Cement slurry gas channeling prevention ability testing device and method

Abstract

The present invention provides a device and method for testing the gas channeling prevention ability of cement slurry. The device includes: a test string that extends in the longitudinal direction; a first fluid injection mechanism that is connected to the lower end of the test string and is used to inject a pre-fluid and cement slurry into the test string; a second fluid injection mechanism that is connected to the lower end of the test string and is used to inject a test gas into the test string; and a gas collection mechanism that is connected to the upper end of the test string and is used to receive the test gas passing through the test string.

Description

Technical Field

[0001] The present invention relates to the technical field of oil and gas well development, and particularly to a device for testing the gas channeling prevention ability of cement slurry. The present invention also relates to a method for testing the gas channeling prevention ability using the above test device. Background Art

[0002] During and after the cementing process of oil and gas wells, if there is a high-pressure gas layer underground, gas channeling is likely to occur. The problem of gas channeling, especially the early gas channeling problem during the cementing process, has long been one of the most intractable problems in the petroleum industry.

[0003] The reasons for the early gas channeling problem during cementing mainly lie in two aspects. One is the driving force for gas channeling, and the other is the formation of gas channeling paths.

[0004] The reason for the driving force of gas channeling is mainly the decrease in annulus pressure caused by cement weight loss. As the cement hydration reaction progresses further, the cement slurry itself has an increasingly high gel strength, which will share part of the original hydrostatic pressure of the cement slurry. This will lead to a decrease in pore pressure within the cement structure. In addition, after the cement slurry enters the annulus, the free water in it continuously filters into the formation, and the progress of the cement slurry hydration reaction will cause the volume of the hydration products to be smaller than the volume of the original cement slurry system. The occurrence of phenomena such as water loss and volume shrinkage will further lead to a decrease in the pore pressure of the cement slurry. The decrease in the pore pressure of the cement slurry will then cause a pressure difference between the formation pressure and the cement slurry pressure, and this pressure difference is the driving force for early gas channeling during cementing.

[0005] The reasons for the formation of gas channeling paths are diverse, including leakage, free fluid, chemical shrinkage, and the pore structure of the cement slurry itself. The pore structure of the cement slurry itself is considered to be one of the most important gas channeling paths. After the cement slurry enters the hydration stage, it gradually changes from a pure liquid state to a gel state with a pore structure. At this time, the cement slurry has not yet formed a dense network structure and has micro-pores itself, which provides a channel for early gas channeling during cementing. However, as the hydration reaction progresses further, the cement slurry gradually transforms into solid cement stone, and the voids inside it will be gradually closed to prevent further gas channeling. During the hydration process of the cement slurry, formation gas will penetrate into the micro-pores of the cement under the action of the pressure difference, thereby affecting the integrity of the cement ring in the annulus. This will seriously reduce the strength of the cement stone and affect the quality of the cement bond in cementing. In addition, if the gas channeling problem is more serious, it will induce the problem of annulus pressure build-up, and may even lead to a blowout accident, causing huge casualties and property losses.

[0006] Although the problem of gas channeling has received extensive attention from those skilled in the art. However, at present, there is no experimental device and method in this field that can accurately simulate the gas channeling process and help technicians effectively master the law of gas channeling. Summary of the Invention

[0007] In view of the above technical problems, the present invention provides a device for testing the gas channeling prevention ability of cement slurry, which enables technicians to effectively test and master the gas channeling prevention performance of cement slurry, so as to facilitate the guidance of actual cementing operations. The present invention also provides a method for testing the gas channeling prevention ability using the above device.

[0008] According to a first aspect of the present invention, there is provided a device for testing the gas channeling prevention ability of cement slurry, comprising: a test string extending in a longitudinal direction; a first fluid injection mechanism connected to the lower end of the test string for injecting a pre-fluid and cement slurry into the test string; a second fluid injection mechanism connected to the lower end of the test string for injecting a test gas into the test string; and a gas collection mechanism connected to the upper end of the test string for receiving the test gas passing through the test string.

[0009] By using the above device for testing, it is possible to effectively simulate the displacement and curing processes of cement slurry, and during this process, by injecting a test gas into the test string and collecting and quantifying it on the other side, it is possible to effectively determine the gas channeling prevention ability of the cement slurry. This is beneficial for operators to effectively master whether a specific cement slurry can be used under the corresponding environmental conditions, and thus has a guiding role in actual cementing operations.

[0010] In one embodiment, the lower end of the test string includes a first inlet opened longitudinally downward and a second inlet opened laterally, the second inlet being located above the first inlet, the first fluid injection mechanism being connected to the first inlet, the second fluid injection mechanism being connected to the second inlet, wherein a cement slurry blocking member is provided at the second inlet, the cement slurry blocking member being configured to prevent cement slurry from flowing into the second fluid injection mechanism, and the cement slurry blocking member is configured as a screen.

[0011] In one embodiment, the second fluid injection mechanism includes: an air injection pump configured to drive the test gas to flow towards the second inlet; a check valve connected between the air injection pump and the second inlet for preventing fluid from flowing in the direction from the second inlet to the check valve.

[0012] In one embodiment, the gas collecting mechanism includes a longitudinally extending collecting container, an intake valve connected between the lower end of the collecting container and the upper end of the test string, and an outlet valve connected at the upper end of the collecting container; wherein, the collecting container is at least partially constructed to be transparent and is provided with measurement scales longitudinally.

[0013] In one embodiment, the device further includes an external pipeline, the first end of the external pipeline communicates with the test string, and the second end communicates with the environment.

[0014] In one embodiment, the first end of the external pipeline is longitudinally located at a distance below the upper end of the test string.

[0015] In one embodiment, the first end of the external pipeline extends downward from the upper end of the test string into the test string, such that the first end is longitudinally located at a distance below the upper end of the test string.

[0016] In one embodiment, the device further includes a first release valve, and the first release valve communicates with the test string between the upper end of the test string and the first end of the external pipeline.

[0017] In one embodiment, the device further includes: a constant temperature mechanism configured to maintain the temperature inside the test string within a predetermined range; and a constant pressure mechanism configured to maintain the pressure inside the test string within a predetermined range.

[0018] According to the second aspect of the present invention, a method for testing the gas channeling prevention ability of cement slurry is proposed, which is carried out using the above-mentioned cement slurry gas channeling prevention ability testing device. The method includes the following steps: injecting a pre-fluid into the test string through the first fluid injection mechanism; injecting cement slurry into the test string through the first fluid injection mechanism to displace the pre-fluid in the test string; injecting a test gas into the test string through the second fluid injection mechanism; determining the amount of the test gas collected in the gas collecting mechanism.

[0019] In one embodiment, the cement slurry gas channeling prevention ability testing device further includes an external pipeline, the first end of the external pipeline communicates with the test string, and the second end communicates with the environment; the process of injecting the pre-fluid into the test string through the first fluid injection mechanism ends after the pre-fluid flows out at the second end of the external pipeline; the process of injecting the cement slurry into the test string through the first fluid injection mechanism ends after the cement slurry flows out at the second end of the external pipeline.

[0020] In one embodiment, the cement slurry gas channeling prevention ability testing device further includes a first release valve, which is connected to the test string between the upper end of the test string and the first end of the external pipeline; when injecting the pre-fluid, the gas collection mechanism is opened to allow the pre-fluid to flow into the gas collection mechanism from the upper end of the test string, and when injecting the cement slurry, the gas collection mechanism is closed to prevent the cement slurry from flowing from the upper end of the test string to the gas collection mechanism, so as to leave pre-fluid in the test string between the first end of the external pipeline and the upper end of the test string; wherein, before injecting the test gas into the test string through the second fluid injection mechanism, a part of the pre-fluid remaining in the test string is discharged through the first release valve. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The present invention will be described below with reference to the drawings.

[0022] Figure 1 is a schematic structural diagram of a cement slurry gas channeling prevention ability testing device according to the present invention.

[0023] Figure 2 shows Figure 1 a schematic structural diagram of the gas collection mechanism in the cement slurry gas channeling prevention ability testing device in

[0024] Figure 3 shows Figure 1 a schematic structural diagram of the constant pressure mechanism in the cement slurry gas channeling prevention ability testing device in

[0025] Figures 4 to 7 shows the use of Figure 1 the cement slurry gas channeling prevention ability testing device in

[0026] Figure 8 a schematic process of conducting a gas channeling prevention ability test using the cement slurry gas channeling prevention ability testing device in

[0027] Figure 9 shows a graph of gas channeling volume and gel strength versus time.

[0028] In the drawings, the same components are denoted by the same reference numerals. In the present application, all the drawings are schematic drawings, only used to illustrate the principle of the present invention and not drawn to actual scale. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0029] The present invention will be introduced below with reference to the drawings.

[0030] Figure 1 Schematically shows the overall structure of a cement slurry gas channeling prevention ability testing device (hereinafter simply referred to as "device") 1 according to an embodiment of the present invention.

[0031] Apparatus 1 includes a longitudinally extending test string 10. The test string 10 has a lower end 11 and an upper end 12. In Figure 1 the preferred embodiment shown, the test string 10 preferably has one or more reduced diameter portions 13 spaced apart longitudinally between the lower end 11 and the upper end 12 to more realistically simulate the environment of an open hole formation. Additionally, the lower end 11 of the test string 10 is configured with a first inlet 11A opening longitudinally downward and a second inlet 11B opening transversely to respectively connect to a first fluid injection mechanism and a second fluid injection mechanism 70 described below. The second inlet 11B is located longitudinally above the first inlet 11A.

[0032] Apparatus 1 includes a first fluid injection mechanism. The first fluid injection mechanism includes an injection pump 80 and an injection valve 130 connected between the injection pump 80 and the first inlet 11A. The injection pump 80 can be used to pump a pre - fluid (e.g., water) and a cement slurry towards the test string 10. The injection valve 130 can be used to control whether the fluid pumped by the injection pump 80 can flow towards the first inlet 11A. Additionally, the first fluid injection mechanism further includes a discharge branch for discharging the cement slurry in the test string 10 after an experimental test. A cement slurry isolation valve 100 is provided in the discharge branch. The discharge branch is parallel to the first inlet 11A and can receive fluid from both the injection pump 80 and the injection valve 130, and the discharge branch can also receive fluid from the first inlet 11A. Thus, as Figure 1 shown, a diversion section is formed between the injection valve 130, the first inlet 11A, and the cement slurry isolation valve 100. The first fluid injection mechanism further includes a second release valve 90 which communicates with the discharge branch downstream of the cement slurry isolation valve 100 (i.e., Figure 1 on the left side in ). A second flowmeter 120 is also provided between the second release valve 90 and the discharge branch. The second release valve 90 can be used to control whether the fluid in the discharge branch is discharged therefrom and can lead to the environment, a waste tank, or any other suitable structure. The second flowmeter 120 can be used to measure the amount of fluid discharged through the second release valve 90.

[0033] Also as Figure 1 shown, apparatus 1 further includes a second fluid injection mechanism 70. The second fluid injection mechanism includes an air injection pump 701 connected to the second inlet 11B. The air injection pump 701 can be used to pump a measurement gas towards the test string 10. For example, the measurement gas can be nitrogen, methane, carbon dioxide, etc. A check valve 702 can also be connected between the air injection pump 701 and the second inlet 11B. The check valve 702 can be used to prevent the measurement gas from flowing back towards the air injection pump 701 and can also prevent other fluids (e.g., pre - fluid and cement slurry) in the test string 10 from flowing towards the air injection pump 701.

[0034] In a preferred embodiment, a cement slurry barrier (not shown) is provided at the second inlet 11B. The cement slurry barrier is, for example, a sieve, or it can be any other suitable structure. By providing this cement slurry barrier, it is possible to prevent the test cement slurry from flowing towards the second fluid injection mechanism 70. It should be understood that even in the case where the one-way valve 702 is provided, the setting of the cement slurry barrier is still meaningful. It can prevent the gradually solidified cement slurry from blocking the outlet of the one-way valve 702, resulting in abnormal testing, and thus reduce the risk of blockage of the second fluid injection mechanism 70. The cement slurry barrier is detachable for easy replacement and maintenance.

[0035] In addition, the device 1 further includes a gas collection mechanism 30. The gas collection mechanism is connected to the upper end 12 of the test string 10. Figure 2 The specific structure of an embodiment of the gas collection mechanism 30 is shown. As Figure 2 shown, the gas collection mechanism 30 includes a collection container 302 that extends generally in the longitudinal direction. The lower end of the collection container 302 is connected to the upper end 12 of the test string 10, and an intake valve 301 is provided therebetween. The intake valve 301 can be used to control whether the fluid in the test string 10 can flow into the collection container 302. The upper end of the collection container 302 is also connected with an outlet valve 303. The outlet valve 303 can be used to control whether the fluid in the test string 10 can be discharged from the collection container 302. The outlet valve 303 can lead to the environment, a waste tank, or any other suitable structure. In addition, the collection container 302 can be made of a transparent material in whole or in part. Thereby, it allows the operator to directly observe the fluid collection situation in the collection container 302. As Figure 2 shown, a measurement scale arranged longitudinally can also be provided on the collection container 302 to help the operator visually determine the amount of the collected test gas on the collection container 302. The collection container 302 can be a graduated cylinder.

[0036] The device 1 further includes an external pipeline 20 ( Figure 1 ). The first end 21 of the external pipeline 20 is connected to the test string 10 between the upper end 12 and the lower end 11 of the test string 10, so that the first end 21 is at a distance below the upper end 12 of the test string 10. A third release valve 204 can be provided at the second end 22 of the external pipeline 20. The third release valve 204 can be used to control whether the fluid can be discharged therefrom. It should be understood that the second end 22 of the external pipeline 20 can lead to the environment, a waste tank, or any other suitable structure.

[0037] In Figure 1In the preferred embodiment shown, the first end of the external pipeline 20 is longitudinally inserted downward from the upper end 12 of the test string 10 into the test string 10 for a certain distance, so as to make the first end 21 be at a certain distance below the upper end 12 of the test string 10. This connection method is more convenient and effective for the seal between the test string 10 and the external pipeline 20, and the cost is lower. In addition, this connection method is also beneficial to avoid the test gas from entering the external pipeline 20, thereby being beneficial to ensuring the accuracy of the gas channeling performance evaluation.

[0038] It should be understood that other methods can also be adopted to realize the connection between the external pipeline 20 and the test string 10 according to needs.

[0039] The external pipeline 20 preferably has a longer length. This is beneficial to increasing the resistance of the test gas entering the external pipeline 20 to further avoid the test gas from entering the external pipeline 20. The longer external pipeline 20 can be constructed with multiple bending parts as Figure 1 shown, so as to reduce the volume and floor area of the device 1.

[0040] In addition, the device 1 may further include a constant pressure mechanism 50. As Figure 1 shown, the constant pressure mechanism 50 can be connected to the external pipeline 20, preferably connected between the first end 21 and the second end 22 of the external pipeline 20. A valve 140 can be provided at the connection between the constant pressure mechanism 50 and the external pipeline 20. The valve 140 can be used to control whether the constant pressure mechanism 50 is connected to the external pipeline 20. When the constant pressure mechanism 50 is connected to the external pipeline 20, the constant pressure mechanism 50 can be used to adjust the pressure in the external pipeline 20 and the test string 10 connected to the external pipeline 20 to keep it within a predetermined range.

[0041] Figure 3 Schematically shows an embodiment of the constant pressure mechanism 50. As Figure 3As shown, the constant pressure mechanism 50 includes a gas storage unit (e.g., a gas cylinder) 501, and a piston container 503 connected between the gas storage unit 501 and the upper end 12 of the test string 10. The gas storage unit 501 can be used to store pressure-regulating gas, such as nitrogen (N2). Nitrogen has a low cost and is safe and reliable. A piston 5031 is provided in the piston container 503 for dividing the space in the piston container 503 into two independent spaces, namely a first space and a second space. The first space is in communication with the gas storage unit 501. The second space is in communication with the test string 10. The constant pressure mechanism 50 may further include a pressure gauge 504 in communication with the first space. A constant pressure pump 502 may also be provided between the gas storage unit 501 and the piston container 503. When the pressures in the first space and the second space are different, the pressure-regulating gas is pumped between the gas storage unit 501 and the first space by the constant pressure pump 502, thereby adjusting the volumes of the first space and the second space, and thereby balancing the pressures in the first space and the second space to make them reach an equilibrium state. At the same time, the pressure in the first space is measured by the pressure gauge 504, and based on this, the amount of fluid injected by the injection pump 80 in the constant pressure pump 502 and the first injection fluid mechanism is controlled, so that the pressures in the first space and the second space reach a predetermined range while being balanced.

[0042] As Figure 1 shown, at the test string 10 between the upper end 12 of the test string 10 and the first end 21 of the external pipeline 20, a first release valve 40 is additionally connected, and a first flowmeter 110 connected between the first release valve 40 and the test string 10. The first release valve 40 can be used to control whether the fluid in the test string 10 flows out therefrom, and can lead to the environment, a waste tank, or any other suitable structure. The first flowmeter 110 is used to measure and determine the amount of fluid flowing out of the first release valve 40.

[0043] In addition, the device 1 further includes a constant temperature mechanism 60. The constant temperature mechanism 60 includes a pipe body 60 surrounding the test string 10 and the external pipeline 20, and a temperature regulator 602. The temperature regulator 602 is connected to the pipe body 60 through a pipeline to form a circulation pipeline. Thus, the temperature control fluid can circulate in the circulation pipeline. In addition, the constant temperature mechanism 60 may further include a temperature detector 603 connected to the pipe body 60. The temperature detector 603 can be used to detect the temperature of the temperature control fluid in the pipe body 60. The temperature regulator 602 can adjust the temperature of the temperature control fluid flowing through it based on the detection result of the temperature detector 603. The temperature control fluid after temperature adjustment can be sent into the pipe body 60 to adjust the temperatures of the test string 10 and the external pipeline 20 surrounded by it to keep them within a predetermined range.

[0044] The following will be combined with Figures 4 to 7A method for testing the gas channeling prevention ability of cement slurry using the above device 1 in the present invention will be described in detail.

[0045] First, open the injection valve 130, the cement slurry isolation valve 100, and the third release valve 204, and inject the preflush fluid into the test string 10 through the injection pump 80. In Figures 4 to 7 the illustrated embodiment, the preflush fluid is water. As Figure 4 shown, the water flows in the direction indicated by the arrow, on the one hand, towards the discharge branch, and on the other hand, enters the test string 10 and thus flows into the external pipeline 20. When water flows out from the second end 22 of the external pipeline 20, the injection pump 80 can be shut down. At this time, as Figure 5 shown, most of the positions in the test string 10, as well as the entire external pipeline 20 and the discharge branch, are filled with water. Only the cavity part in the test string 10 between the upper end 12 of the test string 10 and the first end 21 of the external pipeline 20 is not filled with water. In order to ensure the cement slurry to flush the test string 10, at this time, the third release valve 204 can be closed, and the intake valve 301 and the outlet valve 303 in the gas collection mechanism 30 can be opened. By further pumping water through the injection pump 80, the above cavity part can be filled with water and the collection container 302 can be filled. Until water flows out from the pipeline connected to the outside of the outlet valve 303, the injection pump 80 can be shut down and the intake valve 301, the outlet valve 303, and the cement slurry isolation valve 100 can be closed.

[0046] It should be understood that the above operations of injecting water into the external pipeline 20 and the gas collection mechanism 30 can also be carried out simultaneously, or water can be injected into the gas collection mechanism 30 first and then into the external pipeline 20.

[0047] Thereafter, the cement slurry to be tested is proportioned according to actual needs. A part of the cement slurry can be taken and placed in an existing static gel strength tester to measure the change curve of the static gel strength of the cement with time under the corresponding formation temperature and pressure conditions. Another part of the cement slurry can be used for the gas channeling prevention performance test in the device 1.

[0048] Open the constant temperature mechanism 60 so that the test string 10 and the external pipeline 20 are within the temperature range required for the test to simulate the formation temperature environment.

[0049] Open the injection valve 130 and the third release valve 204, and inject the cement slurry into the test string 10 through the injection pump 80 to displace the preflush fluid (water) therein. When cement slurry flows out from the second end 22 of the external pipeline 20, the injection pump 80 can be shut down and the injection valve 130 and the third release valve 204 can be closed. At this time, as Figure 6 shown, most of the positions in the test string 10 and the entire external pipeline 20 are filled with cement slurry. The discharge branch downstream of the cement slurry isolation valve 100, the vicinity of the upper end 12 of the test string 10, and the gas collection mechanism 30 still remain filled with water.

[0050] Thereafter, the constant pressure mechanism 50 and the valve 140 are opened, and the pressures in the test string 10 and the external pipeline 20 are stably maintained within the expected range through the injection pump 80 and the constant pressure pump 502 to simulate the formation pressure environment.

[0051] On the above basis, the device 1 is left stationary to enable the corresponding hydration and curing processes of the cement slurry.

[0052] At a certain moment when the gas channeling prevention performance needs to be tested, the first release valve 40 and the second release valve 90 can be closed, and the air inlet valve 301 can be opened. The test gas is injected into the test string 10 through the gas injection pump 701. If the test gas floats upward through the cement slurry in the test string 10, it will eventually enter the collection container 302 of the gas collection mechanism 30. The gas channeling volume of the cement slurry at the current moment can be measured by determining the amount of gas in the collection container 302 (i.e., the gas channeling volume), so as to evaluate the gas channeling prevention performance of the cement slurry at the current moment. Thereafter, the gas in the collection container 302 can be discharged by opening the gas outlet valve 303.

[0053] Thereafter, at another moment when the gas channeling prevention performance needs to be tested, the above process can be repeated to evaluate the gas channeling prevention performance at this other moment.

[0054] After the test is completed, the cement slurry isolation valve 100 can be opened to discharge the uncompletely solidified cement slurry in the test string 10. During this process, water can be flushed into the test string 10 through the external pipeline 20 to clean the external pipeline 20 and the test string 10. When the external pipeline 20 is longitudinally inserted downward into the test string 10, the water in the external pipeline 20 can be longitudinally flushed downward into the test string 10, which is further beneficial to the cleaning of the test string 10.

[0055] In addition, the external pipeline 20 and the test string 10 can be slidably connected to allow the external pipeline 20 to change the insertion depth within the test string 10. This is also more beneficial during the cleaning process. However, based on the needs such as sealing, the external pipeline 20 and the test string 10 can also be fixedly connected.

[0056] Figure 8 It is a graph showing the variation of the gel strength and the gas channeling volume with time obtained based on the above device 1 and method. Figure 9 It is a graph showing the relationship between the gel strength and the gas channeling volume obtained based on the above device 1 and method. This can help the operators know the gel strength and the gas channeling volume at different time periods in the initial stage of well cementing, as well as their clear quantitative relationship.

[0057] Finally, it should be noted that the above are only preferred embodiments of the present invention and do not constitute any limitation to the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or perform equivalent replacements on some of the technical features. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A device for testing the gas channeling prevention ability of cement slurry, comprising: A test string, which extends along the longitudinal direction; A first fluid injection mechanism, which is connected to the lower end of the test string and is used to inject a pre-fluid and cement slurry into the test string; A second fluid injection mechanism, which is connected to the lower end of the test string and is used to inject a test gas into the test string; And A gas collection mechanism, which is connected to the upper end of the test string and is used to receive the test gas passing through the test string. The lower end of the test string includes a first inlet opened longitudinally downward and a second inlet opened transversely. The second inlet is located above the first inlet. The first fluid injection mechanism is connected to the first inlet, and the second fluid injection mechanism is connected to the second inlet. Wherein, a cement slurry blocking member is provided at the second inlet, and the cement slurry blocking member is configured to prevent the cement slurry from flowing into the second fluid injection mechanism. The cement slurry blocking member is configured as a screen. The second fluid injection mechanism includes: an air injection pump configured to drive the test gas to flow towards the second inlet; a check valve connected between the air injection pump and the second inlet to prevent the fluid from flowing in the direction from the second inlet to the check valve. The gas collection mechanism includes a longitudinally extending collection container, an intake valve connected between the lower end of the collection container and the upper end of the test string, and an outlet valve connected to the upper end of the collection container. Wherein, at least part of the collection container is configured to be transparent and is provided with measurement scales longitudinally. The device for testing the gas channeling prevention ability of cement slurry further includes an external pipeline. The first end of the external pipeline is connected to the test string, and the second end is connected to the environment.

2. The cement slurry gas channeling prevention ability testing device according to claim 1, wherein The first end of the external pipeline is located at a distance below the upper end of the test string longitudinally.

3. The cement slurry gas channeling prevention ability testing device according to claim 2, wherein The first end of the external pipeline extends downward from the upper end of the test string into the test string, so that the first end is located at a distance below the upper end of the test string longitudinally.

4. The cement slurry gas channeling prevention ability testing device according to claim 3, wherein, It further includes a first release valve, which is connected to the test string between the upper end of the test string and the first end of the external pipeline.

5. The cement slurry gas channeling prevention ability testing device according to claim 1, characterized in that, It further includes: A constant temperature mechanism configured to keep the temperature inside the test string within a predetermined range; And A constant pressure mechanism configured to keep the pressure inside the test string within a predetermined range.

6. A method for testing the gas channeling prevention ability of cement slurry, which is carried out by using the device for testing the gas channeling prevention ability of cement slurry according to any one of claims 1 to 5 above. The method includes the following steps: Injecting a pre-fluid into the test string through the first fluid injection mechanism; Injecting cement slurry into the test string through the first fluid injection mechanism to displace the pre-fluid in the test string; Injecting a test gas into the test string through the second fluid injection mechanism; Determining the amount of the test gas collected in the gas collection mechanism; The cement slurry gas channeling prevention ability testing device further includes an external pipeline, the first end of the external pipeline is connected to the test string, and the second end is connected to the environment; The process of injecting the pre-fluid into the test string through the first fluid injection mechanism ends after the pre-fluid flows out at the second end of the external pipeline; The process of injecting the cement slurry into the test string through the first fluid injection mechanism ends after the cement slurry flows out at the second end of the external pipeline.

7. The cement slurry gas channeling prevention ability testing method according to claim 6, wherein The cement slurry gas channeling prevention ability testing device further includes a first release valve, and the first release valve is connected to the test string between the upper end of the test string and the first end of the external pipeline; When injecting the pre-fluid, open the gas collection mechanism to allow the pre-fluid to flow from the upper end of the test string into the gas collection mechanism. When injecting the cement slurry, close the gas collection mechanism to prevent the cement slurry from flowing from the upper end of the test string to the gas collection mechanism, so as to leave pre-fluid in the test string between the first end of the external pipeline and the upper end of the test string; Wherein, before injecting the test gas into the test string through the second fluid injection mechanism, a part of the pre-fluid remaining in the test string is discharged through the first release valve.

Images