Visual evaluation device and method for performance of plugging agent

Abstract

The invention provides a visual evaluation device and method for performance of a plugging agent. The evaluation device comprises a pumping system, a temperature control system, a visual crack model, an image monitoring system and a data acquisition system, the visual crack model comprises sapphire glass and a lower end cover plate, and the sapphire glass is arranged above the lower end cover plate; an inlet end and an outlet end are arranged at the bottom of the lower end cover plate; the pumping system is connected with the inlet end of the bottom of the lower end cover plate; one end of the temperature control system is connected with the visual crack model, and the other end of the temperature control system is electrically connected with the data acquisition system; and the image monitoring system is arranged above the visual crack model and is electrically connected with the data acquisition system. According to the method, other accessories such as sapphire glass do not need to be replaced, controllable adjustment of the size of the crack structure can be achieved only by changing the specification of the lower end cover plate of the visual crack model, and the machining cost of the device is greatly saved on the basis that the adjustable crack width of the visual crack structure is guaranteed.

Description

Technical Field

[0001] The invention belongs to the field of performance evaluation of plugging agents for oil and gas drilling, and in particular relates to a visual evaluation device and method for plugging agent performance. Background Art

[0002] Well leakage is a common and complex downhole accident in the current oil and gas drilling process. It not only consumes a large amount of working fluid and directly causes significant economic losses, but also increases non-productive time, prolongs the drilling cycle, affects the exploration and development process, and even induces accidents such as drill sticking, well collapse, and blowout.

[0003] In response to the complex problem of well leakage, a large number of plugging materials such as bridging plugging materials, inorganic plugging materials, and polymer plugging materials have also been studied. However, the current evaluation of plugging materials mostly uses conventional pressure-bearing plugging instruments such as PPA static plugging instruments and DL-A / B high-temperature and high-pressure dynamic plugging instruments, which cannot realize the visualization of the migration and plugging of plugging materials in simulated fractures. At present, the research on visualization plugging devices has the disadvantages of complex operation, weak temperature resistance, low compressive strength, and great difference from the real wellbore environment. The existing Chinese patent CN112067749B discloses a microscopic visualization experimental device for the formation mechanism of fracture plugging layer, which is simple to operate and can realize visualization of fractures, but the device uses a syringe as the power, and the working fluid flow rate is low, which is very different from the real situation of the wellbore, and the visualized fracture cannot achieve the effect of high temperature and high pressure resistance. The existing Chinese patent CN114198084A discloses a fractured formation plugging simulation evaluation device and evaluation method, which can more realistically simulate the actual plugging construction situation, but the device is complicated to operate, the crack size is fixed, and it is impossible to achieve a systematic evaluation of cracks of various sizes.

[0004] Therefore, it is of great significance to develop a set of visual plugging experimental equipment that is easy to operate and can realistically simulate the wellbore-fracture flow field, monitor the migration and retention of plugging materials in the fractures, and realize the visualization of the plugging layer formed by the plugging materials in the fractures. Summary of the invention

[0005] In view of the above problems, the present invention proposes a plugging agent performance visualization evaluation device comprising a pumping system, a temperature control system, a visualization crack model, an image monitoring system and a data acquisition system; the visualization crack model comprises sapphire glass and a lower end cover plate, and the sapphire glass is arranged above the lower end cover plate;

[0006] The bottom of the lower end cover plate is provided with an inlet end and an outlet end;

[0007] The pumping system is connected to the inlet end at the bottom of the lower end cover plate;

[0008] One end of the temperature control system is connected to the visual crack model, and the other end is electrically connected to the data acquisition system;

[0009] The image monitoring system is arranged above the visual crack model and is electrically connected to the data acquisition system.

[0010] Furthermore, the evaluation device further comprises a recovery system, and the recovery system comprises a visual crack outlet end back pressure valve and a visual crack outlet end storage tank;

[0011] The visual crack outlet back pressure valve is connected to the outlet on the lower end cover plate;

[0012] The visualization crack outlet end storage tank is connected to the visualization crack outlet end back pressure valve.

[0013] Furthermore, the evaluation device further comprises a pressure sensor, and the pressure sensor comprises a visual crack inlet end pressure sensor and a visual crack outlet end pressure sensor;

[0014] One end of the visual crack inlet pressure sensor and the pumping system are connected to the inlet end of the lower end cover plate through a three-way pipe, and the other end is electrically connected to the data acquisition system;

[0015] One end of the visualized crack outlet pressure sensor is connected to the visualized crack outlet back pressure valve, and the other end is electrically connected to the data acquisition system.

[0016] Furthermore, the visual crack model also includes a glass pressure plate, a glass gasket, a first sealing ring, a main steel frame and a second sealing ring;

[0017] The glass pressing plate, the main steel frame and the lower end cover are arranged in sequence from top to bottom;

[0018] The sapphire glass is arranged between the lower groove of the glass pressing plate and the upper groove of the main steel frame;

[0019] The glass protective pad is arranged between the glass pressing plate and the sapphire glass;

[0020] The first sealing ring is arranged between the sapphire glass and the main steel frame;

[0021] The second sealing ring is arranged between the main steel frame and the lower end cover plate;

[0022] The inlet end and the outlet end are arranged on the lower end cover plate and penetrate through the lower end cover plate.

[0023] Furthermore, a protruding structure is provided on the lower end cover plate; the protruding structure is provided between the inlet end and the outlet end of the lower end cover plate, and a crack structure is formed in the gap between the protruding structure and the sapphire glass.

[0024] Furthermore, the shape of the protruding structure includes a wedge or a cuboid.

[0025] Further, the pumping system includes a displacement pump and an intermediate container;

[0026] The displacement pump is connected to the bottom of the intermediate container.

[0027] The top end of the intermediate container is connected to the inlet end on the lower end cover plate.

[0028] Further, the temperature control system includes a visual crack heating component and a visual crack temperature sensor;

[0029] The visual crack heating component wraps the visual crack model;

[0030] One end of the visualized crack temperature sensor is connected to the visualized crack heating component, and the other end is electrically connected to the data acquisition system.

[0031] Furthermore, a sealable movable piston is provided at the bottom of the intermediate container, and the piston moves up and down in the intermediate container.

[0032] Furthermore, a high-speed rotating agitator is provided at the bottom of the intermediate container, and the high-speed rotating agitator rotates to fully stir the plugging agent.

[0033] Furthermore, a transition zone is provided in the visualized crack model, and the transition zone is provided between the sapphire glass and the inlet end of the lower cover plate. After the plugging agent flows out of the intermediate container, it first flows into the transition zone, and then flows into the crack structure in the visualized crack model under the action of the pressure difference.

[0034] Furthermore, the image monitoring system includes a high frame rate camera.

[0035] The present application also relates to a method for visually evaluating the performance of a plugging agent, comprising the following steps:

[0036] Step S1, adding a pre-configured plugging agent into the intermediate container, then connecting the pipeline, installing the experimental equipment, setting the stirring speed of the intermediate container, and turning it on;

[0037] Step S2, selecting a suitable lower end cover plate, and installing the visual crack model in the order of the lower end cover plate, the second sealing ring, the main steel frame, the first sealing ring, the sapphire glass, the glass gasket, and the glass cover plate from bottom to top;

[0038] Step S3, opening the inlet and outlet valves of the visual crack model, setting the temperature of the visual crack temperature sensor according to the temperature required by the visual crack model experiment and controlling the visual crack heating component to start heating;

[0039] Step S4, after the temperature of the visualized crack model rises to the set temperature and stabilizes, the image monitoring system and the data acquisition system are turned on;

[0040] Step S5, turning on the displacement pump, and monitoring the pressure changes at the inlet and outlet of the visualized fracture model, as well as the migration, retention and plugging of the plugging agent in the visualized fracture model in real time through the image monitoring system, the visualized fracture inlet pressure sensor and the visualized fracture outlet pressure sensor;

[0041] Step S6, after the experiment is finished, turn off the displacement pump, turn off the switch of the visualized fracture temperature sensor, and disassemble and clean the visualized fracture model after the temperature cools to room temperature.

[0042] Furthermore, the plugging agent added in step S1 is a mixture of plugging material and one of bentonite slurry, drilling fluid and well slurry.

[0043] Furthermore, the volume of the plugging agent added in step S1 is 500mL-1000mL.

[0044] Furthermore, in step S2, the lower cover plate may be selected to form a crack structure with the sapphire glass with wedge-shaped cracks of sizes of 1mm-3mm, 2mm-4mm, 2mm-5mm or 3mm-5mm at both ends of the gap; or parallel cracks of sizes of 1mm-1mm, 2mm-2mm or 3mm-3mm.

[0045] Furthermore, in step S3, the setting temperature of the visual crack model is 25-200°C.

[0046] Furthermore, in step S4, the image monitoring system uses a high frame rate camera to collect the running status of the plugging agent in the visual crack model, and the collection mode is high-definition video real-time recording.

[0047] Furthermore, in step S5, the displacement pump mode is one of constant pressure 1-20 MPa and constant flow 5-10 mL / min.

[0048] Furthermore, in step S5, the data acquisition system may acquire the time-varying curves of the pressure at the inlet and outlet ends of the visualized fracture model, as well as the images and video information of the migration, residence and plugging of the plugging agent in the fractures in the visualized fracture model.

[0049] Compared with the prior art, the present invention has the following beneficial effects:

[0050] (1) The present invention provides a visual evaluation device and method for plugging agent performance, which uses sapphire glass as a viewing window, and can realize the visualization study of the plugging agent in the fracture structure in the visual fracture model under the environment of 25-200°C and 0.5-25MPa. It is closer to the high temperature and high pressure environment of the real simulation wellbore-fracture flow field, and the evaluation steps are simple to operate, which can effectively support the evaluation and optimization of plugging agents.

[0051] (2) The present invention uses a high frame rate camera as an image acquisition system to monitor in real time the process and conditions of the migration, residence, and formation of a plugging layer of the plugging agent in the crack structure within the visualized crack model, conduct microscopic mechanism research on the formation mechanism of the crack plugging layer, and guide the research and development of high-performance plugging agents.

[0052] (3) The present invention does not require replacement of sapphire glass and other accessories. The crack structure size can be controlled and adjusted simply by changing the specifications of the lower cover plate of the visualization crack model. On the basis of ensuring that the width of the visualization crack structure is adjustable, the processing cost of the device is greatly saved.

[0053] (4) The present invention leaves a transition area between the inlet end of the visualized crack model and the sapphire glass, so that the plugging agent first goes to the transition area after coming out of the intermediate container, and then flows into the crack structure of the visualized crack model under the action of pressure difference. This design is more in line with the actual situation of the wellbore, and can observe the phenomenon of sealing the plugging agent particle size not matching the crack, further ensuring the accuracy and authenticity of the plugging agent performance evaluation.

[0054] Other features and advantages of the present invention will be described in the following description, and partly become apparent from the description, or understood by practicing the present invention. The purpose and other advantages of the present invention can be realized and obtained by the structures pointed out in the description, claims and drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0055] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0056] Figure 1 A schematic diagram of a device for visually evaluating the performance of a plugging agent in an embodiment of the present invention is shown;

[0057] Figure 2 A top view of a visualized crack model in an embodiment of the present invention is shown;

[0058] Figure 3A cross-sectional view of a visualized crack model in an embodiment of the present invention is shown;

[0059] Figure 4 An exploded view of a visual crack model according to an embodiment of the present invention is shown;

[0060] Figure 5 A schematic diagram of an intermediate container in an embodiment of the present invention is shown.

[0061] In the figure, 1-visualized crack model, 11-glass pressure plate, 12-glass gasket, 13-sapphire glass, 14-first sealing ring, 15-main steel frame, 16-second sealing ring, 17-lower end cover, 2-displacement pump, 3-intermediate container, 31-piston, 32-high-speed rotating agitator, 33-upper plug, 34-lower plug, 35-motor, 36-motor shaft, 37-coupling, 38-sliding rod connecting shaft, 39-sliding rod, 4-visualized crack inlet pressure sensor, 5-visualized crack outlet pressure sensor, 6-visualized crack heating assembly, 7-visualized crack temperature sensor, 8-visualized crack outlet back pressure valve, 9-visualized crack outlet storage tank, 110-image monitoring system, 111-data acquisition system. DETAILED DESCRIPTION

[0062] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0063] like Figure 1 As shown, a visual evaluation device for plugging agent performance includes a pumping system, a temperature control system, a visual crack model 1, an image monitoring system 110 and a data acquisition system 111;

[0064] The visual crack model 1 includes a sapphire glass 13 and a lower end cover plate 17, wherein the sapphire glass 13 is arranged above the lower end cover plate 17;

[0065] The bottom of the lower end cover plate 17 is provided with an inlet end and an outlet end;

[0066] The pumping system is connected to the inlet end at the bottom of the lower end cover plate 17;

[0067] One end of the temperature control system is connected to the visual crack model 1, and the other end is electrically connected to the data acquisition system 111;

[0068] The image monitoring system 110 is disposed above the visualized crack model 1 and is electrically connected to the data acquisition system 111 .

[0069] The evaluation device further comprises a recovery system, and the recovery system comprises a visual crack outlet end back pressure valve 8 and a visual crack outlet end storage tank 9;

[0070] The visual crack outlet back pressure valve 8 is connected to the outlet end of the lower end cover plate 17;

[0071] The visualized crack outlet end storage tank 9 is connected to the visualized crack outlet end back pressure valve 8 .

[0072] The evaluation device further includes a pressure sensor, which includes a visual crack inlet pressure sensor 4 and a visual crack outlet pressure sensor 5;

[0073] One end of the visual crack inlet pressure sensor 4 and the pumping system are connected to the inlet end of the lower end cover plate 17 through a three-way pipe, and the other end is electrically connected to the data acquisition system 111;

[0074] One end of the visualized crack outlet pressure sensor 5 is connected to the visualized crack outlet back pressure valve 8 , and the other end is electrically connected to the data acquisition system 111 .

[0075] like Figure 2 , 3 As shown in , 4, the visual crack model 1 also includes a glass pressure plate 11, a glass gasket 12, a first sealing ring 14, a main steel frame 15 and a second sealing ring 16;

[0076] The glass pressing plate 11, the main steel frame 15 and the lower end cover plate 17 are arranged in sequence from top to bottom;

[0077] The sapphire glass 13 is arranged between the lower groove of the glass pressing plate 11 and the upper groove of the main steel frame 15;

[0078] The glass protection pad 12 is arranged between the glass pressing plate 11 and the sapphire glass 13;

[0079] The first sealing ring 14 is disposed between the sapphire glass 13 and the main steel frame 15;

[0080] The second sealing ring 16 is arranged between the main steel frame 15 and the lower end cover plate 17;

[0081] The inlet end and the outlet end are arranged on the lower end cover plate 17 and penetrate the lower end cover plate 17 .

[0082] The shape of the glass pressing plate 11 is a rectangular parallelepiped structure with a hollow middle, and the hollow shape is also a rectangular parallelepiped structure. The function of the hollow rectangular parallelepiped is to facilitate the observation of the crack structure. The area of ​​the sapphire glass 13 is larger than the area of ​​the hollow rectangular parallelepiped. A plurality of threaded countersunk holes are arranged around the glass pressing plate 11 to connect with the main steel frame 15 through countersunk screws. A groove is arranged at the bottom of the glass pressing plate 11. The size of the groove is the same as that of the sapphire glass 13, and the depth is less than the height of the sapphire glass 13, so that a part of the sapphire glass 13 is embedded in the bottom of the glass pressing plate 11.

[0083] The shape and hollow area of ​​the main steel frame 15 are the same as those of the glass platen 11, but a groove is set at the top of the main steel frame 15, which is the same size as the sapphire glass 13 and has a depth less than the height of the sapphire glass 13, so that a part of the sapphire glass 13 is embedded in the bottom of the glass platen 11. The depth of the bottom groove of the glass platen 11 plus the depth of the top groove of the main steel frame 15 is the same as the thickness of the sapphire glass 13, so that the sapphire glass 13 is just embedded between the glass platen 11 and the main steel frame 15. A first sealing ring 14 is set at the bottom of the groove of the main steel frame 15. The function of the first sealing ring is to prevent the sealing agent from passing through the bottom of the sapphire glass 13 and leaking from the connection between the glass platen 11 and the main steel frame 15.

[0084] The lower end cover plate 17 has the same size as the main steel frame 15, and is also provided with threaded holes around it, which are used to connect with the main steel frame 15 through countersunk screws. A protrusion structure is provided on the lower end cover plate 17, and the protrusion structure is provided between the inlet end and the outlet end of the lower end cover plate 17. The gap between the protrusion structure and the sapphire glass 13 forms a crack structure. The shape of the protrusion structure includes a wedge or a cuboid, so that the crack is a wedge or a cuboid. The protrusion mechanism can also be any other structure according to the needs of the test. The shape of the protrusion structure determines the shape of the crack mechanism. When the protrusion structure is wedge-shaped, the gap between the protrusion structure and the sapphire glass 13 forms a crack structure that is also wedge-shaped, and the widths of the two ends of the wedge-shaped gap include specifications of 1mm-3mm, 2mm-4mm, 2mm-5mm or 3mm-5mm respectively; when the protrusion structure is a rectangular parallelepiped, the gap between the protrusion structure and the sapphire glass 13 forms a crack structure that is a parallel gap, and the widths of the two ends of the parallel gap include specifications of 1mm-1mm, 2mm-2mm or 3mm-3mm respectively. Therefore, the controllable adjustment of the crack size can be achieved by only changing the specifications of the lower end cover plate of the visualized crack, which greatly saves the processing cost of the device while ensuring that the width of the visualized crack is adjustable.

[0085] The lower end cover plate 17 is installed with a second sealing ring 16 , which is arranged outside the inlet end and the outlet end to prevent the plugging agent from leaking from the connection between the lower end cover plate 17 and the main steel frame 15 .

[0086] The pumping system mainly includes a displacement pump 2 and an intermediate container 3. The displacement pump 2 is connected to the bottom of the intermediate container 3, and the top of the intermediate container 3 is connected to the inlet end on the lower end cover plate 17. The displacement pump 2 can pump the plugging slurry in the intermediate container 3 into the fracture mechanism of the visualized fracture model 1 in a constant pressure or constant flow mode.

[0087] The pressure sensor mainly includes a visual crack inlet pressure sensor 4 and a visual crack outlet pressure sensor 5. One end of the visual crack inlet pressure sensor 4 is connected to the inlet end of the lower end cover plate 17 through a three-way pipe with the pumping system, and the other end is electrically connected to the data acquisition system 111. One end of the visual crack outlet pressure sensor 5 is connected to the visual crack outlet back pressure valve 8, and the other end is electrically connected to the data acquisition system 111. The pressure changes at the inlet and outlet of the visual crack model 1 can be monitored in real time.

[0088] The temperature control system mainly includes a visual crack heating component 6 and a visual crack temperature sensor 7; the visual crack heating component 6 wraps the visual crack model 1; one end of the visual crack temperature sensor 7 is connected to the visual crack heating component 6, and the other end is electrically connected to the data acquisition system 111. The temperature of the visual crack model 1 can be accurately controlled and monitored.

[0089] The recovery system mainly includes a visual crack outlet back pressure valve 8 and a visual crack outlet storage tank 9; the visual crack outlet back pressure valve 8 is connected to the outlet on the lower end cover plate 17; the visual crack outlet storage tank 9 is connected to the visual crack outlet back pressure valve 8. The plugging slurry at the outlet of the visual crack model 1 can be recovered.

[0090] The image monitoring system 110 mainly uses a high frame rate camera to observe and record the change process of the plugging material in the visual crack model 1 in real time.

[0091] The data acquisition system 111 can collect data and information of the visualized crack inlet pressure sensor 4 , the visualized crack outlet pressure sensor 5 , the visualized crack temperature sensor 7 and the image monitoring system 110 in real time.

[0092] like Figure 5 As shown, the intermediate container mainly includes an upper plug 33, an outer cylinder, a lower plug 34, a sliding rod 39, a sliding rod bracket, a support plate, a motor seat, a motor 35, a coupling 37, a motor shaft 36, a sliding rod connecting shaft 38, a lock nut and an inner hole of the plug.

[0093] The bottom of the intermediate container 3 is also provided with a sealable movable piston 31, which moves up and down in the intermediate container 3. The fluid in the injection pump is injected into the bottom of the piston 31 through the injection hole of the lower plug 34, and the injected fluid squeezes the piston 31 to move upward, so that the plugging agent on the upper part of the piston 31 flows out into the connecting pipe through the inner hole of the upper plug 33.

[0094] The bottom of the intermediate container 3 is also provided with a high-speed rotating stirrer 32, which rotates to fully stir the plugging agent. Stirring principle: the upper computer controls the motor 35 to rotate, and the motor shaft 36 is connected to the sliding rod connecting shaft 38 through the coupling 37, driving the sliding rod 39 to rotate. The other end of the sliding rod 39 is equipped with a strong magnet, and the rotation of the strong magnet drives the rotating paddle to rotate, thereby realizing the rotation and stirring of the plugging agent inside the container.

[0095] A transition area is provided in the visualized crack model 1, and the transition area is provided between the sapphire glass 13 and the inlet end of the lower end cover plate 17. After the plugging agent flows out of the intermediate container 3, it first flows into the transition area, and then flows into the crack structure in the visualized crack model 1 under the action of the pressure difference.

[0096] The image monitoring system 110 includes a high frame rate camera.

[0097] The present application also relates to a method for visually evaluating the performance of a plugging agent, comprising the following steps:

[0098] Step S1, add the pre-configured plugging agent into the intermediate container 3, then connect the pipeline, install the experimental equipment, set the stirring speed of the intermediate container 3, and start it.

[0099] Step S2, select a suitable lower end cover plate 17, and install the visualized crack model 1 in the order of lower end cover plate 17, second sealing ring 16, main steel frame 15, first sealing ring 14, sapphire glass 13, glass gasket 12, and glass cover plate 11 from bottom to top.

[0100] Step S3, opening the inlet and outlet valves of the visualized crack model 1, setting the temperature of the visualized crack temperature sensor 7 according to the temperature required for the visualized crack model 1 experiment and controlling the visualized crack heating component 6 to start heating.

[0101] Step S4 , after the temperature of the visualized crack model 1 rises to the set temperature and stabilizes, the image monitoring system 110 and the data acquisition system 111 are turned on.

[0102] Step S5, turn on the displacement pump 2, and monitor the pressure changes at the inlet and outlet ends of the visualized fracture model 1, as well as the migration, retention and plugging of the plugging agent in the visualized fracture model 1 in real time through the image monitoring system 110, the visualized fracture inlet pressure sensor 4 and the visualized fracture outlet pressure sensor 5.

[0103] Step S6, after the experiment is finished, turn off the displacement pump 2, turn off the switch of the visual crack temperature sensor 7, and disassemble and clean the visual crack model 1 after the temperature cools down to room temperature.

[0104] Preferably, the plugging agent added in step S1 is a mixture of plugging material and one of bentonite slurry, drilling fluid and well slurry.

[0105] Preferably, the volume of the plugging agent added in step S1 is 500mL-1000mL.

[0106] Preferably, in step S2, the lower cover plate 17 can be selected to form a wedge-shaped gap with two ends having dimensions of 1mm-3mm, 2mm-4mm, 2mm-5mm or 3mm-5mm to form a crack structure with the sapphire glass 13, or a parallel gap with two ends having dimensions of 1mm-1mm, 2mm-2mm or 3mm-3mm.

[0107] Preferably, in step S3, the setting temperature of the visual crack model 1 is 25-200°C.

[0108] Preferably, in step S4, the image monitoring system 110 uses a high frame rate camera to collect the running status of the plugging agent in the visual fracture model 1, and the collection mode is high-definition video real-time recording.

[0109] Preferably, in step S5, the mode of the displacement pump 2 is one of constant pressure 0.5-25 MPa and constant flow 5-10 mL / min.

[0110] Preferably, in step S5, the data acquisition system 111 can collect the pressure change curves of the inlet and outlet ends of the visualized fracture model 1 over time, as well as the image and video information of the migration, residence and plugging of the plugging agent in the fracture of the visualized fracture model 1.

[0111] Example 1

[0112] Step S1, adding self-repairing gel particles into bentonite-based slurry to prepare a 5% concentration of self-repairing gel plugging slurry;

[0113] Step S2, add the pre-configured plugging agent into the intermediate container, connect the pipeline, install the experimental equipment, and set the stirring speed of the intermediate container 3 to 200r / min;

[0114] Step S3, selecting a lower cover plate 17 that can form a 1mm-3mm crack with the sapphire glass 13, and assembling the visual crack model 1 as required.

[0115] Step S4, opening the inlet and outlet valves of the visualized crack model 1, setting the temperature of the visualized crack model 1 to 90°C, and starting the temperature control system for heating.

[0116] Step S5 , after the temperature of the visualized crack model 1 rises to 90° C. and stabilizes, the image monitoring system 110 and the data acquisition system 111 are turned on.

[0117] Step S6, turn on the displacement pump 2, set the displacement mode to constant pressure mode, set the initial pressure to 0.5MPa, and gradually increase the pressure with a pressure gradient of 0.5MPa, and maintain each pressure for 2 minutes after stabilization, until a large amount of liquid flows out from the outlet of the visual fracture model 1. At this time, the maximum pressure is the pressure bearing capacity of the plugging agent. In this process, the pressure changes at the inlet and outlet of the visual fracture model 1, as well as the migration and self-repair of the fracture structure in the visual fracture model 1 are monitored in real time through a high frame rate camera and a pressure sensor.

[0118] Step S7, turn off the displacement pump 2 and the heating switch of the temperature control system, and disassemble and clean the visualized fracture model 1 after the temperature cools to room temperature.

[0119] Example 2

[0120] Step S1, adding fruit shells to bentonite-based slurry to prepare a 12% concentration of fruit shell plugging slurry;

[0121] Step S2, adding pre-configured plugging slurry into the intermediate container 3, connecting pipelines, installing experimental equipment, and setting the stirring speed of the intermediate container 3 to 200 r / min;

[0122] Step S3, selecting a lower cover plate 17 that can form a 2mm-4mm crack with the sapphire glass 13, and assembling the visual crack model 1 as required.

[0123] Step S4, opening the inlet and outlet valves of the visualized crack model 1, setting the temperature of the visualized crack model 1 to 150° C., and starting the temperature control system for heating.

[0124] Step S5 , after the temperature of the visualized crack model 1 rises to 150° C. and stabilizes, the image monitoring system 110 and the data acquisition system 111 are turned on.

[0125] Step S6, turn on the displacement pump 2, set the displacement mode to constant pressure mode, set the initial pressure to 1MPa, and gradually increase the pressure with a pressure gradient of 1MPa, and maintain each pressure for 2 minutes after stabilization, until a large amount of liquid flows out from the outlet of the visual fracture model 1. At this time, the maximum pressure is the pressure bearing capacity of the plugging material. In this process, the pressure changes at the inlet and outlet of the visual fracture model 1, as well as the migration and bridging of the fruit shell in the fracture structure of the visual fracture model 1 are monitored in real time through a high frame rate camera and a pressure sensor.

[0126] Step S7, turn off the displacement pump 2 and the heating switch of the temperature control system, and disassemble and clean the visualized fracture model 1 after the temperature cools to room temperature.

[0127] Example 3

[0128] Step S1, adding a plugging slurry prepared by 2% fiber and 10% fruit shell into the well slurry;

[0129] Step S2, adding pre-configured plugging slurry into the intermediate container 3, connecting pipelines, installing experimental equipment, and setting the stirring speed of the intermediate container 3 to 200 r / min;

[0130] Step S3, selecting a lower cover plate 17 that can form a 1mm-3mm crack with the sapphire glass 13, and assembling the visual crack model 1 as required.

[0131] Step S4, opening the inlet and outlet valves of the visualized crack model 1, setting the temperature of the visualized crack model 1 to 110° C., and starting the temperature control system for heating.

[0132] Step S5 , after the temperature of the visualized crack model 1 rises to 110° C. and stabilizes, the image monitoring system 110 and the data acquisition system 111 are turned on.

[0133] Step S6, turn on the displacement pump 2, set the displacement mode to constant pressure mode, set the initial pressure to 1MPa, and gradually increase the pressure with a pressure gradient of 1MPa, and maintain each pressure for 2 minutes after stabilization, until a large amount of liquid flows out from the outlet of the visualized fracture model 1. At this time, the maximum pressure is the pressure bearing capacity of the plugging material. In this process, the pressure changes at the inlet and outlet of the visualized fracture model 1, as well as the migration and interaction of the husk and fiber in the fracture structure of the visualized fracture model 1 are monitored in real time through a high frame rate camera and a pressure sensor.

[0134] Step S7, turn off the displacement pump 2 and the heating switch of the temperature control system, and disassemble and clean the visualized fracture model 1 after the temperature cools to room temperature.

[0135] Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent substitutions for some of the technical features therein; and these modifications or substitutions do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A visual evaluation device for plugging agent performance, characterized in that: The system comprises a pumping system, a temperature control system, a visual crack model (1), an image monitoring system (110) and a data acquisition system (111); the visual crack model (1) comprises a sapphire glass (13) and a lower end cover plate (17); the sapphire glass (13) is arranged above the lower end cover plate (17); The bottom of the lower end cover plate (17) is provided with an inlet end and an outlet end; The pumping system is connected to the inlet end at the bottom of the lower end cover plate (17); One end of the temperature control system is connected to the visualized crack model (1), and the other end is electrically connected to the data acquisition system (111); The image monitoring system (110) is arranged above the visual crack model (1) and is electrically connected to the data acquisition system (111).

2. The visual evaluation device for plugging agent performance according to claim 1, characterized in that: The evaluation device further comprises a recovery system, wherein the recovery system comprises a visual crack outlet end back pressure valve (8) and a visual crack outlet end storage tank (9); The visualized crack outlet back pressure valve (8) is connected to the outlet end on the lower end cover plate (17); The visualized crack outlet end storage tank (9) is connected to the visualized crack outlet end back pressure valve (8).

3. The visual evaluation device for plugging agent performance according to claim 2, characterized in that: The evaluation device further comprises a pressure sensor, wherein the pressure sensor comprises a visual crack inlet end pressure sensor (4) and a visual crack outlet end pressure sensor (5); One end of the visual crack inlet pressure sensor (4) is connected to the pumping system and the inlet end of the lower end cover plate (17) through a three-way pipe, and the other end is electrically connected to the data acquisition system (111); One end of the visualized crack outlet pressure sensor (5) is connected to the visualized crack outlet back pressure valve (8), and the other end is electrically connected to the data acquisition system (111).

4. The visual evaluation device for plugging agent performance according to claim 1, characterized in that: The visual crack model (1) also includes a glass pressure plate (11), a glass protective gasket (12), a first sealing ring (14), a main steel frame (15) and a second sealing ring (16); The glass pressing plate (11), the main steel frame (15) and the lower end cover plate (17) are arranged in sequence from top to bottom; The sapphire glass (13) is arranged between the lower groove of the glass pressing plate (11) and the upper groove of the main steel frame (15); The glass protective gasket (12) is arranged between the glass pressing plate (11) and the sapphire glass (13); The first sealing ring (14) is arranged between the sapphire glass (13) and the main steel frame (15); The second sealing ring (16) is arranged between the main steel frame (15) and the lower end cover plate (17); The inlet end and the outlet end are arranged on the lower end cover plate (17) and penetrate the lower end cover plate (17).

5. The visual evaluation device for plugging agent performance according to claim 1, characterized in that: The lower end cover plate (17) is provided with a protruding structure; the protruding structure is arranged between the inlet end and the outlet end of the lower end cover plate (17), and the gap between the protruding structure and the sapphire glass (13) forms a crack structure.

6. The visual evaluation device for plugging agent performance according to claim 5, characterized in that: The shape of the protruding structure includes a wedge shape or a rectangular parallelepiped.

7. The visual evaluation device for plugging agent performance according to claim 1, characterized in that: The pumping system comprises a displacement pump (2) and an intermediate container (3); The displacement pump (2) is connected to the bottom of the intermediate container (3). The top end of the intermediate container (3) is connected to the inlet end on the lower end cover plate (17).

8. The visual evaluation device for plugging agent performance according to claim 1, characterized in that: The temperature control system comprises a visual crack heating component (6) and a visual crack temperature sensor (7); The visual crack heating component (6) wraps the visual crack model (1); One end of the visualized crack temperature sensor (7) is connected to the visualized crack heating component (6), and the other end is electrically connected to the data acquisition system (111).

9. The visual evaluation device for plugging agent performance according to claim 7, characterized in that: A sealable movable piston (31) is arranged at the bottom of the intermediate container (3), and the piston (31) moves up and down in the intermediate container (3).

10. The visual evaluation device for plugging agent performance according to claim 9, characterized in that: A high-speed rotating stirrer (32) is provided at the bottom of the intermediate container (3), and the high-speed rotating stirrer (32) rotates to fully stir the plugging agent.

11. The visual evaluation device for plugging agent performance according to claim 1, characterized in that: A transition area is provided in the visualized crack model (1), and the transition area is provided between the sapphire glass (13) and the inlet end of the lower end cover plate (17). After the plugging agent flows out of the intermediate container (3), it first flows into the transition area, and then flows into the crack structure in the visualized crack model (1) under the action of the pressure difference.

12. The visual evaluation device for plugging agent performance according to claim 1, characterized in that: The image monitoring system (110) comprises a high frame rate camera.

13. A visual evaluation method for plugging agent performance based on any one of claims 1 to 12, characterized in that: The following steps are involved: Step S1, adding a pre-configured plugging agent into the intermediate container (3), then connecting the pipeline, installing the experimental equipment, setting the stirring speed of the intermediate container (3), and turning it on; Step S2, selecting a suitable lower end cover plate (17), and installing the visual crack model (1) in the order of the lower end cover plate (17), the second sealing ring (16), the main steel frame (15), the first sealing ring (14), the sapphire glass (13), the glass gasket (12), and the glass cover plate (11) from bottom to top; Step S3, opening the inlet and outlet valves of the visual crack model (1), setting the temperature of the visual crack temperature sensor (7) according to the temperature required for the visual crack model (1) experiment, and controlling the visual crack heating component (6) to start heating; Step S4, after the temperature of the visualized crack model (1) rises to a set temperature and stabilizes, the image monitoring system (110) and the data acquisition system (111) are turned on; Step S5, turning on the displacement pump (2), and monitoring the pressure changes at the inlet and outlet of the visualized fracture model (1), as well as the migration, retention and plugging of the plugging agent in the visualized fracture model (1) in real time through the image monitoring system (110), the visualized fracture inlet pressure sensor (4) and the visualized fracture outlet pressure sensor (5); Step S6, after the experiment is finished, turn off the displacement pump (2), turn off the switch of the visual crack temperature sensor (7), and after the temperature cools down to room temperature, disassemble and clean the visual crack model (1).

14. The method for visually evaluating the performance of a plugging agent according to claim 13, characterized in that: The plugging agent added in step S1 is a mixture of plugging material and one of bentonite slurry, drilling fluid and well slurry.

15. The method for visually evaluating the performance of a plugging agent according to claim 13, characterized in that: The volume of the plugging agent added in step S1 is 500mL-1000mL.

16. The method for visually evaluating the performance of a plugging agent according to claim 13, characterized in that: In step S2, the lower cover plate (17) can be selected to have wedge-shaped cracks of 1mm-3mm, 2mm-4mm, 2mm-5mm or 3mm-5mm at both ends of the crack structure formed with the sapphire glass (13); or parallel cracks of 1mm-1mm, 2mm-2mm or 3mm-3mm.

17. The method for visually evaluating the performance of a plugging agent according to claim 13, characterized in that: In the step S3, the setting temperature of the visual crack model (1) is 25-200°C.

18. The method for visually evaluating the performance of a plugging agent according to claim 13, characterized in that: In step S4, the image monitoring system (110) uses a high frame rate camera to collect the running status of the plugging agent in the visual crack model (1), and the collection mode is high-definition video real-time recording.

19. The method for visually evaluating the performance of a plugging agent according to claim 13, characterized in that: In the step S5, the mode of the displacement pump (2) is one of constant pressure 1-20 MPa and constant flow 5-10 mL / min.

20. The visual evaluation method for plugging agent performance according to claim 13, characterized in that: In step S5, the data acquisition system (111) can collect the time-varying curves of the pressure at the inlet and outlet ends of the visualized fracture model (1), as well as the image and video information of the migration, residence and plugging of the plugging agent in the fractures of the visualized fracture model (1).

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