Low-melting-point alloy wellbore sealing material sealing evaluation device and method

Abstract

The present application relates to carbon dioxide geological utilization and storage technology field, it is a kind of low melting point alloy wellbore plugging material sealing evaluation device and method, the former includes observation cylinder, outer tube, simulation wellbore, gas channeling simulation mechanism, formation pressure regulating mechanism, cooling mechanism, wellbore pressure regulating mechanism and image acquisition unit.The present application is reasonable and compact in structure, alloy material in simulation wellbore is in alloying stage, sealing thimble prevents liquid alloy from flowing into first gas injection hole, after alloy material in simulation wellbore solidifies, sealing thimble is moved downwards, so that the upper end of sealing thimble is located below first gas injection hole, so that gas channeling simulation mechanism and lower part of simulation wellbore are connected, formation pressure regulating mechanism is connected with confining pressure cavity through pressure-increasing hole when working, can simulate the effect on the formation pressure around simulation wellbore, realize low melting point alloy material heating melting-cooling forming process, evaluate the sealing capacity of alloy plug-casing combination under actual downhole working condition.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of geological utilization and storage of carbon dioxide, and is a sealing evaluation device and method for low-melting-point alloy wellbore plugging materials. BACKGROUND

[0002] In the practical application of the geological utilization and storage of carbon dioxide, in addition to injection wells and production wells, there are a large number of shut-in wellbores in the storage site, which are considered to be high-risk locations for carbon dioxide leakage. The general method for plugging the shut-in wellbores is to inject a cement plug, which is tens of meters to hundreds of meters long. Since the cement is exposed to humid carbon dioxide and will be corroded and degraded, under the long-term storage conditions of carbon dioxide, there is a risk of failure of the sealing performance of the cement plug. In recent years, foreign scholars have proposed a new idea of plugging the wellbores by using low-melting-point alloys, and the alloy plug formed has the outstanding advantages of long service life, good sealing performance, corrosion resistance, and fast forming. However, the working environment of the alloy plug cannot be simulated under different formation temperature-pressure conditions and wellbore alloy melting-condensation conditions, which leads to a lack of evaluation of the sealing capacity of the alloy plug-wellbore combination. SUMMARY

[0003] The present application provides a sealing evaluation device and method for low-melting-point alloy wellbore plugging materials, which overcomes the shortcomings of the prior art and effectively solves the problem of the lack of evaluation of the sealing capacity of the alloy plug-wellbore combination due to the inability of the existing test device to simulate different formation temperature-pressure conditions and wellbore alloy melting-condensation conditions.

[0004] One of the technical solutions of the present application is achieved by the following measures: a sealing evaluation device for low-melting-point alloy wellbore plugging materials, comprising an observation cylinder, an outer cylinder, a simulated wellbore, a gas channeling simulation mechanism, a formation pressure adjusting mechanism, a cooling mechanism, a wellbore pressure adjusting mechanism, and an image acquisition unit. The lower part of the observation cylinder is detachably and fixedly installed with the upper part of the outer cylinder. The inner side of the outer cylinder is sleeved with the simulated wellbore. The lower end of the simulated wellbore is fixedly installed with a plug. The lower end of the plug is provided with a first installation hole and a second installation hole penetrating upward and downward. An electric heating rod is arranged in the first installation hole and located above the plug. The lower end of the plug is provided with a first gas injection hole in communication with the second installation hole. A sealing needle is arranged in the second installation hole. The first gas injection hole is connected with the gas channeling simulation mechanism. The gas channeling simulation mechanism is used for inputting a gas source into the first gas injection hole. A lower sealing ring is fixedly installed between the lower end of the simulated wellbore and the inner side of the lower end of the outer cylinder. A surrounding pressure cavity is formed between the upper end of the lower sealing ring, the lower end of the observation cylinder, the inner side of the outer cylinder, and the outer side of the simulated wellbore. The lower end of the lower sealing ring is provided with a pressurizing hole in communication with the surrounding pressure cavity. The pressurizing hole is connected with the formation pressure adjusting mechanism. The outer side of the outer cylinder is provided with the cooling mechanism. The upper end of the observation cylinder is provided with a second gas injection hole penetrating upward and downward. The second gas injection hole is connected with the wellbore pressure adjusting mechanism. The outer side of the observation cylinder is provided with the image acquisition unit for acquiring image information in the observation cylinder.

[0005] The following is a further optimization or / and improvement of one of the above technical solutions:

[0006] The lower end of the plug can be fixed with a boss, the first mounting hole is arranged at the lower end of the boss, the lower end of the second mounting hole extends to the lower end of the boss, the first gas injection hole is arranged outside the boss, the gas channeling simulation mechanism comprises a first delivery pump, a first three-way valve and a pressure gauge, the outlet of the first delivery pump is fixedly communicated with the first port of the first three-way valve through a first connecting pipeline, the second port of the first three-way valve is fixedly communicated with the first gas injection hole through a second connecting pipeline, the second connecting pipeline is provided with the pressure gauge, the lower end of the plug corresponding to the position outside the boss is provided with a fixed through hole penetrating up and down, and a thermometer is arranged in the fixed through hole.

[0007] The image acquisition unit can comprise a first image acquisition module, a second image acquisition module, a processing module and an upper computer, the observation cylinder comprises a top cover, a quartz tube and an adapter, the adapter is arranged between the lower end of the quartz tube and the upper end of the simulated wellbore, an upper sealing ring is arranged between the lower end of the adapter and the inner side of the upper part of the outer cylinder, the top cover is fixedly arranged at the upper end of the quartz tube, an installation through hole is arranged at the upper end of the top cover, the first image acquisition module is arranged in the installation through hole, the second image acquisition module is arranged outside the quartz tube, the first image acquisition module and the second image acquisition module are connected with the processing module, the processing module is connected with the upper computer, and the second gas injection hole is arranged at intervals from the installation through hole.

[0008] The wellbore pressure adjusting mechanism can comprise a second delivery pump and a second three-way valve, the outlet of the second delivery pump is fixedly communicated with the first port of the second three-way valve through a third connecting pipeline, and the second port of the second three-way valve is fixedly communicated with the second gas injection hole through a fourth connecting pipeline.

[0009] The cooling mechanism can comprise a water tank, a cooling liquid delivery pump, annular heating fins, condensing coils and a regulating valve, a plurality of annular heating fins are arranged outside the outer cylinder corresponding to the position between the upper sealing ring and the lower sealing ring, a plurality of condensing coils are wound outside the annular heating fins, the upper port of the condensing coils is fixedly communicated with the inlet of the water tank through a cooling liquid outlet pipeline, the outlet of the water tank is fixedly communicated with the inlet of the cooling liquid delivery pump, the outlet of the cooling liquid delivery pump is fixedly communicated with the lower port of the condensing coils through a cooling liquid inlet pipeline, and a thermostat is arranged in the water tank.

[0010] The formation pressure adjusting mechanism can comprise a third delivery pump and a third three-way valve, the outlet of the third delivery pump is fixedly communicated with the first port of the third three-way valve through a fifth connecting pipeline, and the second port of the third three-way valve is fixedly communicated with the pressure boosting hole through a sixth connecting pipeline.

[0011] The second technical solution of the present application is realized through the following measures: the low-melting-point alloy wellbore sealing material sealing evaluation method comprises the following steps:

[0012] S1, preparation before experiment: adjust the position of the sealing needle so that the first gas injection hole and the upper part of the second mounting hole are not connected with each other, start the second delivery pump and the third delivery pump, increase the pressure in the simulated wellbore and the confining pressure cavity to first and second set values respectively, after the simulated wellbore and the confining pressure cavity are leak-free, start the thermostat and the cooling liquid delivery pump, after the condenser coil is not blocked, stop the second delivery pump, the third delivery pump, the cooling liquid delivery pump and the thermostat, and adjust the second three-way valve and the third three-way valve until the pressure in the simulated wellbore and the confining pressure cavity decreases to a safety value;

[0013] S2, alloy material is put in: disconnect the adapter from the upper sealing ring, add alloy material of a set height into the simulated wellbore, connect the adapter with the upper sealing ring again, start the second delivery pump, increase the pressure in the simulated wellbore to a third set value, stop the second delivery pump after the simulated wellbore is leak-free, and adjust the second three-way valve until the pressure in the simulated wellbore decreases to a safety value;

[0014] S3, set experimental conditions: adjust the second three-way valve, start the second delivery pump, inject liquid medium into the simulated wellbore, start the annular heating sheet, heat the confining pressure cavity and the simulated wellbore to a first set temperature, and increase the pressure in the simulated wellbore and the confining pressure cavity to first and second set values respectively through the second delivery pump and the third delivery pump;

[0015] S4, heat and melt the alloy material: start the electric heating rod, heat the alloy material to a second set temperature, the second set temperature is greater than the melting point of the alloy material, and the second set temperature is lower than the boiling point of the liquid medium in the simulated wellbore; collect the temperature value of the alloy material in the heating process through the thermometer, and analyze the melting rate of the alloy material according to the temperature value in the heating process;

[0016] S5, cool and solidify the alloy material: after the alloy material is completely melted, stop the electric heating rod, start the cooling liquid delivery pump to cool the outer cylinder, collect the temperature value of the alloy material in the cooling process through the thermometer, analyze the cooling rate of the alloy material according to the temperature value in the cooling process, and stop the cooling liquid delivery pump and the thermostat when the temperature of the alloy material decreases to the temperature of the outer cylinder;

[0017] S6, alloy plug sealing test: start the first image acquisition module and the second image acquisition module, adjust the position of the sealing needle so that the first gas injection hole and the upper part of the second mounting hole are connected with each other, start the first delivery pump, input gas medium into the simulated wellbore, and collect the pressure data of the gas medium through the pressure gauge;

[0018] S7, record leakage pressure: The moment when bubbles continuously overflow from the quartz tube is the moment when the alloy material leaks. Record the pressure data collected by the pressure gauge at the moment when the alloy material leaks.

[0019] S8, Capture Leakage Images: After the alloy material leaks, the first image acquisition module and the second image acquisition module start recording video and acquire image information of bubble overflow after a set time interval. The processing module obtains the bubble overflow location and bubble overflow density change based on the bubble overflow image information and analyzes the leakage pattern of the alloy plug.

[0020] S9, Cleaning device completes test: After the test is completed, shut down the first delivery pump, the first image acquisition module, the second image acquisition module, the second delivery pump, the third delivery pump, the coolant delivery pump, and the annular heating element. Adjust the first three-way valve, the second three-way valve, and the third three-way valve to reduce the pressure inside the simulated wellbore and the pressure inside the confining pressure chamber to a safe value. After the simulated wellbore temperature drops to a safe value, disconnect the adapter from the upper sealing ring. After cleaning the alloy material, clean the inner wall of the simulated wellbore and the inner wall of the quartz tube.

[0021] The invention has a reasonable and compact structure. During the alloy melting stage of the simulated wellbore, the upper end of the sealing pin is flush with the upper end of the plug to prevent the liquid alloy from flowing into the first gas injection hole. After the alloy material in the simulated wellbore solidifies, the sealing pin moves down so that the upper end of the sealing pin is below the first gas injection hole, thereby connecting the gas flow simulation mechanism with the lower part of the simulated wellbore. When the formation pressure regulating mechanism is working, it is connected to the confining pressure cavity through the pressure boosting hole, which can simulate the formation pressure around the simulated wellbore.

[0022] This low-melting-point alloy wellbore plugging material sealing evaluation device can simulate the formation temperature and pressure conditions of the plugging section, the temperature and pressure inside the wellbore, and the fluid medium environment. It realizes the heating, melting, and cooling process of low-melting-point alloy materials and evaluates the sealing capability of the alloy plug-casing assembly under actual downhole conditions. Attached Figure Description

[0023] Appendix Figure 1 This is a schematic diagram of the main view cross-sectional structure of the sealing pin in its initial state in Embodiments 1 to 8 of the present invention.

[0024] Appendix Figure 2 This is a schematic diagram of the main cross-sectional structure after the sealing pin is moved down in embodiments one to eight of the present invention.

[0025] Appendix Figure 3 Temperature profiles for the alloy plug during the heating, melting, cooling, and forming process.

[0026] Appendix Figure 4 The pressure curve is used to test the sealing ability of the alloy plug after it has been cooled and formed.

[0027] Appendix Figure 5This is an image of bubbles overflowing, captured by the first image acquisition module.

[0028] Appendix Figure 6 Images of bubbles overflowing and bubble identification results captured at each stage of leakage.

[0029] Appendix Figure 7 Plot the bubble overflow density as a curve.

[0030] The codes in the attached diagram are as follows: 1 for outer cylinder, 2 for simulated wellbore, 3 for plug, 4 for electric heating rod, 5 for sealing pin, 6 for first air injection port, 7 for lower sealing ring, 8 for confining pressure chamber, 9 for pressurization port, 10 for second air injection port, 11 for boss, 12 for first delivery pump, 13 for first three-way valve, 14 for pressure gauge, 15 for first connecting pipeline, 16 for second connecting pipeline, 17 for thermometer, 18 for first image acquisition module, 19 for second image acquisition module, 20 for processing module, and 21 for host computer. 22 is the top cover, 23 is the quartz tube, 24 is the adapter, 25 is the upper sealing ring, 26 is the second delivery pump, 27 is the second three-way valve, 28 is the third connecting pipeline, 29 is the fourth connecting pipeline, 30 is the water tank, 31 is the coolant delivery pump, 32 is the annular heating element, 33 is the condenser coil, 34 is the regulating valve, 35 is the coolant outlet pipeline, 36 is the coolant inlet pipeline, 37 is the third delivery pump, 38 is the third three-way valve, 39 is the fifth connecting pipeline, 40 is the sixth connecting pipeline, and 41 is the alloy material. Detailed Implementation

[0031] The present invention is not limited to the following embodiments, and the specific implementation can be determined according to the technical solution of the present invention and the actual situation.

[0032] In this invention, for ease of description, the description of the relative positions of the components is based on the appendix to the specification. Figure 1 The layout is described using a diagrammatic method, such as the positional relationships of front, back, top, bottom, left, and right, which are based on the instructions attached. Figure 1 The orientation of the layout is determined by the direction of the map.

[0033] The present invention will be further described below with reference to embodiments and accompanying drawings:

[0034] Example 1: As shown in the attached document Figure 1 , 2As shown, the low-melting-point alloy wellbore sealing material sealing evaluation device includes an observation cylinder, an outer cylinder 1, a simulated wellbore 2, a gas channeling simulation mechanism, a formation pressure adjusting mechanism, a cooling mechanism, a wellbore pressure adjusting mechanism, and an image acquisition unit. The lower part of the observation cylinder is detachably and fixedly installed with the upper part of the outer cylinder 1. The inner side of the outer cylinder 1 is sleeved with the simulated wellbore 2. The lower end of the simulated wellbore 2 is fixedly installed with a plug 3. The lower end of the plug 3 is provided with a first installation hole and a second installation hole penetrating up and down. The first installation hole is provided with an electric heating rod 4 located above the plug 3. The lower end of the plug 3 is provided with a first gas injection hole 6 in communication with the second installation hole. The second installation hole is provided with a sealing needle 5. The first gas injection hole 6 is connected with the gas channeling simulation mechanism. The gas channeling simulation mechanism is used for inputting gas source into the first gas injection hole 6. The lower end of the simulated wellbore 2 is fixedly installed with a lower sealing ring 7 between the inner side of the lower end of the outer cylinder 1. A confining pressure cavity 8 is formed between the upper end of the lower sealing ring 7, the lower end of the observation cylinder, the inner side of the outer cylinder 1, and the outer side of the simulated wellbore 2. The lower end of the lower sealing ring 7 is provided with a pressure-increasing hole 9 in communication with the confining pressure cavity 8. The pressure-increasing hole 9 is connected with the formation pressure adjusting mechanism. The outer side of the outer cylinder 1 is provided with the cooling mechanism. The upper end of the observation cylinder is provided with a second gas injection hole 10 penetrating up and down. The second gas injection hole 10 is connected with the wellbore pressure adjusting mechanism. The outer side of the observation cylinder is provided with the image acquisition unit used for acquiring image information in the observation cylinder.

[0035] According to the requirement, the lower outer side of the sealing needle 5 is sealingly screwed in the lower part of the second installation hole. The upper outer side of the sealing needle 5 is sealingly contacted with the upper part of the second installation hole. In this way, the alloy material 41 placed in the simulated wellbore 2 can be prevented from flowing into the second installation hole and the first gas injection hole 6 after melting, blocking the first gas injection hole 6. The upper end of the sealing needle 5 is flush with the upper end of the plug 3 during the alloy melting stage, preventing the liquid alloy from flowing into the first gas injection hole 6. After the alloy material 41 in the simulated wellbore 2 solidifies, the sealing needle 5 is lowered so that the upper end of the sealing needle 5 is located below the first gas injection hole 6, thereby connecting the gas channeling simulation mechanism with the lower part of the simulated wellbore 2. When the formation pressure adjusting mechanism works, the pressure-increasing hole 9 is connected with the confining pressure cavity 8, which can simulate the formation pressure around the simulated wellbore 2.

[0036] The low-melting-point alloy wellbore sealing material sealing evaluation device can simulate the formation temperature and pressure conditions of the sealing section, the wellbore temperature and pressure, and the fluid medium environment, realize the heating and melting-cooling forming process of the low-melting-point alloy material, and evaluate the sealing capacity of the alloy plug-casing combination under actual downhole working conditions.

[0037] According to the actual requirement, the low-melting-point alloy wellbore sealing material sealing evaluation device described above can be further optimized or / and improved:

[0038] Example Two: As an optimization of the above-described examples, as shown in the attached Figure 1 、 2As shown, the lower end of the plug 3 is centrally fixed with a boss 11, the first mounting hole is arranged at the lower end of the boss 11, the lower end of the second mounting hole extends to the lower end of the boss 11, the first gas injection hole 6 is arranged outside the boss 11, the gas channeling simulation mechanism comprises a first delivery pump 12, a first three-way valve 13 and a pressure gauge 14, the outlet of the first delivery pump 12 is fixedly communicated with the first port of the first three-way valve 13 through a first connecting pipeline 15, the second port of the first three-way valve 13 is fixedly communicated with the first gas injection hole 6 through a second connecting pipeline 16, the second connecting pipeline 16 is provided with the pressure gauge 14, the lower end of the plug 3 corresponding to the position outside the boss 11 is provided with a fixed through hole penetrating up and down, and a thermometer 17 is arranged in the fixed through hole.

[0039] The first three-way valve 13 has a first state and a second state, when the first three-way valve 13 is in the first state, the outlet of the first delivery pump 12 is communicated with the first gas injection hole 6, and the outlet of the first delivery pump 12 is not communicated with the third port of the first three-way valve 13, so that the first delivery pump 12 can input medium into the first gas injection hole 6 through the first connecting pipeline 15 and the second connecting pipeline 16 when the first delivery pump 12 works, when the first three-way valve 13 is in the second state, the first gas injection hole 6 is communicated with the third port of the first three-way valve 13, and the outlet of the first delivery pump 12 is not communicated with the third port of the first three-way valve 13, when the plug 3 is inflated, the upper end of the sealing needle 5 is moved to below the right end of the first gas injection hole 6, the right end of the first gas injection hole 6 is communicated with the upper end of the second mounting hole, and a constant flow rate of gas source (the gas source is a non-corrosive gas) can be input into the inside of the simulation wellbore 2 when the first delivery pump 12 works, and the pressure gauge 14 can continuously record the pressure data of the bottom of the alloy material 41 during the gas injection process, when the test is completed, the first three-way valve 13 is switched to the second state, the first delivery pump 12 stops working, and the gas in the simulation wellbore 2 is discharged through the third port of the first three-way valve 13, so that the pressure in the simulation wellbore 2 is reduced to a safety value, facilitating subsequent operation.

[0040] Embodiment three: as an optimization of the above-mentioned embodiments, as shown in the accompanying drawings Figure 1 、 2 As shown, the image acquisition unit comprises a first image acquisition module 18, a second image acquisition module 19, a processing module 20 and an upper computer 21, the observation cylinder comprises a top cover 22, a quartz tube 23 and an adapter 24, the adapter 24 is arranged between the lower end of the quartz tube 23 and the upper end of the simulation wellbore 2, an upper sealing ring 25 is arranged between the lower end of the adapter 24 and the inner side of the upper part of the outer cylinder 1, the top cover 22 is fixedly arranged at the upper end of the quartz tube 23, an installation through hole is arranged at the central upper end of the top cover 22, the first image acquisition module 18 is arranged in the installation through hole, the second image acquisition module 19 is arranged outside the quartz tube 23, the first image acquisition module 18 and the second image acquisition module 19 are connected with the processing module 20, the processing module 20 is connected with the upper computer 21, and the second gas injection hole 10 is arranged at intervals from the installation through hole.

[0041] According to requirements, the inner diameter of the quartz tube 23, the lower inner diameter of the adapter 24, and the inner diameter of the simulated wellbore 2 are the same. The first image acquisition module 18 is a known high frame rate pressure-resistant camera, such as an underwater high-speed camera; the second image acquisition module 19 is a known high frame rate camera; the processing module 20 is a known image processor; the host computer 21 uses known technology; the pressure gauge 14 is a known pressure sensor; and the thermometer 17 is a known temperature sensor. Both the pressure gauge 14 and the thermometer 17 are connected to the processing module 20. The first image acquisition module 18 and the second image acquisition module 19 capture alloy... The processing module 20 processes and calculates the bubble overflow characteristics when material 41 leaks. The first camera is used to detect the overflow bubble density (in existing known technology, bubble density refers to the ratio of bubble area to liquid column cross-sectional area). The second camera is used to monitor the bubble overflow location (the bonding surface between alloy material 41 and simulated well barrel 2, and the body of alloy material 41). The monitoring directions of the first and second cameras are 90 degrees apart. The quartz tube 23 is an existing known temperature and pressure resistant quartz tube. A confining pressure cavity 8 is formed between the upper end of the lower sealing ring 7, the lower end of the upper sealing ring 25, the inner side of the outer cylinder 1, and the outer side of the simulated well barrel 2.

[0042] The pressure-resistant quartz tube 23 in this low-melting-point alloy well plugging material sealing evaluation device is filled with a transparent liquid medium to visualize the leakage gas overflow process. In conjunction with the first image acquisition module 18 and the second image acquisition module 19, it can automatically capture the location and density of the bubble overflow, and study the sealing threshold and leakage evolution law of the alloy material 41 (alloy plug).

[0043] Example 4: As an optimization of the above examples, as shown in the appendix. Figure 1 , 2 As shown, the wellbore pressure regulating mechanism includes a second delivery pump 26 and a second three-way valve 27. A third connecting pipeline 28 is fixedly connected between the outlet of the second delivery pump 26 and the first port of the second three-way valve 27. A fourth connecting pipeline 29 is fixedly connected between the second port of the second three-way valve 27 and the second air injection port 10.

[0044] The second three-way valve 27 has a first state and a second state. In the first state, the outlet of the second delivery pump 26 is connected to the second air injection port 10, while the outlet of the second delivery pump 26 is not connected to the third port of the second three-way valve 27. Thus, when the second delivery pump 26 is working, it can input the medium into the second air injection port 10 through the third connecting pipeline 28 and the fourth connecting pipeline 29. In the second state, the second air injection port 10 is connected to the third port of the second three-way valve 27, while the outlet of the second delivery pump 26 is not connected to the third port of the second three-way valve 27. Thus, the pressurized medium in the simulated wellbore 2 can be discharged through the fourth connecting pipeline 29 and the third port of the second three-way valve 27, and the pressure in the simulated wellbore 2 drops to a safe value, allowing subsequent operations to proceed.

[0045] When the second delivery pump 26 is working, it achieves constant pressure output. When the second delivery pump 26 is working, it is connected to the simulated wellbore 2 through the second air injection hole 10, thereby simulating the pressure of the overlying liquid column (the liquid column formed by the liquid medium above the alloy material 41) and the liquid environment inside the wellbore during the melting-cooling forming process of the alloy material 41.

[0046] Example 5: As an optimization of the above examples, as shown in the appendix. Figure 1 , 2 As shown, the cooling mechanism includes a water tank 30, a coolant delivery pump 31, an annular heating element 32, a condenser coil 33, and a regulating valve 34. Several annular heating elements 32 are provided on the outer side of the outer cylinder 1 corresponding to the position between the upper sealing ring 25 and the lower sealing ring 7. Several condenser coils 33 are wound around the outer side of the annular heating elements 32. The upper end of the condenser coil 33 is fixedly connected to the inlet of the water tank 30 by a coolant outlet line 35. The outlet of the water tank 30 is fixedly connected to the inlet of the coolant delivery pump 31. The outlet of the coolant delivery pump 31 is fixedly connected to the lower end of the condenser coil 33 by a coolant inlet line 36. A thermostat is provided inside the water tank 30.

[0047] According to requirements, the thermostat and water tank 30 constitute a conventionally known cooling water tank. When the coolant delivery pump 31 is working, the constant temperature water flowing in the condenser coil 33 can control the cooling and forming rate of the molten alloy material 41. The coolant delivery pump 31 starts after the alloy material 41 is completely melted. The coolant delivery pump 31 pumps the constant temperature water into the condenser coil 33 from bottom to top. The condenser coil 33 is in close contact with the annular heating element 32. A regulating valve 34 is installed on the coolant inlet line 36. The water flow rate in the condenser coil 33 is adjusted by regulating the regulating valve 34, or the water flow rate in the condenser coil 33 is adjusted by adjusting the pump speed of the coolant delivery pump 31 by the thermostat, thereby realizing the control of the cooling and forming rate of the molten alloy material 41.

[0048] Example 6: As an optimization of the above examples, as shown in the appendix. Figure 1、 2 As shown in the figure, the formation pressure regulating mechanism comprises a third delivery pump 37 and a third three-way valve 38, the outlet of the third delivery pump 37 is fixedly communicated with a first port of the third three-way valve 38 through a fifth connecting pipeline 39, and a second port of the third three-way valve 38 is fixedly communicated with the pressure boosting hole 9 through a sixth connecting pipeline 40.

[0049] The third three-way valve 38 has a first state and a second state, when the third three-way valve 38 is in the first state, the outlet of the third delivery pump 37 is communicated with the pressure boosting hole 9, and the outlet of the third delivery pump 37 is not communicated with a third port of the third three-way valve 38, so that the third delivery pump 37 can input medium into the pressure boosting hole 9 through the fifth connecting pipeline 39 and the sixth connecting pipeline 40 when the third delivery pump 37 works, when the third three-way valve 38 is in the second state, the pressure boosting hole 9 is communicated with the third port of the third three-way valve 38, and the outlet of the third delivery pump 37 is not communicated with the third port of the third three-way valve 38, so that the medium with pressure in the confining pressure cavity 8 can be discharged through the sixth connecting pipeline 40 and the third port of the third three-way valve 38, and the pressure in the confining pressure cavity 8 is reduced to a safety value, so that subsequent operations can be performed.

[0050] Example Seven: As an optimization of the above examples, as shown in the accompanying Figure 1 、 2 As shown in the figure, the low-melting-point alloy wellbore sealing material sealing evaluation method comprises the following steps:

[0051] S1, preparation before experiment: adjust the position of the sealing needle 5 so that the first gas injection hole 6 is not communicated with the upper part of the second mounting hole, open the second delivery pump 26 and the third delivery pump 37, increase the pressure in the simulated wellbore 2 and the confining pressure cavity 8 to a first set value and a second set value respectively, after the simulated wellbore 2 and the confining pressure cavity 8 are found to be leak-free, open the thermostat and the cooling liquid delivery pump 31, after the condenser coil 33 is found to be unblocked, close the second delivery pump 26, the third delivery pump 37, the cooling liquid delivery pump 31 and the thermostat, and adjust the second three-way valve 27 and the third three-way valve 38 until the pressure in the simulated wellbore 2 and the confining pressure cavity 8 is reduced to a safety value;

[0052] S2, put the alloy material 41: disconnect the adapter 24 from the upper sealing ring 25, add the alloy material 41 to the simulated wellbore 2 to a set height, then connect the adapter 24 with the upper sealing ring 25, open the second delivery pump 26, increase the pressure in the simulated wellbore 2 to a third set value, after the simulated wellbore 2 is found to be leak-free, close the second delivery pump 26, and adjust the second three-way valve 27 until the pressure in the simulated wellbore 2 is reduced to a safety value;

[0053] S3, setting experimental conditions: adjusting the second three-way valve 27, opening the second delivery pump 26, injecting liquid medium into the simulated wellbore 2, opening the annular heating sheet 32, heating the confining pressure chamber 8 and the simulated wellbore 2 to a first set temperature, and increasing the pressure in the simulated wellbore 2 and the confining pressure chamber 8 to a first set pressure and a second set pressure respectively by the second delivery pump 26 and the third delivery pump 37;

[0054] S4, heating and melting the alloy material 41: opening the electric heating rod 4, heating the alloy material 41 to a second set temperature, which is greater than the melting point of the alloy material 41 and lower than the boiling point of the liquid medium in the simulated wellbore 2; collecting the temperature values of the alloy material 41 during the heating process by the thermometer 17, and analyzing the melting rate of the alloy material 41 according to the temperature values during the heating process;

[0055] S5, cooling and solidifying the alloy material 41: after the alloy material 41 is completely melted, closing the electric heating rod 4 and opening the cooling liquid delivery pump 31 to cool the outer cylinder 1; collecting the temperature values of the alloy material 41 during the cooling process by the thermometer 17, analyzing the cooling rate of the alloy material 41 according to the temperature values during the cooling process, and closing the cooling liquid delivery pump 31 and the thermostat when the temperature of the alloy material 41 drops to the temperature of the outer cylinder 1;

[0056] S6, alloy plug sealing test: opening the first image acquisition module 18 and the second image acquisition module 19, adjusting the position of the sealing needle 5 so that the first gas injection hole 6 and the upper part of the second mounting hole are in communication with each other, opening the first delivery pump 12, and inputting gas medium into the simulated wellbore 2; the pressure gauge 14 collects the pressure data of the gas medium;

[0057] S7, recording the leakage pressure: the moment when the continuous overflow bubbles in the quartz tube 23 is the moment when the alloy material 41 leaks, and the pressure data collected by the pressure gauge 14 at the moment when the alloy material 41 leaks is recorded;

[0058] S8, capturing the leakage image: after the alloy material 41 leaks, the first image acquisition module 18 and the second image acquisition module 19 start recording, and after a set time interval, the picture information of the bubble overflow is collected, and the processing module 20 analyzes the bubble overflow position and the bubble overflow density change according to the picture information of the bubble overflow, and analyzes the reaction alloy plug leakage evolution law;

[0059] S9, cleaning device complete test: after the completion of the test, the first delivery pump 12, the first image acquisition module 18, the second image acquisition module 19, the second delivery pump, the third delivery pump 37, the cooling liquid delivery pump 31 and the annular heating sheet 32 are closed, the first three-way valve 13, the second three-way valve 27 and the third three-way valve 38 are adjusted, the pressure in the simulated wellbore 2 and the pressure in the confining pressure chamber 8 are reduced to a safe value, the temperature of the simulated wellbore 2 is lowered to a safe value, the adapter 24 is separated from the upper sealing ring 25, and the alloy material 41 is cleaned. After the alloy material 41 is cleaned, the inner wall of the simulated wellbore 2 and the inner wall of the quartz tube 23 are cleaned.

[0060] The specific steps of the sealing evaluation method of the low-melting-point alloy wellbore plugging material are as follows:

[0061] S1, preparation before experiment: adjust the position of the sealing needle 5, the upper end of the sealing needle 5 is flush with the upper end of the plug 3, the first gas injection hole 6 and the upper part of the second mounting hole are not connected with each other, the second delivery pump 26 and the third delivery pump 37 are opened, the pressure in the simulated wellbore 2 and the pressure in the confining pressure chamber 8 are increased to the first set value and the second set value respectively, the sealing performance of the device is ensured to be good, and the simulated wellbore 2 and the confining pressure chamber 8 are leak-free. After the condenser coil 33 is unblocked, the second delivery pump 26, the third delivery pump 37, the cooling liquid delivery pump 31 and the thermostat are closed, the second three-way valve 27 and the third three-way valve 38 are adjusted, and the pressure in the simulated wellbore 2 and the confining pressure chamber 8 is reduced to a safe value (the pressure in the simulated wellbore 2 and the confining pressure chamber 8 is removed).

[0062] S2, alloy material 41 is put in: the adapter 24 is separated from the upper sealing ring 25 (the adapter 24 and the upper sealing ring 25 are connected by threads), a set height of alloy material 41 is added into the simulated wellbore 2 (the alloy height can be adjusted according to the experimental scheme), the adapter 24 and the upper sealing ring 25 are installed together, the second delivery pump 26 is opened, the pressure in the simulated wellbore 2 is increased to the third set value, the air tightness of the test device is tested, the simulated wellbore 2 is leak-free, the second delivery pump 26 is closed, and the second three-way valve 27 is adjusted until the pressure in the simulated wellbore 2 is reduced to a safe value (the pressure in the simulated wellbore 2 is removed).

[0063] S3, set experimental conditions: adjust the second three-way valve 27, open the second delivery pump 26, inject liquid medium into the simulated wellbore 2 (the type and filling height of the liquid medium can be adjusted according to the experimental scheme), open the annular heating sheet 32, heat the confining pressure chamber 8 and the simulated wellbore to the first set temperature, and increase the pressure in the simulated wellbore 2 and the confining pressure chamber 8 to the first set pressure and the second set pressure respectively through the second delivery pump 26 and the third delivery pump 37.

[0064] S4, heating and melting the alloy material 41: after the conditions inside and outside the wellbore are stable, the electric heating rod 4 is turned on, and the power of the electric heating rod 4 can be adjusted to simulate different heating rates; the alloy material 41 is heated to a second set temperature, which is greater than the melting point of the alloy material 41 and is lower than the boiling point of the liquid medium in the simulated wellbore 2; the temperature values of the alloy material 41 during the heating process are collected by the thermometer 17, and the melting rate of the alloy material 41 is analyzed according to the temperature values during the heating process;

[0065] S5, cooling and solidifying the alloy material 41: after the alloy material 41 is completely melted, the electric heating rod 4 is turned off, and the cooling liquid delivery pump 31 is turned on to cool the outer cylinder 1; during the cooling process, the cooling rate can be adjusted by adjusting the valve 34 or by adjusting the working frequency of the cooling liquid delivery pump 31 to simulate different cooling rates; the temperature in the water tank 30 is controlled by the thermostat to be constant, the temperature values of the alloy material 41 during the cooling process are collected by the thermometer 17, and the cooling rate of the alloy material 41 is analyzed according to the temperature values during the cooling process; when the temperature of the alloy material 41 decreases to the temperature of the outer cylinder 1, the cooling liquid delivery pump 31 and the thermostat are turned off;

[0066] S6, alloy plug sealing test: the first image acquisition module 18 and the second image acquisition module 19 are turned on, the position of the sealing needle 5 is adjusted (the upper end of the sealing needle 5 is located below the right end of the first gas injection hole 6), so that the first gas injection hole 6 and the upper part of the second mounting hole are connected to each other, the first delivery pump 12 is turned on, and the gas medium is input into the simulated wellbore 2, and the pressure data of the gas medium are collected by the pressure gauge 14;

[0067] S7, record the leakage pressure: the moment when the continuous overflow bubbles in the quartz tube 23 is the moment when the alloy material 41 leaks, and the pressure data collected by the pressure gauge 14 at the moment when the alloy material 41 leaks are recorded;

[0068] S8, capture the leakage image: after the alloy material 41 leaks, the first image acquisition module 18 and the second image acquisition module 19 start recording, and the picture information of the bubble overflow is collected after a set time interval, the bubble overflow position and the bubble overflow density change are obtained by the processing module 20 according to the picture information of the bubble overflow, and the alloy plug leakage rule is analyzed;

[0069] S9, Cleaning device test completed: After the test is completed, shut down the first delivery pump 12, the first image acquisition module 18, the second image acquisition module 19, the second delivery pump, the third delivery pump 37, the coolant delivery pump 31, and the annular heating element 32. Adjust the first three-way valve 13, the second three-way valve 27, and the third three-way valve 38 to reduce the pressure inside the simulated wellbore 2 and the pressure inside the confining pressure chamber 8 to a safe value. After the temperature of the simulated wellbore 2 drops to a safe value, disconnect the adapter 24 from the upper sealing ring 25, unscrew the adapter 24 from the upper sealing ring 25, and remove the liquid inside the wellbore. Turn on the electric heating rod 4 again to heat the alloy material 41 until it is completely melted and poured out of the wellbore. Turn off the electric heating rod 4. After cleaning the alloy material 41, clean the inner wall of the simulated wellbore 2 and the inner wall of the quartz tube 23 to prepare for the next experiment.

[0070] This method for evaluating the sealing of low-melting-point alloy wellbore plugging materials allows for flexible adjustment of wellbore / formation temperature and pressure conditions, fluid environment within the wellbore, alloy heating and melting rate, alloy cooling and forming rate, alloy material, and alloy dosage. It enables rapid selection of alloy material and forming parameters based on the actual conditions of the well section to be plugged, ensuring the sealing capability of the alloy plug-casing assembly.

[0071] Example 8: As attached Figure 1 As shown, Figures 1 to 7 For a set of experimental results, the temperature of the confining pressure chamber 8 and the simulated wellbore 2 is 40℃, the pressure of the confining pressure chamber 8 is 1.0 MPa, the alloy material 41 is a bismuth-tin alloy (58% bismuth - 42% tin), the liquid medium in the simulated wellbore 2 is water, and the pressure in the simulated wellbore 2 is 1.0 MPa. In the simulated wellbore 2 at a pressure of 1.0 MPa, the boiling point of water is 179.4℃, and the melting point of alloy material 41 is 138℃. Therefore, the heating temperature of the electric heating rod 41.10 should be set between 138℃ and 179.4℃, which is set to 150℃. The flow rate of the first delivery pump 12 is 5 mL / s.

[0072] Figures 3 to 7 The temperature curves of the alloy plug (i.e., alloy material 41) during the heating, melting and cooling process are shown. The heating-cooling rate of the alloy plug can be determined by the slope of the curve. Figure 3 The pressure curve for sealing performance testing after the alloy plug has cooled and formed is shown. Continuous bubble overflow was first observed at 1344 s, corresponding to a bottom pressure of 3.69 MPa for the alloy plug. The bubble overflow image captured by the first image acquisition module 18 is shown below. Figure 4 As can be seen, the leak location is at the cemented surface between the alloy plug and the simulated wellbore 2; as gas medium continues to be injected into the bottom of the alloy plug at a constant rate, the leakage of the alloy plug intensifies. The bubble overflow images captured by the second image acquisition module 19 at each leakage stage and the bubble identification results of the processing module 20 are as follows: Figure 5 As shown, Figure 6 Figure 7To calculate the bubble overflow density and draw the curve, it can be seen that the bubble overflow density increases exponentially with the increase of the pressure at the bottom of the alloy plug.

[0073] The above technical features respectively constitute various embodiments of the present application, which have strong adaptability and implementation effect. Non-essential technical features can be added or reduced according to actual needs to meet the needs of different situations.

Claims

1. A low-melt alloy wellbore plugging material seal evaluation apparatus, characterized by The device comprises an observation cylinder, an outer cylinder, a simulated wellbore, a gas channeling simulation mechanism, a formation pressure adjusting mechanism, a cooling mechanism, a wellbore pressure adjusting mechanism and an image acquisition unit. The lower part of the observation cylinder is detachably fixed with the upper part of the outer cylinder. The inner side of the outer cylinder is sleeved with the simulated wellbore. The lower end of the simulated wellbore is fixedly installed with a plug. The lower end of the plug is provided with a first installation hole and a second installation hole penetrating up and down. An electric heating rod is arranged in the first installation hole and located above the plug. The lower end of the plug is provided with a first gas injection hole in communication with the second installation hole. A sealing needle is arranged in the second installation hole. The first gas injection hole is connected with the gas channeling simulation mechanism. The gas channeling simulation mechanism is used for inputting gas source into the first gas injection hole. A lower sealing ring is fixedly installed between the lower end of the outer cylinder and the lower end of the simulated wellbore. A surrounding pressure cavity is formed between the upper end of the lower sealing ring, the lower end of the observation cylinder, the inner side of the outer cylinder and the outer side of the simulated wellbore. The lower end of the lower sealing ring is provided with a pressure boosting hole in communication with the surrounding pressure cavity. The pressure boosting hole is connected with the formation pressure adjusting mechanism. The outer side of the outer cylinder is provided with the cooling mechanism. The upper end of the observation cylinder is provided with a second gas injection hole penetrating up and down. The second gas injection hole is connected with the wellbore pressure adjusting mechanism. The outer side of the observation cylinder is provided with the image acquisition unit used for acquiring image information in the observation cylinder.

2. The low-melting-point alloy wellbore plugging material seal evaluation apparatus of claim 1, wherein A boss is fixedly arranged at the lower end of the plug. The first installation hole is arranged at the lower end of the boss. The second installation hole extends to the lower end of the boss. The first gas injection hole is arranged at the outer side of the boss. The gas channeling simulation mechanism comprises a first delivery pump, a first three-way valve and a pressure gauge. The outlet of the first delivery pump is fixedly communicated with the first port of the first three-way valve through a first connecting pipeline. The second port of the first three-way valve is fixedly communicated with the first gas injection hole through a second connecting pipeline. The second connecting pipeline is provided with the pressure gauge. The lower end of the plug corresponding to the position of the outer side of the boss is provided with a fixed through hole penetrating up and down. A thermometer is arranged in the fixed through hole.

3. The low-melting-point alloy wellbore plugging material seal evaluation apparatus according to claim 1 or 2, characterized by The image acquisition unit comprises a first image acquisition module, a second image acquisition module, a processing module and an upper computer. The observation cylinder comprises a top cover, a quartz tube and an adapter. The adapter is arranged between the lower end of the quartz tube and the upper end of the simulated wellbore. An upper sealing ring is arranged between the lower end of the adapter and the inner side of the upper part of the outer cylinder. The top cover is fixedly installed at the upper end of the quartz tube. The upper end of the top cover is provided with an installation through hole. The first image acquisition module is arranged in the installation through hole. The second image acquisition module is arranged at the outer side of the quartz tube. The first image acquisition module and the second image acquisition module are connected with the processing module. The processing module is connected with the upper computer. The second gas injection hole is arranged in the installation through hole.

4. The low melt alloy wellbore plugging material seal evaluation apparatus of claim 3, wherein The wellbore pressure adjusting mechanism comprises a second delivery pump and a second three-way valve. The outlet of the second delivery pump is fixedly communicated with the first port of the second three-way valve through a third connecting pipeline. The second port of the second three-way valve is fixedly communicated with the second gas injection hole through a fourth connecting pipeline.

5. The low melt alloy wellbore plugging material seal evaluation apparatus of claim 3, wherein The cooling mechanism comprises a water tank, a cooling liquid delivery pump, annular heating fins, a condensing coil and a regulating valve, a plurality of annular heating fins are arranged outside the outer cylinder corresponding to the position between the upper sealing ring and the lower sealing ring, a plurality of condensing coils are wound outside the annular heating fins, a cooling liquid outlet pipeline is fixedly communicated between the upper end of the condensing coil and the inlet of the water tank, the outlet of the water tank is fixedly communicated with the inlet of the cooling liquid delivery pump, a cooling liquid inlet pipeline is fixedly communicated between the outlet of the cooling liquid delivery pump and the lower end of the condensing coil, and a thermostat is arranged in the water tank.

6. The low-melting-point alloy wellbore plugging material seal evaluation apparatus of claim 4, wherein The cooling mechanism comprises a water tank, a cooling liquid delivery pump, annular heating fins, a condensing coil and a regulating valve, a plurality of annular heating fins are arranged outside the outer cylinder corresponding to the position between the upper sealing ring and the lower sealing ring, a plurality of condensing coils are wound outside the annular heating fins, a cooling liquid outlet pipeline is fixedly communicated between the upper end of the condensing coil and the inlet of the water tank, the outlet of the water tank is fixedly communicated with the inlet of the cooling liquid delivery pump, a cooling liquid inlet pipeline is fixedly communicated between the outlet of the cooling liquid delivery pump and the lower end of the condensing coil, and a thermostat is arranged in the water tank.

7. The low-melting-point alloy shaft sealing material sealing evaluation apparatus according to claim 1 or 2 or 4 or 5 or 6, characterized by The formation pressure adjusting mechanism comprises a third delivery pump and a third three-way valve, a fifth connecting pipeline is fixedly communicated between the outlet of the third delivery pump and the first port of the third three-way valve, and a sixth connecting pipeline is fixedly communicated between the second port of the third three-way valve and the pressure boosting hole.

8. The low-melting-point alloy wellbore plugging material seal evaluation apparatus of claim 3, wherein The formation pressure adjusting mechanism comprises a third delivery pump and a third three-way valve, a fifth connecting pipeline is fixedly communicated between the outlet of the third delivery pump and the first port of the third three-way valve, and a sixth connecting pipeline is fixedly communicated between the second port of the third three-way valve and the pressure boosting hole.

9. A low-melting-point alloy shaft sealing material sealing evaluation method for a low-melting-point alloy shaft sealing material sealing evaluation apparatus according to claim 7 or 8, characterized by The method comprises the following steps: S1, preparation before experiment: adjusting the position of the sealing needle so that the first gas injection hole and the upper part of the second mounting hole are not communicated with each other, starting the second delivery pump and the third delivery pump, increasing the pressure in the simulated wellbore and the confining pressure cavity to first and second set values respectively, after the simulated wellbore and the confining pressure cavity are confirmed to be leak-free, starting the thermostat and the cooling liquid delivery pump, after the condensing coil is confirmed to be unblocked, stopping the second delivery pump, the third delivery pump, the cooling liquid delivery pump and the thermostat, and adjusting the second three-way valve and the third three-way valve until the pressure in the simulated wellbore and the confining pressure cavity drops to a safety value; S2, alloy material injection: disconnecting the adapter from the upper sealing ring, adding alloy material of a set height into the simulated wellbore, connecting the adapter with the upper sealing ring again, starting the second delivery pump, increasing the pressure in the simulated wellbore to a third set value, stopping the second delivery pump after the simulated wellbore is confirmed to be leak-free, and adjusting the second three-way valve until the pressure in the simulated wellbore drops to a safety value; S3, setting experimental conditions: adjusting the second three-way valve, starting the second delivery pump, injecting liquid medium into the simulated wellbore, starting the annular heating fins, heating the confining pressure cavity and the simulated wellbore to a first set temperature, and increasing the pressure in the simulated wellbore and the confining pressure cavity to first and second set pressures respectively through the second delivery pump and the third delivery pump; S4, heating and melting the alloy material: turn on the electric heating rod, heat the alloy material to a second set temperature, the second set temperature is greater than the melting point of the alloy material, and the second set temperature is lower than the boiling point of the liquid medium in the simulated wellbore; the temperature value of the heating process of the alloy material is collected by the thermometer, and the melting rate of the alloy material is analyzed according to the temperature value of the heating process; S5, cooling and solidifying the alloy material: after the alloy material is completely melted, turn off the electric heating rod, open the cooling liquid delivery pump to cool the outer cylinder, collect the temperature value of the cooling process of the alloy material by the thermometer, analyze the cooling rate of the alloy material according to the temperature value of the cooling process, and turn off the cooling liquid delivery pump and the thermostat when the temperature of the alloy material decreases to the temperature of the outer cylinder; S6, alloy plug sealing test: open the first image acquisition module and the second image acquisition module, adjust the position of the sealing needle so that the first gas injection hole and the second installation hole are connected to each other, open the first delivery pump, and input the gas medium into the simulated wellbore, and the pressure data of the gas medium is collected by the pressure gauge; S7, record the leakage pressure: the moment when the quartz tube continuously overflows bubbles is the moment when the alloy material leaks, and the pressure data collected by the pressure gauge at the moment when the alloy material leaks is recorded; S8, capture the leakage image: after the alloy material leaks, the first image acquisition module and the second image acquisition module start recording, and after a set time interval, the picture information of the bubble overflow is collected, the processing module obtains the bubble overflow position and the bubble overflow density change according to the picture information of the bubble overflow, and analyzes the alloy plug leakage rule; S9, cleaning device completes the test: after the test is completed, turn off the first delivery pump, the first image acquisition module, the second image acquisition module, the second delivery pump, the third delivery pump, the cooling liquid delivery pump and the annular heating sheet, adjust the first three-way valve, the second three-way valve and the third three-way valve, reduce the pressure in the simulated wellbore and the pressure in the confining pressure chamber to a safe value, and after the temperature of the simulated wellbore decreases to a safe value, disconnect the adapter from the upper sealing ring, clean the alloy material, and clean the inner wall of the simulated wellbore and the inner wall of the quartz tube.

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