phase change tube 2 is released and enters the loading tube 1, the pressure brought by the carbon dioxide can be transmitted to the water and then transmitted through the water. It can be understood that multiple phase change tubes 2 are connected to the loading tube 1. Therefore, the operator can activate multiple phase change tubes 2 to achieve pressure superposition in the loading tube 1, thereby greatly increasing the burst pressure at the pressure release port. Here, activating the phase change tube 2 refers to the heating device inside the starter, which causes the carbon dioxide to expand in a phase change. In another embodiment, the fracturing fluid can also be oil.

[0039] The hydraulic fracturing simulation device 4 is a commonly used test instrument in this field. It is mainly used to simulate the fracturing process of formation rocks under different confining pressure conditions, thereby improving the authenticity and reliability of fracturing test results. Its specific structure and working principle will not be described in detail here.

[0040] In this embodiment, as Figure 2 As shown, the loading tube 1 includes a main body 11 and a release tube 12 connected to each other, with a pressure release port opened in the release tube 12; multiple detection components 3 are evenly spaced on the main body 11; specifically, the main body 11 is a cylindrical structure, multiple phase change tubes 2 are evenly spaced on the main body 11, multiple pressure sensors 31 are evenly spaced on the main body 11, and multiple temperature sensors 32 are also evenly spaced on the main body 11, so as to facilitate the uniform plotting of temperature and pressure change curves at various points in the loading tube 1 in the later stage.

[0041] The release pipe 12 is connected to one end of the main body 11. The volume of the release pipe 12 is much smaller than that of the main body 11. It is mainly used to release pressure into the hydraulic fracturing simulation device 4. A temperature sensor 32 and a pressure sensor 31 are installed at the pressure release port of the release pipe 12 to obtain the burst pressure value clearly and accurately.

[0042] Furthermore, a gas outlet is provided on the side wall of the phase change tube 2. The phase change tube 2 is rotatably connected to the loading tube 1, and the gas outlet is located inside the loading tube 1. In this embodiment, the phase change tube 2 is a cylindrical structure. The gas outlet is provided on the side wall of the phase change tube 2, and there is only one gas outlet. The phase change tube 2 and the loading tube 1 are detachably connected. When the phase change tube 2 is installed in place, the gas outlet is located inside the loading tube 1. The operator can change the orientation of the gas outlet by rotating the phase change tube 2, thereby conducting phase change fracturing tests under different gas outlet orientations.

[0043] This embodiment also provides a carbon dioxide phase change fracturing test method, using the above-mentioned carbon dioxide phase change fracturing test system, including the following steps:

[0044] S1. Fill the loading tube 1 with fracturing fluid, fill all the phase change tubes 2 with carbon dioxide, and connect the hydraulic fracturing simulation device 4 to the pressure release port of the loading tube 1.

[0045] S2. According to the set time interval, sequentially excite the designated phase change tube 2;

[0046] S3. Record all the detection data of all detection components 3, and plot the pressure change curve and temperature change curve respectively;

[0047] S4. Change the time interval in step S2 and repeat steps S1 to S3 to obtain the time interval corresponding to the maximum burst pressure. The burst pressure is the pressure of the fracturing fluid at the pressure release port.

[0048] Specifically, by setting multiple phase change tubes 2 on the loading tube 1, the pressure of carbon dioxide phase change expansion in the multiple phase change tubes 2 is superimposed in the loading tube 1, thereby obtaining a better blasting effect; then by sequentially activating multiple phase change tubes 2 and adjusting the activation time interval, the optimal activation time of different phase change tubes 2 can be determined, thereby providing data support and reference for actual rock breaking operations.

[0049] In this embodiment, in step S1, the operator sets the carbon dioxide filling amount in the phase change tube 2, the gas outlet orientation, the spacing between the phase change tubes 2, and the excitation sequence of the phase change tubes 2 according to the predetermined test conditions. Through steps S2 and S3, the operator can plot the time-varying curves of pressure and temperature at various points on the main body 11 of the loading tube 1 and at the pressure release port during the first test. Then, through step S4, the time-varying curves of pressure and temperature at various points on the main body 11 of the loading tube 1 and at the pressure release port under different excitation time intervals can be obtained. The purpose is to adjust the pressure superposition and transmission inside the loading tube 1 by continuously changing the excitation time interval between each phase change tube 2, so that the burst pressure at the pressure release port changes. Based on the pressure and temperature time-varying curves plotted above, the operator can obtain the variation law of fracturing fluid temperature and pressure in the loading tube 1, thereby finally determining the maximum burst pressure.

[0050] It is understandable that the propagation of pressure waves in loading tube 1 takes time. Therefore, if multiple phase change tubes 2 arranged at intervals along the length of loading tube 1 are activated simultaneously, the burst pressure generated at the pressure release port will not reach its maximum. Furthermore, the pressure superposition in loading tube 1 will vary depending on the activation interval between phase change tubes 2. Therefore, the staff needs to use this phase change fracturing test to determine the activation time interval between different phase change tubes 2 to ensure that the pressure generated by the vaporization and expansion of carbon dioxide in each phase change tube 2 can be accurately superimposed.

[0051] This carbon dioxide phase change fracturing test method includes four variables: the amount of carbon dioxide filling the phase change tube 2, the distance between phase change tubes 2, the excitation sequence of different phase change tubes 2, and the orientation of the gas outlet on the phase change tube 2. To determine the influence of these variables on the excitation interval of each phase change tube 2, multiple sets of experiments are required to determine the excitation time interval under the aforementioned different conditions. It is understood that in each set of experiments, only one variable is changed.

[0052] When studying the effect of different carbon dioxide filling amounts on the excitation time interval of each phase change tube 2, the staff needs to change the carbon dioxide filling amount in the phase change tube 2 and repeat steps S1 to S4; in this embodiment, the carbon dioxide filling amount in each phase change tube 2 is kept the same when the experiment is carried out.

[0053] When studying the effect of different spacings of phase change tubes 2 on the excitation time interval of each phase change tube 2, the staff needs to change the spacing between the phase change tubes 2 and repeat steps S1 to S4; in this embodiment, when conducting the experiment, multiple phase change tubes 2 are set at equal intervals.

[0054] When studying the effect of different excitation sequences of phase change tubes 2 on the excitation time interval of each phase change tube 2, the staff needs to change the excitation sequence of different phase change tubes 2 and repeat steps S1 to S4.

[0055] When studying the effect of the direction of the gas outlet on the phase change tube 2 on the excitation time interval of each phase change tube 2, the staff needs to change the direction of the gas outlet on the phase change tube 2 located in the loading tube 1 and repeat steps S1 to S4. In this embodiment, when conducting the experiment, changing the direction of the gas outlet means synchronously rotating each phase change tube 2, that is, the direction of the gas outlet on all phase change tubes 2 is the same before and after the change.

[0056] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the implementation of the present invention. Those skilled in the art will be able to make various obvious changes, readjustments, and substitutions without departing from the scope of protection of the present invention. It is neither necessary nor possible to exhaustively describe all embodiments here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. A carbon dioxide phase change fracturing test system, characterized in that, include: Loading tube (1), the loading tube (1) is used to contain fracturing fluid; Multiple phase change tubes (2) are connected sequentially to the loading tube (1) along the length direction of the loading tube (1). The phase change tubes (2) are used to perform phase change expansion of carbon dioxide. Multiple detection components (3) are arranged sequentially along the length of the loading tube (1). Each detection component (3) includes a pressure sensor (31) and a temperature sensor (32). The pressure sensor (31) is used to detect the pressure of the fracturing fluid in the loading tube (1), and the temperature sensor (32) is used to detect the temperature of the fracturing fluid in the loading tube (1). The loading tube (1) has a pressure relief port, and at least one set of the detection components (3) is arranged at the pressure relief port. A hydraulic fracturing simulation device (4) is connected to the pressure release port. The hydraulic fracturing simulation device (4) is used to simulate lithological materials.

2. The carbon dioxide phase change fracturing test system according to claim 1, characterized in that, The loading tube (1) includes a main body (11) and a release tube (12) connected to each other, and the pressure release port is opened in the release tube (12). The multiple detection components (3) on the main body (11) are evenly spaced.

3. The carbon dioxide phase change fracturing test system according to claim 2, characterized in that, The phase change tube (2) has a gas outlet on its side wall. The phase change tube (2) is rotatably connected to the loading tube (1), and the gas outlet is located inside the loading tube (1).

4. A carbon dioxide phase transformation fracturing test method, characterized in that, Using the carbon dioxide phase transformation fracturing test system as described in any one of claims 1-3, the following steps are included: S1. Fill the loading tube (1) with the fracturing fluid, fill all the phase change tubes (2) with carbon dioxide, and connect the hydraulic fracturing simulation device (4) to the pressure release port of the loading tube (1); S2. The designated phase change tubes (2) are activated sequentially according to the set time interval. S3. Record the detection data of all the detection components (3), and plot the pressure change curve and temperature change curve respectively; S4. Change the time interval in step S2 and repeat steps S1 to S3 to obtain the time interval corresponding to the maximum burst pressure, wherein the burst pressure is the pressure of the fracturing fluid at the pressure release port.

5. The carbon dioxide phase transformation fracturing test method according to claim 4, characterized in that, Change the amount of carbon dioxide filling in the phase change tube (2) and repeat steps S1 to S4.

6. The carbon dioxide phase transformation fracturing test method according to claim 4, characterized in that, Change the spacing of the phase change tubes (2) and repeat steps S1 to S4.

7. The carbon dioxide phase transformation fracturing test method according to claim 4, characterized in that, Change the excitation order of the different phase change tubes (2) and repeat steps S1 to S4.

8. The carbon dioxide phase transformation fracturing test method according to claim 4, characterized in that, Change the direction of the gas outlet on the phase change tube (2) located inside the loading tube (1), and repeat steps S1 to S4.

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