Well cementation cement slurry conductivity and hydrostatic column pressure evaluation device and evaluation method

Abstract

The invention discloses a well cementation cement slurry conductivity and hydrostatic column pressure evaluation device and evaluation method, and belongs to the technical field of well cementation cement slurry, the well cementation cement slurry conductivity and hydrostatic column pressure evaluation device comprises a kettle body, an upper kettle body cover, a lower kettle body cover, a heating assembly, a support frame, a rotating shaft, a support, a speed reducer and a master control system; a lateral pressure pipe head, a thermocouple and a heating assembly are arranged on the kettle body, and a rubber sleeve and a simulation sleeve are arranged in the kettle body; a kettle top pressure pipe head is arranged on the upper kettle body cover, and a pressure sensor, a conductivity tester and a fluid channel pipe head are arranged on the lower kettle body cover; the rotating shaft is rotatably mounted on the support; the right end of the rotating shaft is connected with the support frame; the master control system comprises a temperature controller, a pressure detection system, a conductivity acquisition system and a central controller; and the temperature controller is electrically connected with the thermocouple and the heating assembly. By directly evaluating the relationship between the conductivity of various cement slurry systems and the hydrostatic column pressure change, characterization means and basic data are provided for research and test of the well cementation cement slurry weightlessness law.

Description

Technical Field

[0001] The present invention belongs to the technical field of cement slurries for well cementing, and particularly relates to an evaluation device and an evaluation method for the electrical conductivity and hydrostatic pressure of cement slurries for well cementing. Background Art

[0002] A natural gas well is a well drilled from the ground to a gas reservoir for the extraction of natural gas. Due to the active nature of natural gas, during the waiting-for-set stage of well cementing in a natural gas well, natural gas is extremely likely to penetrate into the cement slurry for well cementing, and then into low-pressure formations or even the wellhead, seriously threatening the safety, quality of well cementing operations and the efficiency of subsequent operations, and even posing a potential risk of serious engineering accidents such as blowouts.

[0003] Through research, it has been found that the hydrostatic pressure during the waiting-for-set stage of the cement slurry for well cementing decreases with the increase of hydration time, which is also called "weight loss", thus generating a negative pressure difference between the cement slurry column and the natural gas reservoir and providing a driving force for early gas channeling. Further, relevant scholars and researchers have proposed various weight loss mechanisms of cement slurries in combination with the characterization of the macroscopic properties of cement slurries. For example, a settlement weight loss mechanism has been proposed from the perspective of settlement stability, a gel suspension weight loss mechanism has been proposed from the perspective of static gel strength, and a volume shrinkage weight loss mechanism has been proposed from the perspective of volume shrinkage rate, etc.

[0004] At present, there is no unified experimental method for characterizing the weight loss law of cement slurries for well cementing. Each research institution has established its own evaluation device based on the wellbore conditions and well structure on site, such as the invention patents with publication numbers CN107843721A, CN102392634B, and CN111042801A respectively. However, these existing evaluation devices for the weight loss of cement slurries for well cementing only consider the influence of external conditions on the weight loss law of cement slurries for well cementing, and do not consider that during the hydration process of cement slurries, the change in the content of hydration products and the evolution process of the microstructure are the fundamental reasons for the weight loss of cement slurries for well cementing, resulting in the difficulty of the existing cement slurry weight loss evaluation devices to intuitively reflect the weight loss law of cement slurries and the inability to provide a reliable characterization method and basic data for the weight loss law of cement slurries for well cementing. Therefore, it is urgent to deeply analyze the weight loss mechanism of cement slurries for well cementing, so as to lay a foundation for the research on the gas channeling mechanism of natural gas wells and the development of high-efficiency anti-channeling technologies and materials. Summary of the Invention

[0005] The purpose of the present invention is to provide an evaluation device and an evaluation method for the electrical conductivity and hydrostatic pressure of cement slurries for well cementing in view of the above deficiencies, aiming to solve the problem that the existing evaluation devices are difficult to intuitively reflect the weight loss law of cement slurries. To achieve the above purpose, the present invention provides the following technical solutions:

[0006] A device for evaluating the electrical conductivity and hydrostatic pressure of a cement slurry for well cementing, comprising a kettle body, an upper kettle body cover, a lower kettle body cover, a heating assembly, a support frame, a rotating shaft, a support, a speed reducer and a total control system; the kettle body is a cylindrical structure with openings at both the upper and lower ends, a lateral pressure pipe head and a thermocouple are installed on the side wall of the kettle body, and a pressurizing device is externally connected to the lateral pressure pipe head; a heating assembly is wrapped around the outer wall of the kettle body; a rubber sleeve is provided on the inner wall of the kettle body; a simulated casing is provided in the center of the kettle body, and an annular space for filling the cement slurry is formed between the rubber sleeve and the simulated casing; the upper kettle body cover is detachably installed at the upper end of the kettle body, a kettle top pressure pipe head is provided on the upper kettle body cover, and a high-pressure nitrogen cylinder is externally connected to the kettle top pressure pipe head; the lower kettle body cover is detachably installed at the lower end of the kettle body, and a pressure sensor, a conductivity tester and a fluid channel pipe head are provided on the lower kettle body cover; the pressure sensor and the conductivity tester are used to directly contact the cement slurry filled in the annular space, and respectively and real-time collect the hydrostatic pressure and electrical conductivity of the cement slurry; the fluid channel pipe head penetrates through the lower kettle body cover and is externally connected to a fluid pressurizing device; the support frame is used to support the kettle body and make the kettle body suspended; the rotating shaft is rotatably installed on the support; the right end of the rotating shaft is connected to the support frame, and the left end is connected to the speed reducer; the speed reducer is used to control the inclination angle of the kettle body; the total control system includes a temperature controller, a pressure detection system, a conductivity acquisition system and a central controller; the temperature controller is electrically connected to the thermocouple and the heating assembly respectively; the pressure detection system and the conductivity acquisition system are respectively used to convert the voltage signal collected by the pressure sensor and the electrical signal collected by the conductivity tester into digital signals and transmit them to the central controller; the central controller is electrically connected to the temperature controller, the pressure detection system and the conductivity acquisition system respectively, and is used to store, process and display the signals received from the temperature controller, the pressure detection system and the conductivity acquisition system.

[0007] Further, a handle is installed on the speed reducer; the handle is used to drive the rotation of the rotating shaft, and then drive the support frame and the kettle body to rotate synchronously; an angle measurer is provided on the support.

[0008] Further, it further includes a console; the total control system is installed on the console, and the total control system further includes a display screen; the display screen is electrically connected to the central controller; the display screen includes a temperature display area for displaying the real-time temperature, a pressure display area for displaying the real-time hydrostatic pressure and a conductivity display area for displaying the real-time electrical conductivity.

[0009] Further, the speed reducer is arranged above the console.

[0010] Further, a temperature adjustment button is further provided on the temperature controller.

[0011] Further, the conductivity tester is a DDM-203 type conductivity tester.

[0012] A method for evaluating the electrical conductivity and hydrostatic pressure of a cement slurry for well cementing, using an apparatus for evaluating the electrical conductivity and hydrostatic pressure of a cement slurry for well cementing as described in any one of claims 1 to 6, comprising the following steps:

[0013] Step 1: Assemble the lateral pressure pipe head, thermocouple, upper kettle body cover, and lower kettle body cover onto the kettle body, seal the lateral pressure pipe head on the kettle body, the kettle top pressure pipe head on the upper kettle body cover, and the fluid passage pipe head on the lower kettle body cover, and open the upper kettle body cover. Inject clear water into the kettle body. After the kettle body is filled with clear water, close the upper kettle body cover, open the kettle top pressure pipe head, pressurize the kettle body by 1 MPa through a high-pressure nitrogen cylinder via the kettle top pressure pipe head, and then close the kettle top pressure pipe head. Continuously collect the pressure data inside the kettle body by the pressure sensor for 10 minutes, and transmit the real-time pressure signal inside the kettle body to the central controller. If the pressure does not drop within 10 minutes, it proves that the sealing is qualified, and proceed to Step 2; otherwise, recheck the assembly of the kettle body.

[0014] Step 2: Open the kettle top pressure pipe head to relieve pressure. After the pressure relief is completed, open the upper kettle body cover, install a rubber sleeve and a simulated casing into the kettle body, inject the cement slurry to be tested for performance into the annular space, and then close the upper kettle body cover. Set the temperature and temperature change time required for the test through the central controller, and then control the heating component to heat the kettle body by the temperature controller to control the temperature to the required temperature for the test. Drive the rotating shaft to rotate through the handle to control the kettle body to rotate to the required tilt angle. Inject pressure into the cement slurry in the kettle body through the kettle top pressure pipe head to the pressure required for the experiment. After the pressure injected into the kettle body, the target temperature, and the tilt angle of the kettle body reach the values required for the test, proceed to Step 3.

[0015] Step 3: Start continuously collecting the hydrostatic pressure and electrical conductivity of the cement slurry until the hydrostatic pressure on the display drops to 0, and end the collection. Then, analyze and evaluate the relationship between the hydrostatic pressure value and the electrical conductivity value of the collected cement slurry to reflect the change in the content of hydration products and the evolution of the microstructure during the hydration process of the cement slurry.

[0016] The beneficial effects of the present invention are:

[0017] 1. By testing the changes in electrical conductivity and hydrostatic pressure during the hydration process of the well cementing slurry, the present invention directly evaluates the direct relationship between the electrical conductivity and hydrostatic pressure of various cement slurry systems, can study the content of hydration products and the evolution process of the microstructure during the hydration process of the well cementing slurry, and intuitively reflects the law of cement slurry weight loss. Furthermore, it provides a characterization means and basic data for the study and testing of the law of well cementing slurry weight loss. The testing method is simple and convenient for real-time calculation. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 is a schematic structural diagram of the overall device of the present invention;

[0019] Figure 2 It is a schematic structural diagram of the kettle body of the present invention;

[0020] In the attached drawings: 1 - kettle body, 2 - lateral pressure pipe head, 3 - thermocouple, 4 - upper kettle body cover, 5 - kettle top pressure pipe head, 6 - lower kettle body cover, 7 - pressure sensor, 8 - conductivity tester, 9 - fluid passage pipe head, 10 - support frame, 11 - rotating shaft, 12 - support, 13 - reducer, 14 - handle, 15 - display screen, 16 - temperature display area, 17 - pressure display area, 18 - conductivity display area, 19 - heating component, 21 - rubber sleeve, 22 - annular space, 23 - simulation sleeve. Specific embodiments

[0021] The present invention will be further described in detail below in conjunction with the attached drawings and specific embodiments, but the present invention is not limited to the following embodiments.

[0022] Embodiment 1:

[0023] See the attached Figures 1-2. A device for evaluating the electrical conductivity and hydrostatic pressure of a cement slurry for well cementing, comprising a kettle body 1, an upper kettle body cover 4, a lower kettle body cover 6, a heating assembly 19, a support frame 10, a rotating shaft 11, a support 12, a speed reducer 13 and a total control system; the kettle body 1 is a cylindrical structure with openings at both the upper and lower ends, and a lateral pressure pipe head 2 and a thermocouple 3 are installed on the side wall of the kettle body 1, and the lateral pressure pipe head 2 is externally connected to a pressurizing device; the outer wall of the kettle body 1 is surrounded by a heating assembly 19; a rubber sleeve 21 is provided on the inner wall of the kettle body 1; a simulated casing 23 is provided in the center of the kettle body 1, and an annular space 22 for filling the cement slurry is formed between the rubber sleeve 21 and the simulated casing 23; the upper kettle body cover 4 is detachably installed at the upper end of the kettle body 1, and a kettle top pressure pipe head 5 is provided on the upper kettle body cover 4, and the kettle top pressure pipe head 5 is externally connected to a high-pressure nitrogen cylinder; the lower kettle body cover 6 is detachably installed at the lower end of the kettle body 1, and a pressure sensor 7, a conductivity tester 8 and a fluid channel pipe head 9 are provided on the lower kettle body cover 6; the pressure sensor 7 and the conductivity tester 8 are used to directly contact the cement slurry filled in the annular space 22, and respectively collect the hydrostatic pressure and electrical conductivity of the cement slurry in real time; the fluid channel pipe head 9 penetrates through the lower kettle body cover 6 and is externally connected to a fluid pressurizing device; the support frame 10 is used to support the kettle body 1 and suspend the kettle body 1; the rotating shaft 11 is rotatably installed on the support 12; the right end of the rotating shaft 11 is connected to the support frame 10, and the left end is connected to the speed reducer 13; the speed reducer 13 is used to control the tilt angle of the kettle body 1; the total control system includes a temperature controller, a pressure detection system, a conductivity acquisition system and a central controller; the temperature controller is electrically connected to the thermocouple 3 and the heating assembly 19 respectively; the pressure detection system and the conductivity acquisition system are respectively used to convert the voltage signal collected by the pressure sensor 7 and the electrical signal collected by the conductivity tester 8 into digital signals and transmit them to the central controller; the central controller is electrically connected to the temperature controller, the pressure detection system and the conductivity acquisition system respectively, and is used to store, process and display the signals received from the temperature controller, the pressure detection system and the conductivity acquisition system. From the above structure, it can be seen that the kettle body 1 is a cylindrical structure with openings at both the upper and lower ends, which is used to load the well cementing slurry required for testing, provide a sealed environment of high temperature and high pressure for the cement slurry, and cure the cement slurry. The lateral pressure pipe head 2 and the thermocouple 3 are installed on the side wall of the kettle body 1. The lateral pressure pipe head 2 is located on the side wall of the kettle body 1 and penetrates through the kettle body 1, and is externally connected to a pressurizing device. The pressurizing device can inject high pressure between the inner wall of the kettle body 1 and the outer wall of the rubber sleeve 21 through the lateral pressure pipe head 2 to simulate the formation pressure. The thermocouple 3 is used to collect the temperature signal inside the kettle body 1 in real time and transmit the collected temperature signal in real time to the temperature controller. The heating assembly 19 is used to heat the kettle body 1, and the heating assembly 19 is controlled by the temperature controller. The temperature controller can adjust the output power of the heating assembly 19 surrounding the outer wall of the kettle body 1 and the heating rate of the cement slurry in the kettle body 1 in real time according to the temperature signal transmitted by the thermocouple 3.The rubber sleeve 21 is sleeved on the inner wall of the kettle body 1 to prevent the cement slurry from directly contacting the inner wall surface of the kettle body 1, and the rubber sleeve 21 is detachable. After the current simulation test is completed, the staff can replace the new rubber sleeve 21 to enable the device to quickly conduct the next test. A simulation sleeve 23 is also provided in the center of the kettle body 1, and an annular space 22 for filling the cement slurry is formed between the rubber sleeve 21 and the simulation sleeve 23 for injecting the cement slurry. The upper kettle cover 4 is used to seal the upper end of the kettle body 1. Specifically, the upper kettle cover 4 can be a kettle cover with a disk-shaped structure with external threads. The upper end of the kettle body 1 is provided with internal threads matching the external threads of the upper kettle cover 4, and the upper kettle cover 4 and the kettle body 1 are sealed through the cooperation of the internal threads and the external threads. The kettle top pressure pipe head 5 penetrates through the entire upper kettle cover 4 and is externally connected to a high-pressure nitrogen cylinder. Through the high-pressure nitrogen cylinder and the kettle top pressure pipe head 5, pressure can be applied to the kettle body 1 to test the sealing performance of the kettle body 1 or provide the required pressure for the cement slurry whose performance is to be measured in the kettle body 1. After the sealing test or the cement slurry performance test is completed, the pressure inside the kettle body 1 can be released through the kettle top pressure pipe head 5. The pressure sensor 7 and the conductivity tester 8 are both installed on the lower kettle cover 6 and both penetrate through the lower kettle cover 6. Among them, the used pressure sensor 7 can be an NS-W type cavityless pressure sensor. The test end face of the pressure sensor 7 is directly in contact with the cement slurry in the kettle body 1 to collect the hydrostatic pressure of the cement slurry in real time, and then transmit the pressure signal to the pressure detection system. The used conductivity tester 8 is a DDM-203 type conductivity tester. The conductivity tester 8 is also directly in contact with the cement slurry in the kettle body 1, can collect the conductivity of the cement slurry in real time, and then transmit the conductivity signal to the conductivity acquisition system. The fluid channel pipe head 9 penetrates through the lower kettle cover 6 and is externally connected to a fluid pressurizing device, and the change process of the hydrostatic pressure of the cement slurry can be simulated through the fluid pressurizing device to test whether the external fluid can penetrate into the cement slurry. The support frame 10 is used to support the kettle body 1 and suspend the kettle body 1, and both ends of the support frame 10 are respectively connected to the kettle body 1 and the rotating shaft 11. The rotating shaft 11 can be rotatably installed on the support 12 through parts such as bearings. The right end of the rotating shaft 11 is connected to the support frame 10, and the left end is connected to the reducer 13. When the rotating shaft 11 rotates, it will drive the kettle body 1 to rotate synchronously, so that the kettle body 1 rotates to the required inclination angle for testing. To accurately control the rotation angle of the kettle body 1, a protractor can also be installed on the end face of the support 12, and a pointer can be installed on the rotating shaft 11 near the protractor. The staff can accurately obtain the inclination angle of the kettle body 1 by reading the reading of the pointer on the protractor. The total control system includes a temperature controller, a pressure detection system, a conductivity acquisition system, and a central controller. Among them, the temperature controller is electrically connected to the thermocouple 3 and the heating component 19 respectively. The temperature controller is used to receive the temperature signal transmitted by the thermocouple 3 in real time and transmit it to the central controller. Then, according to the temperature signal, the central controller adjusts the output power of the heating component 19 in real time, and further adjusts the temperature of the kettle body 1 to the required temperature for testing.Both the pressure detection system and the conductivity acquisition system include an A / D converter inside. Therefore, the pressure detection system can convert the voltage signal collected by the pressure sensor into a digital signal through the A / D converter and transmit it to the central controller. Similarly, the conductivity acquisition system can convert the electrical signal collected by the conductivity tester into a digital signal through the A / D converter and transmit it to the central controller. The central controller is electrically connected to the temperature controller, the pressure detection system, and the conductivity acquisition system respectively, and can store, process, and display the signals received from the temperature controller, the pressure detection system, and the conductivity acquisition system. Specifically, the central controller can be a computer system. During the working process, the central controller first confirms whether the pressure, target temperature, and tilt angle of the kettle body 1 injected meet the requirements for testing. If the requirements are met, the central controller starts to control the pressure detection system and the conductivity acquisition system to respectively collect the hydrostatic pressure and conductivity of the cement slurry in the kettle body 1 in real time. Since during the hydration process of the cement slurry itself, the change in the content of hydration products and the evolution of the microstructure will cause changes in conductivity and hydrostatic column pressure, therefore, by directly evaluating the relationship between the conductivity and the hydrostatic column pressure of various cement slurry systems for well cementing, the content of hydration products and the evolution process of the microstructure during the hydration process of the well cementing slurry can be studied, and further provide a characterization means and basic data for the study and testing of the weight loss law of the well cementing slurry. An evaluation device for the conductivity and hydrostatic column pressure of well cementing slurry of the present invention can directly evaluate the direct relationship between the conductivity and the hydrostatic column pressure of various well cementing slurry systems, can intuitively reflect the law of cement slurry weight loss, provide a characterization means and basic data for the study and testing of the weight loss law of well cementing slurry, and ultimately can play an auxiliary role in the study of the weight loss mechanism and gas channeling mechanism of well cementing slurry in oil and gas wells. The testing method is simple and convenient for real-time observation and calculation.

[0024] Embodiment 2:

[0025] See appendix Figures 1-2 On the basis of Embodiment 1, a handle 14 is installed on the speed reducer 13; the handle 14 is used to drive the rotation of the rotating shaft 11, and then drive the support frame 10 and the kettle body 1 to rotate synchronously; an angle measuring device is provided on the support 12. From the above structure, it can be known that the speed reducer 13 can be selected as a WPKA worm and worm gear speed reducer. A handle 14 is installed on the speed reducer 13. By rotating the handle 14, the rotation of the rotating shaft 11 can be driven, and then the rotating shaft 11 drives the support frame 10 and the kettle body 1 to rotate synchronously. Then, the rotation angle of the kettle body 1 is measured by the angle measuring device installed on the upper end surface of the support 12 to confirm whether it meets the required angle for testing.

[0026] It also includes a console; the master control system is installed on the console, and the master control system also includes a display screen 15; the display screen 15 is electrically connected to the central controller; the display screen 15 includes a temperature display area 16 for displaying the real-time temperature, a pressure display area 17 for displaying the real-time hydrostatic pressure, and a conductivity display area 18 for displaying the real-time conductivity. From the above structure, it can be seen that the master control system is installed on the console, and the display screen 15 of the master control system is placed on the front side of the console. The display screen 15 includes three areas, namely the temperature display area 16 for displaying the real-time temperature, the pressure display area 17 for displaying the real-time hydrostatic pressure, and the conductivity display area 18 for displaying the real-time conductivity, which is convenient for the staff to record the values of the temperature, hydrostatic pressure and conductivity of the cement slurry and observe the numerical changes in real time.

[0027] The speed reducer 13 is arranged above the console. From the above structure, it can be seen that the speed reducer 13 is fixed above the console, making the equipment structure compact.

[0028] The temperature controller is also provided with a temperature adjustment button. From the above structure, it can be seen that the temperature adjustment button is electrically connected to the temperature controller, and the staff can manually set the required temperature for the test through the temperature adjustment button.

[0029] The conductivity tester 8 is a DDM-203 type conductivity tester. From the above structure, it can be seen that the DDM-203 type conductivity tester has a wide application range and is easy to install.

[0030] Embodiment 3:

[0031] See Appendix Figures 1-2 On the basis of Embodiment 2, a method for evaluating the conductivity and hydrostatic pressure of cement slurry for well cementing uses a device for evaluating the conductivity and hydrostatic pressure of cement slurry for well cementing according to any one of claims 1 to 6, and includes the following steps:

[0032] Step 1: Assemble the lateral pressure pipe head 2, thermocouple 3, upper kettle cover 4 and lower kettle cover 6 onto the kettle body 1, seal the lateral pressure pipe head 2 on the kettle body 1, the kettle top pressure pipe head 5 on the upper kettle cover 4 and the fluid passage pipe head 9 on the lower kettle cover 6, and open the upper kettle cover 4 to inject clear water into the kettle body 1; after the kettle body 1 is filled with clear water, close the upper kettle cover 4, open the kettle top pressure pipe head 5, pressurize the kettle body 1 by 1 MPa through the high-pressure nitrogen cylinder via the kettle top pressure pipe head 5, and then close the kettle top pressure pipe head 5; continuously collect the pressure data in the kettle body 1 by the pressure sensor 7 for 10 minutes, and transmit the real-time pressure signal inside the kettle body 1 to the central controller. The central controller can display the real-time pressure data through the display screen 15. If the pressure indication on the display does not drop within 10 minutes, it proves that the sealing is qualified and proceed to Step 2; otherwise, re-check the assembly of the kettle body 1;

[0033] Step 2: Open the pressure pipe head 5 at the top of the autoclave to relieve pressure. After the pressure relief is completed, open the upper autoclave cover 4, install the rubber sleeve 21 and the simulation casing 23 into the autoclave body 1, inject the cement slurry to be tested for performance into the annular space 22, and then close the upper autoclave cover 4; Set the temperature and temperature change time required for the test through the central controller, and then the temperature controller controls the heating component 19 to heat the autoclave body 1 to the temperature required for the test; Drive the rotating shaft 11 to rotate through the handle 14 to control the autoclave body 1 to rotate to the required inclination angle for the test; Inject pressure into the cement slurry in the autoclave body 1 through the pressure pipe head 5 at the top of the autoclave to the pressure required for the experiment. After the pressure injected into the autoclave body 1, the target temperature, and the inclination angle of the autoclave body 1 reach the values required for the test, proceed to Step 3;

[0034] In this step, if it is necessary to simulate the formation pressure, the lateral pressure pipe head 2 can be opened to inject the simulated required pressure between the inner wall of the autoclave body 1 and the outer wall of the rubber sleeve 21. If the test does not require simulating the formation pressure, close the lateral pressure pipe head 2.

[0035] Step 3: Start continuously collecting the hydrostatic pressure and conductivity of the cement slurry until the hydrostatic pressure on the display decreases to 0, and end the collection; Then, through the collected hydrostatic pressure value and conductivity value of the cement slurry, analyze and evaluate the relationship between the hydrostatic pressure value and the conductivity value, reflecting the change in the content of hydration products and the evolution of the microstructure during the hydration process of the cement slurry.

[0036] After the experiment is completed, the central controller controls the pressure detection system and the conductivity acquisition system to stop collecting data, closes the temperature controller in the total control system. After the device cools down to room temperature, relieve pressure through the pressure pipe head 5 at the top of the autoclave and the lateral pressure pipe head 2 in sequence, disassemble the thermocouple 3, the heating component 19, the upper autoclave cover 4, and the lower autoclave cover 6, and remove the cement slurry in the autoclave body 1.

[0037] The above are only the preferred embodiments of the present invention, and do not limit the patent scope of the present invention accordingly. Any equivalent structure or equivalent process transformation made by using the content of the specification and drawings of the present invention, or directly or indirectly applied to other related technical fields, shall be included in the patent protection scope of the present invention by the same token.

Claims

1. An evaluation device for the electrical conductivity and static liquid column pressure of a cement slurry for well cementing, characterized in that: It includes a kettle body (1), an upper kettle body cover (4), a lower kettle body cover (6), a heating component (19), a support frame (10), a rotating shaft (11), a support (12), a speed reducer (13) and a total control system; The kettle body (1) is a cylindrical structure with openings at both the upper and lower ends. A lateral pressure pipe head (2) and a thermocouple (3) are installed on the side wall of the kettle body (1), and the lateral pressure pipe head (2) is externally connected to a pressurizing device; The outer wall of the kettle body (1) is surrounded by a heating component (19); A rubber sleeve (21) is provided on the inner wall of the kettle body (1); A simulation sleeve (23) is provided in the center of the interior of the kettle body (1), and an annular space (22) for filling cement slurry is formed between the rubber sleeve (21) and the simulation sleeve (23); The upper kettle body cover (4) is detachably installed at the upper end of the kettle body (1). A kettle top pressure pipe head (5) is provided on the upper kettle body cover (4), and the kettle top pressure pipe head (5) is externally connected to a high-pressure nitrogen cylinder; The lower kettle body cover (6) is detachably installed at the lower end of the kettle body (1). A pressure sensor (7), a conductivity tester (8) and a fluid channel pipe head (9) are provided on the lower kettle body cover (6); The pressure sensor (7) and the conductivity tester (8) are used to directly contact the cement slurry filled in the annular space (22), and respectively collect the static liquid column pressure and conductivity of the cement slurry in real time; The fluid channel pipe head (9) penetrates through the lower kettle body cover (6) and is externally connected to a fluid pressurizing device; The support frame (10) is used to support the kettle body (1) and suspend the kettle body (1); The rotating shaft (11) is rotatably installed on the support (12); The right end of the rotating shaft (11) is connected to the support frame (10), and the left end is connected to the speed reducer (13); The speed reducer (13) is used to control the tilt angle of the kettle body (1); The total control system includes a temperature controller, a pressure detection system, a conductivity acquisition system and a central controller; The temperature controller is electrically connected to the thermocouple (3) and the heating component (19) respectively; The pressure detection system and the conductivity acquisition system are respectively used to convert the voltage signal collected by the pressure sensor (7) and the electrical signal collected by the conductivity tester (8) into digital signals and transmit them to the central controller; The central controller is electrically connected to the temperature controller, the pressure detection system and the conductivity acquisition system respectively, and is used to store, process and display the signals received from the temperature controller, the pressure detection system and the conductivity acquisition system.

2. The evaluation device for the electrical conductivity and static liquid column pressure of the cement slurry for well cementing according to claim 1, wherein: A handle (14) is installed on the speed reducer (13); The handle (14) is used to drive the rotating shaft (11) to rotate, and then drive the support frame (10) and the kettle body (1) to rotate synchronously; An angle measurer is provided on the support (12).

3. The evaluation device for the electrical conductivity and static liquid column pressure of the cement slurry for well cementing according to claim 1, wherein: It also includes a console; The total control system is installed on the console, and the total control system also includes a display screen (15); The display screen (15) is electrically connected to the central controller; The display screen (15) includes a temperature display area (16) for displaying the real-time temperature, a pressure display area (17) for displaying the real-time static liquid column pressure, and a conductivity display area (18) for displaying the real-time conductivity.

4. The evaluation device for the electrical conductivity and hydrostatic pressure of a cement slurry for well cementing according to claim 3, characterized in that: The speed reducer (13) is arranged above the console.

5. The evaluation device for the electrical conductivity and static liquid column pressure of the cement slurry for well cementing according to claim 1, wherein: The thermostat is also provided with a temperature adjustment button.

6. The evaluation device for the electrical conductivity and hydrostatic pressure of the cement slurry for well cementing according to claim 1, wherein: The conductivity tester (8) is a DDM-203 type conductivity tester.

7. A method for evaluating the electrical conductivity and static liquid column pressure of a cement slurry for well cementing, which uses an apparatus for evaluating the electrical conductivity and static liquid column pressure of a cement slurry for well cementing as described in any one of claims 1 to 6, and is characterized in that, It includes the following steps: Step 1: Assemble the lateral pressure pipe head (2), the thermocouple (3), the upper kettle body cover (4) and the lower kettle body cover (6) onto the kettle body (1), seal the lateral pressure pipe head (2) on the kettle body (1), the kettle top pressure pipe head (5) on the upper kettle body cover (4) and the fluid passage pipe head (9) on the lower kettle body cover (6), and open the upper kettle body cover (4) to inject clear water into the kettle body (1); after the kettle body (1) is filled with clear water, close the upper kettle body cover (4), open the kettle top pressure pipe head (5), pressurize the kettle body (1) to 1 MPa through the high-pressure nitrogen cylinder via the kettle top pressure pipe head (5), and then close the kettle top pressure pipe head (5); continuously collect the pressure data inside the kettle body (1) by the pressure sensor (7) for 10 minutes, and transmit the real-time internal pressure signal of the kettle body (1) to the central controller. If the pressure does not drop within 10 minutes, it proves that the sealing performance is qualified and proceed to Step 2; otherwise, recheck the assembly of the kettle body (1). Step 2: Open the kettle top pressure pipe head (5) to relieve pressure. After the pressure relief is completed, open the upper kettle body cover (4), install the rubber sleeve (21) and the simulation sleeve (23) into the kettle body (1), inject the cement slurry to be tested for performance into the annular space (22), and then close the upper kettle body cover (4); set the test required temperature and temperature change time through the central controller, and then control the heating component (19) by the thermostat to heat the kettle body (1) to the test required temperature; drive the rotating shaft (11) to rotate by the handle (14) to control the kettle body (1) to rotate to the test required inclination angle; inject pressure into the cement slurry in the kettle body (1) through the kettle top pressure pipe head (5) to the experimental required pressure. After the pressure injected into the kettle body (1), the target temperature and the inclination angle of the kettle body (1) reach the values required for the test, proceed to Step 3. Step 3: Start continuously collecting the static liquid column pressure and conductivity of the cement slurry until the static liquid column pressure on the display drops to 0 and end the collection; then, through the collected static liquid column pressure value and conductivity value of the cement slurry, analyze and evaluate the relationship between the liquid column pressure value and the conductivity value, reflecting the change in the content of hydration products and the evolution of the microstructure during the hydration process of the cement slurry.

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