High-density crosslinked fracturing fluid viscoelasticity evaluation device

Abstract

The utility model belongs to oil and gas field development technical field discloses a kind of high-density crosslinking fracturing fluid viscoelasticity evaluation device.Support frame has the operating surface extending along horizontal direction, drive mechanism is set to support frame, drive mechanism includes take-up drive and tow rope, take-up drive can reel or release tow rope, test mechanism includes stirring assembly, accommodation pipe and test ball, stirring assembly is set to operating surface, for stirring the fracturing fluid to be measured in accommodation pipe, accommodation pipe is set along vertical direction, and it is equipped with scale along vertical direction, test ball is connected to tow rope, test ball is in release position when tow rope is in taut state, test ball can fall into accommodation pipe under the action of gravity when tow rope is in slack state. Through the above setting, the high-density crosslinking fracturing fluid viscoelasticity evaluation device of the application can analyze the whole process viscoelasticity change of fracturing fluid from base fluid to gelatin.

Description

Technical Field

[0001] This utility model relates to the field of oil and gas field development technology, and in particular to a viscoelasticity evaluation device for high-density cross-linked fracturing fluid. Background Technology

[0002] In the field of unconventional oil and gas resource development, fracturing technology is a core means of improving reservoir permeability and production, and its effectiveness directly determines the production and economics of a single well. As exploration and development extend to ultra-deep formations (well depth > 8000 meters), the extreme temperatures at the bottom of the well (180-260℃) and the complexity of geological conditions increase exponentially, posing performance challenges to fracturing materials. The huge drilling investment in ultra-deep wells (cost exceeding 100 million yuan per well) and the construction risks require fracturing systems to possess temperature resistance stability, sand suspension reliability, and long-term effectiveness. Any sand blockage accident will result in treatment costs several times higher than those of conventional wells.

[0003] For ultra-deep reservoirs, a high-performance, high-temperature weighted crosslinked fracturing fluid system is required. On one hand, a high-temperature resistant thickener-crosslinker synergistic system needs to be designed based on molecular engineering principles. After optimization of the network chain entanglement density and crosslinking point distribution, it can resist chain segment breakage and viscosity decay caused by high temperatures. The system undergoes a dynamic process from base fluid to the formation of a weak gel and then a strong gel after the addition of the crosslinker. Its viscoelastic properties directly affect proppant carrying capacity, fracture propagation, and operational effectiveness. On the other hand, a high-density weighting agent (density > 1.2 g / cm³) needs to be incorporated. 3 This system increases the hydrostatic pressure to balance formation energy while reducing the pump pressure requirements and optimizing equipment load matching through density control. Notably, the addition of weighting agents significantly alters the density and initial viscoelastic properties of the base fluid, increasing the complexity of the crosslinked network phase changes and making its full-process viscoelastic analysis more challenging. These factors necessitate precise control to ensure the stability and proppant-carrying capacity of the fracturing fluid in the high-temperature and ultra-high-temperature environments of deep formations. The core effectiveness of the entire system relies on the construction of a thermally stable, high-strength three-dimensional gel network, whose dynamic viscoelastic characteristics directly control the suspension and transport efficiency of proppant particles within the complex fracture network.

[0004] However, existing methods for evaluating the viscoelasticity of fracturing fluids have the following problems: Flat plate rheometers obtain linear viscoelastic modulus parameters through small-amplitude oscillatory shearing, but the operating window is long, resulting in insufficient timeliness. They cannot analyze the dynamic changes in viscoelasticity based on the crosslinking network changes of the fracturing fluid, and can only analyze the static viscoelasticity of specific stages (such as base fluid or strong gel), failing to monitor dynamic changes during the crosslinking process in real time. The hanging method analyzes viscoelasticity by observing the natural morphology of the gel, but relies on the operator's hanging technique and experience, lacking quantitative characterization dimensions. While it can assess the viscoelasticity of the strong gel stage, it depends on the sample morphology and cannot measure the base fluid or weak gel stage. Furthermore, it cannot establish a thermodynamic viscoelasticity evaluation, making it highly subjective. In addition, existing domestic standards do not cover the viscoelasticity evaluation of the entire fracturing fluid process, especially dynamic testing methods for high-temperature weighted crosslinking systems. These problems prevent rapid analysis of the viscoelastic changes of crosslinked fracturing fluids throughout the entire process of heating and crosslinking, making it difficult to accurately predict the proppant-carrying capacity of fracturing fluids under complex conditions in ultra-deep wells, thus restricting material optimization and process design.

[0005] Therefore, there is an urgent need for a high-density cross-linked fracturing fluid viscoelasticity evaluation device to solve the above-mentioned technical problems. Utility Model Content

[0006] The purpose of this invention is to provide a high-density cross-linked fracturing fluid viscoelasticity evaluation device that can analyze the viscoelasticity changes of fracturing fluid from base fluid to gel in real time and with high accuracy.

[0007] To achieve this objective, the present invention adopts the following technical solution:

[0008] A viscoelasticity evaluation device for high-density cross-linked fracturing fluid, comprising:

[0009] The support frame has a working surface that extends horizontally;

[0010] A drive mechanism is provided on the support frame. The drive mechanism includes a winding / unwinding driver and a traction rope. The winding / unwinding driver is capable of winding up or unwinding the traction rope.

[0011] The testing mechanism includes a stirring assembly, a receiving tube, and a test ball. The stirring assembly is disposed on the working surface and is used to stir the fracturing fluid to be tested in the receiving tube. The receiving tube is arranged vertically and has graduation lines in the vertical direction. The test ball is connected to the traction rope. When the traction rope is in a slack state, the test ball falls into the receiving tube under its own weight. The release and retraction actuator can reset the test ball to the release position through the traction rope.

[0012] Optionally, the drive mechanism further includes a plurality of fixed pulleys, which are spaced apart on the support frame, and the traction rope is wound around the plurality of fixed pulleys along an L-shaped path.

[0013] Optionally, the output end of the retraction driver is connected to one end of the traction rope, and the test ball is detachably connected to the other end of the traction rope.

[0014] Optionally, the stirring assembly includes a stirring driver, a turntable, and multiple blades. The stirring driver is disposed on the support frame, the turntable is placed at the bottom inside the receiving tube, and the multiple blades are spaced apart circumferentially along the turntable. The output end of the stirring driver is connected to the turntable and can drive the turntable to rotate in the vertical direction.

[0015] Optionally, the high-density cross-linked fracturing fluid viscoelasticity evaluation device further includes a heating mechanism, which includes a heating component placed in the receiving tube for heating the fracturing fluid to be tested within the receiving tube.

[0016] Optionally, the heating mechanism further includes a temperature sensor for detecting the temperature of the fracturing fluid to be tested within the accommodating tube and providing temperature control information.

[0017] Optionally, the inner wall of the receiving tube is provided with a drag-reducing coating.

[0018] Optionally, the testing mechanism further includes a buffer pad disposed on the support frame, and the test ball abuts against the buffer pad when it is in the release position.

[0019] Optionally, the side wall of the accommodating tube is connected to an inlet pipe, and the extension direction of the inlet pipe is set at an angle of 20° to 90° with the axial direction of the accommodating tube.

[0020] Optionally, the opening size of the inlet pipe gradually decreases along the vertically downward direction.

[0021] The beneficial effects of this utility model are:

[0022] This invention provides a viscoelasticity evaluation device for high-density cross-linked fracturing fluid, comprising a support frame, a drive mechanism, and a testing mechanism. The support frame has a horizontally extending working surface, which provides stable support and serves as a mounting reference surface for each component, ensuring the overall stability of the device and improving testing accuracy. The drive mechanism is mounted on the support frame and includes a retraction actuator and a traction rope. A test ball is connected to the traction rope, and the retraction actuator can retract or release the traction rope to automatically release and reset the test ball, improving testing efficiency and automation. The testing mechanism includes a stirring assembly, a container tube, and a test ball. The stirring assembly is located on the working surface and is used to stir the fracturing fluid to be tested within the container tube, simulating the mixing process of the fracturing fluid under actual working conditions, ensuring liquid homogeneity, and providing accurate initial conditions for viscoelasticity testing. The container tube is vertically oriented and has graduations along the vertical direction to facilitate user monitoring of the liquid level and density calculation of the fracturing fluid within the container tube. When the traction rope is in a slack state, the test ball falls into the receiving tube under its own weight. The release and retraction actuator can reset the test ball to the release position via the traction rope, so as to facilitate real-time monitoring of the dynamic changes in the crosslinking process. With the above settings, the high-density crosslinked fracturing fluid viscoelasticity evaluation device of this application can analyze the viscoelasticity changes of fracturing fluid from base fluid to gel in real time and accurately. Attached Figure Description

[0023] Figure 1 This is a front view of the high-density cross-linked fracturing fluid viscoelasticity evaluation device provided in this embodiment of the utility model;

[0024] Figure 2 This is a side view of the high-density cross-linked fracturing fluid viscoelasticity evaluation device provided in this embodiment of the utility model;

[0025] Figure 3 This is a top view of the high-density cross-linked fracturing fluid viscoelasticity evaluation device provided in this embodiment of the utility model;

[0026] Figure 4 This is a schematic diagram of the test ball falling according to an embodiment of the present invention;

[0027] Figure 5 This is a top view of a portion of the structure of the stirring assembly provided in this embodiment of the utility model.

[0028] In the picture:

[0029] 1. Support frame; 11. Working surface; 2. Drive mechanism; 21. Retraction driver; 22. Traction rope; 23. Fixed pulley; 3. Testing mechanism; 31. Stirring assembly; 311. Stirring driver; 312. Turntable; 313. Blade; 32. Containing tube; 321. Liquid inlet tube; 33. Test ball; 34. Buffer pad. Detailed Implementation

[0030] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present invention and not intended to limit it. Furthermore, it should be noted that, for ease of description, the accompanying drawings show only the parts relevant to the present invention, not the entire structure.

[0031] In the description of this utility model, unless otherwise explicitly specified and limited, the terms "connected," "linked," and "fixed" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model based on the specific circumstances.

[0032] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0033] In the description of this embodiment, the terms "upper," "lower," "right," etc., refer to the orientation or positional relationship shown in the accompanying drawings. They are used only for ease of description and simplification of operation, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this utility model. In addition, the terms "first" and "second" are only used for distinction in description and have no special meaning.

[0034] In the field of unconventional oil and gas resource development, fracturing technology is a core means of improving reservoir permeability and production, and its effectiveness directly determines the production and economics of a single well. As exploration and development extend to ultra-deep formations (well depth > 8000 meters), the extreme temperatures at the bottom of the well (180-260℃) and the complexity of geological conditions increase exponentially, posing performance challenges to fracturing materials. The huge drilling investment in ultra-deep wells (cost exceeding 100 million yuan per well) and the construction risks require fracturing systems to possess temperature resistance stability, sand suspension reliability, and long-term effectiveness. Any sand blockage accident will result in treatment costs several times higher than those of conventional wells.

[0035] For ultra-deep reservoirs, a high-performance, high-temperature weighted crosslinked fracturing fluid system is required. On one hand, a high-temperature resistant thickener-crosslinker synergistic system needs to be designed based on molecular engineering principles. After optimization of the network chain entanglement density and crosslinking point distribution, it can resist chain segment breakage and viscosity decay caused by high temperatures. The system undergoes a dynamic process from base fluid to the formation of a weak gel and then a strong gel after the addition of the crosslinker. Its viscoelastic properties directly affect proppant carrying capacity, fracture propagation, and operational effectiveness. On the other hand, a high-density weighting agent (density > 1.2 g / cm³) needs to be incorporated. 3 This system increases the hydrostatic pressure to balance formation energy while reducing the pump pressure requirements and optimizing equipment load matching through density control. Notably, the addition of weighting agents significantly alters the density and initial viscoelastic properties of the base fluid, increasing the complexity of the crosslinked network phase changes and making its full-process viscoelastic analysis more challenging. These factors necessitate precise control to ensure the stability and proppant-carrying capacity of the fracturing fluid in the high-temperature and ultra-high-temperature environments of deep formations. The core effectiveness of the entire system relies on the construction of a thermally stable, high-strength three-dimensional gel network, whose dynamic viscoelastic characteristics directly control the suspension and transport efficiency of proppant particles within the complex fracture network.

[0036] However, existing methods for evaluating the viscoelasticity of fracturing fluids have the following problems: Flat plate rheometers obtain linear viscoelastic modulus parameters through small-amplitude oscillatory shearing, but the operating window is long, resulting in insufficient timeliness. They cannot analyze the dynamic changes in viscoelasticity based on the crosslinking network changes of the fracturing fluid, and can only analyze the static viscoelasticity of specific stages (such as base fluid or strong gel), failing to monitor dynamic changes during the crosslinking process in real time. The hanging method analyzes viscoelasticity by observing the natural morphology of the gel, but relies on the operator's hanging technique and experience, lacking quantitative characterization dimensions. While it can assess the viscoelasticity of the strong gel stage, it depends on the sample morphology and cannot measure the base fluid or weak gel stage. Furthermore, it cannot establish a thermodynamic viscoelasticity evaluation, making it highly subjective. In addition, existing domestic standards do not cover the viscoelasticity evaluation of the entire fracturing fluid process, especially dynamic testing methods for high-temperature weighted crosslinking systems. These problems prevent rapid analysis of the viscoelastic changes of crosslinked fracturing fluids throughout the entire process of heating and crosslinking, making it difficult to accurately predict the proppant-carrying capacity of fracturing fluids under complex conditions in ultra-deep wells, thus restricting material optimization and process design.

[0037] Therefore, there is an urgent need for a high-density cross-linked fracturing fluid viscoelasticity evaluation device to solve the above-mentioned technical problems.

[0038] like Figures 1-5As shown, this embodiment provides a viscoelasticity evaluation device for high-density cross-linked fracturing fluid, which includes a support frame 1, a drive mechanism 2, and a testing mechanism 3. The support frame 1 has a working surface 11 extending horizontally. The drive mechanism 2 is disposed on the support frame 1 and includes a winding / unwinding driver 21 and a traction rope 22. The winding / unwinding driver 21 can wind up or unwind the traction rope 22. The testing mechanism 3 includes a stirring assembly 31, a receiving tube 32, and a test ball 33. The stirring assembly 31 is disposed on the working surface 11 and is used to stir the fracturing fluid to be tested in the receiving tube 32. The receiving tube 32 is arranged vertically and has scale lines in the vertical direction. The test ball 33 is connected to the traction rope 22. When the traction rope 22 is in a slack state, the test ball 33 falls into the receiving tube 32 under its own weight. The winding / unwinding driver 21 can reset the test ball 33 to the release position through the traction rope 22.

[0039] In this embodiment, the support frame 1 has a working surface 11 extending horizontally. The working surface 11 provides stable support and serves as a mounting reference surface for each component, thereby ensuring the stability of the overall structure of the device and improving the accuracy of the test. The drive mechanism 2 is mounted on the support frame 1 and includes a winding / unwinding driver 21 and a traction rope 22. The test ball 33 is connected to the traction rope 22. The winding / unwinding driver 21 can wind up or unwind the traction rope 22 to achieve automatic release and reset of the test ball 33, improving testing efficiency and automation. The test mechanism 3 includes a stirring assembly 31, a receiving tube 32, and a test ball 33. The stirring assembly 31 is mounted on the working surface 11 and is used to stir the fracturing fluid to be tested in the receiving tube 32, thereby simulating the mixing process of the fracturing fluid under actual working conditions, ensuring liquid homogeneity, and providing accurate initial conditions for viscoelastic testing. The receiving tube 32 is arranged vertically and has graduations along the vertical direction to facilitate user monitoring of the liquid level and density calculation of the fracturing fluid to be tested in the receiving tube 32. When the traction rope 22 is in a slack state, the test ball 33 falls into the receiving tube 32 under its own weight. The release driver 21 can reset the test ball 33 to the release position through the traction rope 22, so as to monitor the dynamic changes of the crosslinking process in real time. With the above settings, the high-density crosslinked fracturing fluid viscoelasticity evaluation device of this embodiment can analyze the viscoelasticity changes of the fracturing fluid from the base fluid to the gel in real time and accurately.

[0040] The specific structure of the high-density cross-linked fracturing fluid viscoelasticity evaluation device is described below:

[0041] Specifically, in this embodiment, the overall height of the support frame 1 is 1.6m to meet testing requirements. The support frame 1 includes a support plate and support rods. The support plate measures 1300×960×50mm to provide a sufficient working surface 11. The support plate has multiple legs to achieve the balance and shock absorption functions of the device. The support rods are L-shaped and are positioned on the working surface 11 to form an overall support structure. The specific structure of the support rods is not specified here.

[0042] The support legs can be four or eight, and no further restrictions are imposed here.

[0043] Specifically, the drive mechanism 2 also includes multiple fixed pulleys 23, which are spaced apart on the support frame 1. The traction rope 22 is wound around the multiple fixed pulleys 23 along an L-shaped path, thereby optimizing the tension path of the traction rope 22, ensuring the smooth movement of the traction rope 22, and saving space.

[0044] More specifically, in this embodiment, the traction rope 22 is an aramid fiber core steel wire rope (4.2m in length, 1-2mm in diameter), which has high strength and low elongation, ensuring the accuracy of the movement of the test ball 33. In other embodiments, the traction rope 22 may also be made of nylon fiber rope, thus providing different strength and flexibility options.

[0045] Specifically, the output end of the retraction driver 21 is connected to one end of the traction rope 22, and the test ball 33 is detachably connected to the other end of the traction rope 22 to facilitate the replacement and maintenance of the test ball 33.

[0046] More specifically, in this embodiment, the retraction driver 21 is an electromagnetic drum, the output end of which is connected to one end of the traction rope 22, thereby realizing the automatic release and reset of the test ball 33. This improves testing efficiency and automation, avoiding errors and inconvenience caused by manual operation. In this embodiment, the test ball 33 is a steel ball (5mm in diameter, 80g in weight) connected to the other end of the traction rope 22 via an insert-type buckle, thus enabling quick replacement of the test ball 33 and reliable connection. In other embodiments, the test ball 33 can also be connected to the traction rope 22 via a detachable method such as a snap-fit. It should be noted that those skilled in the art are familiar with the specific structure and working principle of the electromagnetic drum, and will not elaborate further here.

[0047] Specifically, during the test, when the electromagnetic drum was de-energized, the wire rope was unrestrained and in a relaxed state, and the steel ball was released from a position 11.3 meters above the working surface (effective drop height) and then fell freely, causing the drum inside the electromagnetic drum to rotate clockwise; while when the electromagnetic drum was energized, the drum could rotate at 1 m / s 2The acceleration rotates counterclockwise to wind up the steel wire rope, lifting the steel ball to the release position with a reset accuracy of ≤0.5mm. In this process, electromagnetic control automates the test cycle. Each test cycle includes a free-fall impact phase with the steel ball and a motor-driven reset phase, ensuring the accuracy and repeatability of the test process and avoiding test errors and inefficiencies caused by manual operation.

[0048] The take-up and take-off driver 21 can be either a DC motor or an AC motor to adapt to different testing requirements. The test ball 33 can be a steel ball or a ceramic ball. Operators can select test balls 33 of different materials according to testing requirements to adapt to different testing conditions, which will not be explained in detail here.

[0049] Specifically, the stirring assembly 31 includes a stirring driver 311, a turntable 312, and multiple blades 313. The stirring driver 311 is mounted on the support frame 1, the turntable 312 is placed at the bottom inside the containment tube 32, and the multiple blades 313 are spaced apart along the circumference of the turntable 312. The output end of the stirring driver 311 is connected to the turntable 312, which can drive the turntable 312 to rotate in the vertical direction. With the above configuration, after adding functional additives such as crosslinking agents to the containment tube 32, it is possible to achieve thorough mixing, eliminate the internal stress of the test ball 33, ensure the uniformity of the temperature field of the test fluid, and simulate the shear environment.

[0050] More specifically, in this embodiment, the stirring driver 311 is a stepper motor, and the bottom of the turntable 312 has a groove for detachable connection to the output shaft of the stepper motor, facilitating the disassembly and maintenance of each component. The blades 313 are welded to the turntable 312 to ensure the stability and durability of the stirring assembly 31. With the above configuration, this device can provide stepless speed regulation stirring function from 0 to 3000 rpm. In other embodiments, the stirring driver 311 can also be a servo motor; this will not be discussed in detail here, as long as the above functions can be achieved.

[0051] More specifically, in this embodiment, the top view of the blade 313 is crescent-shaped, so that after the crosslinking agent is added to the receiving tube 32, the rotation of the blade 313 can achieve thorough mixing, thereby eliminating the internal stress generated when the test ball 33 falls into the receiving tube 32. Moreover, the diameter of the turntable 312 is 60mm, and there are three blades 313. The three blades are evenly distributed on the turntable 312 along the circumference of the circular turntable 312. The chord length of the blades 313 is 50mm, which can optimize the stirring effect and ensure uniform mixing of the liquid. The specific dimensions of the above components are not limited here.

[0052] In addition, a 5mm thick nitrile rubber protective pad is bonded to the top of the turntable 312 to reduce the impact energy of the test ball 33 falling, and to protect the turntable 312 and the blade 313 from damage due to impact.

[0053] Specifically, the high-density cross-linked fracturing fluid viscoelasticity evaluation device also includes a heating mechanism, which includes a heating component placed in the containment tube 32 for heating the fracturing fluid to be tested in the containment tube 32, thereby achieving precise temperature control of the fracturing fluid to be tested, ensuring the stability and repeatability of the test conditions, and avoiding test errors caused by temperature changes.

[0054] More specifically, in this embodiment, the heating assembly includes a nickel-chromium alloy heating wire, and the blade 313 is provided with a hollow cavity for accommodating the nickel-chromium alloy heating wire. Through the above arrangement, the temperature control and shearing effect of the fracturing fluid to be tested can be realized, and it is beneficial to construct a heat conduction channel.

[0055] Specifically, the heating mechanism also includes a temperature sensor, which is used to detect the temperature of the fracturing fluid to be tested in the containment tube 32 and provide temperature control information (such as a microcontroller or PLC). The temperature control information can control the operation of the heating component, thereby achieving a temperature range of -20 to 220℃ and a temperature control accuracy of ±0.1℃. Moreover, through the coordinated cooperation of the heating mechanism and the testing mechanism 3, the uniformity of the temperature field of the fracturing fluid to be tested is ensured.

[0056] Specifically, the receiving tube 32 has a structural dimension of 0.8m in height, 80mm in inner diameter, and 20mm in wall thickness, and is made of high borosilicate glass, which has good transparency and high temperature resistance. The inner wall of the receiving tube 32 is coated with a drag-reducing coating. This drag-reducing coating is made of fluoroplastic to eliminate the tube wall effect. The outer wall of the receiving tube 32 has vertically extending graduations (the graduation range is 0–750mm, with a scale division of 0.5mm) to facilitate liquid level monitoring and to calculate the fracturing fluid density based on the rate of liquid level change, volume, and mass.

[0057] Specifically, the testing mechanism 3 also includes a buffer pad 34, which is disposed on the support frame 1. When the test ball 33 is in the release position, it abuts against the buffer pad 34, which can effectively absorb the impact energy of the test ball 33 during the reset and lifting process, protect the components of the device, and extend its service life. The buffer pad 34 can be a silicone pad or a rubber pad, which will not be described in detail here, as long as it can achieve the above-mentioned functions.

[0058] Specifically, the side wall of the container tube 32 is connected to an inlet pipe 321. The extension direction of the inlet pipe 321 is set at an angle of 20° to 90° with the axial direction of the container tube 32 to meet the requirements of quantitative addition rate of additives into the container tube 32.

[0059] More specifically, the opening size of the inlet pipe 321 gradually decreases in the vertically downward direction to ensure a smooth inflow of additives and reduce splashing.

[0060] It should be noted that the high-density cross-linked fracturing fluid viscoelasticity evaluation device provided in this embodiment can achieve a leap from "offline static, discontinuity-based evaluation" to "online dynamic, full-process evaluation". It uses the "improved falling ball impact method" to dynamically capture the viscoelastic changes in the cross-linking process of fracturing fluid without complex calculations. It covers the full-cycle dynamic viscoelasticity evaluation of fracturing fluid from base fluid mixing, weak cross-linked gel formation, gel network strengthening, proppant carrying, and under different temperature shear conditions. It fills the gap of traditional methods that can only perform static or limited dynamic viscoelasticity evaluation, thereby improving the timeliness, comprehensiveness, and process guidance of the evaluation. It provides data feedback for fracturing fluid formulation optimization and proppant carrying fluid ratio adjustment, which is conducive to improving the engineering applicability and decision support of the evaluation results.

[0061] In addition, when using the high-density cross-linked fracturing fluid viscoelasticity evaluation device, users base their testing on the following approach: the dwell time t of the test ball 33 in the fracturing fluid under test is used as the benchmark. stop (i.e., t1, t2, t3, t in the following text) 2’ t 3’ ...) is the core parameter, determined by the stopping time t stop The ratio R to the reference time t0 of the Newtonian fluid (i.e., R = t) stop The viscoelastic changes were divided into 10 stages ( / t0). Each stage corresponds to a specific tanδ range and fluid behavior characteristics, thus achieving continuous characterization of the fracturing fluid from the base fluid to the cross-linked strengthening fluid. At the same time, combined with the sand-carrying test, the sand-carrying capacity of the fracturing fluid was systematically evaluated.

[0062] The working process of the high-density cross-linked fracturing fluid viscoelasticity evaluation device is explained below:

[0063] Step 1: Prepare a reference Newtonian fluid: The following test procedure uses glycerol as a Newtonian fluid, which can provide a standard viscoelastic reference point to ensure the accuracy and comparability of the test results;

[0064] Step 2: Prepare the materials for the fracturing fluid to be tested: Prepare 5 kg of 0.45% hydroxypropyl guar gum solution, 1 kg of organoboron crosslinking agent, and 1 kg of organic base pH adjuster to ensure the standardization and repeatability of the test and avoid deviations in test results due to inconsistent formulations.

[0065] Step 3: Determine the volume of leaf 313: Pour a known volume V0 (mL) of purified water into a clean and dry container 32 to submerge leaf 313, record the initial liquid level reading h0 (cm), and calculate the volume V of leaf 313. jiang :

[0066] V jiang =π×4 2 ×h0-V0;

[0067] By calibrating the volume of the blade 313, the accuracy of the stirring assembly 31 in the test is ensured, and deviations in the stirring effect caused by the uncertainty of the volume of the blade 313 are avoided.

[0068] Step 4: Determine the density of glycerol: Under constant temperature conditions of 25℃±0.1℃, weigh 3000.00g of spectroscopically pure glycerol sample using an analytical balance (accuracy 0.01g) and record the mass m. G Then pour the glycerin into the container 32, and read the scale value h after the liquid level stabilizes. g (cm), and calculate the density ρ of glycerol. g ,in:

[0069]

[0070] Then, the measured density of glycerol was compared with the standard value (i.e., the density of glycerol at 25℃, 1.2613 g / cm³). 3 The comparison is allowed with a deviation range of ≤0.2% to ensure the accuracy of the reference fluid and to verify the accuracy of the density measurement by this device;

[0071] Step 5: Determine the stopping time of the test ball 33 in glycerin: Press the power-off switch of the retraction drive 21 (electromagnetic drum), and the test ball 33 falls from the release position. Measure and record the time t0 from the contact of the test ball 33 with the liquid surface to complete stopping, so as to calculate the viscoelastic ratio value later. Then press the power-on switch of the retraction drive 21, and the test ball 33 is lifted back to the release position. The glycerin is poured out, and the container tube 32 is cleaned and dried.

[0072] Step Six: Determine the density of the base solution: Under constant temperature conditions of 25℃±0.1℃, weigh 3000.00g of the prepared hydroxypropyl guar gum solution using an analytical balance (accuracy 0.01g), record the mass m1, and then pour a 0.45% hydroxypropyl guar gum solution into the container tube 32 through the open end of the inlet tube 321 to form the base solution. After the liquid level stabilizes, read the scale value h1 (cm) and calculate the density ρ1 of the base solution.

[0073]

[0074] In this process, by measuring the density of the base fluid, the initial state of the fracturing fluid to be tested is ensured to be accurate, thus avoiding subsequent testing errors caused by inaccurate base fluid density.

[0075] It should be noted that in this embodiment, the base fluid refers to a 0.45% hydroxypropyl guar gum solution, while the fracturing fluid to be tested refers to a solution formed by adding functional additives such as crosslinking agents and pH adjusters to the base fluid. Moreover, after the addition of the crosslinking agent, the base fluid will undergo crosslinking, gradually changing from a base fluid state to a weak gel, and then to a strong gel state.

[0076] Step 7: Determine the stopping time of the test ball 33 in the base liquid: Press the power-off switch of the take-up and release driver 21, and the test ball 33 falls from the release position. Measure and record the time t1 from the contact of the test ball 33 with the liquid surface to complete stop. Then press the power-on switch of the take-up and release driver 21, and the electromagnetic drum can rewind at 1 m / s. 2 The acceleration reverses the coiling motion, thereby lifting the test ball 33 to the release position.

[0077] Step 8: Determine the stopping time of the test ball 33 in the crosslinked fracturing fluid (without sand): Add 0.3% volume concentration of crosslinking agent and 0.1% volume concentration of pH adjuster from the opening end of the inlet pipe 321 using a syringe, start the stirring assembly 31, and start stirring at a speed of 300r / min. Stir for 5 seconds at regular intervals to ensure that the crosslinking agent and pH adjuster are evenly dispersed. Simultaneously, the heating element is activated, and the temperature is controlled to rise at a rate of 5℃ / min. Then, the test ball 33 is released, and the time t2 from contact with the liquid surface to complete cessation is recorded. The test ball 33 is then reset. Stirring is repeated for 5 seconds to eliminate drop stress, followed by a 2-second settling period to allow the fluid to return to hydrostatic equilibrium. The test ball 33 is then dropped again, and the time t3 from contact with the liquid surface to complete cessation is recorded. This test procedure is repeated (specifically, releasing the test ball 33, waiting for it to completely stop, resetting the test ball 33, stirring for 5 seconds, and settling for 2 seconds), for a total test duration of 10 minutes. The test frequency is approximately once every 15 seconds (including the test ball 33 reset time), with a theoretical test count of 40 times, resulting in multiple sets. It is understandable that by measuring the stopping time of the test ball 33 in the crosslinked fracturing fluid and dynamically monitoring the viscoelastic changes during the crosslinking process, test errors caused by uneven crosslinking can be avoided.

[0078] Step 9: Calculate the ratio R of the stopping time of test ball 33 in the fracturing fluid to the stopping time of test ball 33 in glycerol. t :

[0079]

[0080] Then, based on the calculated time ratio R... t In "tanδ-R" t The "Value Correlation Stage Division Table (Fracturing Fluid Viscoelasticity Evaluation)" determines the stage and tanδ range of the viscoelastic properties of the fracturing fluid under test (where δ is the phase angle, and tanδ is defined as the ratio of the loss modulus (G”) to the storage modulus (G’) of the material under dynamic load; when tanδ < 1, the material is mainly elastic; when tanδ > 1, the material is mainly viscous). This is determined by R... t The value is divided into stages, indirectly reflecting the change in tanδ, and the number of stages can be increased or decreased according to needs:

[0081] Phase [RC t range]] tan delta range Viscoelastic properties 1 [R t >0.95]]> tan delta > 10 Purely viscous fluid 2 0.80 < R < 0.95 t 0.80 < R < 0.95 1 < tan delta < 10 Weakly viscoelastic (viscosity dominated) 3 0.60 < R < 0.80 t 0.60 < R < 0.80 0.5 < tan delta < 1 Medium viscoelasticity 4 0.40 < R < 0.60 t ≤0.60]]> 0.2 < tan delta < 0.5 Stronger viscoelasticity 5 0.30 < R < 0.40 t ≤0.40]]> 0.1 < tan delta < 0.2 High viscoelasticity (near gel state) 6 0.20 < R t ≤ 0.30 0.05 < tan delta < 0.1 Weak gel state 7 0.15 < R t ≤ 0.20 0.02 < tan delta < 0.05 Medium strength gel 8 0.10 < R t ≤ 0.15 0.01 < tan delta < 0.02 Strong gel state 9 0.05 < R t ≤ 0.10 0.005 < tan delta < 0.01 Strong gel state 10 [R t ≤0.05]]> tan delta < 0.005 Purely elastic solid

[0082] tanδ-R t Value-related stage division table (evaluation of fracturing fluid viscoelasticity)

[0083] Step 10: Determine the stopping time of test ball 33 in the crosslinked fracturing fluid (with added sand): Add 0.3% (v / v) crosslinking agent and 0.1% (v / v) pH adjuster to the opening of inlet pipe 321 using a syringe. Start the stirring assembly 31 at a speed of 300 r / min and stir for 5 seconds at intervals to ensure uniform dispersion of the crosslinking agent and pH adjuster. Simultaneously turn on the heating assembly and control the temperature rise at a rate of 5℃ / min. Then release test ball 33 and record the time t from contact with the liquid surface to complete stopping. 2’ Then, test ball 33 is reset. A 40-70 mesh 25% mass concentration (which can be set according to the process design) proppant (such as quartz sand or ceramsite of different mesh sizes) is slowly added to the receiving tube 32 through a sand-adding funnel. The rotation speed of the stirring assembly 31 is increased to 1500 r / min, and the mixture is stirred for 5 seconds to ensure uniform sand dispersion. Then, a 2-second delay is allowed for the fluid to return to hydrostatic equilibrium, and test ball 33 falls again. The time t from contact with the liquid surface to complete cessation of the test ball 33 is recorded. 3’ Repeat the above test steps (specifically including releasing test ball 33, waiting for test ball 33 to completely stop, resetting test ball 33, stirring for 5 seconds, and allowing it to stand for 2 seconds), for a total test duration of 10 minutes, with a test frequency of approximately once every 15 seconds (including reset time), and a theoretical number of tests of 40. It is understandable that by adding proppant and measuring the stopping time of test ball 33, the effect of proppant addition on the viscoelasticity of fracturing fluid is evaluated, avoiding test errors caused by uneven proppant addition.

[0084] Step 11: Calculate viscoelasticity (the technical principle is the same as in Step 9, and will not be repeated here). Then, determine the viscoelasticity stage and tanδ range of the cross-linked fracturing fluid (with added sand) to be tested according to the table, and analyze the influence of sand addition on viscoelasticity.

[0085] Step 12, Test sand-carrying capacity: In critical stages (such as tanδ-R) tDifferent sand ratios (10%, 15%, 20%, 25%, 30%) of 40-70 mesh sand were added to the fracturing fluid in stages 5, 7, and 9 of the value correlation stage division table. The sand settling velocity and distribution uniformity were observed, and the sand drop rate per 1 minute was recorded. The earliest stage with a sand drop rate of less than 5% was selected as the sand addition timing (e.g., stage 5). Within the target stage, the sand concentration was gradually increased to the critical point where the sand drop rate equaled 5%, and the maximum allowable sand ratio was recorded as the design upper limit (e.g., 25% sand ratio for stage 5). It can be understood that the appropriate sand ratio for a given stage or time is evaluated by the sand drop rate observed at different sand concentrations, and this result is used to correspond to the sand addition timing during ultra-deep well construction.

[0086] Step 13, Results Output (including base fluid density, viscoelasticity at different times, optimal sand addition time, and appropriate sand concentration): Fracturing fluid base fluid density 1.236 g / cm³ 3 After adding the crosslinking agent, the liquid viscoelasticity is in stage 1 (tanδ > 10) after 10 seconds, stage 2 (1 ≤ tanδ ≤ 10) after 25 seconds, stage 5 (0.2 ≤ tanδ ≤ 0.5) after 40 seconds, and stage 6 (0.05 ≤ tanδ ≤ 0.1) after 55 seconds. In stage 5, 40-70 mesh sand with a volume concentration of 25% is added. The sand drop rate is 5% per minute, and this is recorded as 55 seconds after adding the crosslinking agent. The maximum sand concentration is 25%.

[0087] Obviously, the above embodiments of this utility model are merely examples for clearly illustrating the present utility model, and are not intended to limit the implementation of the present utility model. Those skilled in the art can make various obvious changes, readjustments, and substitutions without departing from the protection scope of this utility model. It is neither necessary nor possible to exhaustively describe all embodiments here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this utility model should be included within the protection scope of the claims of this utility model.

Claims

1. A viscoelasticity evaluation device for high-density cross-linked fracturing fluid, characterized in that, include: The support frame (1) has a working surface (11) extending in the horizontal direction; A drive mechanism (2) is provided on the support frame (1). The drive mechanism (2) includes a winding and unwinding driver (21) and a traction rope (22). The winding and unwinding driver (21) is capable of winding or unwinding the traction rope (22). The testing mechanism (3) includes a stirring assembly (31), a container tube (32), and a test ball (33). The stirring assembly (31) is set on the working surface (11) and is used to stir the fracturing fluid to be tested in the container tube (32). The container tube (32) is set in the vertical direction and has scale lines in the vertical direction. The test ball (33) is connected to the traction rope (22). When the traction rope (22) is in a slack state, the test ball (33) falls into the container tube (32) under its own weight. The release and take-up driver (21) can reset the test ball (33) to the release position through the traction rope (22).

2. The high-density cross-linked fracturing fluid viscoelasticity evaluation device according to claim 1, characterized in that, The drive mechanism (2) also includes a plurality of fixed pulleys (23), which are spaced apart on the support frame (1), and the traction rope (22) is wound around the plurality of fixed pulleys (23) along an L-shaped path.

3. The high-density cross-linked fracturing fluid viscoelasticity evaluation device according to claim 1, characterized in that, The output end of the retraction driver (21) is connected to one end of the traction rope (22), and the test ball (33) is detachably connected to the other end of the traction rope (22).

4. The high-density cross-linked fracturing fluid viscoelasticity evaluation device according to claim 1, characterized in that, The stirring assembly (31) includes a stirring driver (311), a turntable (312), and multiple blades (313). The stirring driver (311) is disposed on the support frame (1). The turntable (312) is placed at the bottom inside the receiving tube (32). The multiple blades (313) are arranged at intervals along the circumference of the turntable (312). The output end of the stirring driver (311) is connected to the turntable (312) and can drive the turntable (312) to rotate in the vertical direction.

5. The high-density cross-linked fracturing fluid viscoelasticity evaluation device according to claim 1, characterized in that, The high-density cross-linked fracturing fluid viscoelasticity evaluation device also includes a heating mechanism, which includes a heating component placed in the accommodating tube (32) for heating the fracturing fluid to be tested in the accommodating tube (32).

6. The high-density cross-linked fracturing fluid viscoelasticity evaluation device according to claim 5, characterized in that, The heating mechanism also includes a temperature sensor, which is used to detect the temperature of the fracturing fluid to be tested in the accommodating tube (32) and provide temperature control information.

7. The high-density cross-linked fracturing fluid viscoelasticity evaluation device according to claim 1, characterized in that, The inner wall of the receiving tube (32) is provided with a drag-reducing coating.

8. The high-density cross-linked fracturing fluid viscoelasticity evaluation device according to claim 1, characterized in that, The testing mechanism (3) also includes a buffer pad (34), which is disposed on the support frame (1), and the test ball (33) abuts against the buffer pad (34) when it is in the release position.

9. The high-density cross-linked fracturing fluid viscoelasticity evaluation device according to any one of claims 1-8, characterized in that, The side wall of the accommodating tube (32) is connected to an inlet tube (321), and the extension direction of the inlet tube (321) is set at an angle of 20° to 90° with the axial direction of the accommodating tube (32).

10. The high-density cross-linked fracturing fluid viscoelasticity evaluation device according to claim 9, characterized in that, The opening size of the liquid inlet pipe (321) gradually decreases along the vertically downward direction.

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