A sand carrying capacity simulation experiment device and method for a wellbore with a continuous oil pipe

Abstract

The present invention discloses a sand-carrying capacity simulation experiment device for a wellbore with a continuous oil pipe, comprising an outer pipe for simulating a wellbore, an inner pipe for simulating a continuous oil pipe, a gas-liquid-solid injection system and a wellbore monitoring system, wherein the inner pipe is movably installed on the outer pipe and extends into the outer pipe cavity, an electric rotating head is installed at the end of the inner pipe extending into the outer pipe, a first outlet of the gas-liquid-solid injection system is connected to the top of the inner pipe exposed outside the outer pipe to inject water into the inner pipe, a second outlet of the gas-liquid-solid injection system is connected to the injection port arranged at the end of the outer pipe to inject a gas-liquid-solid mixture into the inner cavity of the outer pipe, and the wellbore monitoring system is used to observe the amount of sand produced by the inner pipe in the outer pipe cavity under various operation conditions simulated by the inner pipe in the outer pipe cavity. The present invention adds a simulation structure of a continuous oil pipe into the wellbore for the first time, and achieves real-time and accurate monitoring of the sand-carrying flow state at different wellbore positions by performing the movable operation of lifting and lowering the continuous oil pipe, the rotation operation and the sand flushing operation.

Description

Technical Field

[0001] The invention relates to the technical field of a wellbore sand carrying capacity simulation device, in particular to a wellbore sand carrying capacity simulation experimental device and method with a continuous oil pipe. Background Art

[0002] In the natural gas hydrate pilot production project, a small amount of mud and a large amount of small-particle formation sand are often brought into the production wellbore. In order to prevent the formation sand from clogging or affecting the normal pilot production operation of the wellbore, it is necessary to carry the formation sand from the wellbore to the operating platform through the wellbore sand carrying method to prevent sand jam, sand blockage or sand burial in the production wellbore, so as not to affect the normal production operation of the artificial lift structure. However, in the actual pilot production project, the operators cannot directly observe the formation sand situation in the wellbore, and thus cannot judge the sand carrying capacity of the wellbore. If the sand carrying capacity is weak, it may still cause problems such as sand jam and sand blockage. Therefore, it is necessary to simulate the sand carrying capacity of the wellbore in the laboratory so that in the actual pilot production project, a pilot production operation wellbore device that meets the sand carrying needs can be set up.

[0003] In the existing wellbore sand carrying capacity simulation experimental devices, most of them only use vertical wellbore as the research object, and simply analyze and compare the sand carrying capacity of the wellbore under different gas-liquid ratios or flow rates. For example, the Chinese invention applications with publication numbers CN109211516A and CN108894772A focus on the gas injection or gas production vertical wellbore and the gas-water flow characteristics and pressure distribution laws in the drainage gas production process, or analyze the migration and sedimentation laws of sand particles in the wellbore. Among these existing technologies, there is almost no reference to the wellbore sand carrying capacity in the case of continuous tubing assisted wellbore sand carrying operations. Therefore, it is necessary to simulate the sand carrying capacity of the wellbore under the action of continuous tubing so that the simulation results can better guide actual production operations. Summary of the invention

[0004] In view of the deficiencies in the prior art, the purpose of the present invention is to provide a wellbore sand carrying capacity simulation experiment device with a continuous oil pipe, which can solve the problem of the wellbore sand carrying capacity simulation experiment under the assistance of the continuous oil pipe.

[0005] The technical scheme for achieving the purpose of the present invention is: a sand carrying capacity simulation experimental device for a wellbore with a continuous oil pipe, comprising an outer pipe for simulating a wellbore, an inner pipe for simulating a continuous oil pipe, a gas-liquid-solid injection system and a wellbore monitoring system, wherein the inner pipe extends from a first inlet at the top of the outer pipe into the outer pipe cavity along the axial direction of the outer pipe and is movably installed on the outer pipe, so that the inner pipe can move freely along the axial direction of the outer pipe and rotate freely relative to the outer pipe in the outer pipe cavity, the outer pipe and the inner pipe are matched in shape, and an electric rotating head is installed at the end of the inner pipe extending into the outer pipe,

[0006] The first outlet of the gas-liquid-solid injection system is communicated with the top of the inner tube exposed outside the outer tube to inject water into the inner tube, and the second outlet of the gas-liquid-solid injection system is communicated with the injection port arranged at the end of the outer tube to inject the gas-liquid-solid mixture into the inner cavity of the outer tube.

[0007] The wellbore monitoring system is used to observe the amount of sand produced in the outer tube cavity under various simulated operation conditions of the inner tube in the outer tube cavity, wherein the simulated various operations at least include simulated lifting and lowering, rotation and sand flushing operations of the inner tube.

[0008] Furthermore, the outer tube includes an L-shaped tube body for simulating a horizontal wellbore and a straight tube body for simulating a vertical wellbore.

[0009] Furthermore, it also includes a fixed support device, the outer tube is movably mounted on the fixed support device, and the inclination angle of the outer tube can be adjusted to simulate the sand carrying capacity of the wellbore under different inclination angles.

[0010] Furthermore, the gas-liquid-solid injection system includes a sand adding tank for storing formation sand, a liquid storage tank for storing liquid water, a gas cylinder for storing gas, a mud pump, and a gas-liquid-solid mixer. The gas-liquid-solid mixer is used to mix formation sand, liquid water and gas into a gas-liquid-solid mixture. The first output ends of the sand adding tank and the liquid storage tank are respectively connected to the input end of the mud pump through a pipeline, the second output end of the liquid storage tank is connected to the inner pipe through another pipeline, the output end of the mud pump is connected to the input end of the gas-liquid-solid mixer through a pipeline, and the output end of the gas cylinder is connected to the input end of the gas-liquid-solid mixer through a pipeline.

[0011] Furthermore, one-way valves are arranged on the pipes between the sand adding tank and the mud pump, the pipes between the liquid storage tank and the mud pump, the pipes between the liquid storage tank and the inner pipe, and the pipes between the gas cylinder and the gas-liquid-solid mixer. The one-way valves are used to prevent the corresponding objects from flowing back.

[0012] A liquid flow meter and a temperature and pressure sensor are arranged on the pipeline between the liquid storage tank and the mud pump, which are used to respectively measure the water flow rate and temperature and pressure output to the mud pump; a gas flow meter and a temperature and pressure sensor are arranged on the pipeline between the gas cylinder and the gas-liquid-solid mixer; a liquid flow meter and a pump are arranged on the pipeline between the liquid storage tank and the inner pipe; a control valve is also installed on the pipeline between the mud pump and the gas-liquid-solid mixer, and the control valve is used to control the amount of liquid-solid mixture output by the mud pump to the gas-liquid-solid mixer; a control valve and a temperature and pressure sensor are arranged on the pipeline between the gas-liquid-solid mixer and the injection port.

[0013] Furthermore, it also includes a separation and sand settling system, which includes a three-phase separator and a sand settling tank. The input end of the three-phase separator is connected to the first outlet on the top of the outer tube, the first output end of the three-phase separator is connected to the gas-liquid-solid mixer through a pipeline, the second output end of the three-phase separator is connected to the gas-liquid-solid mixer through a pipeline, and the third output end of the three-phase separator is connected to the sand settling tank through a pipeline. The three-phase separator is used to separate the gas-liquid-solid mixture into gas, liquid water and formation sand respectively.

[0014] Furthermore, a liquid flow meter and a temperature and pressure sensor are installed on the pipeline between the first output end and the gas-liquid-solid mixer, and a gas flow meter and a temperature and pressure sensor are installed on the pipeline between the second output end and the gas-liquid-solid mixer.

[0015] Furthermore, a gravity sensor is installed on the pipe between the three-phase separator and the sand settling tank. The gravity sensor is used to measure the weight of the formation sand separated by the three-phase separator in real time. The weight of the formation sand quantitatively represents the sand carrying capacity of the wellbore.

[0016] Furthermore, the wellbore monitoring system includes a data processing terminal, a plurality of three-phase flow detectors and a plurality of cameras, wherein the cameras include a mobile high-speed camera and a fixed high-speed camera installed at a fixed position, wherein the fixed high-speed camera is used to aim at a certain position of the outer tube for shooting, and the mobile high-speed camera moves along the axial direction of the outer tube for shooting.

[0017] Each three-phase flow detector is fixedly installed on the inner wall of the outer tube cavity along the axial direction of the outer tube. At least one three-phase flow detector is installed in the upper, middle and lower sections of the outer tube. The three-phase flow detector is used to measure in real time the ratio of the gas, liquid and solid three phases flowing through each position of the wellbore.

[0018] An experimental method using the wellbore sand carrying capacity simulation experimental device with a coiled tubing comprises the following steps:

[0019] Step 1: Add formation sand to the sand adding tank, add gas to the gas cylinder, add liquid water to the liquid storage tank, and control the amount of formation sand, gas and liquid water injected into the liquid-solid mixer and the ratio of the three;

[0020] Step 2: The gas-liquid-solid mixer fully stirs the formation sand, gas and liquid water to form a gas-liquid-solid mixture, and controls the flow rate and flow velocity to inject the gas-liquid-solid mixture into the outer tube cavity through the injection port at the bottom of the outer tube, so that a stable flow pattern is formed in the outer tube cavity and no formation sand is carried out from the first outlet at the top of the outer tube;

[0021] Step 3: Start the inner tube to simulate various operations in the outer tube cavity, so that the inner tube performs lifting and lowering, rotation and sand flushing operations in the outer tube cavity respectively, and adjust and control the lifting and lowering operation frequency, rotation operation frequency or sand flushing operation fluid volume and flow rate of the inner tube, and repeat the above operations for a period of time until no formation sand is carried out from the first outlet in the outer tube cavity;

[0022] Step 4: Observe the amount of formation sand carried out by the outer tube circulation through the wellbore observation system, conduct a simulation experiment on the sand carrying capacity of the wellbore with continuous oil tubing, and obtain relevant experimental data.

[0023] The beneficial effects of the present invention are as follows: the present invention adds a simulated structure of a continuous oil pipe to the wellbore for the first time, and by performing the lifting and lowering operations, rotating operations and sand flushing operations of the continuous oil pipe, the sand carrying capacity of the wellbore driven solely by the flow rate and the sand carrying capacity of the wellbore assisted by the continuous oil pipe under the same experimental conditions can be compared and analyzed, and a sand carrying law analysis and flow assurance water injection scheme that are more in line with the hydrate test production conditions can be obtained. For the first time, a gas-liquid-solid three-phase mixture is injected into the bottom of the outer pipe serving as the wellbore through multiple injection ports (i.e., the multiple injection ports in the figure) to simulate the actual sand production situation in the hydrate test production wellbore. The three-phase flow detector is installed on the inner diameter pipe wall of the wellbore, and is installed at the top, middle and bottom positions of the wellbore respectively. The ratio of the gas-liquid-solid three-phases flowing instantly at the top, middle and bottom positions of the wellbore can be measured in real time, so as to achieve real-time and accurate monitoring of the sand carrying flow state at different wellbore positions. The use of gravity sensors in the quality monitoring of sand settling tanks can measure in real time the changing process of sand being carried out of the wellbore, providing simulation experimental support for analyzing the sand carrying rules of the wellbore under different variable parameters.

[0024] Compared with other wellbore sand carrying law experimental devices, the present invention can more accurately simulate the actual situation of the production wellbore during the hydrate trial production process. The design of the experimental device can not only carry out the gas-liquid-solid three-phase flow pattern and the wellbore sand carrying law under different gas-liquid ratios and different flow velocities of wellbores of different specifications, but also can carry out the gas-liquid-solid three-phase flow pattern and the wellbore sand carrying law under different gas-liquid ratios, different flow velocities and different sand flushing conditions of wellbores of different specifications with continuous oil pipe assisted wellbore sand carrying operation, so as to provide a more accurate and actual experimental basis for the flow assurance water injection plan of the natural gas hydrate production wellbore. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 A schematic diagram of the structure installed under the vertical wellbore;

[0026] Figure 2 Schematic diagram of the structure under the wellbore for installing a horizontal well. Specific implementation plan

[0027] The present invention will be further described below in conjunction with the accompanying drawings and specific implementation plans:

[0028] like Figure 1 and Figure 2 As shown, a sand-carrying capacity simulation experimental device for a wellbore with a continuous oil pipe includes an outer pipe for simulating a wellbore, an inner pipe for simulating a continuous oil pipe, a gas-liquid-solid injection system and a wellbore monitoring system. The wellbore monitoring system is used to observe the amount of sand produced in the outer pipe cavity as a simulated wellbore under various operating conditions of the inner pipe as a simulated continuous oil pipe, that is, to monitor the sand-carrying capacity of the outer pipe of the simulated wellbore. The inner pipe extends from the first inlet at the top of the outer pipe into the outer pipe cavity along the axial direction of the outer pipe. The shapes of the outer pipe and the inner pipe are adapted so that the inner pipe can be well extended into the cavity of the inner pipe. An electric rotating head is installed at the end of the inner pipe extending into the outer pipe. The electric rotating head is used to rotate the gas-liquid-solid mixture in the outer pipe cavity to simulate rotation and sand flushing operations. The inner pipe is movably installed on the outer pipe, so that the inner pipe can move freely along the axial direction of the outer pipe and rotate freely relative to the outer pipe in the outer pipe cavity. That is, the inner pipe can perform lifting and lowering operations, rotation operations and sand flushing operations in the outer pipe cavity.

[0029] in, Figure 2 It is shown in the figure that three outer tubes of different diameters are installed. When it is necessary to simulate wellbores of different sizes, that is, when the outer tubes need to be replaced, the inner tube can be directly inserted into the corresponding outer tube, so as to achieve the purpose of rapid replacement and thus simulate the sand carrying capacity in wellbores of different sizes.

[0030] The inner tube can be lifted up, lowered and rotated directly by manual operation, that is, a person holds one end of the inner tube exposed outside the outer tube and moves the inner tube so that the inner tube moves along the axial direction of the outer tube and rotates the inner tube so that the inner tube rotates relative to the outer tube, thereby achieving the purpose of simulating lifting and lowering operations and rotating operations.

[0031] Of course, the inner tube can also be driven to move and rotate by a driving device, which includes a motor (i.e., the driving motor in the figure), a lifting platform and a fixed rod (i.e., the fixing device in the figure), the fixed rod is fixedly installed on one side of the lifting platform, the motor is connected to the fixed rod in a transmission manner, the motor is used to drive the fixed rod to rotate, the fixed rod is connected to the inner tube in a transmission manner, thereby driving the inner tube to rotate in the outer tube cavity. The lifting platform can be raised and lowered freely, thereby driving the fixed rod to rise and fall, so that the inner tube connected to the fixed rod in a transmission manner moves along the axial direction of the outer tube.

[0032] The connection between the inner tube and the first inlet at the top of the outer tube is sealed by a sealing ring or other sealing member to prevent the gas-liquid-solid mixture in the outer tube cavity from flowing out from the top or external gas substances from mixing into the outer tube cavity.

[0033] The gas-liquid-solid injection system is connected to the top of the inner tube exposed outside the outer tube through the first outlet to inject water into the inner tube, and the gas-liquid-solid injection system is connected to the injection port (corresponding to the multi-point injection port in the figure) arranged at the end of the outer tube through the second outlet to inject the gas-liquid-solid mixture into the inner cavity of the outer tube. Among them, multiple injection ports are dug at the end of the outer tube, and each injection port is arranged at the end of the outer tube at intervals.

[0034] As another implementation of the embodiment, it also includes a fixed support device, by installing the outer tube on the fixed support device, so that the outer tube and the inner tube are installed on the fixed support device as a whole. The outer tube is movably installed on the fixed support device to adjust the inclination angle of the outer tube to simulate the sand carrying capacity of the wellbore under different inclination angles. The outer tube is an L-shaped tube body or a straight tube body, the L-shaped tube body simulates the horizontal wellbore, and the straight tube body simulates the vertical wellbore. Correspondingly, the inner tube is adapted to the shape of the outer tube, that is, the inner tube is also an L-shaped tube body or a straight tube body.

[0035] The gas-liquid-solid injection system includes a sand adding tank for storing formation sand, a liquid storage tank for storing liquid water, a gas cylinder for storing gas, a mud pump, and a gas-liquid-solid mixer. The first output ends of the sand adding tank and the liquid storage tank are respectively connected to the input end of the mud pump through a pipeline, and the second output end of the liquid storage tank is connected to the inner tube through another pipeline, so as to facilitate the liquid (i.e., water flow) in the liquid storage tank to be input into the inner tube for simulating a continuous oil pipe. The output end of the mud pump is connected to the input end of the gas-liquid-solid mixer through a pipeline, and the output end of the gas cylinder is connected to the input end of the gas-liquid-solid mixer through a pipeline. Among them, the pipeline connected to the output end of the gas cylinder and the pipeline connected to the output end of the mud pump are connected to the input end of the mixer after merging, or the gas cylinder and the mud pump are each connected to the input end of the gas-liquid-solid mixer through a pipeline. The formation sand stored in the sand adding tank and the liquid stored in the liquid storage tank are input into the mud pump through the pipeline. The formation sand and the liquid are mixed into a liquid-solid mixture in the mud pump. By setting the displacement and pressure of the mud pump, the output and flow rate of the liquid-solid mixture can be well controlled. The gas cylinder outputs the stored gas into the gas-liquid-solid mixer and mixes it with the liquid-solid mixture in the gas-liquid-solid mixer to form a gas-liquid-solid mixture. The gas-liquid-solid mixer then outputs the gas-liquid-solid mixture through the pipeline and injects it into the cavity of the outer tube through the injection port on the outer tube.

[0036] Preferably, a one-way valve (i.e., corresponding to one-way valve 3, one-way valve 2, one-way valve 4, one-way valve 1 in the figure, respectively) is provided on the pipeline between the sand adding tank and the mud pump, the pipeline between the liquid storage tank and the mud pump, the pipeline between the liquid storage tank and the inner tube, and the pipeline between the gas cylinder and the gas-liquid-solid mixer to prevent backflow, including preventing formation sand from backflowing into the sand adding tank, liquid from backflowing into the liquid storage tank, gas from backflowing (backflowing) into the gas cylinder, and liquid-solid mixture from backflowing into the mud pump. A liquid flow meter (corresponding to the liquid flow meter 1 in the figure) and a temperature and pressure sensor (corresponding to the temperature and pressure sensor 2 in the figure) are provided on the pipeline between the liquid storage tank and the mud pump to measure the water flow rate and temperature and pressure output to the mud pump. Similarly, a gas flow meter (corresponding to the gas flow meter 1 in the figure) and a temperature and pressure sensor (corresponding to the temperature and pressure sensor 1 in the figure) are provided on the pipeline between the gas cylinder and the gas-liquid-solid mixer, and a liquid flow meter (corresponding to the liquid flow meter 3 in the figure) and a pump are provided on the pipeline between the liquid storage tank and the inner tube. The pump plays a role in generating thrust for the water flow output from the liquid storage tank, so that it can be output to the inner tube with a greater flow rate and impulse, simulating the scene of seawater flushing the continuous oil pipe during the actual test production operation. A control valve (corresponding to the control valve 1 in the figure) is also installed on the pipeline between the mud pump and the gas-liquid-solid mixer. The control valve is used to control the amount of liquid-solid mixture output by the mud pump to the gas-liquid-solid mixer to prevent the output from being too much or too little. A control valve (corresponding to the control valve 2 in the figure) and a temperature and pressure sensor (corresponding to the temperature and pressure sensor 3 in the figure) are also provided on the pipeline between the gas-liquid-solid mixer and the injection port, so as to control the gas-liquid-solid output output to the injection port and measure the temperature and pressure in the current pipeline.

[0037] The wellbore monitoring system includes a data processing terminal (a general-purpose computer can be selected), a number of three-phase flow detectors (three three-phase flow detectors 1, 2, 3 are shown in the figure) and a number of cameras. The cameras include a mobile high-speed camera (corresponding to the mobile high-speed camera in the figure) and a fixed high-speed camera installed in a fixed position (corresponding to the high-speed camera 1, high-speed camera 2, and high-speed camera 3 in the figure). The fixed high-speed camera is used to aim at a certain position of the outer pipe for shooting to observe the sand production at a certain position in the outer pipe. The fixed position high-speed camera can be installed at different positions. The mobile height camera can be manually operated or moved along the slide rail to shoot the outer pipe, so as to observe the sand production at various locations of the outer pipe. Each liquid flow meter, gas flow meter and temperature and pressure sensor on the above-mentioned pipelines are electrically connected to the data processing terminal, so that the measured parameters can be uploaded to the data processing terminal and subsequently processed by the data processing terminal. The dotted line in the figure means that the measured parameter data needs to be uploaded to the data processing terminal.

[0038] Each three-phase flow detector is fixedly installed on the inner wall of the outer tube cavity along the axial direction of the outer tube, including at least the upper, middle and lower sections of the cavity, that is, for a horizontal wellbore, at least one three-phase flow detector is installed on the horizontal section, curved section and vertical section of the outer tube, and for a vertical wellbore, at least one three-phase flow detector is installed on the front section, middle section and rear section of the outer tube. The ratio of the gas-liquid-solid three-phase flowing through the horizontal section, curved section and vertical section of the wellbore is measured in real time, so as to better detect the gas-liquid-solid three-phase flow pattern under different gas-liquid ratios and different flow rate adjustments.

[0039] As another embodiment of the embodiment, it also includes a separation and sand settling system, which includes a three-phase separator and a sand settling tank, and the input end of the three-phase separator is connected to the first outlet at the top of the outer tube. The first output end of the three-phase separator is connected to the gas-liquid-solid mixer through a pipeline, the second output end of the three-phase separator is connected to the gas-liquid-solid mixer through a pipeline, and the third output end of the three-phase separator is connected to the sand settling tank through a pipeline. The gas-liquid-solid mixture circulated out of the outer tube with sand is discharged to the three-phase separator after passing through the first outlet. After the three-phase separator separates the gas-liquid-solid mixture, the solid formation sand is discharged into the sand settling tank through the third output channel, and the gas and liquid are sent to the gas-liquid-solid mixer through their respective pipelines to realize the recycling of gas and liquid phases.

[0040] Preferably, a gravity sensor is also installed on the pipe between the three-phase separator and the sand settling tank. The gravity sensor is used to measure in real time the weight of the formation sand separated by the three-phase separator. The weight of the formation sand also represents the amount of formation sand circulated out of the outer pipe, thereby quantitatively simulating the sand carrying capacity of the wellbore.

[0041] Similarly, a liquid flow meter (corresponding to the liquid flow meter 2 in the figure) and a temperature and pressure sensor (corresponding to the temperature and pressure sensor 6 in the figure) are installed on the pipeline between the first output end of the three-phase separator and the gas-liquid-solid mixer, a gas flow meter (corresponding to the gas flow meter 2 in the figure) and a temperature and pressure sensor (corresponding to the temperature and pressure sensor 5 in the figure) are installed on the pipeline between the second output end of the three-phase separator and the gas-liquid-solid mixer, and a temperature and pressure sensor (corresponding to the temperature and pressure sensor 4 in the figure) is installed on the pipeline between the input end of the three-phase separator and the first outlet at the top of the outer tube.

[0042] Based on the above device, the present invention also provides an experimental method, comprising the following steps:

[0043] Step 1: Add formation sand to the sand adding tank, add gas to the gas cylinder, and add liquid water to the liquid storage tank. The amount of formation sand, gas and liquid water injected into the liquid-solid mixer and the ratio of the three are controlled by a one-way control valve.

[0044] Step 2: The liquid-solid mixer fully stirs the formation sand, gas and liquid water to form a gas-liquid-solid mixture, and controls the flow rate and flow velocity to inject the gas-liquid-solid mixture into the outer tube cavity through the injection port at the bottom of the outer tube, so that a stable flow pattern is formed in the outer tube cavity and no formation sand is carried out from the first outlet at the top of the outer tube.

[0045] Step 3: Start the inner tube so that it can be lifted up and lowered, rotated and sand-flushed in the outer tube cavity respectively, and adjust and control the lifting and lowering frequency of the inner tube, the rotation frequency or the amount and flow rate of the sand-flushing operation, and repeat the above operations for a period of time until no formation sand is carried out from the first outlet in the outer tube cavity.

[0046] Step 4: Observe the amount of formation sand carried out by the outer tube circulation through the wellbore observation system to achieve the purpose of simulating the sand carrying capacity of the wellbore with continuous oil tubing and obtain relevant experimental data.

[0047] Among them, the sand carrying capacity can also be quantitatively measured by gravity sensors.

[0048] The present invention adds the simulation structure of the continuous oil pipe to the wellbore for the first time. By performing the lifting and lowering activities, rotation operations and sand flushing operations of the continuous oil pipe, the sand carrying capacity of the wellbore driven by the flow rate alone and the sand carrying capacity of the wellbore assisted by the continuous oil pipe under the same experimental conditions can be compared and analyzed, and the sand carrying law analysis and flow guarantee water injection scheme that are more in line with the hydrate test production conditions can be obtained. For the first time, the gas-liquid-solid three-phase mixture is injected into the bottom of the outer pipe as the wellbore through multiple injection ports (i.e., the multiple injection ports in the figure) to simulate the actual sand production situation in the hydrate test production wellbore. The three-phase flow detector is installed on the inner diameter pipe wall of the wellbore, and is installed at the top, middle and bottom positions of the wellbore respectively. The ratio value of the gas-liquid-solid three-phase flowing instantly at the top, middle and bottom positions of the wellbore can be measured in real time, so as to achieve real-time and accurate monitoring of the sand carrying flow state at different wellbore positions. The gravity sensor is used in the quality monitoring of the sand settling tank, and the change process of sand particles being carried out of the wellbore can be measured in real time, so as to analyze the sand carrying law of the wellbore under different variable parameters.

[0049] Compared with other wellbore sand carrying law experimental devices, the present invention can more accurately simulate the actual situation of the production wellbore during the hydrate trial production process. The design of the experimental device can not only carry out the gas-liquid-solid three-phase flow pattern and the wellbore sand carrying law under different gas-liquid ratios and different flow velocities of wellbores of different specifications, but also can carry out the gas-liquid-solid three-phase flow pattern and the wellbore sand carrying law under different gas-liquid ratios, different flow velocities and different sand flushing conditions of wellbores of different specifications with continuous oil pipe assisted wellbore sand carrying operation, so as to provide a more accurate and actual experimental basis for the flow assurance water injection plan of the natural gas hydrate production wellbore.

[0050] The embodiment disclosed in this specification is only an example of a unilateral feature of the present invention, and the protection scope of the present invention is not limited to this embodiment, and any other functionally equivalent embodiments fall within the protection scope of the present invention. For those skilled in the art, various other corresponding changes and deformations can be made according to the technical solutions and concepts described above, and all of these changes and deformations should fall within the protection scope of the claims of the present invention.

Claims

1. A sand carrying capacity simulation test device for a wellbore with a coiled tubing, characterized in that: The invention comprises an outer tube for simulating a wellbore, an inner tube for simulating a coiled tubing, a gas-liquid-solid injection system and a wellbore monitoring system. The inner tube extends from a first inlet at the top of the outer tube into the outer tube cavity along the axial direction of the outer tube and is movably mounted on the outer tube so that the inner tube can freely move along the axial direction of the outer tube and freely rotate relative to the outer tube in the outer tube cavity. The outer tube and the inner tube are matched in shape, and an electric rotating head is mounted at the end of the inner tube extending into the outer tube. The first outlet of the gas-liquid-solid injection system is communicated with the top of the inner tube exposed outside the outer tube to inject water into the inner tube, and the second outlet of the gas-liquid-solid injection system is communicated with the injection port arranged at the end of the outer tube to inject the gas-liquid-solid mixture into the inner cavity of the outer tube. The wellbore monitoring system is used to observe the amount of sand produced in the outer tube cavity under various simulated operation conditions of the inner tube in the outer tube cavity, wherein the simulated various operations at least include the simulated lifting and lowering, rotation and sand flushing operations of the inner tube. It also includes a number of three-phase flow detectors, each of which is fixedly installed on the inner wall of the outer tube cavity along the axial direction of the outer tube, and at least one three-phase flow detector is installed in the upper, middle and lower sections of the outer tube. The three-phase flow detector is used to measure in real time the ratio of the three phases of gas, liquid and solid flowing through various positions in the wellbore, and each three-way flow detector is located on the side of the outer tube where the second outlet is located close to the first inlet.

2. The sand carrying capacity simulation test device of a wellbore with a coiled tubing according to claim 1, characterized in that: The outer pipe includes an L-shaped pipe body for simulating a horizontal wellbore and a straight pipe body for simulating a vertical wellbore.

3. The sand carrying capacity simulation test device of a wellbore with a coiled tubing according to claim 2, characterized in that: It also includes a fixed support device, on which the outer tube is movably mounted, and the inclination angle of the outer tube can be adjusted to simulate the sand carrying capacity of the wellbore under different inclination angles.

4. The sand carrying capacity simulation experimental device of a wellbore with a coiled tubing according to claim 3 is characterized in that: The gas-liquid-solid injection system includes a sand adding tank for storing formation sand, a liquid storage tank for storing liquid water, a gas cylinder for storing gas, a mud pump, and a gas-liquid-solid mixer. The gas-liquid-solid mixer is used to mix formation sand, liquid water and gas into a gas-liquid-solid mixture. The first output ends of the sand adding tank and the liquid storage tank are respectively connected to the input end of the mud pump through a pipeline, the second output end of the liquid storage tank is connected to the inner pipe through another pipeline, the output end of the mud pump is connected to the input end of the gas-liquid-solid mixer through a pipeline, and the output end of the gas cylinder is connected to the input end of the gas-liquid-solid mixer through a pipeline.

5. The sand carrying capacity simulation test device of a wellbore with a coiled tubing according to claim 4, characterized in that: One-way valves are installed on the pipes between the sand tank and the mud pump, the pipes between the liquid storage tank and the mud pump, the pipes between the liquid storage tank and the inner pipe, and the pipes between the gas cylinder and the gas-liquid-solid mixer. The one-way valves are used to prevent the corresponding objects from flowing back. A liquid flow meter and a temperature and pressure sensor are arranged on the pipeline between the liquid storage tank and the mud pump, which are used to respectively measure the water flow rate and temperature and pressure output to the mud pump; a gas flow meter and a temperature and pressure sensor are arranged on the pipeline between the gas cylinder and the gas-liquid-solid mixer; a liquid flow meter and a pump are arranged on the pipeline between the liquid storage tank and the inner pipe; a control valve is also installed on the pipeline between the mud pump and the gas-liquid-solid mixer, and the control valve is used to control the amount of liquid-solid mixture output by the mud pump to the gas-liquid-solid mixer; a control valve and a temperature and pressure sensor are arranged on the pipeline between the gas-liquid-solid mixer and the injection port.

6. The sand carrying capacity simulation test device of a wellbore with a coiled tubing according to claim 5, characterized in that: It also includes a separation and sand settling system, which includes a three-phase separator and a sand settling tank. The input end of the three-phase separator is connected to the first outlet on the top of the outer tube, the first output end of the three-phase separator is connected to the gas-liquid-solid mixer through a pipeline, the second output end of the three-phase separator is connected to the gas-liquid-solid mixer through a pipeline, and the third output end of the three-phase separator is connected to the sand settling tank through a pipeline. The three-phase separator is used to separate the gas-liquid-solid mixture into gas, liquid water and formation sand.

7. The sand carrying capacity simulation test device of a wellbore with a coiled tubing according to claim 6, characterized in that: A liquid flow meter and a temperature and pressure sensor are installed on the pipeline between the first output end and the gas-liquid-solid mixer, and a gas flow meter and a temperature and pressure sensor are installed on the pipeline between the second output end and the gas-liquid-solid mixer.

8. The sand carrying capacity simulation test device of a wellbore with a coiled tubing according to claim 7, characterized in that: A gravity sensor is also installed on the pipe between the three-phase separator and the sand settling tank. The gravity sensor is used to measure the weight of the formation sand separated by the three-phase separator in real time. The weight of the formation sand quantitatively represents the sand carrying capacity of the wellbore.

9. The sand carrying capacity simulation test device of a wellbore with a coiled tubing according to claim 8, characterized in that: The wellbore monitoring system includes a data processing terminal and several cameras, the cameras include a mobile high-speed camera and a fixed high-speed camera installed in a fixed position. The fixed high-speed camera is used to aim at a certain position of the outer tube for shooting, and the mobile height camera moves along the axial direction of the outer tube for shooting.

10. An experimental method using the wellbore sand carrying capacity simulation experimental device with a coiled tubing as claimed in claim 9, comprising the following steps: Step 1: Add formation sand to the sand adding tank, add gas to the gas cylinder, add liquid water to the liquid storage tank, and control the amount of formation sand, gas and liquid water injected into the liquid-solid mixer and the ratio of the three; Step 2: The gas-liquid-solid mixer fully stirs the formation sand, gas and liquid water to form a gas-liquid-solid mixture, and controls the flow rate and flow velocity to inject the gas-liquid-solid mixture into the outer tube cavity through the injection port at the bottom of the outer tube, so that a stable flow pattern is formed in the outer tube cavity and no formation sand is carried out from the first outlet at the top of the outer tube; Step 3: Start the inner tube to simulate various operations in the outer tube cavity, so that the inner tube performs lifting and lowering, rotation and sand flushing operations in the outer tube cavity respectively, and adjust and control the lifting and lowering operation frequency, rotation operation frequency or sand flushing operation fluid volume and flow rate of the inner tube, and repeat the above operations for a period of time until no formation sand is carried out from the first outlet in the outer tube cavity; Step 4: Observe the amount of formation sand carried out by the outer tube circulation through the wellbore observation system, conduct a simulation experiment on the sand carrying capacity of the wellbore with continuous oil tubing, and obtain relevant experimental data.

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