Cement slurry water invasion evaluation device and evaluation method

Abstract

The invention belongs to the technical field of oil and gas well cementation, and particularly provides a cement slurry water invasion evaluation device and method, a kettle barrel, a slurry cup and a center rod are sequentially sleeved from outside to inside, the upper end of the kettle barrel is connected with a kettle cover, the upper end of the center rod is located in the kettle cover, and the upper end of the center rod and the kettle barrel are both connected with the liquid outlet end of a pressure control device; the computer is electrically connected with the pressure control device and the temperature control device. The problems that according to an existing cement paste water invasion prevention instrument and method, the influence of stratum water erosion on cement paste after the cement paste is displaced in place is mostly considered, and the influence of stratum water erosion on the cement paste in the displacement state is not considered, so that the evaluation result is inaccurate, and the well cementation quality is influenced are solved. The factor that the cement paste encounters different water layer segment lengths in the displacement process is considered, the cement paste erosion of different water layers with different segments is simulated by adjusting the stirring time of the water-containing simulation rock core and the paddle on the cement paste, and the method is closer to the actual working condition on site.

Description

Technical Field

[0001] The present invention belongs to the technical field of oil and gas well cementing, and particularly relates to a device and method for evaluating water invasion of cement slurry. Background Art

[0002] In recent years, major oilfields at home and abroad have gradually entered the middle and late stages of exploration and development. With the in-depth development of oilfield water injection, formation water production has occurred to varying degrees in each block, and a multi-pressure system with coexisting underground high-pressure, normal-pressure, and low-pressure layers exists. In some oilfields, the formation pressure system is even disordered. At the same time, it is difficult to fully implement the measures of stopping production and injection to improve the cementing quality of adjustment wells. During the cementing process, formation fluids are still in a seepage state, and cement is easily eroded by formation water in the annulus, affecting the bonding quality of the cement stone interface and forming micro-gaps, seriously affecting the sealing integrity of the wellbore. Existing cement slurry waterproof invasion instruments and methods mostly consider the influence of formation water erosion on cement slurry after the cement slurry is displaced in place, and do not consider the erosion of cement slurry by formation water under the displacement state. In engineering practice, when other conditions are the same (such as cement slurry performance, construction parameters, formation temperature, etc.), the cementing quality of long water layer sections is significantly worse than that of short water layer sections, indicating that formation water also has an obvious erosion effect on cement slurry during the displacement process. It is necessary to consider the influence of water invasion during displacement on the performance of cement slurry in the design of cement slurry waterproof invasion performance evaluation methods and related devices.

[0003] Chinese patent document with publication number CN106640062A discloses a simulation evaluation instrument and method for water invasion of cement slurry for well cementing. This evaluation instrument mainly consists of a kettle body, a water bath, an intermediate container, and a nitrogen source. There are kettle body top cover A and kettle body top cover B at the upper part of the kettle body, and a kettle body bottom cover at the lower part; there is cement slurry and a simulated core inside the kettle body, and there is a vertically non-penetrating hole in the center of the simulated core; kettle body top cover A is connected to the intermediate container and the nitrogen source through a water inlet, kettle body top cover B is connected to the nitrogen source through an air injection port, and the kettle body bottom cover has 2 cement slurry injection ports and an air outlet. Although this device can simulate the process of water invasion in cementing, evaluate the water resistance of the cement slurry system, and also measure the bonding strength and channeling pressure at the contact interface between the simulated core and the cement slurry. However, during the experiment, the cement slurry in this device does not flow, and it still evaluates the influence of formation water erosion on cement slurry after the cement slurry is displaced in place, without considering the influence of water invasion during displacement on the performance of cement slurry. Summary of the Invention

[0004] The purpose of a device and method for evaluating water invasion of cement slurry provided by the present invention is to overcome the problem in the prior art that existing cement slurry waterproof invasion instruments and methods mostly consider the influence of formation water erosion on cement slurry after the cement slurry is displaced in place, without considering the erosion of cement slurry by formation water under the displacement state, resulting in inaccurate evaluation results and affecting the cementing quality.

[0005] To this end, the present invention provides a device for evaluating water invasion of cement slurry, which includes a central rod, a slurry cup and a kettle body. The kettle body includes a kettle lid, a kettle barrel, a computer, a pressure control device and a temperature control device. The kettle barrel, the slurry cup and the central rod are sleeved from outside to inside in sequence. The upper end of the kettle barrel is connected to the kettle lid. The upper end of the central rod is located inside the kettle lid. The upper end of the central rod and the kettle barrel are both connected to the liquid outlet end of the pressure control device. The computer is electrically connected to the pressure control device and the temperature control device respectively.

[0006] Preferably, the central rod includes a first sealing joint, a slurry shaft, a connecting block, a simulated core and slurry blades. The upper end of the slurry shaft is connected to the first sealing joint. The connecting block is sleeved on the outer side of the upper part of the slurry shaft. The simulated cores are sleeved on the outer sides of the middle and lower parts of the slurry shaft. One end of the slurry blade is connected to the outer side of the slurry shaft. The central axis of the slurry shaft is hollow.

[0007] Preferably, the upper end of the slurry shaft is open, the lower end of the slurry shaft is closed, the shape of the lower end of the slurry shaft is conical, and the tip of the cone points downward.

[0008] Preferably, the slurry cup includes an upper cover, a pressing member, a slurry cup barrel and a bottom cover. The upper cover, the slurry cup barrel and the bottom cover are connected in sequence from top to bottom. The pressing member is connected inside the upper cover.

[0009] Preferably, a conical groove is provided at the center of the upper surface of the bottom cover. The lower end of the slurry shaft is connected to the conical groove.

[0010] Preferably, the slurry cup further includes a locator. A card slot is provided on the side surface of the locator; a positioning pin is provided at the lower end of the bottom cover.

[0011] Preferably, a central hole is provided axially at the center of the kettle lid; the kettle body further includes a second sealing joint; the pressure control device includes a first booster pump, a second booster pump, a first electromagnetic pressure relief valve and a second electromagnetic pressure relief valve. The liquid output end of the first booster pump is connected to the second sealing joint through a pipeline. The second sealing joint is connected inside the central hole. The first electromagnetic pressure relief valve is connected to the liquid delivery pipeline between the first booster pump and the second sealing joint; the liquid output end of the second booster pump and the second electromagnetic pressure relief valve are both connected to the kettle barrel.

[0012] Preferably, a locator clip is provided on the inner wall of the kettle barrel below the kettle lid. The locator clip is connected to the card slot.

[0013] Preferably, the kettle body further includes a transmission rod and a motor. A driving disc is provided at the lower end inside the kettle barrel. The lower surface of the driving disc is connected to the output end of the motor through the transmission rod. The motor is electrically connected to the computer.

[0014] An evaluation method for a device for evaluating water invasion of cement slurry includes the following steps:

[0015] S1. Connect the slurry cup cylinder to the upper surface of the bottom cover. Place the central rod of the simulated core with saturated formation water into the slurry cup cylinder. Add the prepared cement slurry into the slurry cup cylinder. Place a pressing component on the slurry cup cylinder and connect the upper cover. Install a connecting block and a locator on the slurry shaft passing through the upper cover to complete the assembly of the slurry cup and the central rod.

[0016] S2. Place the assembled slurry cup and central rod into the autoclave cylinder. Add a liquid medium into the annulus between the autoclave cylinder and the slurry cup. The central rod passing through the locator is located in the central hole of the autoclave cover. Cover the autoclave cover on the autoclave cylinder. Connect the liquid output end of the first booster pump to the second sealing joint through a pipeline, and the second sealing joint is connected into the central hole. Complete the assembly of the central rod, the slurry cup and the autoclave body.

[0017] S3. Turn on the computer, establish connections with the pressure control device and the temperature control device, and start the control with the cement slurry entering the annulus between the central rod and the slurry cup cylinder, including the following specific steps:

[0018] S31. Drive the slurry cup to rotate by controlling the motor to keep the cement slurry in a simulated flowing state.

[0019] S32. Control the temperature control device to heat the cement slurry to the bottom hole circulating temperature.

[0020] S33. Control the first booster pump to raise the pressure in the central rod to the target pressure to simulate the formation pressure. Control the second booster pump to raise the pressure of the simulated formation water in the autoclave body to the target pressure to simulate the liquid column pressures of the drilling fluid and the cementing fluid.

[0021] S34. According to the liquid column pressures of the drilling fluid and the cementing fluid, the formation pressure and the formation temperature during the displacement process, the computer controls the pressure control device and the temperature control device to simulate the pressure and temperature changes during the displacement process.

[0022] S35. When the simulated displacement experiment is completed, stop the motor and control the pressure in the autoclave body to reduce the cement slurry to the clear water liquid column pressure during the initial strength formation period.

[0023] S37. Remove the central rod and the cement ring, and measure the cementation strength between the simulated core and the cement by the gas channeling method to complete the evaluation of the water invasion of the cement slurry.

[0024] The beneficial effects of the present invention:

[0025] 1. The cement slurry water invasion evaluation device and evaluation method provided by the present invention, after the central rod, slurry cup and kettle body are combined, the motor is controlled to drive the slurry cup to rotate, so as to keep the cement slurry and the simulated formation water in the central rod in a simulated flowing state; the cement slurry is fully stirred by the central rod to simulate the shear action suffered by the cement in the annulus; the computer controls the pressure control device and temperature control device to simulate the pressure and temperature changes during the displacement process; to find out the degree of erosion of different cement slurries by formation water at different displacement speeds, evaluate the cement stone interface bonding strength, and adjust the performance of the cement slurry based on this, improve the water invasion resistance of the cement slurry, enhance the understanding of the erosion of formation water on the cement slurry, and improve the cementing quality under water invasion conditions.

[0026] 2. The cement slurry water invasion evaluation device and evaluation method provided by the present invention, the kettle body mainly includes a kettle lid, a kettle barrel, a computer, a pressurizing device and a temperature control flow device, with a simple structure, used to simulate the formation environment and create an experimental environment.

[0027] 3. The cement slurry water invasion evaluation device and evaluation method provided by the present invention, the upper lid is used to press the pressing member to ensure that the cement slurry in the slurry cup is isolated from the temperature and pressure increasing medium (simulated formation water) in the kettle body.

[0028] 4. The cement slurry water invasion evaluation device and evaluation method provided by the present invention simulate the displacement process of the cement slurry in the water-bearing formation, consider the factor that the length of the water layer section encountered by the cement slurry during the displacement process is different, and simulate the erosion of the cement slurry by different lengths of water layers by adjusting the stirring time of the cement slurry by the water-containing simulated core and the slurry blade, which is closer to the actual working conditions on site. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] The present invention will be further described in detail below with reference to the drawings.

[0030] Figure 1 It is a schematic structural diagram of the central rod;

[0031] Figure 2 It is a schematic structural diagram of the slurry cup;

[0032] Figure 3 It is a schematic structural diagram of the kettle body.

[0033] Description of the reference numerals in the drawings: 1. Central rod; 2. Slurry cup; 3. Kettle body;

[0034] 101. Sealing joint one; 102. Slurry shaft; 103. Connecting block; 104. Simulated core; 105. Slurry blade; 106. Filter screen;

[0035] 201. Upper cover; 202. Slurry cup cylinder; 203. Bottom cover; 2031. Conical groove; 204. Locator; 205. Card slot; 206. Locating pin; 207. Metal pressing sheet; 208. Rubber pressing sheet; 209. Metal ring; 210. Plastic film;

[0036] 301. Kettle cover; 3011. Central hole; 302. Kettle cylinder; 303. Computer; 304. Sealing joint two; 305. Booster pump one; 306. Booster pump two; 307. Locator clip; 308. Driving disc; 309. Transmission rod; 310. Motor; 311. Cooling water circulation pump; 312. Cooling water circulation pipeline; 313. Heating wire; 314. Electromagnetic pressure relief valve one; 315. Electromagnetic pressure relief valve two. Specific implementation mode

[0037] The principles and features of the present invention will be described below with reference to the accompanying drawings.

[0038] Example 1:

[0039] As Figures 1 - 3 shown, a device for evaluating water invasion of cement slurry includes a central rod 1, a slurry cup 2 and a kettle body 3. The kettle body 3 includes a kettle cover 301, a kettle cylinder 302, a computer 303, a pressure control device and a temperature control device. The kettle cylinder 302, the slurry cup 2 and the central rod 1 are sleeved from outside to inside in sequence. The upper end of the kettle cylinder 302 is connected to the kettle cover 301. The upper end of the central rod 1 is located inside the kettle cover 301. The upper end of the central rod 1 and the kettle cylinder 302 are both connected to the liquid outlet end of the pressure control device. The computer 303 is electrically connected to the pressure control device and the temperature control device respectively.

[0040] Specifically, the computer 303 is an existing computer, and no detailed description is made here. It only needs to meet the usage requirements.

[0041] The kettle body 3 is used to simulate the formation environment and create an experimental environment. After the combination of the central rod 1, the slurry cup 2 and the kettle body 3, the computer 303 drives the slurry cup 2 to rotate by controlling the kettle body 3. The rotation of the slurry cup 2 drives the central rod 1 to rotate, keeping the cement slurry and the formation water in a simulated flowing state. The cement slurry is fully stirred by the central rod 1 to simulate the shear action of the cement in the annulus. The computer 303 simulates the pressure and temperature changes during the displacement process by controlling the pressure control device and the temperature control device. It explores the degree of water invasion of different cement slurries under different displacement speeds, evaluates the cement stone interface bonding strength, and adjusts the properties of the cement slurry based on this, improves the water invasion resistance of the cement slurry, enhances the understanding of the erosion of the formation water on the cement slurry, and improves the cementing quality under water invasion conditions.

[0042] Example 2:

[0043] On the basis of Embodiment 1, the central rod 1 includes a first sealing joint 101, a slurry shaft 102, a connecting block 103, a simulated core 104, and a slurry blade 105. The upper end of the slurry shaft 102 is connected to the first sealing joint 101. The connecting block 103 is sleeved on the outer side of the upper part of the slurry shaft 102. The simulated cores 104 are sleeved on the outer sides of the middle and lower parts of the slurry shaft 102. One end of the slurry blade 105 is connected to the outer side of the slurry shaft 102. The central axis of the slurry shaft 102 is hollow.

[0044] Specifically, the slurry shaft 102 is a metal hollow tube. The first sealing joint 101 is a male thread for connecting the upper part. The lower part of the slurry shaft 102 is drilled. A layer of simulated core 104 is attached to the outside of the slurry shaft 102. The slurry shaft 102 is provided with slurry blades 105. The dimensions of the slurry blades 105 are designed according to the blades of the cement pressurizing thickening instrument in GBT10238 - 2015 - Oil Well Cement to ensure sufficient stirring of the cement slurry and simulate the shear force exerted on the cement slurry in the annulus.

[0045] Preferably, the upper end of the slurry shaft 102 is open, the lower end of the slurry shaft 102 is closed, the shape of the lower end of the slurry shaft 102 is conical, and the tip of the cone points downward.

[0046] Specifically, the upper end of the slurry shaft 102 is open, which is convenient for injecting pressure liquid (injecting formation water and controlling the formation water pressure); the lower end of the slurry shaft 102 is closed to prevent liquid leakage and it is not easy to reach the target pressure; the conical structure is convenient for limiting and connecting.

[0047] Preferably, a filter screen 106 is connected inside the slurry shaft 102 at the position of the simulated core 104.

[0048] Embodiment 3:

[0049] On the basis of Embodiment 2, the slurry cup 2 includes an upper cover 201, a pressing member, a slurry cup cylinder 202, and a bottom cover 203. The upper cover 201, the slurry cup cylinder 202, and the bottom cover 203 are connected in sequence from top to bottom. The pressing member is connected inside the upper cover 201.

[0050] Specifically, the upper cover 201 is used to press the pressing member to ensure that the cement slurry in the slurry cup is isolated from the temperature - increasing and pressure - increasing medium in the kettle body.

[0051] Preferably, the pressing member includes a metal pressing sheet 207, a rubber pressing sheet 208, and a metal ring 209. The metal pressing sheet 207, the rubber pressing sheet 208, and the metal ring 209 are connected in sequence from top to bottom; the pressing effect is better.

[0052] Preferably, a conical groove 2031 is formed at the center of the upper surface of the bottom cover 203, and the lower end of the pulp shaft 102 is connected to the conical groove 2031. The structure is simple, and the limiting and connecting effects are good. Specifically, the lower end of the pulp shaft 102 is in contact with the conical groove 2031. In an ideal state, only the tip of the cone contacts the bottom of the conical groove of the bottom cover, minimizing the frictional contact area between them.

[0053] Preferably, the pulp cup 2 further includes a locator 204, and a clamping groove 205 is formed on the side surface of the locator 204; a positioning pin 206 is connected to the lower end of the bottom cover 203.

[0054] Preferably, through holes are axially formed in the center of the locator 204, the upper cover 201, the metal pressing sheet 207, the rubber pressing sheet 208, and the metal ring 209; among them, the through holes of the locator 204, the upper cover 201, the metal pressing sheet 207, and the rubber pressing sheet 208 have the same diameter, which plays a better role in connecting and positioning the pulp shaft 102.

[0055] Specifically, the clamping groove 205 is used to connect the kettle barrel 302; the locator 204 is used to clamp the center rod 1 to ensure that the center rod 1 does not rotate during the experiment; the positioning pin 206 facilitates the positioning connection of the driving disc 308 to prevent the pulp cup 2 from shifting horizontally. The number of positioning pins 206 is 2.

[0056] Preferably, the upper cover 201 and the pulp cup barrel 202 are connected by screw threads, and the pulp cup barrel 202 and the bottom cover 203 are connected by screw threads; the installation and disassembly are convenient.

[0057] Preferably, a layer of plastic film 210 is provided on the inner wall of the pulp cup barrel 202. When the cement solidifies, it is convenient to take out the cement barrel.

[0058] Example 4:

[0059] On the basis of Example 3, a central hole 3011 is axially formed in the center of the kettle cover 301; the kettle body 3 further includes a second sealing joint 304; the pressure control device includes a first booster pump 305, a second booster pump 306, a first electromagnetic pressure relief valve 314, and a second electromagnetic pressure relief valve 315. The liquid output end (water) of the first booster pump 305 is connected to the second sealing joint 304 through a pipeline, the second sealing joint 304 is connected to the central hole 3011, and the first electromagnetic pressure relief valve 314 is connected to the liquid delivery pipeline between the first booster pump 305 and the second sealing joint 304; the liquid output end (water output end) of the second booster pump 306 and the second electromagnetic pressure relief valve 315 are both connected to the kettle barrel 302.

[0060] Specifically, the kettle lid 301 is threadedly connected and sealed with the kettle barrel 302 to ensure the sealing performance of the entire kettle body. A central hole 3011 is axially opened in the center of the kettle lid 301. The first booster pump 305 is connected and sealed with the kettle lid 301 through a pipeline. There is a second sealing joint 304 at the end of the pipeline. The second sealing joint 304 includes a quick-install sealing joint 3041 (female buckle, with a spring buckle, which is clamped during sealing. After pressure relief, the spring buckle can be pressed to open the quick-install sealing joint) and a threaded sealing joint 3042. The second sealing joint 304 can seal the central hole 3011 of the kettle lid 301. During the experiment, the upper sealing joint 101 (male buckle) of the central rod is connected to the quick-install sealing joint 3041 (female buckle), and the threaded sealing joint 3042 is inserted into the central hole 3011 and tightened to ensure that the pressure of the first booster pump 305 can be transmitted into the central rod (inside the pulp shaft 102). The first electromagnetic pressure relief valve 314 and the second electromagnetic pressure relief valve 315 can record the flow rate.

[0061] Preferably, a locator clip 307 is arranged and connected on the inner wall of the kettle barrel 302 below the kettle lid 301, and the locator clip 307 is connected to the clamping groove 205.

[0062] It is convenient to realize positioning and clamping.

[0063] Preferably, the kettle body 3 further includes a transmission rod 309 and a motor 310. A driving disk 308 is arranged at the lower end inside the kettle barrel 302. The lower surface of the driving disk 308 is connected to the output end of the motor 310 through the transmission rod 309, and the motor 310 is electrically connected to the computer 303.

[0064] The motor 310 is controlled by the computer 303. The motor 310 drives the driving disk 308 to rotate through the transmission rod 309, and then drives the pulp cup 2 to rotate to simulate the flow rate.

[0065] Preferably, the temperature control device includes a cooling water circulation pump 311, a cooling water circulation pipeline 312 and a heating wire 313. Heating wires 313 and cooling water pipelines are distributed on the inner wall of the kettle barrel 302. The cooling water circulation pump 311 is connected to the cooling water pipeline through the cooling water circulation pipeline 312. The heating wire 313 is used to heat the liquid medium in the kettle barrel 302. The cooling water circulation pump 311 injects cold water into the cooling water pipeline through the cooling water circulation pipeline 312 to cool the medium in the kettle barrel 302. The heating wire 313 is connected with a temperature sensor, and the temperature sensor is electrically connected to the computer 310. The temperature of the medium in the kettle barrel 302 can be better controlled through the computer 310, and the accuracy is high.

[0066] Example 5:

[0067] Based on Example 4, an evaluation method for a cement slurry water invasion evaluation device includes the following steps:

[0068] S1. The slurry cup cylinder 202 is connected above the bottom cover 203. The central rod 1 with the simulated core 104 saturated with water is placed into the slurry cup cylinder 202 (the conical tip at the lower end of the slurry shaft 102 is placed in the conical groove 2031 of the bottom cover, ensuring that only the tip contacts the bottom cover). Prepared cement slurry is added into the slurry cup cylinder 202 (the cement slurry is prepared according to the standard of GB / T10238). A pressing member is placed above the slurry cup cylinder 202 and the upper cover 201 is connected; a connecting block 103 and a locator 204 are installed on the slurry shaft 102 passing through the upper cover 201, completing the assembly of the slurry cup 2 and the central rod 1;

[0069] S2. The assembled slurry cup 2 and central rod 1 are placed into the autoclave cylinder 302. Simulated formation water is added into the annulus between the autoclave cylinder 302 and the slurry cup 2. The central rod 1 passing through the locator 204 is located in the central hole 3011 of the autoclave cover 301. The autoclave cover 301 is covered on the autoclave cylinder 302. The liquid output end (simulated formation water output end) of the booster pump 1 305 is connected to the sealing joint 2 304 through a pipeline, and the sealing joint 2 304 is connected inside the central hole 3011; the assembly of the central rod 1, the slurry cup 2 and the autoclave body 3 is completed;

[0070] S3. Turn on the computer 303, establish connections with the pressure control device and the temperature control device, and start control with the cement slurry entering the annulus between the central rod 1 and the slurry cup cylinder 202, including the following specific steps:

[0071] S31. Drive the slurry cup 2 to rotate by controlling the motor 310 (the motor speed is adjusted according to the real-time flow rate of the cement slurry. It is recommended to use 150 r / min as the benchmark speed for the conventional displacement rate. When the displacement decreases, the speed is adjusted proportionally), keeping the cement slurry in a simulated flowing state; determine the shearing time of the cement slurry by the blade 105 according to the flowing time of the cement slurry in the annulus during the actual displacement process, so as to distinguish the different impacts on the cement slurry caused by long and short water layer sections;

[0072] S32. Control the temperature control device (heating wire) to gradually heat up the cement slurry (in accordance with the computer program settings) to the bottom hole circulating temperature;

[0073] S33. Control the booster pump 1 305 to raise the pressure inside the central rod 1 to the target pressure, simulating the formation pressure; control the booster pump 2 306 to raise the pressure of the simulated formation water in the autoclave body 3 to the target pressure, simulating the liquid column pressure of the drilling fluid and the cementing fluid;

[0074] Specifically, control the first booster pump 305 and the second booster pump 306 to increase the pressure of the central rod 1 and the simulated formation water pressure in the autoclave 3 to the drilling fluid, cementing fluid column pressure and formation pressure when the cement slurry just exits the casing at the same pressure increase rate. Generally, at this time, the drilling fluid and cementing fluid column pressure should be greater than the formation pressure. When boosting the pressure, the pressure of the central rod 1 and the medium pressure in the autoclave should be increased to the formation pressure (smaller pressure) at the same speed, and then the central rod 1 stops boosting the pressure. The simulated formation water in the autoclave 3 slowly rises to the drilling fluid and cementing fluid column pressure to ensure the pressure difference between the central rod 1 and the cement slurry;

[0075] S34. According to the drilling fluid, cementing fluid column pressure, formation pressure and formation temperature during the displacement process, the computer 303 simulates the pressure and temperature changes during the displacement process by controlling the pressure control device and the temperature control device;

[0076] Specifically, according to the drilling fluid, cementing fluid column pressure, formation pressure and formation temperature during the displacement process, the computer 303 controls the real-time pressure of the first booster pump 305 and the second booster pump 306, as well as the heating wire and the cooling water circulation pump to ensure the pressure and temperature changes during the simulated displacement process; during the experiment, the computer 303 controls the first electromagnetic pressure relief valve 314 and the second electromagnetic pressure relief valve 315 to ensure that the pressure of the central rod and the simulated formation water in the autoclave 3 is at the program set value and records the flow rate;

[0077] S35. When the simulated displacement experiment is completed, the motor 310 stops rotating, and the pressure in the autoclave 3 is controlled to reduce the cement slurry to the clear water column pressure during the initial strength formation period;

[0078] Specifically, when the simulated displacement experiment is completed, the motor stops rotating, and the pressure in the autoclave is slowly reduced to the clear water column pressure during the initial strength formation period of the cement slurry. At this time, there should be a positive pressure difference between the pressure of the central rod (formation pressure) and the pressure of the autoclave (clear water column pressure), and it is static for 24 h or 48 h, based on the electric logging time of the same type of wells in this oilfield;

[0079] S37. Remove the central rod 1 and the cement ring, and measure the cementing strength between the simulated core and the cement by the gas channeling method to complete the evaluation of the water invasion of the cement slurry.

[0080] Existing cement slurry water invasion prevention instruments and methods mostly consider the influence of formation water erosion on cement slurry after the cement slurry is displaced in place, without considering the erosion of cement slurry by formation water during the displacement process. In engineering practice, when other conditions are the same (such as cement slurry performance, construction parameters, formation temperature, etc.), the cementing quality in long water layer sections is significantly worse than that in short water layer sections, indicating that formation water also has an obvious erosion effect on cement slurry during the displacement process. It is necessary to consider the influence of water invasion during the displacement process on the performance of cement slurry in the evaluation method of cement slurry water invasion prevention performance and the design of related devices. The present invention simulates the displacement process of cement slurry in a water-bearing formation, considering the factor of different lengths of water layer sections encountered by the cement slurry during the displacement process. By adjusting the stirring time of the cement slurry by the water-containing simulated core and the impeller, it simulates the erosion of the cement slurry by water layer sections of different lengths, which is closer to the actual working conditions on site.

[0081] In the description of the present invention, it should be understood that if there are terms such as "upper", "lower", "inner", etc. indicating the orientation or position relationship, they are based on the orientation or position relationship shown in the drawings, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, the terms describing the position relationship in the drawings are only for illustrative purposes and cannot be understood as a limitation to the present invention.

[0082] The above examples are only illustrative of the present invention and do not constitute a limitation to the protection scope of the present invention. Any design identical or similar to the present invention falls within the protection scope of the present invention.

Claims

1. A device for evaluating water invasion of cement slurry, characterized in that: It includes a central rod (1), a slurry cup (2) and a kettle body (3). The kettle body (3) includes a kettle lid (301), a kettle cylinder (302), a computer (303), a pressure control device and a temperature control device. The kettle cylinder (302), the slurry cup (2) and the central rod (1) are sleeved from outside to inside in sequence. The upper end of the kettle cylinder (302) is connected to the kettle lid (301). The upper end of the central rod (1) is located inside the kettle lid (301). The upper end of the central rod (1) and the kettle cylinder (302) are both connected to the liquid outlet end of the pressure control device. The computer (303) is electrically connected to the pressure control device and the temperature control device respectively.

2. The device for evaluating water invasion of cement slurry according to claim 1, characterized in that: The central rod (1) includes a first sealing joint (101), a slurry shaft (102), a connecting block (103), a simulated core (104) and slurry blades (105). The upper end of the slurry shaft (102) is connected to the first sealing joint (101). The connecting block (103) is sleeved on the outer side of the upper part of the slurry shaft (102). The simulated cores (104) are sleeved on the outer sides of the middle part and the lower part of the slurry shaft (102). One end of the slurry blade (105) is connected to the outer side of the slurry shaft (102). The central axis of the slurry shaft (102) is hollow.

3. The device for evaluating water invasion of cement slurry according to claim 2, characterized in that: The upper end of the slurry shaft (102) is open, and the lower end of the slurry shaft (102) is closed. The shape of the lower end of the slurry shaft (102) is conical, and the tip of the cone points downward.

4. The device for evaluating water invasion of cement slurry according to claim 3, characterized in that: The slurry cup (2) includes an upper cover (201), a pressing member, a slurry cup cylinder (202) and a bottom cover (203). The upper cover (201), the slurry cup cylinder (202) and the bottom cover (203) are connected in sequence from top to bottom. The pressing member is connected inside the upper cover (201).

5. The device for evaluating water invasion of cement slurry according to claim 4, characterized in that: A conical groove (2031) is opened at the center of the upper surface of the bottom cover (203). The lower end of the slurry shaft (102) is connected to the conical groove (2031).

6. The device for evaluating water invasion of cement slurry according to claim 5, characterized in that: The slurry cup (2) further includes a locator (204). A clamping groove (205) is opened on the side surface of the locator (204). A positioning pin (206) is arranged at the lower end of the bottom cover (203).

7. The device for evaluating water invasion of cement slurry according to claim 6, characterized in that: A central hole (3011) is axially opened at the center of the kettle lid (301). The kettle body (3) further includes a second sealing joint (304). The pressure control device includes a first booster pump (305), a second booster pump (306), an electromagnetic pressure relief valve one (314) and an electromagnetic pressure relief valve two (315). The liquid output end of the first booster pump (305) is connected to the second sealing joint (304) through a pipeline. The second sealing joint (304) is connected inside the central hole (3011). The electromagnetic pressure relief valve one (314) is connected to the infusion pipeline between the first booster pump (305) and the second sealing joint (304). The liquid output end of the second booster pump (306) and the electromagnetic pressure relief valve two (315) are both connected to the kettle cylinder (302).

8. The device for evaluating water invasion of cement slurry according to claim 7, characterized in that: A locator clip (307) is arranged and connected to the inner wall of the kettle cylinder (302) below the kettle lid (301). The locator clip (307) is connected to the clamping groove (205).

9. The device for evaluating water invasion of cement slurry according to claim 8, characterized in that: The kettle body (3) further includes a transmission rod (309) and a motor (310). A drive disk (308) is provided at the lower end inside the kettle cylinder (302). The lower surface of the drive disk (308) is connected to the output end of the motor (310) through the transmission rod (309), and the motor (310) is electrically connected to the computer (303).

10. A method for evaluating a device for evaluating water invasion of cement slurry, characterized in that: It includes the following steps: S1. Connect the slurry cup cylinder (202) to the upper surface of the bottom cover (203). Place the central rod (1) of the simulated core (104) with saturated formation water into the slurry cup cylinder (202). Add the prepared cement slurry into the slurry cup cylinder (202). Place a pressing member on the slurry cup cylinder (202) and connect the upper cover (201). Install a connecting block (103) and a locator (204) on the slurry shaft (102) passing through the upper cover (201) to complete the assembly of the slurry cup (2) and the central rod (1). S2. Place the assembled slurry cup (2) and central rod (1) into the kettle cylinder (302). Add a liquid medium into the annulus between the kettle cylinder (302) and the slurry cup (2). The central rod (1) passing through the locator (204) is located in the central hole (3011) of the kettle cover (301). Cover the kettle cover (301) on the kettle cylinder (302). The liquid output end of the first booster pump (305) is connected to the second sealing joint (304) through a pipeline, and the second sealing joint (304) is connected into the central hole (3011) to complete the assembly of the central rod (1), the slurry cup (2) and the kettle body (3). S3. Turn on the computer (303), establish connections with the pressure control device and the temperature control device, and start the control with the cement slurry entering the annulus between the central rod (1) and the slurry cup cylinder (202), including the following specific steps: S31. Drive the slurry cup (2) to rotate by controlling the motor (310) to keep the cement slurry in a simulated flowing state. S32. Control the temperature control device to raise the temperature of the cement slurry to the bottom hole circulating temperature. S33. Control the first booster pump (305) to raise the pressure inside the central rod (1) to the target pressure to simulate the formation pressure. Control the second booster pump (306) to raise the pressure of the simulated formation water inside the kettle body (3) to the target pressure to simulate the liquid column pressures of the drilling fluid and the cementing fluid. S34. According to the liquid column pressures of the drilling fluid and the cementing fluid, the formation pressure and the formation temperature during the displacement process, the computer (303) controls the pressure control device and the temperature control device to simulate the pressure and temperature changes during the displacement process. S35. When the simulated displacement experiment is completed, the motor (310) stops rotating, and control the pressure inside the kettle body (3) to reduce the cement slurry to the clear water liquid column pressure during the initial strength formation period. S37. Remove the central rod (1) and the cement ring, and measure the cementation strength between the simulated core and the cement by the gas channeling method to complete the evaluation of the water invasion of the cement slurry.

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