Bridging leaking stoppage experiment system and bridging leaking stoppage experiment method

Abstract

The invention relates to the technical field of bridging leaking stoppage, in particular to a bridging leaking stoppage experiment system and a bridging leaking stoppage experiment method, and aims to solve the technical problem that the rheological property of leaking stoppage slurry is not considered in a bridging leaking stoppage experiment. The bridging leaking stoppage experiment system comprises a slurry supply main path, a first branch path, a second branch path and a slurry driving module, the first branch path is communicated with the slurry supply main path to form a first circulation loop, the second branch path is connected with the first branch path in parallel and forms a second circulation loop with the slurry supply main path, and the slurry driving module is used for temporarily storing and heating slurry from the slurry supply main path. And the slurry is discharged to the first branch or the second branch at a preset flow speed, so that the formed first circulation loop can test the rheological property of the slurry, and the second circulation loop can simulate a bridging plugging experiment. The bridging leaking stoppage experiment system can simulate a leakage channel and test the rheological property of slurry, enriches indoor bridging leaking stoppage evaluation means, and provides powerful support for research of a bridging leaking stoppage mechanism and evaluation of bridging leaking stoppage materials.

Description

Technical Field

[0001] The present invention relates to the technical field of bridging plugging, and particularly relates to a bridging plugging experiment system and a bridging plugging experiment method. Background Art

[0002] Well leakage refers to the phenomenon that a large amount of drilling fluid leaks into the formation during the drilling process. It not only causes a large loss of working fluid, directly resulting in 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 stuck pipe, well collapse, and blowout. At present, with the exploration and development of oil and gas resources expanding into deep and ultra-deep, unconventional and other resource fields, and combined with factors such as more complex formations and long open hole sections, the occurrence of drilling fluid leakage is frequent. For this, the most commonly used treatment method is bridging plugging.

[0003] To ensure the effect of bridging plugging, generally, a bridging plugging experiment needs to be carried out first to observe the bridging mechanism of the plugging material in the crack. For example, a complex formation leakage channel simulation device disclosed in a Chinese patent with the application number CN201810443378.7 can effectively simulate different leakage formations by simulating permeable, fissured, and porous leakage and performing multi-fracture, pore-fracture, and fracture-cavity simulation combinations, so as to better evaluate the plugging effect; a crack self-adjusting device of a plugging instrument disclosed in a Chinese patent with the application number CN202320707284.2 can dynamically adjust the crack opening by hydraulically adjusting the position of the upper end of the crack, solving the problem that the existing plugging instrument cannot simulate the dynamic change of the crack.

[0004] It should be noted here that in the simulation experiments of the above patents, only the relationship between the success or failure of the bridging of the plugging material and the leakage channel is involved, and the influence of the rheology of the plugging slurry on the bridging of the plugging material is not considered, resulting in a lack of strong support for the research on the bridging mechanism of the plugging material. Summary of the Invention

[0005] The purpose of the present invention is to provide a bridging plugging experiment system and a bridging plugging experiment method to solve the technical problem that the rheology of the plugging slurry is not considered in the existing bridging plugging experiment.

[0006] To solve the above technical problems, the technical solution provided by the present invention is as follows:

[0007] In the first aspect, the present invention provides a bridging plugging experiment system, including: a main slurry supply path, a first branch path, and a second branch path. Among them, the first branch path is connected to the main slurry supply path to form a first circulation loop, and the second branch path is connected in parallel with the first branch path and forms a second circulation loop with the main slurry supply path;

[0008] The main slurry supply path includes a slurry storage tank and a first valve, and the first valve is used to control the on-off of the main slurry supply path;

[0009] The first branch includes a straight pipe, a second valve, a third valve, a first heating module, and a differential pressure sensor. Among them, the second valve is connected between the inlet of the straight pipe and the main slurry supply path, the third valve is connected between the outlet of the straight pipe and the main slurry supply path, the first heating module is used to heat the slurry in the straight pipe and measure the temperature of the slurry in the straight pipe, and the differential pressure sensor is used to measure the differential pressure at both ends of the straight pipe;

[0010] The second branch includes a crack simulation module, a fourth valve, and a fifth valve. Among them, the fourth valve is connected between the inlet of the crack simulation module and the main slurry supply path, and the fifth valve is connected between the outlet of the crack simulation module and the main slurry supply path;

[0011] The bridging plugging experiment system further includes a slurry driving module, which is communicatively connected to the main slurry supply path, and the communication point is outside the main path where the first valve is connected to the slurry storage tank. The slurry driving module is used to temporarily store and heat the slurry from the main slurry supply path, and discharge the slurry to the first branch or the second branch at a preset flow rate.

[0012] Further, the crack simulation module includes a simulation chamber, a mold, and an adjustment assembly;

[0013] The simulation chamber has a simulation groove, a visual window is provided on the bottom wall of the simulation groove, and through holes are provided on both opposite side walls;

[0014] The mold is slidably connected to the simulation chamber in a posture of blocking the opening of the simulation groove, and a sunken groove is provided on the surface of the mold facing the bottom wall of the simulation groove. One end of the sunken groove is close to one of the through holes, and the other end extends towards the other through hole;

[0015] The adjustment assembly is arranged in the simulation chamber and is in transmission connection with the mold to drive the mold to move towards or away from the bottom wall of the simulation groove.

[0016] Further, the adjustment assembly includes a lower end cover and an adjustment bolt;

[0017] The mold is fixedly connected to the lower end cover;

[0018] The lower end cover covers the opening of the simulation groove and is connected to the simulation chamber through the adjustment bolt.

[0019] Further, the crack simulation module further includes a scale ruler, which is arranged in the simulation chamber, on the side of the opening of the simulation groove, and its length direction is consistent with the sliding direction of the mold.

[0020] Further, the simulation chamber includes a housing, a transparent plate and an upper end cover;

[0021] The housing is in the shape of a cylinder with both ends open;

[0022] The transparent plate is inside the housing, is sealingly fitted with the housing, and encloses the simulation groove with the housing;

[0023] The upper end cover covers one of the openings of the housing and is fixedly connected to the housing to fasten the transparent plate to the housing, and a window penetrating through itself is provided on the upper end cover.

[0024] Further, the crack simulation module further includes a mounting support and a rotary drive;

[0025] The simulation chamber is rotationally fitted with the mounting support, and the rotation axis is perpendicular to the sliding path of the mold and the extension path of the sinking groove respectively;

[0026] The rotary drive is arranged on the mounting support and is in transmission connection with the simulation chamber to drive the simulation chamber to flip around the rotation axis.

[0027] Further, the slurry driving module includes a piston container, a main liquid inlet path and a main liquid discharge path;

[0028] The piston container includes a container body and a sliding piston. Among them, the container body is in the shape of a cylinder with both ends open, one end of which is communicated with the main slurry supply path, the other end is respectively communicated with the main liquid inlet path and the main liquid discharge path, the sliding piston is arranged in the container body, is sealingly fitted with the container body, and can slide along the axial direction of the sealing body;

[0029] The main liquid inlet path includes a liquid storage tank, a flow meter, a first water pump and a sixth valve, and the flow meter, the first water pump and the sixth valve are sequentially connected between the liquid storage tank and the container body;

[0030] The main liquid discharge path includes a seventh valve, and the seventh valve is used to control the on-off of the main liquid discharge path.

[0031] Further, the slurry driving module further includes a liquid inlet branch communicated with the other end of the container body;

[0032] The liquid inlet branch includes a second water pump and an eighth valve, and the second water pump is communicated with the liquid storage tank;

[0033] The first branch further includes a first pressure sensor and a second pressure sensor. Among them, the first pressure sensor is connected between the second valve and the fourth valve, the second pressure sensor is connected between the second valve and the first pressure sensor, and a ninth valve is provided at the inlet of the second pressure sensor.

[0034] Further, the slurry driving module further includes a pressure measuring branch;

[0035] The pressure measuring branch is communicated with the main liquid inlet path, and the communication point is on the main path where the first water pump is communicated with the sixth valve. The pressure measuring branch includes an accumulator and a third pressure sensor, and the accumulator and the third pressure sensor are sequentially distributed on the pressure measuring branch.

[0036] In a second aspect, the present invention also provides a bridging plugging experiment method. This method is based on the above-mentioned bridging plugging experiment system and includes the following steps:

[0037] S1: Open the first valve and the sixth valve, start the first water pump, and stop the first water pump when the pressure value measured by the third pressure sensor increases sharply;

[0038] S2: Close the sixth valve, open the seventh valve, discharge the slurry in the slurry storage tank to the piston container, and stop discharging the slurry after no liquid flows out of the main liquid discharge path;

[0039] S3: Open the sixth valve, the second valve and the third valve, close the seventh valve and the first valve, start the first water pump, and stop the first water pump after the slurry returns to the slurry storage tank through the straight pipe;

[0040] S4: Open the first valve, repeat step S2, and after the piston container is filled with slurry again, heat the slurry in the piston container and the straight pipe until the temperature reaches the experimental temperature;

[0041] S5: Repeat step S3, adjust the rotation speed of the first water pump, and monitor the flow rate data collected by the flow meter and the pressure difference data collected by the pressure difference sensor;

[0042] S6: Sequentially repeat step S4 and step S5, test the pressure difference at both ends of the straight pipe at different flow rates at the determined experimental temperature, and close all valves and water pumps after the test is completed;

[0043] S7: From the inner diameter and length of the straight pipe, and in combination with the collected flow rate data and pressure difference data, and at the same time according to the model satisfied by the slurry, such as the Bingham model, the power-law model, the Herschel-Bulkley model, substitute into the corresponding formula to calculate the flow rate and the pressure difference per unit length;

[0044] S8: Pour cement slurry into the settling tank and design the surface of the cement slurry according to the simulation type.

[0045] S9: After the cement slurry solidifies into cement stone, install the mold in the simulation chamber, and adjust the distance between the cement stone and the bottom wall of the simulation tank by rotating the adjusting bolt. At the same time, adjust the angle between the simulation chamber and the horizontal plane by rotating the driver.

[0046] S10: Open the first valve and the sixth valve, start the first water pump, and stop the first water pump when the pressure value measured by the third pressure sensor increases sharply.

[0047] S11: Close the sixth valve, open the seventh valve, discharge the slurry in the slurry storage tank to the piston container, and stop discharging the slurry after no liquid flows out of the main drainage path.

[0048] S12: Open the sixth valve, the fourth valve and the fifth valve, close the seventh valve and the first valve, start the first water pump, and control the rotation speed of the first water pump. When the slurry flows through the crack simulation module, observe the migration process of the particles between the cement stone and the bottom wall of the simulation tank through the viewing window.

[0049] S13: If the pressure detected by the first pressure sensor increases sharply, stop the first water pump.

[0050] S14: If it is necessary to evaluate the pressure-bearing capacity of the plugging layer, close the sixth valve and the ninth valve, open the eighth valve, and start the second water pump.

[0051] In summary of the above technical solutions, the technical effects that the bridging plugging experiment system provided by the present invention can achieve are as follows:

[0052] In this bridging plugging experiment system, the slurry driving module can temporarily store the slurry injected from the slurry storage tank and provide power for the stored slurry to flow. The first valve, the second valve, the third valve, the fourth valve and the fifth valve cooperate and are selectively opened and closed, and can respectively discharge the slurry to the slurry storage tank, and discharge the slurry entering the slurry driving module from the slurry storage tank to the first branch or the second branch.

[0053] Continuing from the above, when the slurry is discharged into the first branch, the slurry will enter the straight pipe and then return to the slurry storage tank, completing the circulating flow in the first circulation loop. During this process, the slurry driving module cooperates with the first heating module to adjust the flow rate and temperature of the slurry. At the same time, combined with the differential pressure sensor, the differential pressure at both ends of the straight pipe corresponding to different flow rates of the slurry at a determined experimental temperature can be measured. Thus, based on the inner diameter and length data of the straight pipe, and by aggregating the collected flow rate data and differential pressure data, and according to the model satisfied by the slurry, such as the Bingham model, power-law model, or Herschel-Bulkley model, substituting into the corresponding formula can calculate the differential pressure per unit length. Here, the first circulation loop realizes the test of the rheology of the slurry.

[0054] Continuing from the above, when the slurry is discharged into the second branch, the slurry will enter the fracture simulation module and then return to the slurry storage tank, completing the circulating flow in the second circulation loop. During this process, at the same time, the slurry driving module adjusts the flow rate of the slurry to make it corresponding to the flow rate in the first circulation loop. In this way, the second circulation loop realizes the simulation of the bridging plugging experiment at a determined flow rate.

[0055] It can be seen that compared with the prior art, this bridging plugging experiment system can not only simulate the leakage channel but also test the rheology of the slurry, achieving the purpose of enriching the indoor bridging plugging evaluation means and providing strong support for the research of the bridging plugging mechanism and the evaluation of indoor bridging plugging materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0056] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following will briefly introduce the drawings required for the description of the specific embodiments or the prior art. Obviously, the following drawings are some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0057] Figure 1 Schematic diagram of the bridging plugging experiment system provided by the embodiment of the present invention;

[0058] Figure 2 Front view of the fracture simulation module provided by the embodiment of the present invention;

[0059] Figure 3 Side view of the fracture simulation module provided by the embodiment of the present invention;

[0060] Figure 4 and Figure 5 Cross-sectional views of the fracture simulation module provided by the embodiment of the present invention at different cross-sections;

[0061] Figure 6 Top view of the cement slurry after curing on the mold provided by the embodiment of the present invention;

[0062] Figure 7 Flow data diagram collected by the flowmeter provided by the embodiment of the present invention;

[0063] Figure 8 Differential pressure data diagram collected by the differential pressure sensor provided by the embodiment of the present invention;

[0064] Figure 9 Slurry flow velocity - differential pressure relationship diagram;

[0065] Figure 10 Pressure data diagram collected by the first pressure sensor provided by the embodiment of the present invention.

[0066] Icons: 1 - slurry storage tank; 2 - first valve; 3 - straight pipe; 4 - second valve; 5 - third valve; 6 - first heating module; 7 - differential pressure sensor;

[0067] 8 - crack simulation module; 81 - simulation chamber; 82 - mold; 83 - adjustment component; 84 - scale ruler; 85 - mounting support; 86 - rotary drive; 811 - simulation groove; 812 - through hole; 813 - housing; 814 - transparent plate; 815 - upper end cover; 831 - lower end cover; 832 - adjustment bolt;

[0068] 9 - fourth valve; 10 - fifth valve;

[0069] 11 - piston container; 111 - container body; 112 - sliding piston;

[0070] 12 - liquid storage tank; 13 - flowmeter; 14 - first water pump; 15 - sixth valve; 16 - seventh valve; 17 - second water pump; 18 - eighth valve; 19 - first pressure sensor; 20 - second pressure sensor; 21 - ninth valve; 22 - energy storage device; 23 - third pressure sensor; 24 - tenth valve; 25 - eleventh valve; 26 - twelfth valve; 27 - temperature sensor; 28 - electric contact pressure gauge; 29 - safety valve. Detailed implementation manners

[0071] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. Usually, the components of the embodiments of the present invention described and illustrated in the drawings here can be arranged and designed in various different configurations.

[0072] Accordingly, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely represents selected embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts fall within the scope of protection of the present invention.

[0073] The following will describe in detail some embodiments of the present invention in conjunction with the accompanying drawings. Without conflict, the following embodiments and the features in the embodiments can be combined with each other.

[0074] In the current bridging plugging experiment, only the relationship between the success of the bridging of the plugging material and the leakage channel is involved, and the influence of the rheology of the plugging slurry on the bridging of the plugging material is not considered, resulting in a lack of strong support for the research on the bridging mechanism of the plugging material.

[0075] In view of this, the present invention provides a bridging plugging experiment system, including a main slurry supply path, a first branch path, and a second branch path. Among them, the first branch path is connected to the main slurry supply path to form a first circulation loop, the second branch path is connected in parallel with the first branch path, and forms a second circulation loop with the main slurry supply path; the main slurry supply path includes a slurry storage tank 1 and a first valve 2, and the first valve 2 is used to control the on-off of the main slurry supply path; the first branch path includes a straight pipe 3, a second valve 4, a third valve 5, a first heating module 6, and a differential pressure sensor 7. Among them, the second valve 4 is connected between the inlet of the straight pipe 3 and the main slurry supply path, the third valve 5 is connected between the outlet of the straight pipe 3 and the main slurry supply path, the first heating module 6 is used to heat the slurry in the straight pipe 3 and measure the temperature of the slurry in the straight pipe 3, and the differential pressure sensor 7 is used to measure the differential pressure at both ends of the straight pipe 3; the second branch path includes a crack simulation module 8, a fourth valve 9, and a fifth valve 10. Among them, the fourth valve 9 is connected between the inlet of the crack simulation module 8 and the main slurry supply path, and the fifth valve 10 is connected between the outlet of the crack simulation module 8 and the main slurry supply path; the bridging plugging experiment system further includes a slurry driving module, the slurry driving module is connected to the main slurry supply path, and the connection point is outside the main path where the first valve 2 is connected to the slurry storage tank 1. The slurry driving module is used to temporarily store and heat the slurry from the main slurry supply path, and discharge the slurry to the first branch path or the second branch path at a preset flow rate.

[0076] In this bridging plugging experiment system, the slurry driving module can temporarily store the slurry injected from the slurry storage tank 1 and provide power for the stored slurry to flow; the first valve 2, the second valve 4, the third valve 5, the fourth valve 9, and the fifth valve 10 cooperate and are selectively opened and closed, and can correspondingly discharge the slurry to the slurry storage tank 1, and discharge the slurry entering the slurry driving module from the slurry storage tank 1 to the first branch path or the second branch path.

[0077] Continuing from the above, when the slurry is discharged into the first branch, it will enter the straight pipe 3 and then return to the slurry storage tank 1 to complete the circulating flow in the first circulation loop. During this process, the slurry driving module cooperates with the first heating module 6 to adjust the flow rate and temperature of the slurry. At the same time, combined with the differential pressure sensor 7, the differential pressure at both ends of the straight pipe 3 corresponding to different flow rates of the slurry at a determined experimental temperature can be measured. Thus, based on the inner diameter and length data of the straight pipe 3, and integrating the collected flow rate data and differential pressure data, and according to the model satisfied by the slurry, such as the Bingham model, the power-law model, and the Herschel-Bulkley model, substituting into the corresponding formula to calculate the differential pressure per unit length. Here, the first circulation loop realizes the test of the rheology of the slurry.

[0078] Continuing from the above, when the slurry is discharged into the second branch, it will enter the fracture simulation module 8 and then return to the slurry storage tank 1 to complete the circulating flow in the second circulation loop. During this process, at the same time, the slurry driving module adjusts the flow rate of the slurry to make it correspond to the flow rate in the first circulation loop. In this way, the second circulation loop realizes the simulation of the bridging plugging experiment at a determined flow rate.

[0079] It can be seen that compared with the prior art, this bridging plugging experiment system can not only simulate the leakage channel but also test the rheology of the slurry, achieving the purpose of enriching the indoor bridging plugging evaluation means and providing strong support for the research of the bridging plugging mechanism and the evaluation of indoor bridging plugging materials.

[0080] The following Figures 1 to 6 will elaborate on the bridging plugging experiment system provided in this embodiment in detail:

[0081] Refer to Figure 1 , the first circulation loop successively includes: the slurry storage tank 1, the first valve 2, the slurry driving module, the twelfth valve 26, the temperature sensor 27, the first pressure sensor 19, the second pressure sensor 20, the second valve 4, the straight pipe 3, the differential pressure sensor 7, and the third valve 5. Its main function is to test the rheology of the slurry. The slurry storage tank 1 is connected with a tenth valve 24, an eleventh valve 25, and a high-pressure gas source.

[0082] Continuing from the above, the slurry driving module includes a piston container 11, which has two functions. One is to temporarily store the slurry injected from the slurry storage tank 1, and the other is to provide the driving force for the stored slurry to flow. The piston container 11 includes a container body 111 and a sliding piston 112. Among them, the container body 111 is in the shape of a cylinder with both ends open, and its upper end is connected to the main slurry supply path, and its lower end is respectively connected to the main liquid inlet path, the main liquid discharge path, and the liquid inlet branch path; the sliding piston 112 is arranged inside the container body 111, is hermetically fitted with the container body 111, and can slide along the axial direction of the sealed body; the main liquid inlet path includes a liquid storage tank 12, a flow meter 13, a first water pump 14, and a sixth valve 15. The flow meter 13, the first water pump 14, and the sixth valve 15 are sequentially connected between the liquid storage tank 12 and the container body 111. And on the main path where the first water pump 14 is connected to the sixth valve 15, a pressure measurement branch path is also connected. The pressure measurement branch path includes an accumulator 22, a third pressure sensor 23, and an electric contact pressure gauge 28; the main liquid discharge path includes a seventh valve 16, and the seventh valve 16 is used to control the on-off of the main liquid discharge path; the liquid inlet branch path includes a second water pump 17 and an eighth valve 18, and the second water pump 17 is connected to the liquid storage tank 12.

[0083] Here, it should be added that a second heating module is provided on the container body 111. Both the second heating module and the first heating module 6 use heating jackets, and the heating jackets respectively wrap around the container body 111 and the straight pipe 3 to heat the slurry in the container body 111 and the straight pipe 3. The pipelines and joints connecting components such as the piston container 11, the temperature sensor 27, the first pressure sensor 19, the second pressure sensor 20, and the second valve 4 are all wrapped with heat insulation materials. A filter screen is added at the connection of the differential pressure sensor 7 and the straight pipe 3, and the differential pressure sensor 7 can also be replaced by two pressure sensors.

[0084] Continuing from the above, the minimum size of the fluid flow through the slurry storage tank 1, the first valve 2, the piston container 11, the twelfth valve 26, the second valve 4, the straight pipe 3, the third valve 5, and the tenth valve 24 is 20 mm; preferably, the volume of the slurry storage tank 1 is 8 - 10 L; preferably, the first valve 2, the twelfth valve 26, the second valve 4, the third valve 5, and the tenth valve 24 use ball valves; preferably, the maximum measurement range of the second pressure sensor 20 is 1 MPa; preferably, the inner wall of the straight pipe 3 is smooth and its length is not less than 2.5 m; preferably, the eleventh valve 25 is connected to the high-pressure gas source in a quick-insert manner for easy disassembly. The high-pressure gas source is compressed air with a pressure of 0.7 MPa; preferably, the liquid storage volume of the container body 111 is 3 - 5 L; preferably, the maximum displacement of the first water pump 14 is not less than 256 mL / s, and the maximum working pressure of the second water pump 17 is 10 - 30 MPa.

[0085] Continue to refer to Figure 1, the second circulation loop successively includes: a slurry storage tank 1, a first valve 2, a slurry driving module, a twelfth valve 26, a temperature sensor 27, a first pressure sensor 19, a second pressure sensor 20, a second valve 4, a safety valve 29, a fourth valve 9, a fracture simulation module 8, and a fifth valve 10. Its main function is to simulate the bridging plugging experiment. Here, it should be added that preferably, the fourth valve 9 and the fifth valve 10 are ball valves; preferably, the through diameters of the fourth valve 9 and the fifth valve 10 are not less than 20 mm.

[0086] Continuing from the above, regarding the fracture simulation module 8, specifically:

[0087] Refer to Figures 2 to 6 , the fracture simulation module 8 is used to simulate the leakage channel, including: a simulation chamber 81, a mold 82, and an adjustment component 83; the simulation chamber 81 includes a housing 813, a transparent plate 814, and an upper end cover 815. The housing 813 is in the shape of a cylinder with both ends open, and through holes 812 are provided on its two opposite side walls. A scale ruler 84 is provided at the bottom of the housing 813; the transparent plate 814 is made of a transparent visible glass plate and is sealed with the inner wall of the housing 813 by a combined sealing ring to enclose a simulation groove 811 with the housing 813; the upper end cover 815 is covered on one of the openings of the housing 813 and is connected to the housing 813 by a flange to fasten the transparent plate 814 to the housing 813, and a window penetrating through itself is provided on the upper end cover 815. The mold 82 is integrally in the shape of a cuboid, and a sunken groove is provided at the top. Cement slurry is placed in the sunken groove, and the cement slurry solidifies into cement stone. A leakage channel is formed between the cement stone and the transparent visible glass plate. Here, it should be added that one or more holes with independently designed shapes and scales can be preset on the upper surface of the cement stone to simulate the fracture-cavity type leakage channel; the cement stone in the sunken groove of the mold 82 can be replaced with outcrop rocks such as carbonate rock, sandstone, and shale to better simulate the formation leakage channel; the cement stone in the sunken groove of the mold 82 can be replaced with quartz sand, steel beads, transparent glass beads, crushed stone particles, drill cuttings, etc. to simulate the formation leakage channel.

[0088] Continuing from the above, more preferably, the adjustment component 83 includes a lower end cover 831 and an adjustment bolt 832; the mold 82 is fixedly connected to the lower end cover 831; the lower end cover 831 is covered on the opening of the simulation groove 811 and is connected to the housing 813 by the adjustment bolt 832. By rotating the adjustment bolt 832, the gap size between the top of the mold 82 and the transparent visible glass plate can be changed, that is, the opening degree of the simulated leakage channel can be changed. Here, the scale ruler 84 can quantify the specific size of the opening degree.

[0089] Continuing with the above, the crack simulation module 8 further includes a mounting support 85 and a rotary drive 86; the simulation chamber 81 is rotatably engaged with the mounting support 85, and the rotation axis is perpendicular to the sliding path of the mold 82 and the extension path of the sink; the rotary drive 86 is disposed on the mounting support 85 and is drivingly connected to the simulation chamber 81 to drive the simulation chamber 81 to flip around the rotation axis. Here, the rotary drive 86 consists of a motor and a reducer that can rotate forward and backward, and can drive the simulation chamber 81 to perform a 360° flip, so as to realize the simulation of the inclination angle of the leakage channel.

[0090] It should be supplemented here that, preferably, the diameter of the through-hole 812 is not less than 20 mm; the measuring range of the scale 84 is 20 mm; the opening range of the simulated leakage channel is 2 - 8 mm; two windows are provided on the upper end cover 815, the window is 480 mm long and 50 mm wide; a sink is provided on the top of the mold 82, the sink is 30 mm deep, 1000 mm long and 50 mm wide; the hole size is 10 - 30 mm.

[0091] When performing a bridging plugging experiment based on the above bridging plugging experiment system, regarding the test method for the rheology of the slurry, the main steps are as follows:

[0092] A1: Open the tenth valve 24, the first valve 2, and the sixth valve 15, close the eighth valve 18, the seventh valve 16, the twelfth valve 26, and the third valve 5, then turn on the first water pump 14, inject the clear water in the liquid storage tank 12 into the lower part of the piston container 11, and the sliding piston moves upward until the pressure value measured by the third pressure sensor 23 increases sharply, then stop the first water pump 14. At this time, the sliding piston is at the uppermost position.

[0093] A2: Remove the high-pressure gas source connected to the eleventh valve 25, pour the pre-prepared slurry through the outlet of the tenth valve 24 until the entire slurry storage tank 1 is full, then close the eleventh valve 25 and connect the high-pressure gas source.

[0094] A3: Close the tenth valve 24 and the sixth valve 15, open the seventh valve 16, then open the eleventh valve 25, use high-pressure gas to press the slurry to the upper part of the piston container 11. After no liquid flows out of the seventh valve 16, close the eleventh valve 25, open the tenth valve 24, and release the air pressure.

[0095] A4: Open the sixth valve 15, the twelfth valve 26, and the third valve 5, close the seventh valve 16, turn on the first water pump 14, and the slurry returns to the slurry storage tank 1 through the straight pipe 3, and the internal connection pipeline of the loop is filled with slurry.

[0096] A5: Repeat step A3. After the slurry fills the piston container 11 again, turn on the heating jacket to adjust the heating temperature, observe the temperature measured by the temperature sensor 27 until the temperature of the slurry in the piston container 11 and the straight pipe 3 reaches the experimental temperature.

[0097] A6: Repeat step A4, adjust the rotational speed of the first water pump 14, and monitor the flow rate collected by the flowmeter 13 and the differential pressure data collected by the differential pressure sensor 7 on the straight pipe 3.

[0098] A7: Repeat steps A5 and A6. At the determined experimental temperature, test the differential pressure across the straight pipe 3 at different flow velocities.

[0099] A8: Given the inner diameter D and length L of the straight pipe 3 and the collected data, the flow velocity v and the differential pressure per unit length Δp / L can be calculated. Here, assuming the slurry satisfies the Bingham model, the formula is: Assuming the slurry satisfies the power-law model, the formula is: Assuming the slurry satisfies the Herschel-Bulkley model, the formula is:

[0100] Regarding the experimental method for simulating bridging plugging, the main steps are as follows:

[0101] B1: Pour cement slurry into the sink of the mold 82. If simulating a straight-seam type leakage channel, the cement slurry should be flush with the surface of the sink. If simulating a seam-cavity type leakage channel, place spherical, ellipsoidal or other shaped impression molds on the cement slurry. After the cement cures, remove the impression mold, and self-designed holes will be formed on the surface of the cement stone.

[0102] B2: Install the cured mold 82 on the lower end cover 831 and adjust the opening degree of the leakage channel by adjusting the bolt 832.

[0103] B3: Adjust the inclination angle between the crack simulation module 8 and the horizontal plane by controlling the forward and reverse rotation of the motor on the mounting support 85.

[0104] B4: Open the tenth valve 24, the first valve 2, and the sixth valve 15, close the eighth valve 18, the seventh valve 16, the twelfth valve 26, and the third valve 5. Then turn on the first water pump 14 to inject the clear water in the liquid storage tank 12 into the lower part of the piston container 11, and the sliding piston moves upward until the pressure value measured by the third pressure sensor 23 increases sharply. Stop the first water pump 14. At this time, the sliding piston is at the uppermost position.

[0105] B5: Disconnect the high-pressure gas source connected to the eleventh valve 25, pour the pre-prepared slurry through the outlet of the tenth valve 24 until the entire slurry storage tank 1 is full, close the eleventh valve 25 and connect the high-pressure gas source.

[0106] B6: Close the tenth valve 24 and the sixth valve 15, open the seventh valve 16, then open the eleventh valve 25, use high-pressure gas to press the slurry to the upper part of the piston container 11. After no liquid flows out of the seventh valve 16, close the eleventh valve 25, open the tenth valve 24, and release the air pressure.

[0107] B7: Close the second valve 4, the first valve 2, and the seventh valve 16, open the sixth valve 15, the twelfth valve 26, the fourth valve 9, and the fifth valve 10, turn on the first water pump 14, and control the rotation speed of the first water pump 14. The slurry flows through the crack simulation module 8 to conduct a bridging plugging experiment at a determined flow rate. Through the window and the transparent plate 814, the particle migration process in the leakage channel can be observed.

[0108] B8: If a sharp increase in pressure is detected on the first pressure sensor 19, it indicates that the leakage channel has been plugged, then stop the first water pump 14.

[0109] B9: If it is necessary to evaluate the pressure-bearing capacity of the plugging layer, close the sixth valve 15 and the ninth valve 21, open the eighth valve 18, turn on the second water pump 17, and detect the pressure data on the first pressure sensor 19.

[0110] To more clearly illustrate the testing of the slurry rheology and the process of the bridging plugging experiment, the following gives a detailed test case. Using the above experimental system, the straight pipe 3 is 2.5 m long and has an inner diameter of 20 mm. Prepare an 8 L slurry in advance. The slurry formula by mass ratio is: 100 parts of 0.4% xanthan gum solution, 15 parts of 1 - 3 mm fruit shell particles, 5 parts of 3 - 5 mm fruit shell particles, 2.5 parts of 2 - 3 mm swelling gel, 2 parts of 1 - 3 mm resin sheets, and 0.5 part of 10 - 20 mm fibers. The bridging plugging experiment simulates a fracture-vug leakage channel with a fracture aperture of 6 mm. Experimental requirements: (1) Test the rheology of the slurry at 90 °C; (2) Observe the plugging process of the plugging particles in the fracture-vug leakage channel; (3) Evaluate the plugging performance of the slurry. The specific steps are as follows:

[0111] S1: Preparation of the fracture-vug leakage channel. Pour G-class oil well cement slurry with a water-cement ratio of 0.5 into the sink of the mold 82. Place three stamps in the shape of a hemisphere, a semi-ellipsoid, and a triangular pyramid on the cement slurry. Scrape the upper surface of the cement slurry flat and let it stand for 24 hours. After the cement slurry cures, remove the stamps, and three holes are formed on the surface of the cement stone, as Figure 6 shown. Install the cured mold 82 on the lower end cover 831, and adjust the aperture of the leakage channel to 6 mm by adjusting the bolt 832.

[0112] S2: Adjust the crack simulation module 8 to the horizontal plane by controlling the forward and reverse rotation of the motor on the mounting support 85.

[0113] S3: Manually open the first valve 2, the tenth valve 24, and the sixth valve 15, close the twelfth valve 26, the third valve 5, the fifth valve 10, the seventh valve 16, and the eighth valve 18, then turn on the first water pump 14 to inject the clear water in the liquid storage tank 12 into the lower part of the piston container 11. The piston moves upward until the pressure value measured by the third pressure sensor 23 increases sharply, and then stop the first water pump 14. At this time, the piston is at the uppermost position.

[0114] S4: Remove the high-pressure gas source connected to the eleventh valve 25, open the tenth valve 24 and the eleventh valve 25, and use a funnel to pour the pre-prepared slurry through the outlet of the tenth valve 24 until the entire slurry storage tank 1 is full, then close the eleventh valve 25 and connect the high-pressure gas source.

[0115] S5: Close the tenth valve 24 and the sixth valve 15, open the first valve 2 and the seventh valve 16, then open the eleventh valve 25, and use high-pressure gas to squeeze the slurry from the slurry storage tank 1 into the upper part of the piston container 11. After no liquid flows out of the seventh valve 16, close the eleventh valve 25, open the tenth valve 24, and release the air pressure in the slurry storage tank 1.

[0116] S6: Open the twelfth valve 26, the second valve 4, the third valve 5, and the sixth valve 15, close the first valve 2 and the seventh valve 16, turn on the first water pump 14, and the slurry is squeezed from the piston container 11 into the straight pipe 3 and back into the slurry storage tank 1, and the inside of the pipeline is filled with slurry.

[0117] S7: Close the twelfth valve 26 and the third valve 5, repeat step S5, and after the slurry fills the piston container 11 again, turn on the heating jacket to adjust the heating temperature until the temperature of the slurry in the piston container 11 and the straight pipe 3 reaches 90 °C.

[0118] S8: Repeat step S6, adjust the rotation speed of the first water pump 14 to 100 r / min, and the computer collects the flow rate collected by the flowmeter 13 as Figure 7 shown, and the pressure difference of the pressure difference sensor 7 on the straight pipe 3 is as Figure 8 shown. Take the average value of the stable data, the flow velocity is 0.04268 m / s, the pressure difference is 3.783 KPa, and the pressure difference per unit length is 1513 Pa.

[0119] S9: Repeat steps S7 and S8, adjust the rotation speed of the first water pump 14 to 200 r / min, 300 r / min, etc. respectively, and test the pressure difference data at different rotation speeds.

[0120] S10: Assume that the slurry satisfies the Bingham model, use the flow velocity as the horizontal axis and the pressure difference per unit length as the vertical axis to make a scatter plot in the Cartesian coordinate system, and use the formula for fitting, as Figure 9As shown in the figure, assuming that the slope of the fitting line is k and the intercept is d, the plastic viscosity and dynamic shear force of the slurry are as follows:

[0121] μ p = kD 2 / 32 = 0.1256 Pa·s;

[0122] τ 0 = 3dD / 16 = 3.213 Pa;

[0123] Through Figure 8 it can be seen that there is an obvious peak pressure difference of 8.5 KPa. This peak is the starting pressure difference of the slurry. At this time, the slurry converts from static to dynamic, and the shear force corresponds to the static shear force. Then the static shear force of the slurry is:

[0124]

[0125] S11: Repeat step S7, open the twelfth valve 26, the fourth valve 9, the fifth valve 10, the sixth valve 15, close the first valve 2, the second valve 4, the third valve 5, the seventh valve 16, adjust the rotation speed of the first water pump 14 to 100 r / min, turn on the first water pump 14, and the slurry is squeezed from the piston container 11 into the crack simulation module 8. Observe the particle migration process in the leakage channel through the viewing window.

[0126] S12: It is found in the experiment that the pressure on the first pressure sensor 19 increases sharply and the leakage channel is blocked, then stop the first water pump 14.

[0127] S13: Close the sixth valve 15 and the ninth valve 21, open the eighth valve 18, turn on the second water pump 17, and the pressure data on the first pressure sensor 19 is as shown in the appendix Figure 10 As shown, then the pressure-bearing capacity of the slurry plugging is about 2.1 MPa.

[0128] It can be seen from this that the present invention provides a solution for testing the rheology of complex bridging slurries, which can simulate straight cracks and crack-cavity type leakage channels, facilitating experimenters to independently design the opening of the cracks, the shape and size of the cavities, and the inclination angle of the leakage channels according to their needs, providing strong support for the research of the bridging plugging mechanism and the evaluation of indoor bridging plugging materials.

[0129] Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements on some or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A bridge plugging test system, It is characterized in that include: A slurry supply main path, a first branch path, and a second branch path, wherein the first branch path is connected to the slurry supply main path to form a first circulation loop, and the second branch path is connected in parallel with the first branch path and forms a second circulation loop with the slurry supply main path; The main slurry supply path comprises a slurry storage tank (1) and a first valve (2), wherein the first valve (2) is used to control the on / off of the main slurry supply path; The first branch comprises a straight pipe (3), a second valve (4), a third valve (5), a first heating module (6) and a differential pressure sensor (7), wherein the second valve (4) is connected between the inlet of the straight pipe (3) and the main slurry supply path, the third valve (5) is connected between the outlet of the straight pipe (3) and the main slurry supply path, the first heating module (6) is used to heat the slurry in the straight pipe (3) and measure the temperature of the slurry in the straight pipe (3), and the differential pressure sensor (7) is used to measure the differential pressure at both ends of the straight pipe (3); The second branch comprises a fracture simulation module (8), a fourth valve (9) and a fifth valve (10), wherein the fourth valve (9) is connected between the inlet of the fracture simulation module (8) and the slurry supply main path, and the fifth valve (10) is connected between the outlet of the fracture simulation module (8) and the slurry supply main path; The bridging plugging experimental system also includes a slurry driving module, which is connected to the slurry supply main road, and the connection point is outside the main road connecting the first valve (2) and the slurry storage tank (1). The slurry driving module is used to temporarily store and heat the slurry from the slurry supply main road, and discharge the slurry to the first branch or the second branch at a preset flow rate.

2. The bridging plugging experimental system according to claim 1, It is characterized in that The crack simulation module (8) comprises a simulation chamber (81), a mold (82) and an adjustment component (83); The simulation chamber (81) has a simulation groove (811), a visual window is provided on the bottom wall of the simulation groove (811), and through-holes (812) are provided on two opposite side walls; The mold (82) is slidably connected to the simulation chamber (81) in a posture of blocking the opening of the simulation groove (811), and a sink groove is provided on a side of the mold (82) facing the bottom wall of the simulation groove (811), one end of the sink groove is close to one of the through-holes (812), and the other end extends toward the other through-hole (812); The adjustment component (83) is arranged on the simulation chamber (81) and is transmission-connected to the mold (82) so as to drive the mold (82) to move toward or away from the bottom wall of the simulation tank (811).

3. The bridging plugging experimental system according to claim 2, It is characterized in that The adjustment assembly (83) comprises a lower end cover (831) and an adjustment bolt (832); The mold (82) is fixedly connected to the lower end cover (831); The lower end cover (831) covers the opening of the simulation groove (811) and is connected to the simulation chamber (81) through the adjusting bolt (832).

4. The bridging plugging experiment system according to claim 2, wherein, the crack simulation module (8) further includes a scale ruler (84), the scale ruler (84) is arranged in the simulation chamber (81), on the side of the opening of the simulation groove (811), and its length direction is consistent with the sliding direction of the mold (82).

5. The bridging plugging experiment system according to claim 2, wherein, the simulation chamber (81) includes a housing (813), a transparent plate (814) and an upper end cover (815); the housing (813) is in a cylindrical shape with both ends open; the transparent plate (814) is arranged inside the housing (813), is in sealing cooperation with the housing (813), and encloses the simulation groove (811) with the housing (813); the upper end cover (815) covers one of the openings of the housing (813) and is fixedly connected to the housing (813) to fasten the transparent plate (814) to the housing (813), and a window penetrating through itself is provided on the upper end cover (815).

6. The bridging plugging experiment system according to any one of claims 2 to 5, wherein, the crack simulation module (8) further includes a mounting support (85) and a rotary drive (86); the simulation chamber (81) is rotationally matched with the mounting support (85), and the rotation axis is respectively perpendicular to the sliding path of the mold (82) and the extension path of the sinking groove; the rotary drive (86) is arranged on the mounting support (85) and is in transmission connection with the simulation chamber (81) to drive the simulation chamber (81) to turn around the rotation axis.

7. The bridging plugging experiment system according to claim 1, wherein, the slurry driving module includes a piston container (11), a main liquid inlet path and a main liquid discharge path; the piston container (11) includes a container body (111) and a sliding piston (112). Among them, the container body (111) is in a cylindrical shape with both ends open, one end of which is communicated with the main slurry supply path, and the other end is respectively communicated with the main liquid inlet path and the main liquid discharge path. The sliding piston (112) is arranged inside the container body (111), is in sealing cooperation with the container body (111), and can slide along the axial direction of the sealing body; the main liquid inlet path includes a liquid storage tank (12), a flow meter (13), a first water pump (14) and a sixth valve (15). The flow meter (13), the first water pump (14) and the sixth valve (15) are sequentially connected between the liquid storage tank (12) and the container body (111); the main liquid discharge path includes a seventh valve (16), and the seventh valve (16) is used to control the on-off of the main liquid discharge path.

8. The bridging plugging experiment system according to claim 7, wherein, The slurry driving module further includes a liquid inlet branch communicated with the other end of the container body (111); The liquid inlet branch includes a second water pump (17) and an eighth valve (18), and the second water pump (17) is communicated with the liquid storage tank (12); The first branch further includes a first pressure sensor (19) and a second pressure sensor (20). Among them, the first pressure sensor (19) is connected between the second valve (4) and the fourth valve (9), the second pressure sensor (20) is connected between the second valve (4) and the first pressure sensor (19), and a ninth valve (21) is arranged at the inlet of the second pressure sensor (20).

9. The bridging plugging experiment system according to claim 7, characterized in that the slurry driving module further includes a pressure measuring branch; The pressure measuring branch is communicated with the main liquid inlet path, and the communication point is on the main path where the first water pump (14) is communicated with the sixth valve (15). The pressure measuring branch includes an accumulator (22) and a third pressure sensor (23), and the accumulator (22) and the third pressure sensor (23) are sequentially distributed on the pressure measuring branch.

10. A bridging plugging experiment method, characterized in that based on the bridging plugging experiment system according to any one of claims 1 to 9, including the following steps: S1: Open the first valve (2) and the sixth valve (15), start the first water pump (14), and stop the first water pump (14) when the pressure value measured by the third pressure sensor (23) increases sharply; S2: Close the sixth valve (15), open the seventh valve (16), discharge the slurry in the slurry storage tank (1) to the piston container (11), and stop discharging the slurry after no liquid flows out of the main liquid discharge path; S3: Open the sixth valve (15), the second valve (4) and the third valve (5), close the seventh valve (16) and the first valve (2), start the first water pump (14), and stop the first water pump (14) after the slurry returns to the slurry storage tank (1) through the straight pipe (3); S4: Open the first valve (2), repeat step S2, and heat the slurry in the piston container (11) and the straight pipe (3) until the temperature reaches the experimental temperature after the slurry fills the piston container (11) again; S5: Repeat step S3, adjust the rotation speed of the first water pump (14), and monitor the flow data collected by the flowmeter (13) and the differential pressure data collected by the differential pressure sensor (7); S6: Sequentially repeat step S4 and step S5, test the differential pressure at both ends of the straight pipe (3) at different flow rates at the determined experimental temperature, and close all valves and water pumps after the test is completed; S7: From the inner diameter and length of the straight pipe (3), and by integrating the collected flow data and differential pressure data, and at the same time according to the model satisfied by the slurry, such as the Bingham model, the power-law model, the Herschel-Bulkley model, substitute into the corresponding formula to calculate the flow rate and the differential pressure per unit length; S8: Pour cement slurry into the settling tank and design the surface of the cement slurry according to the simulation type; S9: After the cement slurry solidifies into cement stone, install the mold (82) in the simulation chamber (81), and adjust the distance between the cement stone and the bottom wall of the simulation tank (811) by rotating the adjusting bolt (832), and at the same time adjust the angle between the simulation chamber (81) and the horizontal plane by rotating the driver (86); S10: Open the first valve (2) and the sixth valve (15), start the first water pump (14), and stop the first water pump (14) when the pressure value measured by the third pressure sensor (23) increases sharply; S11: Close the sixth valve (15), open the seventh valve (16), discharge the slurry in the slurry storage tank (1) to the piston container (11), and stop discharging the slurry after no liquid flows out of the main drainage path; S12: Open the sixth valve (15), the fourth valve (9) and the fifth valve (10), close the seventh valve (16) and the first valve (2), start the first water pump (14), and control the rotation speed of the first water pump (14). When the slurry flows through the crack simulation module (8), observe the migration process of the particles between the cement stone and the bottom wall of the simulation tank (811) through the viewing window; S13: If the pressure detected by the first pressure sensor (19) increases sharply, stop the first water pump (14); S14: If it is necessary to evaluate the pressure-bearing capacity of the plugging layer, close the sixth valve (15) and the ninth valve (21), open the eighth valve (18), and start the second water pump (17).

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