A proppant flowback experimental apparatus and method

Abstract

This application discloses a proppant recirculation experimental apparatus and method, comprising a sand mixing module, a screw module, a simulation module, a wellbore module, and a filtration module connected in sequence. The simulation module is also connected to a flowback module, and the wellbore module is also connected to a fluid replenishment module. Specifically: the sand mixing module mixes fracturing fluid and proppant to obtain a proppant-carrying fluid and delivers it to the screw module; the screw module delivers the proppant-carrying fluid to the simulation module according to a preset flow rate; the simulation module receives the proppant-carrying fluid during the fracturing injection stage, controls the fracturing fluid filtration loss, and receives the first flowback fluid from the flowback module when closed, mixes it to obtain a first flowback proppant-carrying fluid, and delivers it to the wellbore module; the wellbore module receives the first flowback proppant-carrying fluid and the second flowback fluid from the fluid replenishment module, mixes them to obtain a second flowback proppant-carrying fluid, and sends it to the filtration module; the filtration module filters and intercepts the processed proppant and calculates the proppant ratio. This method can accurately simulate multi-fracture conditions and improve the accuracy of proppant recirculation law research.

Description

Technical Field

[0001] This application relates to the field of oil extraction technology, and in particular to a proppant reflux experimental apparatus and method. Background Technology

[0002] In the field of oil extraction, hydraulic fracturing is one of the key technologies for improving reservoir permeability. During fracturing, proppant is injected into the formation fractures along with the fracturing fluid, forming a propping channel to maintain the fracture conductivity. However, if the proppant return is uncontrolled during the flowback stage, it can lead to fracture closure, wellbore blockage, and equipment wear, severely impacting equipment lifespan. Therefore, accurately simulating the migration, placement, and flowback patterns of proppant within fractures has become a core requirement for optimizing fracturing processes and flowback regimes. Currently, traditional proppant flowback experimental devices mainly simulate the fracturing process using single-fracture models, but they have significant shortcomings: on the one hand, existing devices struggle to accurately simulate the complex flow conditions of multiple fracture flowback fluids converging into the wellbore, failing to reproduce the proppant migration and accumulation behavior in multi-cluster perforation environments; on the other hand, the control precision for fracturing fluid loss within fractures is insufficient, and the simple design of the mixing mechanism between the flowback fluid and the proppant-carrying fluid leads to deviations between the experimentally obtained key parameters such as sandbank morphology changes and critical flowback velocities and actual operating conditions, making effective optimization difficult.

[0003] Therefore, how to accurately simulate multi-crack conditions, precisely control filtrate loss and backflow liquid mixing process, and improve the accuracy of proppant reflux law research is an urgent problem to be solved. Summary of the Invention

[0004] In view of this, the proppant reflux experimental apparatus and method provided in this application can accurately simulate multi-crack conditions, precisely control filtrate loss and flowback liquid mixing processes, and improve the accuracy of proppant reflux law research. The proppant reflux experimental apparatus and method provided in this application are implemented as follows:

[0005] This application provides a proppant recirculation experimental device, comprising a sand mixing module, a screw module, a simulation module, a wellbore module, and a filter module connected in sequence. The simulation module is also connected to a flowback module, and the wellbore module is also connected to a fluid replenishment module.

[0006] The sand mixing module is used to receive fracturing fluid and proppant, mix the fracturing fluid and proppant to obtain sand-carrying fluid, and deliver the sand-carrying fluid to the screw module.

[0007] The screw module is used to receive the sand-carrying fluid and to deliver the sand-carrying fluid to the simulation module according to a preset discharge rate.

[0008] The backflow module is used to deliver the first backflow liquid to the simulation module;

[0009] The simulation module is used to receive the proppant-carrying fluid and control the filtration loss of the fracturing fluid in the proppant-carrying fluid when the fracturing injection stage is turned on; when the fracturing injection stage is turned off, it receives the first flowback fluid delivered by the flowback module, mixes the first flowback fluid with the proppant-carrying fluid to obtain the first flowback proppant-carrying fluid, and delivers the first flowback proppant-carrying fluid to the wellbore module.

[0010] The fluid replenishment module is used to deliver the second flowback fluid to the wellbore module;

[0011] The wellbore module is used to receive the first return sand-carrying fluid and the second return fluid delivered by the replenishment module, mix the first return sand-carrying fluid and the second return fluid to obtain the second return sand-carrying fluid, and send the second return sand-carrying fluid to the filtration module.

[0012] The filtration module is used to receive the second backflow sand-carrying liquid, filter and intercept the second backflow sand-carrying liquid to obtain the treated proppant, and calculate the sand ratio from the treated proppant.

[0013] In some embodiments, the simulation module further includes multiple filter outlets, each filter outlet being equipped with an independent flow regulating valve, wherein:

[0014] The filtration port is used to adjust the opening degree of the independent flow regulating valve, thereby controlling the amount of fracturing fluid lost from the proppant-carrying fluid.

[0015] In some embodiments, the wellbore module further includes a plurality of perforations, wherein:

[0016] The perforation is used to adjust the injection rate of the second return fluid.

[0017] In some embodiments, the sand mixing module further includes a sand mixing tank and a stirring device, wherein:

[0018] The mixing tank is used to receive and store the fracturing fluid and the proppant;

[0019] The stirring device is used to mix and stir the fracturing fluid and the proppant in the mixing tank.

[0020] In some embodiments, the simulation module further includes a plurality of sand-flushing ports, wherein:

[0021] The sand flushing port is used to flush the simulation module after the simulation module delivers the first return sand-carrying fluid to the wellbore module.

[0022] This application provides a proppant reflux test method, including:

[0023] The fracturing fluid and proppant are received through the sand mixing module, and the fracturing fluid and proppant are mixed to obtain a sand-carrying fluid, which is then delivered to the screw module.

[0024] The screw module receives the sand-carrying fluid and delivers it to the simulation module according to a preset discharge rate.

[0025] The first backflow liquid is delivered to the simulation module through the backflow module;

[0026] The simulation module receives the proppant-carrying fluid and controls the filtration loss of the fracturing fluid in the proppant-carrying fluid when the fracturing injection stage is started; when the fracturing injection stage is closed, it receives the first flowback fluid delivered by the flowback module, mixes the first flowback fluid with the proppant-carrying fluid to obtain the first flowback proppant-carrying fluid, and delivers the first flowback proppant-carrying fluid to the wellbore module.

[0027] The second flowback fluid is delivered to the wellbore module through the fluid replenishment module;

[0028] The wellbore module receives the first return sand-carrying fluid and the second return fluid delivered by the replenishment module. The first return sand-carrying fluid and the second return fluid are mixed to obtain the second return sand-carrying fluid, which is then sent to the filtration module.

[0029] The filter module receives the second backflow sand-carrying liquid, filters and intercepts the second backflow sand-carrying liquid to obtain the treated proppant, and calculates the sand ratio from the treated proppant.

[0030] In some embodiments, the simulation module further includes multiple filter outlets, each filter outlet being equipped with an independent flow regulating valve, and the method includes:

[0031] The opening of the independent flow regulating valve is adjusted through the filtration port, thereby controlling the amount of fracturing fluid lost from the proppant-carrying fluid.

[0032] In some embodiments, the wellbore module further includes multiple perforations, and the method includes:

[0033] The injection rate of the second return fluid is adjusted through the perforation hole.

[0034] In some embodiments, the sand mixing module further includes a sand mixing tank and a stirring device, and the method includes:

[0035] The fracturing fluid and the proppant are received and stored through the mixing tank.

[0036] The fracturing fluid and the proppant in the mixing tank are mixed and stirred by the stirring device.

[0037] In some embodiments, the simulation module further includes a plurality of sand-flushing ports, and the method includes:

[0038] After the simulation module delivers the first backflow sand-carrying fluid to the wellbore module through the sand flushing port, the simulation module is flushed.

[0039] This application provides a proppant recirculation experimental apparatus and method, comprising a sand mixing module, a screw module, a simulation module, a wellbore module, and a filtration module connected in sequence. The simulation module is connected to a flowback module, and the wellbore module is connected to a fluid replenishment module. The sand mixing module mixes fracturing fluid and proppant to obtain a proppant-carrying fluid, which is then delivered to the screw module. The screw module delivers the proppant-carrying fluid to the simulation module at a preset flow rate. During the fracturing injection stage, the simulation module controls the fracturing fluid filtration loss. When closed, it receives the first flowback fluid from the flowback module, mixes it to obtain the first flowback proppant-carrying fluid, and delivers it to the wellbore module. The wellbore module receives the first flowback proppant-carrying fluid and the second flowback fluid from the fluid replenishment module, mixes them to obtain the second flowback proppant-carrying fluid, and sends it to the filtration module. The filtration module filters and intercepts the processed proppant and calculates the proppant ratio. This allows for precise simulation of multi-fracture conditions, accurate control of filtration loss and flowback fluid mixing processes, improves the accuracy of proppant recirculation studies, and solves the technical problems mentioned in the background art. Attached Figure Description

[0040] To more clearly illustrate the technical solutions of the embodiments of this application, the drawings used in the description of the embodiments of this application or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0041] Figure 1 This is a schematic diagram of the structure of a proppant reflux experimental apparatus provided in an embodiment of this application;

[0042] Figure 2 This is a schematic diagram of the simulation module in a proppant reflux experimental apparatus provided in an embodiment of this application;

[0043] Figure 3 This is a schematic diagram of the wellbore module in a proppant reflux experimental device provided in an embodiment of this application. Detailed Implementation

[0044] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the specific technical solutions of this application will be further described in detail below with reference to the accompanying drawings of the embodiments of this application. The following embodiments are used to illustrate this application, but are not intended to limit the scope of this application.

[0045] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein is for the purpose of describing embodiments of this application only and is not intended to limit this application.

[0046] In the following description, references are made to “some embodiments,” which describe a subset of all possible embodiments. However, it is understood that “some embodiments” may be the same subset or different subsets of all possible embodiments and may be combined with each other without conflict.

[0047] It should be noted that the terms "first, second, third" used in the embodiments of this application are used to distinguish similar or different objects and do not represent a specific order of objects. It can be understood that "first, second, third" can be interchanged in a specific order or sequence where permitted, so that the embodiments of this application described herein can be implemented in an order other than that illustrated or described herein.

[0048] In view of this, the present application provides a schematic diagram of the structure of a proppant reflux experimental apparatus, as shown in the embodiment. Figure 1 As shown, the system includes a sand mixing module 101, a screw module 102, a simulation module 103, a wellbore module 104, and a filter module 105 connected in sequence. The simulation module 103 is also connected to the backflow module 106, and the wellbore module 104 is also connected to the fluid replenishment module 107.

[0049] The sand mixing module 101 is used to receive fracturing fluid and proppant, mix the fracturing fluid and proppant to obtain sand-carrying fluid, and deliver the sand-carrying fluid to the screw module 102.

[0050] In this embodiment, the sand mixing module 101 is the starting part of the entire device, which is used to receive fracturing fluid and proppant and mix them thoroughly to obtain sand-carrying fluid.

[0051] The sand mixing module 101 may be equipped with a corresponding feed port, which is connected to the supply sources of fracturing fluid and proppant via pipelines, allowing the fracturing fluid and proppant to flow into the sand mixing module 101. The module contains a mixing chamber with a stirring device. Activating the stirring device ensures that the fracturing fluid and proppant are uniformly mixed to form a sand-carrying fluid. The mixed sand-carrying fluid is then transported to the screw module 102 via a discharge pipe connected to the screw module 102.

[0052] The screw module 102 is used to receive the sand-carrying fluid and to deliver the sand-carrying fluid to the simulation module 103 according to a preset discharge rate.

[0053] In this embodiment of the application, the screw module 102 receives the sand-carrying liquid from the sand mixing module 101 and delivers it to the simulation module 103 according to a preset discharge rate.

[0054] The screw module 102 receives the sand-carrying liquid via a discharge pipe connected to the sand-mixing module 101. The module is equipped with a flow control component, which can be preset to control the discharge rate of the sand-carrying liquid. During the conveying process, the flow control component monitors the flow rate in real time to ensure that the sand-carrying liquid is delivered to the simulation module 103 at a stable preset discharge rate.

[0055] The backflow module 106 is used to deliver the first backflow liquid to the simulation module 103.

[0056] In this embodiment, the backflow module 106 is mainly used to deliver the first backflow liquid to the simulation module 103. The backflow module 106 has a container for storing the first backflow liquid, and delivers the first backflow liquid to the simulation module 103 through a pipeline. The flow rate and pressure of the delivery can be adjusted according to actual needs.

[0057] The simulation module 103 is used to receive the proppant-carrying fluid and control the filtration loss of the fracturing fluid in the proppant-carrying fluid when the fracturing injection stage is opened; when the fracturing injection stage is closed, it receives the first flowback fluid delivered by the flowback module 106, mixes the first flowback fluid with the proppant-carrying fluid to obtain the first flowback proppant-carrying fluid, and delivers the first flowback proppant-carrying fluid to the wellbore module 104.

[0058] In this embodiment, the simulation module 103 plays different roles at different stages, mainly simulating the fracturing injection and flowback processes. The simulation module 103 receives proppant-carrying fluid through a pipeline connected to the screw module 102. The module contains a structure for controlling the fracturing fluid loss. After the fracturing injection stage is closed, the simulation module 103 receives the first flowback fluid through a pipeline connected to the flowback module 106. Inside the module, the first flowback fluid mixes with the previously injected proppant-carrying fluid, carrying some proppant to form the first flowback proppant-carrying fluid. The formed first flowback proppant-carrying fluid is then transported to the wellbore module 104 through a pipeline connected to the wellbore module 104.

[0059] The fluid replenishment module 107 is used to deliver the second return fluid to the wellbore module 104.

[0060] In this embodiment, the function of the replenishment module 107 is to deliver the second flowback fluid to the wellbore module 104. The replenishment module 107 is equipped with a container for storing the second flowback fluid, and the second flowback fluid is delivered to the wellbore module 104 via a pipeline.

[0061] The wellbore module 104 is used to receive the first return sand-carrying fluid and the second return fluid delivered by the fluid replenishment module 107, mix the first return sand-carrying fluid and the second return fluid to obtain the second return sand-carrying fluid, and send the second return sand-carrying fluid to the filter module 105.

[0062] In this embodiment, the wellbore module 104 receives the first flowback carrying fluid and the second flowback fluid delivered by the replenishment module 107, and mixes them. The wellbore module 104 receives the first flowback carrying fluid and the second flowback fluid through pipes connected to the simulation module 103 and the replenishment module 107, respectively. Inside the module, the two fluids naturally mix to form the second flowback carrying fluid, which is then delivered to the filtration module 105 through a pipe connected to the filtration module 105.

[0063] The filter module 105 is used to receive the second return sand-carrying liquid, filter and intercept the second return sand-carrying liquid to obtain the treated proppant, and calculate the sand ratio from the treated proppant.

[0064] In this embodiment of the application, the filtration module 105 receives the second backflow sand-carrying liquid, filters and intercepts it, and finally obtains the processed proppant and calculates the sand ratio.

[0065] The filter module 105 receives the second flowback proppant fluid through a pipe connected to the wellbore module 104. The module contains a filter component that intercepts the proppant from the second flowback proppant fluid. The intercepted proppant is collected and measured, and the proppant ratio is calculated based on relevant experimental data to analyze the proppant backflow.

[0066] This application's embodiments achieve quantitative research on the proppant reflux process through multi-module collaboration, precise parameter control, and multi-condition simulation, solving the problems of inaccurate simulation and low data reliability in the prior art.

[0067] In the above Figure 1 As shown, this application embodiment also provides a structural schematic diagram of the simulation module 103 in a proppant reflux experimental apparatus. For example... Figure 2 As shown, the simulation module 103 also includes multiple filter outlets 1031, each filter outlet 1031 being equipped with an independent flow regulating valve 1032, wherein:

[0068] The filter outlet 1031 is used to adjust the opening of the independent flow regulating valve 1032, thereby controlling the amount of fracturing fluid lost from the proppant-carrying fluid.

[0069] In this embodiment, the main structure of the simulation module 103 is a cavity resembling a crack, which is used to contain the sand-carrying fluid and simulate the actual situation of formation fractures. Multiple filtration ports 1031 are uniformly distributed on the cavity wall of the simulation module 103. The number and spacing of these filtration ports 1031 can be adjusted according to the actual formation conditions simulated in the experiment to more accurately simulate the filtration characteristics of different formations.

[0070] Each filter outlet 1031 is equipped with an independent flow regulating valve 1032. These regulating valves can be either electric or manual. If automated and precise control is required, electric regulating valves are preferred; if the control accuracy requirement is not extremely high and cost-effectiveness is the priority, manual regulating valves are also a viable option.

[0071] Before performing proppant refluxing, it is necessary to first determine the amount of fracturing fluid to be controlled at each 1031 filtration port. This can be calculated using relevant mathematical models or empirical formulas, referencing parameters such as the actual formation's permeability and porosity.

[0072] If a manual regulating valve is used, the independent flow regulating valve 1032 of each filter port 1031 is adjusted to a suitable opening degree by rotating the knob of the regulating valve according to the calculated filtration loss.

[0073] If an electric regulating valve is used, it can be operated through a control system connected to the regulating valve. The required fracturing fluid loss for each filtration port 1031 is input into the control system, which will automatically calculate the corresponding valve opening based on a preset algorithm and send a control signal to the electric regulating valve to adjust it to the appropriate opening.

[0074] This application can also monitor the filtration loss of fracturing fluid in real time. A flow sensor can be installed at the outlet of each filtration port 1031, and the flow sensor will transmit the real-time monitored filtration loss data to the control system or monitoring equipment.

[0075] If the monitored filtration loss deviates from the preset value, for manually adjustable valves, the valve opening will be manually adjusted again according to the deviation; for electrically adjustable valves, the control system will automatically fine-tune the valve opening according to the deviation to ensure that the filtration loss of fracturing fluid always meets the requirements.

[0076] This application's embodiment solves the problems of coarse filtration simulation and inaccurate variable control in traditional experimental devices by designing an independent filtration port 1031 for filtration control. This makes the study of proppant migration and flowback patterns closer to actual formation conditions and provides a reliable basis for fracturing process optimization.

[0077] In the above Figure 1As shown, this application embodiment also provides a structural schematic diagram of the wellbore module 104 in a proppant reflux experimental apparatus. For example... Figure 3 As shown, the wellbore module 104 also includes multiple perforations 1041, wherein:

[0078] Perforation 1041 is used to adjust the injection rate of the second return fluid.

[0079] In this embodiment of the application, the well module 104 is a tubular structure (such as a horizontal pipe with an inner diameter of 127 mm and a length of 3 m). Multiple perforations 1041 are evenly distributed on the pipe wall, with a spacing of 0.5 m between the perforations 1041. The hole diameter can be designed to be 1 cm, 1.5 cm, or other specifications according to experimental requirements.

[0080] Each perforation 1041 is connected to the replenishment module 107 via an independent pipe, and a flow control device is installed on the pipe to precisely control the flow rate of the second return fluid through a single perforation 1041.

[0081] Calculate the laboratory-scale discharge corresponding to the field return discharge rate based on similarity criteria (such as Reynolds number similarity) (e.g., 60~120 m³ / d in the simulated field corresponds to 0.5~3 L / min in the laboratory), and select an orifice plate that matches the target discharge rate (the larger the orifice diameter, the higher the flow rate).

[0082] When the fluid replenishment module 107 is activated, the second flowback fluid is injected into the wellbore through the orifice plate. The larger the orifice diameter, the more second flowback fluid is injected per unit time, thus achieving flow rate adjustment.

[0083] Simultaneously opening multiple perforations 1041 (such as 3 or 5) increases the total flow area by increasing the number of perforations 1041, thereby increasing the total injection discharge rate of the second return fluid; conversely, closing some perforations 1041 can reduce the discharge rate.

[0084] For example, when simulating low displacement flow, only two perforations 1041 are opened; when simulating high displacement, all five perforations 1041 are opened to achieve graded control of displacement.

[0085] A flow sensor (such as a turbine flow meter) is installed on the independent pipe of each perforation 1041 to monitor the injection flow rate of the second return fluid in real time and transmit the data to the control system.

[0086] When there is a deviation between the actual flow rate and the preset discharge rate, the discharge rate accuracy (error ≤ ±2%) can be ensured by adjusting the orifice diameter (replacing the orifice or adjusting the opening) or the pump speed of the replenishment module 107.

[0087] After the second flowback fluid is injected into the wellbore through the perforation 1041, it mixes with the first flowback proppant-carrying fluid from the simulation module 103 in the wellbore. The adjustment of the flow rate of the perforation 1041 directly affects the flow rate of the mixture and the proppant migration state.

[0088] This application embodiment, through the combination of multiple perforations 1041 and dynamic adjustment, realizes the flexible adjustment of the second backflow fluid injection rate, providing a precise experimental means for simulating multi-crack confluence conditions. Working in conjunction with other modules of the device, it effectively improves the comprehensiveness and reliability of proppant backflow law research.

[0089] In some embodiments, the sand mixing module 101 further includes a sand mixing tank and a stirring device, wherein: the sand mixing tank is used to receive and store fracturing fluid and proppant; and the stirring device is used to mix and stir the fracturing fluid and proppant within the sand mixing tank.

[0090] Specifically, the sand mixing tank is a cylindrical or square sealed container, preferably made of stainless steel to withstand the corrosion of fracturing fluid, and the tank volume is designed according to the experimental scale (e.g., 5L, 10L).

[0091] A fixed amount of base fluid (such as water-based guar gum solution) is injected through the fracturing fluid inlet, and then quartz sand or ceramsite is added through the proppant inlet according to the sand ratio (such as 6% by volume).

[0092] The formula for calculating sand ratio is as follows: (1)

[0093] in For sand ratio, For the volume of the proppant, The volume of fracturing fluid is controlled by volume measurement or weighing to ensure accurate proportioning.

[0094] After mixing, the sand-carrying liquid is transported to the screw module 102.

[0095] This embodiment ensures uniform dispersion of proppant in fracturing fluid through the structured design of the sand mixing tank and the efficient mixing of the stirring device, providing reliable initial conditions for the stable delivery of the subsequent screw module 102 and the sandbank laying of the simulation module 103.

[0096] In some embodiments, the simulation module 103 further includes a plurality of sand flushing ports, wherein the sand flushing ports are used to flush the simulation module 103 after the simulation module 103 delivers the first return sand-carrying fluid to the wellbore module 104.

[0097] The simulation module 103 has 2-4 sand flushing ports at the top and bottom, symmetrically distributed to ensure that the flushing fluid covers the entire cross-section of the crack. The diameter of the sand flushing ports is designed to be 10-20mm, matching commonly used flushing pipelines.

[0098] Depending on the type of residual proppant, select clean water or a flushing solution containing a small amount of surfactant and store it in a flushing solution storage tank.

[0099] This application embodiment achieves efficient removal of residual proppant after the experiment by setting sand flushing ports at the top and bottom of the simulation module 103. This solves the problems of incomplete and time-consuming manual cleaning in traditional devices, ensuring the accuracy of experimental data and the reusability of the device.

[0100] This application also provides a proppant reflux test method, including:

[0101] The fracturing fluid and proppant are received through the sand mixing module 101, and the fracturing fluid and proppant are mixed to obtain the sand-carrying fluid, which is then delivered to the screw module 102.

[0102] In this embodiment, according to the sand ratio designed in the experiment (e.g., 6% or 8% by volume), fracturing fluid (e.g., water-based guar gel with a viscosity of 4m) is injected through the feed inlet of the sand mixing tank. ) and proppant (20 / 40 mesh quartz sand). The sand ratio calculation formula is: (2) Control the proportioning accuracy by volume measurement or weighing method (error ≤ ±0.5%).

[0103] Start the stirring device in the mixing tank until the proppant is evenly dispersed in the fracturing fluid.

[0104] The screw module 102 receives the sand-carrying fluid and delivers it to the simulation module 103 according to a preset discharge rate.

[0105] In this embodiment of the application, the experimental displacement is converted according to similarity criteria (Reynolds number, Froude number). For example, the simulated field displacement of 60 m³ / d corresponds to the laboratory displacement of 15 L / min, and the preset displacement is set through the screw module 102.

[0106] After the screw module 102 is started, when the sand-carrying liquid is delivered to multiple inlets of the simulation module 103, the flow rate is evenly distributed through the valve group to ensure that the injection speed of each inlet is consistent.

[0107] The simulation module 103 receives the proppant-carrying fluid and controls the filtration loss of the fracturing fluid in the proppant-carrying fluid when the fracturing injection stage is started; when the fracturing injection stage is closed, it receives the first flowback fluid delivered by the flowback module 106, mixes the first flowback fluid with the proppant-carrying fluid to obtain the first flowback proppant-carrying fluid, and delivers the first flowback proppant-carrying fluid to the wellbore module 104.

[0108] In this embodiment, the inlet valve of the simulation module 103 is opened and the outlet valve is closed, allowing fracturing fluid to be injected into the fracture from the inlet. Simultaneously, the opening of the independent flow regulating valve 1032 of the fracturing port 1031 is adjusted according to the simulated formation filtration requirements, and the fracturing fluid filtration rate of each fracturing port 1031 is monitored.

[0109] Record the proppant settling process. When the height and length of the sand embankment change by less than 5% within 5 minutes, the sand embankment is considered stable. Close the inlet valve and end the fracturing injection stage.

[0110] Open the outlet valve of simulation module 103 and close the inlet valve. The flowback module 106 injects the first flowback fluid in reverse at a gradually increasing flow rate of 0.5~3L / min. The flowback fluid washes over the sandbank and carries some proppant to form the first flowback sand-carrying fluid, which is then transported to the wellbore module 104 through the outlet.

[0111] The wellbore module 104 receives the first return sand-carrying fluid and the second return fluid delivered by the replenishment module 107. The first return sand-carrying fluid and the second return fluid are mixed to obtain the second return sand-carrying fluid, which is then sent to the filtration module 105.

[0112] In this embodiment, the fluid replenishment module 107 injects a second flowback fluid (simulating other fracture flowback fluids) into the horizontal wellbore through perforations 1041 (1 cm in diameter, 0.5 m in spacing) in the wellbore wall. The injection rate is set according to experimental requirements (e.g., 0.5~2 L / min), and the flow rate is controlled by the combination of the number of perforations 1041 (opening 1~5 perforations 1041) or by adjusting the diameter.

[0113] The first flowback fluid carrying sand mixes with the second flowback fluid inside the wellbore to form the second flowback fluid carrying sand.

[0114] The second return sand-carrying liquid is received through the filter module 105, and the second return sand-carrying liquid is filtered and intercepted to obtain the treated proppant. The sand ratio is calculated from the treated proppant.

[0115] In this embodiment, after the second backflow sand-carrying liquid flows into the filtration module 105, it intercepts proppant particles through an 80-mesh filter screen (0.18 mm aperture).

[0116] Based on the actual mass of the refluxed proppant obtained by weighing, and combined with the total mass of proppant initially added in the experiment, the sand ratio is calculated using the formula: (3), where m is the actual mass of the refluxed proppant and M is the total mass of the proppant.

[0117] This application embodiment achieves full-process simulation of proppant from "mixed sand laying" to "reflow" through precise control and phased operation of each module. Combined with data processing, it provides a scientific experimental basis for the optimization of hydraulic fracturing process.

[0118] In some embodiments, the simulation module 103 further includes a plurality of filtration ports 1031, each filtration port 1031 being provided with an independent flow regulating valve 1032. The method includes: adjusting the opening size of the independent flow regulating valve 1032 through the filtration port 1031, and controlling the filtration loss of fracturing fluid in the proppant-carrying fluid by adjusting the opening size.

[0119] Specifically, based on parameters such as permeability and porosity of the actual formation simulated in the experiment, the target filtration loss of the fracturing fluid in the proppant-carrying fluid during the experiment is calculated using relevant mathematical models or empirical formulas. For example, for a certain low-permeability formation, the target filtration loss of the fracturing fluid in the proppant-carrying fluid is determined to be 5 ml per minute in the initial stage of fracturing injection.

[0120] In the case of manually adjusting valves, based on the target filtration loss and experience accumulated from previous experiments, or the flow rate opening curve of the adjusting valve, manually rotate the knob of the adjusting valve to adjust the independent flow rate regulating valve 1032 of each filtration port 1031 to a preliminary estimated opening. For example, based on experience, to achieve a filtration loss of 5 ml per minute, the opening of the regulating valve of a certain filtration port 1031 may need to be adjusted to 30%, so rotate the regulating valve to the corresponding position.

[0121] In the case of an electric regulating valve, the target filtration rate to be achieved for each filtration port 1031 is input through the control system connected to the electric regulating valve.

[0122] The control system automatically calculates the corresponding valve opening based on a preset algorithm and sends a control signal to the electric regulating valve. Upon receiving the signal, the electric regulating valve automatically adjusts to the appropriate opening. For example, if the control system calculates based on the flow-opening model that to achieve a filtration loss of 5 ml per minute, the regulating valve opening of a certain filtration port 1031 should be 32%, it will control the regulating valve to adjust to an opening of 32%.

[0123] Throughout the experiment, the fracturing fluid loss at each filtration port 1031 was continuously monitored in real time using flow sensors. The monitoring data was recorded for subsequent analysis of the experimental results. For example, the fluid loss data for each filtration port 1031 was recorded every minute.

[0124] This embodiment of the application precisely controls the fracturing fluid loss by adjusting the opening degree of the independent flow regulating valve 1032 of the filter outlet 1031 in the simulation module 103. This precise control helps improve the accuracy and reliability of experimental results, providing more valuable reference for actual fracturing engineering.

[0125] In some embodiments, the wellbore module 104 further includes a plurality of perforations 1041, and the method includes adjusting the injection rate of the second flowback fluid through the perforations 1041.

[0126] Based on the on-site multi-fracture flowback conditions (such as the convergence of 3 fracture clusters and a single fracture flowback rate of 20 m³ / d), the second flowback fluid injection rate at the laboratory scale (such as a target flow rate of 1 L / min) is calculated using similarity criteria (geometric similarity ratio 1:100, flow rate similarity ratio 1:500).

[0127] Based on the parameters of well module 104 (inner diameter 127mm, number of perforations 1041 5, orifice diameter 1cm), the Bernoulli equation is used to calculate the relationship between the flow rate and opening degree of a single perforation 1041, and the initial parameters of each perforation 1041 are determined.

[0128] The number of perforations 1041 opened is controlled by the valve group (e.g., 1 to 5 perforations 1041 are opened), and the total discharge is the discharge of a single perforation 1041 multiplied by the number of openings. For example, when simulating low discharge flow, 2 perforations 1041 are opened (total discharge 0.4 L / min), and when simulating high discharge, 5 perforations 1041 are opened (total discharge 1 L / min).

[0129] The flow rate of the mixed fluid is measured by a flow meter inside the wellbore (e.g., target flow rate of 0.5 m / s). Combined with the first flowback carrying fluid discharge rate (e.g., 1 L / min) and the total discharge rate of the second flowback fluid (e.g., 1.5 L / min), the accuracy of the discharge rate setting for perforation 1041 is verified (error ≤ ±3%).

[0130] When injected at a low flow rate (0.5 L / min), the second flowback fluid slowly flows into the wellbore through perforation 1041 to simulate the low flow rate flowback of the far-well fracture and observe the accumulation morphology of the proppant at the bottom of the wellbore (such as the formation of stable sand dunes).

[0131] During high-flow-rate injection (3L / min), the high-speed jet from the perforation 1041 carries the proppant in suspension and migration, simulating the high-speed backflow of near-wellbore fractures, and studying the effect of critical proppant-carrying velocity on wellbore blockage.

[0132] By setting different discharge rates for perforations 1041 (e.g., 0.3 L / min for the near-end perforation 1041 and 0.2 L / min for the far-end perforation 1041), the uneven backflow caused by permeability differences in various fractures in the field was simulated, and the influence of asymmetric confluence on the proppant convergence path was analyzed.

[0133] This application embodiment achieves precise adjustment of the second backflow fluid injection rate by combining the control of the fixed aperture perforation 1041 with the intelligent adjustment of the dynamically adjustable perforation 1041, providing a flexible and reliable experimental method for studying the proppant migration law under multi-crack confluence conditions.

[0134] In some embodiments, the sand mixing module 101 further includes a sand mixing tank and a stirring device, and the method includes receiving and storing fracturing fluid and proppant through the sand mixing tank.

[0135] The fracturing fluid and proppant in the mixing tank are mixed and stirred using a stirring device.

[0136] Specifically, based on the sand ratio (e.g., 6% or 8% by volume) and total volume (e.g., 10L) of the experimental design, calculate the required fracturing fluid volume (e.g., 9.4L) and proppant volume (e.g., 0.6L), and prepare the corresponding raw materials (e.g., 20 / 40 mesh quartz sand, guar gel fracturing fluid).

[0137] Connect the fracturing fluid inlet of the mixing tank to the fracturing fluid storage tank via a high-pressure hose. Open the valve of the fracturing fluid storage tank and inject the fracturing fluid into the mixing tank using a centrifugal pump or gravity flow. When the tank reaches 80% of the preset volume, reduce the injection rate until the target volume (e.g., 9.4L) is reached to prevent liquid overflow.

[0138] The embodiments of this application ensure uniform mixing of fracturing fluid and proppant through precise feed control of the mixing tank and efficient mixing operation of the stirring device, providing stable initial conditions for proppant reflux experiments.

[0139] In some embodiments, the simulation module 103 further includes a plurality of sand flushing ports, and the method includes flushing the simulation module 103 through the sand flushing ports after the simulation module 103 delivers the first backflow sand-carrying fluid to the wellbore module 104.

[0140] Specifically, the connecting valves between simulation module 103 and screw module 102 and wellbore module 104 are closed to cut off the main flow path and prevent flushing fluid from entering other modules. The flushing port is connected to the flushing fluid storage tank via a high-pressure hose, and the pressure forces the flushing fluid into simulation module 103 from the top flushing port. The flushing fluid flows downward along the fracture, flushing away the proppant remaining on the top and side walls, and the waste fluid is discharged from the bottom flushing port.

[0141] Close the top flush port and switch to the bottom flush port for water intake. Maintain the same pressure and flow rate, allowing the flushing fluid to flow upwards and remove proppant deposits at the bottom and corners of the cracks.

[0142] This application embodiment achieves efficient removal of residual proppant after the experiment by simulating the bidirectional flushing process of the sand flushing port of module 103, solving the problems of incomplete and time-consuming traditional manual cleaning.

[0143] Some modules in the apparatus described in this application can be described in the general context of computer-executable instructions that are executed by a computer, such as program modules. Generally, program modules include routines, programs, objects, components, data structures, classes, etc., that perform a specific task or implement a specific abstract data type. This application can also be practiced in distributed computing environments where tasks are performed by remote processing devices connected via a communication network. In distributed computing environments, program modules can reside in local and remote computer storage media, including storage devices.

[0144] The apparatus or module described in the above embodiments can be implemented by a computer chip or physical entity, or by a product with a certain function. For ease of description, the above apparatus is described by dividing it into various modules according to their functions. When implementing the embodiments of this application, the functions of each module can be implemented in one or more software and / or hardware. Of course, a module that implements a certain function can also be implemented by combining multiple sub-modules or sub-units.

[0145] The methods, apparatus, or modules described in this application can be implemented in a computer-readable program code manner. The controller can be implemented in any suitable manner, such as a microprocessor or processor and a computer-readable medium storing computer-readable program code (e.g., software or firmware) executable by the (micro)processor, logic gates, switches, application-specific integrated circuits (ASICs), programmable logic controllers, and embedded microcontrollers. Examples of controllers include, but are not limited to, the following microcontrollers: ARC 625D, Atmel AT91SAM, Microchip PIC18F26K20, and Silicon Labs C8051F320. A memory controller can also be implemented as part of the control logic of a memory. Those skilled in the art will also recognize that, in addition to implementing the controller in purely computer-readable program code manner, the same functionality can be achieved by logically programming the method steps to make the controller take the form of logic gates, switches, application-specific integrated circuits, programmable logic controllers, and embedded microcontrollers. Therefore, such a controller can be considered a hardware component, and the means included within it for implementing various functions can also be considered as structures within the hardware component. Alternatively, the device used to implement various functions can be viewed as either a software module that implements the method or a structure within a hardware component.

[0146] This application also provides an apparatus, the apparatus comprising: a processor; a memory for storing processor-executable instructions; wherein, when the processor executes the executable instructions, it implements the method described in this application.

[0147] This application also provides a non-volatile computer-readable storage medium storing a computer program or instructions thereon, which, when executed, enables the method described in this application embodiment to be implemented.

[0148] Furthermore, in the various embodiments of the present invention, each functional module can be integrated into a processing module, or each module can exist independently, or two or more modules can be integrated into a single module.

[0149] The aforementioned storage media include, but are not limited to, Random Access Memory (RAM), Read-Only Memory (ROM), Cache, Hard Disk Drive (HDD), or Memory Card. The memory can be used to store computer program instructions.

[0150] As can be seen from the above description of the embodiments, those skilled in the art can clearly understand that this application can be implemented by means of software plus necessary hardware. Based on this understanding, the technical solution of this application, in essence, or the part that contributes to the prior art, can be embodied in the form of a software product, or it can be embodied in the process of data migration. The computer software product can be stored in a storage medium, such as ROM / RAM, magnetic disk, optical disk, etc., and includes several instructions to cause a computer device (which may be a personal computer, mobile terminal, server, or network device, etc.) to execute the methods described in various embodiments or some parts of the embodiments of this application.

[0151] The various embodiments described in this specification are presented in a progressive manner. Similar or identical parts between embodiments can be referred to interchangeably. Each embodiment focuses on its differences from other embodiments. All or part of this application can be used in numerous general-purpose or special-purpose computer system environments or configurations. Examples include: personal computers, server computers, handheld or portable devices, tablet devices, mobile communication terminals, multiprocessor systems, microprocessor-based systems, programmable electronic devices, network PCs, minicomputers, mainframe computers, and distributed computing environments including any of the above systems or devices, etc.

[0152] The above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit this application. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of this application.

Claims

1. A proppant flowback experiment apparatus, characterized in that, The device comprises a sand mixing module, a screw module, a simulation module, a wellbore module and a filtering module connected in sequence, the simulation module is further connected with a flowback module, and the wellbore module is further connected with a liquid supplementing module, wherein: The sand mixing module is used for receiving fracturing fluid and proppants, mixing the fracturing fluid and the proppants, obtaining sand-carrying fluid, and delivering the sand-carrying fluid to the screw module. The screw module is used for receiving sand-carrying fluid and delivering the sand-carrying fluid to the simulation module according to a preset displacement. The flowback module is used for delivering first flowback fluid to the simulation module. The simulation module is used for receiving sand-carrying fluid when a fracturing injection stage is opened, controlling the fluid loss of the fracturing fluid in the sand-carrying fluid, receiving first flowback fluid delivered by the flowback module when the fracturing injection stage is closed, mixing the first flowback fluid with the sand-carrying fluid, obtaining first flowback sand-carrying fluid, and delivering the first flowback sand-carrying fluid to the wellbore module. The liquid supplementing module is used for delivering second flowback fluid to the wellbore module. The wellbore module is used for receiving the first flowback sand-carrying fluid and the second flowback fluid delivered by the liquid supplementing module, mixing the first flowback sand-carrying fluid and the second flowback fluid, obtaining second flowback sand-carrying fluid, and delivering the second flowback sand-carrying fluid to the filtering module. The filtering module is used for receiving the second flowback sand-carrying fluid, filtering and intercepting the second flowback sand-carrying fluid, obtaining processed proppants, and calculating the sand rate of the processed proppants.

2. A proppant flowback experiment apparatus according to claim 1, wherein, The simulation module further comprises a plurality of fluid loss ports, each of which is provided with an independent flow regulating valve, wherein: The fluid loss port is used for adjusting the opening size of the independent flow regulating valve, and controlling the fluid loss of the fracturing fluid in the sand-carrying fluid through the opening size.

3. The proppant flowback experiment apparatus of claim 1, wherein, The wellbore module further comprises a plurality of perforations, wherein: The perforation is used for adjusting the injection displacement of the second flowback fluid.

4. The proppant flowback experiment apparatus of claim 1, wherein, The sand mixing module further comprises a sand mixing tank and a stirring device, wherein: The sand mixing tank is used for receiving and storing the fracturing fluid and the proppants. The stirring device is used for mixing and stirring the fracturing fluid and the proppants in the sand mixing tank.

5. The proppant flowback experiment apparatus of claim 2, wherein, The simulation module further comprises a plurality of sand flushing ports, wherein: The sand flushing port is used for flushing the simulation module after the simulation module delivers the first flowback sand-carrying fluid to the wellbore module.

6. A proppant flowback experiment method characterized by, The method is applied to the proppant flowback experiment device of any one of claims 1-5, and the method comprises: The sand mixing module is used for receiving fracturing fluid and proppants, mixing the fracturing fluid and the proppants, obtaining sand-carrying fluid, and delivering the sand-carrying fluid to the screw module. The screw module is used for receiving sand-carrying fluid and delivering the sand-carrying fluid to the simulation module according to a preset displacement. The flowback module is used for delivering first flowback fluid to the simulation module. The simulation module receives the sand-carrying fluid when the fracturing injection stage is opened, and controls the filtration loss of the fracturing fluid in the sand-carrying fluid; when the fracturing injection stage is closed, the simulation module receives the first flowback fluid delivered by the flowback module, mixes the first flowback fluid with the sand-carrying fluid to obtain first flowback sand-carrying fluid, and delivers the first flowback sand-carrying fluid to the wellbore module; The liquid supplementing module delivers second flowback fluid to the wellbore module; The wellbore module receives the first flowback sand-carrying fluid and the second flowback fluid delivered by the liquid supplementing module, mixes the first flowback sand-carrying fluid with the second flowback fluid to obtain second flowback sand-carrying fluid, and delivers the second flowback sand-carrying fluid to the filtration module; The filtration module receives the second flowback sand-carrying fluid, filters and intercepts the second flowback sand-carrying fluid to obtain treated proppant, and calculates the treated proppant to obtain a sand rate.

7. The method of claim 6, wherein, The simulation module further comprises a plurality of filtration ports, each filtration port being provided with an independent flow regulating valve, and the method comprises: The filtration ports are used to adjust the opening size of the independent flow regulating valves, and the filtration loss of the fracturing fluid in the sand-carrying fluid is controlled by the opening size.

8. The method of claim 6, wherein, The wellbore module further comprises a plurality of perforations, and the method comprises: The perforations are used to adjust the injection rate of the second flowback fluid.

9. The method of claim 6, wherein, The sand mixing module further comprises a sand mixing tank and a stirring device, and the method comprises: The sand mixing tank is used to receive and store the fracturing fluid and the proppant; The stirring device is used to mix and stir the fracturing fluid and the proppant in the sand mixing tank.

10. The method of claim 7, wherein, The simulation module further comprises a plurality of sand flushing ports, and the method comprises: The sand flushing ports are used to flush the simulation module after the simulation module delivers the first flowback sand-carrying fluid to the wellbore module.

Images