A method, device and equipment for predicting the performance of a fracturing fluid through a pore

Abstract

The application provides a method, device and equipment for predicting the perforation performance of a fracturing fluid. The method injects the fracturing fluid to be tested into a closed loop circulation test system, the main pipeline of the test section of the system is consistent with the size of the mine casing, and the perforation parameters of the perforation plate are consistent with the actual conditions of the mine. First, the bypass loop is opened for pre-circulation until the fluid is stable, and then the test section is switched to make the fluid flow through the perforation hole. After the flow rate and pressure are stable, samples are taken synchronously upstream and downstream of the perforation plate, the viscosities before and after the perforation are measured respectively, and the viscosity loss rate is calculated. The above process is repeated by adjusting the experimental conditions to obtain the viscosity loss rate under multiple conditions, so as to determine the change rule of the perforation performance of the fracturing fluid to be tested under different conditions and improve the accuracy of the prediction result.

Description

Technical Field

[0001] This application relates to the field of oil and gas field fracturing fluid performance testing technology, and in particular to a method, apparatus and equipment for predicting the perforation performance of fracturing fluid. Background Technology

[0002] In shale oil horizontal well volumetric fracturing operations, fracturing fluid enters the formation at high speed from the wellbore through perforations, undergoing extremely high shear and stretching flows. This leads to polymer molecular chain breakage and viscosity reduction, affecting proppant carrying capacity and stimulation effectiveness. In actual operations, the fracturing fluid needs to pass through the perforation multiple times and contains a high concentration of proppant, further exacerbating viscosity loss.

[0003] The relevant technologies mainly employ rotational viscometers and capillary rheometers to apply pure shear fields to measure rheological parameters, and small-scale orifice simulation devices with advection pump displacement systems to complete a single pure liquid phase flow in the scaled-down orifice. In addition, a high-speed stirring degradation simulation device can be used to apply continuous shear to the fracturing fluid with a constant-speed stirring paddle and then detect the viscosity.

[0004] However, the devices and methods for predicting the fracturing fluid perforation performance of related technologies cannot accurately reproduce the flow conditions of the perforation in the mine, simulate the cumulative shear effect and sand-bearing conditions, and the accuracy of the prediction results is low. Summary of the Invention

[0005] This application provides a method, apparatus, and device for predicting the perforation performance of fracturing fluid, which addresses the technical problem of low accuracy in prediction results in related technologies.

[0006] In a first aspect, embodiments of this application provide a method for predicting the perforation performance of fracturing fluid, comprising:

[0007] During the testing of the fracturing fluid to be tested, upstream and downstream samples of the fracturing fluid to be tested are obtained under multiple experimental conditions in the same test section; different experimental conditions are used at least for the orifice plate indicating different orifice geometric parameters in the test section; upstream samples are taken from upstream of the orifice plate, and downstream samples are taken from downstream of the orifice plate; the test section is used to simulate wellbore orifices;

[0008] For each experimental condition, the viscosity loss rate is calculated based on the viscosity of the upstream sample before the through-hole and the viscosity of the downstream sample after the through-hole.

[0009] Based on the viscosity loss rate, the variation law of the perforation performance of the fracturing fluid under different experimental conditions was determined.

[0010] This application provides a method for predicting the perforation performance of fracturing fluid. By using a main pipeline with the same size as the casing in the mining area and an orifice plate with the same perforation parameters, the tensile-shear composite flow characteristics of downhole fluid entering the orifice from a large cross section are reproduced with high fidelity. A pre-circulation process is performed using a bypass loop to effectively avoid flow field disturbances during the pipeline start-up phase, ensuring the stability of fracturing fluid performance before perforation. Furthermore, by simultaneously sampling upstream and downstream of the orifice plate, the viscosity natural recovery error caused by sampling time difference is reduced, ensuring the effectiveness of viscosity comparison before and after perforation. In addition, multiple sets of viscosity loss rate data under different displacement, orifice parameters, and sand-bearing conditions are obtained through multi-condition cyclic testing, fully covering all variables in mining operations. This solves the technical problem that related fracturing fluid perforation performance prediction devices and methods cannot accurately reproduce the flow conditions of mining perforations, simulate cumulative shear effects, and sand-bearing conditions, thereby improving the accuracy of perforation performance prediction.

[0011] Optionally, different experimental conditions are also used to indicate at least one of the following: the discharge rate of the fracturing fluid to be tested through the orifice plate in the test section, and the number of times the fracturing fluid to be tested passes through the orifice plate in the test section.

[0012] Here, this application accurately reproduces the tensile-shear composite flow characteristics of fluid rushing into the orifice from a large cross section of the wellbore by precisely controlling the displacement and orifice geometry parameters, thus solving the problem of flow pattern distortion; by using a closed-loop circulation mechanism to simulate the working condition of fracturing fluid passing through the orifice multiple times, the gradual decay law of viscosity with the increase of the number of times it passes through the orifice is restored, making up for the deficiency that a single flow experiment cannot reflect the cumulative shear effect.

[0013] Optionally, the displacement can be switched between multiple displacement gradients, and the orifice geometry parameters can be switched between multiple roughnesses.

[0014] Here, this application achieves high-fidelity coverage of the entire construction scenario in the mine through the gradient design of displacement and orifice roughness: each displacement gradient matches the mainstream construction range of shale oil horizontal wells, solving the technical problem that low-condition data cannot be extrapolated due to insufficient shear rate; each roughness gradient corresponds to the full life cycle state of the orifice in the early stage of well completion, the normal service period and after erosion, reducing the error caused by the difference in orifice wear degree, and further improving the consistency between the orifice performance prediction data and the actual working conditions in the mine.

[0015] Optionally, upstream and downstream samples of the fracturing fluid under various experimental conditions in the same test section can be obtained, including:

[0016] Under the same experimental conditions, N parallel groups of upstream and downstream samples were obtained; where N is any positive integer greater than 1.

[0017] Calculate the viscosity loss rate based on the viscosity before and after the via, including:

[0018] Calculate the viscosity loss rate for each parallel group separately, and take the average viscosity loss rate of each parallel group as the viscosity loss rate under the experimental conditions.

[0019] Here, this application effectively reduces the random errors of a single sampling caused by the heterogeneity of fracturing fluid, local flocculation, or sampling randomness by setting up N parallel samplings under the same experimental conditions and using the mean calculation method. This ensures that the experimental data can truly reflect the intrinsic characteristics of the fluid under specific experimental conditions. Furthermore, based on adapting to the multiphase fluid characteristics of fracturing fluid, the reasonable configuration of the sample size improves the experimental accuracy and testing efficiency, further ensuring the consistency between the final prediction results and the actual working conditions in the mine.

[0020] Optionally, based on the viscosity loss rate, the variation law of the perforation performance of the fracturing fluid under different experimental conditions is determined, including:

[0021] Obtain the initial molecular weight distribution and the molecular weight distribution after perforation of the fracturing fluid to be tested in order to determine the molecular weight fracture ratio;

[0022] Based on the correlation between molecular weight fracture ratio and multiple viscosity loss rates, a molecular weight viscosity degradation prediction model for the fracturing fluid under test is established; wherein, the molecular weight viscosity degradation prediction model is used to characterize the quantitative relationship between viscosity loss and molecular chain fracture of the fracturing fluid under test.

[0023] Here, this application introduces a prediction model to obtain the initial and post-perforation molecular weight distribution to determine the molecular weight fracture ratio. Based on this, a quantitative correlation is established between the molecular weight fracture ratio and the viscosity loss rate. This enables reliable extrapolation of the viscosity response under untested conditions based on molecular structure parameters, improving the extrapolation accuracy of performance prediction. It also provides a basis for the directional design of fracturing fluid molecular structure and the improvement of shear resistance, further enhancing the adaptability of the prediction results to actual mine conditions.

[0024] Optionally, after determining the variation law of the perforation performance of the fracturing fluid under different experimental conditions based on the viscosity loss rate, the method further includes:

[0025] The viscosity loss rate under multiple experimental conditions is stored in the system experimental database;

[0026] Using a preset allowable viscosity loss rate as a constraint, construction parameter optimization suggestions are generated based on the system's experimental database.

[0027] Here, this application achieves the management and reuse of experimental data by uniformly archiving viscosity loss rate data under multiple working conditions into a system experimental database, reducing the resource consumption of repetitive basic verification experiments. It also uses the preset allowable viscosity loss rate value corresponding to the minimum requirement of sand carrying capacity in the corresponding mine as a constraint to match the fracturing fluid system, displacement range and sand concentration upper limit that meet the performance requirements from the database. The resulting construction parameter optimization suggestions can be directly adapted to the mine scenario without additional scaling correction, effectively reducing the parameter debugging cost of on-site construction and improving the reliability of construction design and the adaptability to actual mine working conditions.

[0028] Secondly, embodiments of this application provide a closed-loop experimental system, comprising:

[0029] Mixing tank, used to hold the fracturing fluid to be tested;

[0030] The pumping device is connected to the outlet of the mixing tank and is used to drive the fracturing fluid to be tested to circulate.

[0031] The test section is used for wellbore perforation simulation. The inlet of the test section is connected to the outlet of the pumping device. The test section is equipped with a main pipe with the same size as the mine casing and a perforation plate set on the main pipe. The perforation plate is machined with perforation holes with the same perforation parameters as the mine.

[0032] The bypass circuit has its inlet connected between the outlet of the pumping unit and the inlet of the test section, and its outlet connected to the inlet of the mixing tank. The bypass circuit is used to allow the fracturing fluid to be tested to bypass the test section during the pre-circulation stage.

[0033] A sealed receiving chamber is located on the outlet side of the perforation plate and is used to collect fracturing fluid after it passes through the perforation hole.

[0034] The sampling device includes a first sampling port located upstream of the perforated plate and a second sampling port located within a sealed receiving cavity, for simultaneously sampling upstream and downstream of the perforated plate.

[0035] The return liquid pipeline has its inlet connected to the outlet of the sealed receiving chamber and its outlet connected to the inlet of the mixing tank. The return liquid pipeline, together with the pumping device and the test section, forms a closed-loop circulation circuit.

[0036] Optionally, it also includes:

[0037] A proppant supply device is installed above the mixing tank for quantitatively adding proppant into the mixing tank;

[0038] A concentration monitoring device is installed at the outlet pipeline of the mixing tank to monitor the proppant concentration in the fracturing fluid to be tested in real time.

[0039] The control device is connected to the proppant supply device and the concentration monitoring device respectively, and is used to control the sand addition rate of the proppant supply device according to the feedback signal of the concentration monitoring device.

[0040] Optionally, the perforated plate can be replaced on the main pipe.

[0041] Thirdly, embodiments of this application provide a device for predicting the perforation performance of fracturing fluid, comprising:

[0042] At least one processor and memory;

[0043] The memory stores the instructions that the computer executes;

[0044] At least one processor executes computer execution instructions stored in memory, causing at least one processor to perform the first aspect above and the various methods for predicting fracturing fluid perforation performance that may be involved in the first aspect.

[0045] This application provides a method, apparatus, and equipment for predicting the perforation performance of fracturing fluid. The method employs a main pipeline with dimensions matching the casing size and an orifice plate matching the perforation parameters, faithfully reproducing the tensile-shear composite flow characteristics of downhole fluid entering the orifice from a large cross-section. A pre-circulation process is implemented using a bypass loop, effectively avoiding flow field disturbances during pipeline startup and ensuring stable fracturing fluid performance before perforation. Simultaneous sampling upstream and downstream of the orifice plate reduces viscosity recovery errors caused by sampling time differences, ensuring the effectiveness of viscosity comparison before and after perforation. Furthermore, multi-condition cyclic testing obtains multiple sets of viscosity loss rate data under different flow rates, orifice parameters, and sand-bearing conditions, comprehensively covering all variables in mine construction scenarios. This solves the technical problems of related technologies where fracturing fluid perforation performance prediction devices and methods cannot accurately reproduce mine perforation flow conditions, simulate cumulative shear effects, and sand-bearing conditions, thereby improving the accuracy of perforation performance prediction. Attached Figure Description

[0046] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application.

[0047] Figure 1 A schematic diagram of a prediction system architecture for fracturing fluid perforation performance provided in an embodiment of this application;

[0048] Figure 2 A flowchart illustrating a method for predicting the perforation performance of fracturing fluid provided in this application embodiment;

[0049] Figure 3 A flowchart illustrating a method for conducting experiments under multiple operating conditions, provided in an embodiment of this application;

[0050] Figure 4 A flowchart illustrating a method for determining the performance variation law of vias provided in an embodiment of this application;

[0051] Figure 5 A schematic diagram of the workflow of a mine-grade fracturing fluid perforation performance prediction system provided in this application embodiment;

[0052] Figure 6 A schematic diagram of a closed-loop experimental system provided in this application embodiment;

[0053] Figure 7 A schematic diagram of the structure of a fracturing fluid perforation performance prediction device provided in an embodiment of this application;

[0054] Figure 8 This is a schematic diagram of a device for predicting the perforation performance of fracturing fluid, provided in an embodiment of this application.

[0055] The accompanying drawings illustrate specific embodiments of this application, which will be described in more detail below. These drawings and descriptions are not intended to limit the scope of the concept in any way, but rather to illustrate the concept of this application to those skilled in the art through reference to particular embodiments. Detailed Implementation

[0056] Exemplary embodiments will now be described in detail, examples of which are illustrated in the accompanying drawings. When the following description relates to the drawings, unless otherwise indicated, the same numbers in different drawings denote the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with this application. Rather, they are merely examples of apparatuses and methods consistent with some aspects of this application.

[0057] In related technologies, the prediction of fracturing fluid perforation performance mainly relies on laboratory experimental methods such as rotational viscometers, capillary rheometers, or small-diameter simulated channels. However, these instruments can only provide a pure shear field, making it difficult to reproduce the tensile-shear composite flow characteristics experienced by the fluid as it enters the orifice from a large cross-section of the wellbore. The shear rate of the related experimental devices differs by orders of magnitude from the shear rate and millisecond-level residence time in the field, making it impossible to extrapolate experimental results under low shear conditions to high shear conditions. Most related tests are single-pass flow tests, which cannot simulate the dynamic degradation process of fracturing fluid circulating through the orifice dozens of times during field construction, making it difficult to reflect the gradual decay law of viscosity in the later stages of construction. Related devices can generally only test pure liquid phase fracturing fluids, making it difficult to quantify the mechanical wear effect of proppant particles on polymer molecular chains, resulting in a large deviation between experimental data and actual sand-bearing conditions.

[0058] To address the technical problems in related technologies, this application provides a method, apparatus, and equipment for predicting the perforation performance of fracturing fluid. By adopting a main pipeline with the same size as the casing in the mine and an orifice plate with the same perforation parameters as the mine, the downhole tensile-shear composite flow characteristics are reproduced with high fidelity. With the help of closed-loop circulation and bypass pre-circulation design, flow field disturbance is reduced and the cumulative shear effect is restored. Combined with upstream and downstream synchronous sampling and multi-condition gradient testing, high-confidence viscosity loss rate data are obtained. Then, a molecular weight viscosity degradation prediction model is constructed by fusion of macro and micro data, and the experimental data is archived into a system database to output construction parameter optimization suggestions.

[0059] Optional, Figure 1 This is a schematic diagram of a fracturing fluid perforation performance prediction system architecture provided in an embodiment of this application. The fracturing fluid perforation performance prediction system is a computer device. Figure 1 In the above architecture, at least one of data acquisition device 101, processing device 102 and display device 103 is included.

[0060] It is understood that the structures illustrated in the embodiments of this application do not constitute a specific limitation on the architecture of a predictive system for fracturing fluid perforation performance. In other feasible embodiments of this application, the above architecture may include more or fewer components than illustrated, or combine some components, or split some components, or arrange different components, which can be determined according to the actual application scenario and is not limited here. Figure 1 The components shown can be implemented in hardware, software, or a combination of both.

[0061] In the specific implementation process, the data acquisition device 101 may include an input / output interface or a communication interface, and the data acquisition device 101 can be connected to the processing device through the input / output interface or the communication interface.

[0062] The processing equipment 102 can reproduce the downhole tensile-shear composite flow characteristics with high fidelity by using a main pipeline with the same size as the mine casing and an orifice plate with the same perforation parameters as the mine. With the help of closed-loop circulation and bypass pre-circulation design, it can reduce flow field disturbance and restore the cumulative shear effect. Combined with upstream and downstream synchronous sampling and multi-condition gradient testing, it can obtain high-confidence viscosity loss rate data. Then, it can construct a molecular weight viscosity degradation prediction model by fusing macro and micro data, and archive the experimental data into the system database to output construction parameter optimization suggestions.

[0063] The display device 103 can also be a touch screen or the screen of a terminal device, used to receive user commands while displaying the above-mentioned content, so as to realize interaction with the user.

[0064] It should be understood that the aforementioned processing device can be implemented by a processor reading instructions from memory and executing those instructions, or it can be implemented by a chip circuit.

[0065] Furthermore, the network architecture and business scenarios described in the embodiments of this application are for the purpose of more clearly illustrating the technical solutions of the embodiments of this application, and do not constitute a limitation on the technical solutions provided in the embodiments of this application. As those skilled in the art will know, with the evolution of network architecture and the emergence of new business scenarios, the technical solutions provided in the embodiments of this application are also applicable to similar technical problems.

[0066] Figure 2 This is a flowchart illustrating a method for predicting the perforation performance of fracturing fluid provided in an embodiment of this application. The execution entity of this embodiment can be... Figure 1 The specific execution entity of the processing device 102 can be determined according to the actual application scenario. For example... Figure 2 As shown, the method may include:

[0067] S201. Inject the fracturing fluid to be tested into the closed-loop circulation test system.

[0068] Optionally, the closed-loop test system includes a test section for simulating wellbore perforations and a bypass loop connecting the test section. The test section is equipped with a main pipe of the same size as the mine casing and a perforation plate on the main pipe. The perforation plate is equipped with perforation holes of the same size as the mine perforation parameters.

[0069] The closed-loop circulation test system provides a circulating test environment for fracturing fluid through-hole testing and supports subsequent pre-circulation, stable flow, switching test paths, changing test conditions, and repeated testing. The test section is the part of the closed-loop circulation test system used to simulate the flow process at the wellbore orifice. A main pipe with the same size as the casing in the mine (such as 114.3mm, 124.3mm, etc.) is set in this section to make the fracturing fluid flow channel size as close as possible to the actual conditions of the target well section.

[0070] The main pipeline is equipped with perforation plates, which provide perforation holes and form flow channel contraction points. The diameter, number, arrangement angle, and channel length or equivalent thickness of the perforations are determined according to the perforation parameters in the mine, so that the fracturing fluid undergoes a perforation process corresponding to that in the field during the experiment. The bypass loop is connected to the test section and performs the pre-circulation path switching function at the initial stage of system startup, allowing the fracturing fluid to complete circulation stabilization without passing through the perforation holes.

[0071] In one possible implementation, injecting the fracturing fluid to be tested into a closed-loop circulation test system means inputting the fracturing fluid, which has been prepared according to a predetermined formula, into a test device capable of forming a continuous circulation flow. The fracturing fluid then passes sequentially through the circulation drive component, connecting pipeline, test section, and bypass loop in a closed pipeline and returns to the storage area, forming a repeatable flow path.

[0072] S202. Open the bypass circuit for pre-circulation, and close the bypass circuit after the fracturing fluid to be tested has stabilized, so that the fracturing fluid to be tested passes through the perforation orifice via the test section.

[0073] Optionally, pre-circulation by opening the bypass circuit refers to allowing the fracturing fluid to circulate preferentially along the bypass circuit before the formal perforation test, instead of immediately entering the test section with perforation holes, in order to eliminate instantaneous fluctuations caused by pump start-up, pipeline filling, fluid level fluctuations, and uneven fluid conditions during the initial injection stage.

[0074] Optionally, a bypass loop is an alternative flow path connected to the test section. Its opening and closing can be achieved by switching valve groups. In bypass mode, the test section can be isolated or in a low-flow state. After the flow stabilizes, the bypass loop is closed, and fracturing fluid is introduced into the test section, flowing through the main pipeline to the perforation plate and through the perforation orifice. Flow stabilization here can be achieved by continuously monitoring flow rate and pressure. Stability is determined when the upstream flow rate reaches a set value and fluctuates within an allowable range within a preset time window, and the downstream back pressure also remains within an allowable fluctuation range.

[0075] S203. After the flow rate and pressure of the fracturing fluid to be tested have stabilized, samples are taken simultaneously upstream and downstream of the orifice plate to obtain upstream and downstream samples.

[0076] Optionally, upstream and downstream samples of the fracturing fluid under various experimental conditions in the same test section can be obtained, including:

[0077] Under the same experimental conditions, N parallel groups of upstream and downstream samples were obtained; where N is any positive integer greater than 1.

[0078] Calculate the viscosity loss rate based on the viscosity before and after the via, including:

[0079] Calculate the viscosity loss rate for each parallel group separately, and take the average viscosity loss rate of each parallel group as the viscosity loss rate under the experimental conditions.

[0080] Here, this application effectively reduces the random errors of a single sampling caused by the heterogeneity of fracturing fluid, local flocculation, or sampling randomness by setting up N parallel samplings under the same experimental conditions and using the mean calculation method. This ensures that the experimental data can truly reflect the intrinsic characteristics of the fluid under specific experimental conditions. Furthermore, based on adapting to the multiphase fluid characteristics of fracturing fluid, the reasonable configuration of the sample size improves the experimental accuracy and testing efficiency, further ensuring the consistency between the final prediction results and the actual working conditions in the mine.

[0081] Among them, the viscosity before perforation refers to the viscosity value of the upstream sample measured under predetermined testing conditions, which is used to characterize the rheological state of the fracturing fluid before it enters the perforation orifice; the viscosity after perforation refers to the viscosity value of the downstream sample measured under the same testing conditions as the upstream sample, which is used to characterize the rheological state of the fracturing fluid after it passes through the perforation orifice.

[0082] In one possible implementation, after the upstream and downstream samples are taken, their viscosity can be measured separately under the same testing conditions. The viscosity measurement of the downstream sample is recorded as the viscosity after the through-hole (μ2), and the viscosity measurement of the upstream sample is recorded as the viscosity before the through-hole (μ1), where μ1 and μ2 use the same unit. For fracturing fluids with time-dependent or structural recovery characteristics, the time interval from the end of sampling to the start of testing should be kept as consistent as possible to avoid measurement deviations caused by different settling times. This application does not limit this aspect.

[0083] Furthermore, the upstream and downstream sampling ports of the perforation plate are respectively located on the front and rear sides of the perforation plate in the main pipeline of the test section. The sampling ports can be connected to the sampling container through pressure-resistant sampling pipes, and the sampling actions on both sides are carried out synchronously after the flow rate and pressure of the fracturing fluid to be tested have stabilized. N parallel groups of samples are repeatedly obtained under the same temperature, flow rate, and perforation plate conditions, with only the sampling batches differing between parallel groups, thus ensuring that each group of samples corresponds to the same experimental conditions. The viscosity before and after the perforation can be measured using a rotational viscometer, rheometer, or viscosity testing device with equivalent measurement accuracy. The measured data are processed using the same calculation method to obtain the viscosity loss rate of each group, and then their arithmetic mean is output. Other models of the above viscosity testing device can also be selected in practical applications, and this embodiment does not limit this.

[0084] By simultaneously acquiring corresponding samples before and after the perforation plate, and repeatedly measuring and averaging multiple parallel groups under the same experimental conditions, the viscosity loss rate can directly correspond to the actual through-hole condition. Simultaneous sampling reduces the impact of experimental condition drift on the test results, and parallel group averaging reduces single-measurement deviation, thereby improving the consistency and stability of the test results and allowing the performance differences of fracturing fluid under different perforation conditions to be reflected more accurately.

[0085] S204. Calculate the viscosity loss rate based on the viscosity after the via and the viscosity before the via.

[0086] The viscosity loss rate of each sample after passing through the pores satisfies the following formula:

[0087]

[0088] in, For the viscosity sampled upstream, The viscosity was sampled downstream. The average viscosity loss rate of three parallel sample groups was taken as the final result for this experimental condition.

[0089] when When the value increases, it indicates that the viscosity of the fracturing fluid decreases more significantly after passing through the perforation orifice under the experimental conditions; when A decrease in the value indicates that the fracturing fluid has a strong ability to maintain viscosity under the experimental conditions.

[0090] In one possible implementation, obtain and The data is then entered into the data processing unit, which automatically executes the formula to calculate and output the viscosity loss rate, while simultaneously saving the corresponding test number, orifice parameters, flow rate, upstream pressure, downstream pressure, temperature, and sampling time. To eliminate random errors, synchronous sampling and viscosity testing can be repeated under the same experimental conditions. The average of the calculated viscosity loss rates is then used as the representative result for that experimental condition. When the deviation between repeated results exceeds a set threshold, the flow rate stability, sampling synchronization, and temperature consistency are rechecked before the test is repeated.

[0091] S205. Change the experimental conditions of the closed-loop cycle experimental system and perform the step of opening the bypass loop for pre-cycle to calculate the viscosity loss rate, so as to obtain multiple viscosity loss rates corresponding to multiple experimental conditions.

[0092] Optionally, changing the experimental conditions refers to adjusting the experimental parameters affecting the perforation behavior of the fracturing fluid after completing a set of tests, and repeating the complete process of pre-circulation, stabilization, synchronous sampling, viscosity testing, and viscosity loss rate calculation under the new parameter conditions. The object of the change in experimental conditions can be the operating parameters of the closed-loop circulation experimental system, the structural parameters of the test section, or the parameters of the fracturing fluid system. As long as the change in these parameters can reflect the differences in perforation conditions that may occur during field construction, it can be included in this method. In this method, the perforation plate, in addition to its role in forming the perforation hole, can also serve as a physical carrier for changing the experimental conditions. By replacing the perforation plate with different perforation geometry parameters, the fracturing fluid can repeatedly complete the perforation test under different degrees of constriction and different channel forms.

[0093] For example, using displacement as a variable experimental parameter, a round rubber slick was prepared, and its initial viscosity was measured to be 12.5 mPa·s. This was injected into the mixing tank of a closed-loop circulation experimental system, and a bypass loop was opened for pre-circulation. After pre-circulation, the viscosity was remeasured and found to be 12.3 mPa·s, with a deviation of 1.6% from the initial viscosity, meeting the experimental requirements. Subsequently, the system switched to the testing section, using a single-hole perforated plate with a 10 mm aperture as the testing module. Through-hole experiments were conducted sequentially at three displacement conditions: 0.3 m³ / min, 0.7 m³ / min, and 1.0 m³ / min. Under each displacement condition, after the closed-loop circulation system stabilized, samples were simultaneously taken upstream and downstream of the perforated plate. Three parallel samples were taken for each experimental condition for viscosity testing, and the viscosity loss rate under each experimental condition was calculated.

[0094] The experimental results are as follows: When the flow rate is 0.3 m³ / min and the corresponding orifice velocity is 35 m / s, the viscosity before passing through the orifice is 12.3 mPa·s, and the viscosity after passing through the orifice is 11.8 mPa·s, with a viscosity loss rate of 4.1%; when the flow rate is 0.7 m³ / min and the corresponding orifice velocity is 82 m / s, the viscosity before passing through the orifice is 12.3 mPa·s, and the viscosity after passing through the orifice is 10.1 mPa·s, with a viscosity loss rate of 17.9%; when the flow rate is 1.0 m³ / min and the corresponding orifice velocity is 118 m / s, the viscosity before passing through the orifice is 12.3 mPa·s, and the viscosity after passing through the orifice is 8.5 mPa·s, with a viscosity loss rate of 30.9%.

[0095] For example, using the fracturing fluid system type as a variable experimental parameter, a single-hole plate with a 10mm aperture was used as the test module, and the discharge rate was fixed at 0.7m³ / min. Seven types of fracturing fluids were prepared, including guar gum slickwater, guar gum stock solution, guar gum gel, polymer gel, low-viscosity linear polymer, medium-viscosity linear polymer, and high-viscosity linear polymer. The through-hole test was completed sequentially according to the same experimental procedure as in the example above. For each type of fluid, three parallel samples were taken at a discharge rate of 0.7m³ / min for viscosity testing and viscosity loss rate was calculated.

[0096] The experimental results are as follows: The initial viscosity of guar gum slipper was 12.5 mPa·s, and the viscosity after passing through the vias was 10.1 mPa·s, with a viscosity loss rate of 19.2%; the initial viscosity of the guar gum stock solution was 35.0 mPa·s, and the viscosity after passing through the vias was 24.5 mPa·s, with a viscosity loss rate of 30.0%; the initial viscosity of the guar gum gel was 85.0 mPa·s, and the viscosity after passing through the vias was 52.7 mPa·s, with a viscosity loss rate of 38.0%; the initial viscosity of the polymer gel was 90.0 mPa·s, and the viscosity after passing through the vias was... The initial viscosity of the low-viscosity linear adhesive was 18.0 mPa·s, and the viscosity after passing through the hole was 13.3 mPa·s, with a viscosity loss rate of 26.1%. The initial viscosity of the medium-viscosity linear adhesive was 45.0 mPa·s, and the viscosity after passing through the hole was 31.5 mPa·s, with a viscosity loss rate of 30.0%. The initial viscosity of the high-viscosity linear adhesive was 72.0 mPa·s, and the viscosity after passing through the hole was 43.2 mPa·s, with a viscosity loss rate of 40.0%.

[0097] For example, using proppant as a variable experimental parameter, a single-hole plate with a pore size of 10 mm was used as the test module, and slickwater was used as the test liquid. Through-hole experiments were conducted under both proppant-free and proppant-supported experimental conditions. The proppant used was 40 / 70 mesh quartz sand with a sand concentration of 200 kg / m³. The discharge rate gradients were set to 0.3 m³ / min, 0.7 m³ / min, and 1.0 m³ / min, with three parallel samples taken at each discharge rate. First, the through-hole experiment under the proppant-free condition was completed following the same experimental procedure as in the example above. Then, proppant was added to the mixing tank until the sand concentration reached 200 kg / m³, and the sand feeder and stirring device were started. The through-hole experiment was repeated under the same discharge rate gradient.

[0098] The experimental results are as follows: When the displacement is 0.3 m³ / min, the viscosity loss rate without proppant is 4.1%, and the viscosity loss rate with proppant is 10.4%, with an additional loss of +6.3%; when the displacement is 0.7 m³ / min, the viscosity loss rate without proppant is 17.9%, and the viscosity loss rate with proppant is 25.6%, with an additional loss of +7.7%; when the displacement is 1.0 m³ / min, the viscosity loss rate without proppant is 30.9%, and the viscosity loss rate with proppant is 40.8%, with an additional loss of +9.9%.

[0099] The above embodiments are merely illustrative descriptions of the technical solutions of the present invention and do not constitute a limitation on the scope of protection of the present invention. Those skilled in the art can reasonably replace or combine experimental parameters based on the above embodiments, such as changing the orifice diameter, number of orifices, and orifice type of the orifice plate, adjusting the displacement gradient and proppant concentration, or selecting other types of fracturing fluid systems for through-hole viscosity loss evaluation; all of these should fall within the scope of protection of this application.

[0100] S206. Based on multiple viscosity loss rates, determine the variation law of the perforation performance of the fracturing fluid under different experimental conditions.

[0101] Optionally, the perforation performance variation law refers to the trend, range, or sensitivity relationship of viscosity loss rate of different types of fracturing fluids under different flow rates, pressures, orifice parameters, temperatures, or sand content conditions as experimental conditions change. Multiple viscosity loss rates correspond to multiple clearly recorded experimental conditions. Therefore, a mapping relationship can be established between each set of experimental condition parameters and its corresponding η value. This mapping relationship can then be summarized and analyzed to obtain the perforation performance evaluation results of the fracturing fluid under test. This law can manifest as a monotonic change in viscosity loss rate with the increase of a single parameter, or as a distribution characteristic of a significant increase in viscosity loss rate in certain regions under multi-parameter coupling conditions. Based on this law, the viscosity retention capacity of fracturing fluids under different near-field construction conditions can be predicted.

[0102] For example, using a closed-loop circulation function, the viscosity change of the same fracturing fluid after 5, 10, and 20 consecutive perforations was measured, and a viscosity decay curve as a function of the number of perforations was established. Cumulative shear experiments were conducted to record the viscosity values ​​of the same batch of fracturing fluid after 1, 3, 5, 10, and 20 perforations, and a power-law decay model was established.

[0103]

[0104] in, The viscosity after the Nth through-hole is... The initial viscosity of the fracturing fluid. The cumulative shear attenuation index k of the fracturing fluid is calculated through this step, which represents the number of consecutive perforations of the fracturing fluid.

[0105] This application provides a method for predicting the perforation performance of fracturing fluid. By using a main pipeline with the same size as the casing in the mining area and an orifice plate with the same perforation parameters, the tensile-shear composite flow characteristics of downhole fluid entering the orifice from a large cross section are reproduced with high fidelity. A pre-circulation process is performed using a bypass loop to effectively avoid flow field disturbances during the pipeline start-up phase, ensuring the stability of fracturing fluid performance before perforation. Furthermore, by simultaneously sampling upstream and downstream of the orifice plate, the viscosity natural recovery error caused by sampling time difference is reduced, ensuring the effectiveness of viscosity comparison before and after perforation. In addition, multiple sets of viscosity loss rate data under different displacement, orifice parameters, and sand-bearing conditions are obtained through multi-experimental cyclic testing, fully covering all variables in mining operations. This solves the technical problem that the fracturing fluid perforation performance prediction devices and methods in related technologies cannot accurately reproduce the flow conditions of mining perforations, simulate cumulative shear effects, and sand-bearing conditions, thereby improving the accuracy of perforation performance prediction.

[0106] exist Figure 2 Based on the embodiments shown, the following, in conjunction with Figure 3 The method of multi-condition experimentation in the above-mentioned method for predicting the perforation performance of fracturing fluid is explained in detail.

[0107] Figure 3 Please refer to the flowchart illustrating a method for conducting experiments under multiple operating conditions provided in this application embodiment. Figure 3 ,include:

[0108] S301. Change the type of fracturing fluid to be tested.

[0109] Optionally, when changing the type of fracturing fluid to be tested, different formulations of slickwater, guar gum fracturing fluid, clean fracturing fluid, or other fracturing systems (such as guar gum slickwater, guar gum stock solution, guar gum gel, polymer gel, polymer low / medium / high viscosity linear adhesive, etc.) can be replaced in the same device, while keeping the test section structure unchanged, in order to compare the through-hole response of different fluid systems.

[0110] S302. Change the displacement of the closed-loop test system, the concentration of the proppant, or replace the orifice plate with different orifice geometry parameters.

[0111] Optionally, when adding proppant and changing its concentration, the proppant can first be uniformly dispersed in the fracturing fluid to be tested according to a preset mass fraction, and then the suspension can be stabilized by circulation mixing. Subsequently, a through-hole test can be performed to obtain the viscosity loss change under sand-containing conditions. When changing orifice plates with different orifice geometry parameters, a detachable installation structure can be used to fix the orifice plate to the corresponding position on the main pipeline. Test conditions can be switched by replacing orifice plates with different orifice diameters, orifice length ratios, or inlet shapes. When using the circulation function for continuous through-hole testing, the system can be kept in a closed loop, allowing the fracturing fluid to be tested to return to the loop and recirculate into the test section after each through-hole pass, and its performance degradation can be recorded during continuous circulation.

[0112] Optionally, the displacement can be switched between multiple displacement gradients, and the orifice geometry parameters can be switched between multiple roughnesses.

[0113] Here, this application achieves high-fidelity coverage of the entire construction scenario in the mine through the gradient design of displacement and orifice roughness: each displacement gradient matches the mainstream construction range of shale oil horizontal wells, solving the technical problem that low-condition data cannot be extrapolated due to insufficient shear rate; each roughness gradient corresponds to the full life cycle state of the orifice in the early stage of well completion, the normal service period and after erosion, reducing the error caused by the difference in orifice wear degree, and further improving the consistency between the orifice performance prediction data and the actual working conditions in the mine.

[0114] Optionally, changing the displacement includes switching between five displacement gradients: 0.3 m³ / min, 0.5 m³ / min, 0.7 m³ / min, 0.85 m³ / min, and 1.0 m³ / min. Changing the proppant concentration includes switching between a proppant-free condition and four sand concentration levels: 100 kg / m³, 200 kg / m³, and 300 kg / m³. Changing the orifice geometry includes replacing the orifice plate with roughness Ra=3.2 μm, Ra=6.3 μm, and Ra=12.5 μm.

[0115] Optionally, a sieving unit can be further configured in the proppant mixing module to classify the proppant according to different particle sizes (e.g., 40 / 70 / 140 mesh). The multi-stage filtration structure of the sieving unit enables online classification of proppant particle sizes, ensuring independent mixing of particles with different sizes. For example, 40-mesh particles are used to simulate the wear effect of coarse particles, while 140-mesh particles are used to study the cutting effect of fine particles on polymer molecular chains. This design allows experiments to quantify the differences in the contribution of proppant particles of different sizes to viscosity loss and provides a basis for the matching design of particle size and fracturing fluid system during construction.

[0116] Optionally, multiple rotatable orifice plate mounting positions are set in the test section, and the orifice diameter (e.g., 8 / 10 / 12 mm) can be switched online via a hydraulic drive device. The test section adopts a modular design, with each channel independently configured with an orifice plate, sampling port, and back pressure control valve, supporting single-channel independent operation or multi-channel parallel testing. The hydraulic drive device controls the rapid switching of the orifice plate through a preset program (single replacement time less than or equal to 15 minutes), without the need for machine downtime for disassembly and assembly, significantly improving experimental efficiency. For example, in multi-channel parallel mode, the effects of 8 mm, 10 mm, and 12 mm orifice diameters on fracturing fluid viscosity loss can be tested simultaneously to form a comparative dataset.

[0117] Optionally, a transparent orifice plate can be selected, which can be made of quartz glass or sapphire glass and has the same geometry as a standard metal orifice plate. It is equipped with a high-speed camera (frame rate greater than or equal to 10,000 fps) and a pulsed laser illumination system to capture transient flow field images of the fracturing fluid through the orifice.

[0118] In one possible implementation, the displacement can be changed by adjusting the circulating pump speed, flow valve opening, or frequency converter control parameters, allowing the fracturing fluid to pass through the test section at different volumetric flow rates, thus creating different orifice flow shear environments. When changing the type of fracturing fluid, different formulations of slickwater, guar gum fracturing fluid, clean fracturing fluid, or other fracturing systems can be substituted within the same device, while maintaining the test section structure, to compare the through-hole response of different fluid systems. When adding proppant and changing its concentration, the proppant can be first uniformly dispersed in the fracturing fluid to be tested at a preset mass fraction, then the suspension is stabilized through circulation mixing, followed by through-hole testing to obtain changes in viscosity loss under sand-containing conditions. When changing orifice plates with different orifice geometry parameters, a detachable installation structure can be used to fix the orifice plate at the corresponding position on the main pipeline. Test conditions can be switched by replacing orifice plates with different orifice diameters, orifice length ratios, or inlet shapes.

[0119] Optionally, the closed-loop circulation test system first injects the fracturing fluid to be tested into the main pipeline and pre-circulates it through a bypass loop to stabilize the flow field before switching to the test section. Then, at a set flow rate, the fracturing fluid flows through the orifice plate, and viscosity is measured at both upstream and downstream. When it is necessary to investigate the effect of sand content, the fracturing fluid, after adding proppant, is mixed with a sand-mixing device to achieve the target sand concentration, and then flow tests are conducted while keeping other conditions constant. When it is necessary to investigate the effect of orifice surface, orifice plates with different roughnesses are directly replaced, and the same sampling and testing process is repeated. Switching between the above different experimental conditions can be completed under the unified scheduling of the controller. The controller outputs control signals for pump speed, valve position, and sand mixing amount according to preset parameters, thereby obtaining the viscosity loss rate under the corresponding experimental condition.

[0120] S303. Utilize the circulation function of the closed-loop circulation test system to allow the fracturing fluid to be tested to pass through the perforation orifice multiple times continuously.

[0121] In one possible implementation, when using the circulation function to perform multiple consecutive through-hole operations, the system can be kept in a closed loop, allowing the fracturing fluid to be tested to return to the loop and recirculate into the test section after each through-hole operation, and its performance degradation can be recorded during the continuous circulation process.

[0122] Optionally, an electric heating belt and an infrared thermal imager are integrated into the test section to monitor the fracturing fluid temperature rise (0 to 100°C) and thermodynamic state in real time. The electric heating belt adjusts its power through a temperature control algorithm to ensure that the temperature fluctuation in the test section is controlled within ±1°C. The infrared thermal imager captures the temperature distribution of the fracturing fluid flowing through the orifice at a frequency of 10Hz, and analyzes the coupling effect of temperature rise on viscosity loss using a viscosity-temperature relationship model. For example, experiments have shown that when the temperature rises to 50°C, the viscosity loss rate of guar gum slickwater increases by 8.3% compared to normal temperature conditions, revealing the accelerated viscosity degradation mechanism under high-temperature conditions. This application does not limit the scope of the embodiments.

[0123] Optionally, an electro-hydraulic proportional valve is integrated into the sealed receiving chamber to dynamically adjust the orifice outlet back pressure according to the formation pressure (0 to 20 MPa). The electro-hydraulic proportional valve adjusts its opening in real time via feedback signals from a pressure sensor, simulating the outlet pressure environment under different reservoir permeability conditions. For example, when simulating a low-permeability reservoir (back pressure 15 MPa), the fracturing fluid viscosity loss rate increases by 12.4% compared to atmospheric pressure conditions, revealing the nonlinear effect of back pressure on shear rate and viscosity recovery. This system provides experimental evidence for optimizing fracturing fluid construction strategies in high-permeability reservoirs. This application does not limit the scope of this embodiment.

[0124] When the aforementioned experimental conditions are combined with orifice flow tests, the system can generate comparative results under different discharge rates, fluid types, sand concentrations, orifice parameters, and multiple orifice flow conditions within the same apparatus, and output the corresponding viscosity loss rate accordingly. This allows the fracturing fluid under test to be evaluated under multiple experimental conditions close to field construction conditions, thereby revealing the variation law of its orifice flow performance.

[0125] Optionally, different experimental conditions are also used to indicate at least one of the following: the discharge rate of the fracturing fluid to be tested through the orifice plate in the test section, and the number of times the fracturing fluid to be tested passes through the orifice plate in the test section.

[0126] Here, this application accurately reproduces the tensile-shear composite flow characteristics of fluid rushing into the orifice from a large cross section of the wellbore by precisely controlling the displacement and orifice geometry parameters, thus solving the problem of flow pattern distortion; by using a closed-loop circulation mechanism to simulate the experimental condition of fracturing fluid passing through the orifice multiple times, the gradual decay law of viscosity with the increase of the number of times it passes through the orifice is restored, making up for the deficiency that a single flow experiment cannot reflect the cumulative shear effect.

[0127] Based on any of the above embodiments, the following, in conjunction with Figure 4 The method for predicting the perforation performance of fracturing fluids described above, which determines the variation law of perforation performance of the fracturing fluid under different experimental conditions based on multiple viscosity loss rates, is explained in detail.

[0128] Figure 4 This is a flowchart illustrating a method for determining the performance variation law of vias, provided as an embodiment of this application. Please refer to... Figure 4 ,include:

[0129] S401. Obtain the initial molecular weight distribution and the molecular weight distribution after perforation of the fracturing fluid to be tested, so as to determine the molecular weight fracture ratio.

[0130] The initial molecular weight distribution is used to characterize the molecular weight baseline information of the fracturing fluid in the unperforated state, while the molecular weight distribution after perforation is used to characterize the changes in the molecular chains of the fracturing fluid after passing through the perforation hole. The molecular weight fracture ratio is used to quantify the magnitude of molecular weight change before and after perforation, and can establish a correlation with the viscosity loss rate under different experimental conditions.

[0131] In one possible implementation, upstream and downstream samples can be obtained under different flow rates, proppant concentrations, orifice geometry parameters, or multiple perforation cycles, and their molecular weight distribution can be determined. The molecular weight distribution can be obtained using gel permeation chromatography, laser scattering detection, or other methods suitable for polymer molecular weight characterization. The molecular weight breakage ratio can then be calculated by combining number-average molecular weight, weight-average molecular weight, or characteristic peak shift. Subsequently, the molecular weight breakage ratios obtained under each experimental condition are fitted with the corresponding viscosity loss rates. A predictive model can be established using linear regression, multinomial regression, or machine learning mapping, ensuring that the model output reflects the viscosity retention capacity changes of the fracturing fluid under different perforation conditions.

[0132] The molecular weight cleavage ratio satisfies the following formula:

[0133]

[0134] Among them, the weight-average molecular weight of the upstream sample is denoted as . The weight-average molecular weight of the downstream sample is denoted as . The larger the absolute value of the molecular weight breakage ratio, the more severe the degree of chain breakage of the polymer chains in the fracturing fluid due to shearing during the perforation process.

[0135] S402. Based on the correlation between molecular weight fracture ratio and multiple viscosity loss rates, establish a molecular weight viscosity degradation prediction model for the fracturing fluid to be tested.

[0136] Among them, the molecular weight viscosity degradation prediction model is used to characterize the quantitative relationship between viscosity loss and molecular chain breakage of the fracturing fluid under test, and is used to predict degradation behavior under subsequent experimental conditions.

[0137] Optionally, the molecular weight fracture ratio obtained under each experimental condition can be fitted with the corresponding viscosity loss rate. A prediction model can be established using linear regression, multinomial regression, or machine learning mapping, so that the model output can reflect the change in viscosity retention capacity of the fracturing fluid under different perforation conditions.

[0138] This approach links microscopic molecular chain fracture information with macroscopic viscosity loss results within the same evaluation framework. This allows the variation in perforation performance to be reflected not only by multiple viscosity loss rates but also by further explaining the sources of difference through the molecular weight fracture ratio. The resulting molecular weight viscosity degradation prediction model can be used to predict the perforation degradation trend of fracturing fluids under different experimental conditions and provide quantitative basis for fracturing fluid system selection and construction parameter matching.

[0139] Optionally, after determining the variation law of the perforation performance of the fracturing fluid under different experimental conditions based on the viscosity loss rate, the method further includes:

[0140] The viscosity loss rate under multiple experimental conditions is stored in the system experimental database;

[0141] Using a preset allowable viscosity loss rate as a constraint, construction parameter optimization suggestions are generated based on the system's experimental database.

[0142] Here, this application achieves the management and reuse of experimental data by uniformly archiving viscosity loss rate data under multiple working conditions into a system experimental database, reducing the resource consumption of repetitive basic verification experiments. It also uses the preset allowable viscosity loss rate value corresponding to the minimum requirement of sand carrying capacity in the corresponding mine as a constraint to match the fracturing fluid system, displacement range and sand concentration upper limit that meet the performance requirements from the database. The resulting construction parameter optimization suggestions can be directly adapted to the mine scenario without additional scaling correction, effectively reducing the parameter debugging cost of on-site construction and improving the reliability of construction design and the adaptability to actual mine working conditions.

[0143] The system experimental database is used to establish a correlation between different experimental conditions and corresponding viscosity loss rates. Experimental conditions may include information such as displacement, proppant concentration, orifice plate geometry parameters, and the type of fracturing fluid being tested. Each record in the database corresponds to a complete through-hole performance test result and can be indexed and managed according to experimental condition category, numerical range, or liquid system. The storage medium for the system experimental database can be a relational database on a server or a distributed storage unit. Database table entries must include at least the experimental condition identifier, viscosity before through-hole, viscosity after through-hole, viscosity loss rate, and sampling timestamp for subsequent querying, comparison, and retrieval. In practical applications, other models or other storage formats can also be selected for the storage medium; this application does not limit this.

[0144] Among them, the construction parameter optimization suggestion refers to the output of suggested results to guide the adjustment of fracturing construction parameters based on the viscosity loss rate corresponding to different experimental conditions in the system experimental database, under the constraint of the preset allowable value of viscosity loss rate.

[0145] For example, according to the results of step S205, the viscosity loss rate increases significantly with the increase of the discharge rate, indicating that there is a significant possibility of shear viscosity reduction in the round rubber slick under high discharge conditions. Based on the viscosity loss rate data obtained under the above multiple working conditions, a basis can be provided for the selection of the discharge rate in on-site construction. For example, it is recommended that the discharge rate be controlled within 0.7 m³ / min when using this fracturing fluid system, at which time the viscosity loss rate is about 18%, which can still meet the sand carrying requirements.

[0146] For example, based on the results of step S205, among the seven types of fracturing fluids, guar gum slickwater has the lowest viscosity loss rate and the best shear resistance; guar gum gel and polymer high-viscosity linear gel have relatively high viscosity loss rates, at 38.0% and 40.0% respectively, and are more sensitive to orifice shear. Based on the above comparative data, if the construction scheme pursues high discharge rate, it is recommended to give priority to guar gum slickwater; if high-viscosity liquids are required for sand carrying operations, it is recommended to use polymer gel, whose viscosity loss rate is 35.0%, lower than that of guar gum gel (38.0%), or the discharge rate can be appropriately reduced to control the viscosity loss within an acceptable range.

[0147] For example, according to the results of step S205, the viscosity loss rate increases significantly under proppant conditions, and the additional loss is greater with higher flow rates. The mechanical wear of the fracturing fluid polymer chains by proppant particles is the main cause of the additional loss. Based on the above experimental data, it is recommended that during high-flow-rate proppant-carrying operations, a low-propellant slug or pre-flush fluid can be injected in the early stage to reduce the impact of initial erosion on the viscosity of the fracturing fluid.

[0148] Optionally, based on the viscosity loss rate, the variation law of the perforation performance of the fracturing fluid under different experimental conditions is determined, including:

[0149] Obtain the initial molecular weight distribution and the molecular weight distribution after perforation of the fracturing fluid to be tested in order to determine the molecular weight fracture ratio;

[0150] Based on the correlation between molecular weight fracture ratio and multiple viscosity loss rates, a molecular weight viscosity degradation prediction model for the fracturing fluid under test is established; wherein, the molecular weight viscosity degradation prediction model is used to characterize the quantitative relationship between viscosity loss and molecular chain fracture of the fracturing fluid under test.

[0151] Here, this application introduces a prediction model to obtain the initial and post-perforation molecular weight distribution to determine the molecular weight fracture ratio. Based on this, a quantitative correlation is established between the molecular weight fracture ratio and the viscosity loss rate. This enables reliable extrapolation of the viscosity response under untested conditions based on molecular structure parameters, improving the extrapolation accuracy of performance prediction. It also provides a basis for the directional design of fracturing fluid molecular structure and the improvement of shear resistance, further enhancing the adaptability of the prediction results to actual mine conditions.

[0152] This application also provides a field-grade fracturing fluid perforation performance prediction system, including a closed-loop circulation pipeline unit, a perforation simulation unit, a proppant mixing and injection module, a pressure and flow regulation module, and a data acquisition and control unit. Combined with the above-mentioned field-grade fracturing fluid perforation performance prediction system, this application embodiment can predict the perforation performance of fracturing fluid. Below, in conjunction with... Figure 5 This application provides a detailed description of the workflow of a mine-grade fracturing fluid perforation performance prediction system provided in its embodiments.

[0153] Figure 5 This is a schematic diagram illustrating the workflow of a field-grade fracturing fluid perforation performance prediction system provided in this application embodiment. Please refer to... Figure 5 ,include:

[0154] Specifically, the closed-loop circulation pipeline unit includes a mixing tank, a main circulation pump, a high-pressure main pipeline (with a diameter of 114mm to 124mm), a bypass circuit, a test section, and a return pipeline. These components are sequentially connected to form a closed-loop circulation channel for the fracturing fluid. The mixing tank is equipped with a stirrer and a concentration probe. The stirrer is used to ensure uniform mixing of the fracturing fluid and adequate suspension of the proppant, while the concentration probe is used to monitor the concentration changes of the proppant in the mixing tank in real time.

[0155] The perforation simulation unit is set up in the test section and includes a perforation plate with preset perforation geometry parameters, used to simulate the sudden narrowing flow channel structure of the perforation hole. The hole diameter, number of holes, and channel type of the perforation plate are selected according to the actual perforation parameters in the mine.

[0156] The proppant mixing and injection module is connected to the mixing tank and includes a sand feeder and supporting pipelines. It is used to inject proppant into the mixing tank according to the target sand concentration under sand-carrying conditions.

[0157] The pressure and flow regulation module, including the fracturing pump truck, is installed on the outlet pipeline of the main circulation pump. It is used to regulate the discharge rate and pressure in the closed-loop circulation system to simulate the borehole conditions under different construction discharge rates. The discharge rate regulation range of the fracturing pump truck is from 0.3 m³ / min to 1.0 m³ / min.

[0158] The data acquisition and control unit is connected to the pressure sensor, flow meter, concentration probe and viscosity detection device respectively, and is used to collect and record pressure, flow rate, proppant concentration and viscosity data in real time during the operation of the closed loop system, and to perform coordinated control of the various modules of the system.

[0159] The workflow of the mine-grade fracturing fluid perforation performance prediction system provided in this embodiment is as follows:

[0160] Step 1: Construct a closed-loop circulation pipeline unit by sequentially connecting the mixing tank, main circulation pump, bypass circuit, test section, and return pipeline to confirm that the system is well sealed.

[0161] Step 2: Install perforation plates in the test section and select the corresponding hole diameter and number of holes according to the perforation parameters of the mine.

[0162] Step 3: Inject the fracturing fluid to be tested into the mixing tank, open the bypass circuit for pre-circulation, and ensure that the fracturing fluid is fully homogenized in the system. Monitor the upstream and downstream viscosity values ​​through the data acquisition and control unit. Once the deviation meets the preset requirements, switch to the test section to begin formal testing.

[0163] Step 4: Adjust the discharge rate to the target value using the pressure and flow regulation module. If sand-carrying conditions are involved, add proppant to the mixing tank to the target sand concentration using the proppant mixing and injection module. Start the mixing tank's stirring device to ensure the proppant is evenly suspended. Simultaneously, monitor the proppant concentration in real time using the mixing tank's stirring and concentration probe to ensure the sand concentration remains stable at the target value.

[0164] Step 5: After the fracturing fluid is stably diverted in the test section, the fracturing fluid samples upstream and downstream of the orifice plate are collected synchronously through the data acquisition and control unit for viscosity detection, and the viscosity loss rate under this experimental condition is calculated.

[0165] Step 6: Change the experimental conditions and repeat steps 3 to 5 to obtain viscosity loss rate datasets under multiple experimental conditions.

[0166] Step 7: Analyze the changes in molecular weight distribution of fracturing fluid before and after perforation under various experimental conditions using gel permeation chromatography, calculate the molecular weight fracture ratio, and perform correlation analysis with the viscosity loss rate under the corresponding experimental conditions to establish a molecular weight-viscosity degradation prediction model for this type of fracturing fluid.

[0167] Step 8: Using the closed-loop circulation function, measure the viscosity change of the same fracturing fluid after 5, 10, and 20 consecutive through-hole cycles, and establish a power-law decay model of viscosity with the number of through-hole cycles.

[0168] Step 9: Input the actual construction parameters of the mine into the above degradation prediction model and power-law decay model to predict the viscosity loss rate and residual viscosity of the fracturing fluid under actual perforation conditions, providing a basis for the selection of construction discharge rate, the optimization of fracturing fluid system and the optimization of sand concentration scheme.

[0169] Figure 6 A schematic diagram of a closed-loop experimental system provided in this application embodiment includes:

[0170] Mixing tank, used to hold the fracturing fluid to be tested;

[0171] The pumping device is connected to the outlet of the mixing tank and is used to drive the fracturing fluid to be tested to circulate.

[0172] The test section is used for wellbore perforation simulation. The inlet of the test section is connected to the outlet of the pumping device. The test section is equipped with a main pipe with the same size as the mine casing and a perforation plate set on the main pipe. The perforation plate is machined with perforation holes with the same perforation parameters as the mine.

[0173] The bypass circuit has its inlet connected between the outlet of the pumping unit and the inlet of the test section, and its outlet connected to the inlet of the mixing tank. The bypass circuit is used to allow the fracturing fluid to be tested to bypass the test section during the pre-circulation stage.

[0174] A sealed receiving chamber is located on the outlet side of the perforation plate and is used to collect fracturing fluid after it passes through the perforation hole.

[0175] The sampling device includes a first sampling port located upstream of the perforated plate and a second sampling port located within a sealed receiving cavity, for simultaneously sampling upstream and downstream of the perforated plate.

[0176] The return liquid pipeline has its inlet connected to the outlet of the sealed receiving chamber and its outlet connected to the inlet of the mixing tank. The return liquid pipeline, together with the pumping device and the test section, forms a closed-loop circulation circuit.

[0177] Optionally, it also includes:

[0178] A proppant supply device is installed above the mixing tank for quantitatively adding proppant into the mixing tank;

[0179] A concentration monitoring device is installed at the outlet pipeline of the mixing tank to monitor the proppant concentration in the fracturing fluid to be tested in real time.

[0180] The control device is connected to the proppant supply device and the concentration monitoring device respectively, and is used to control the sand addition rate of the proppant supply device according to the feedback signal of the concentration monitoring device.

[0181] Optionally, the perforated plate can be replaced on the main pipe.

[0182] It is understood that the structures illustrated in the embodiments of this application do not constitute a specific limitation on the prediction system for fracturing fluid perforation performance. In other feasible embodiments of this application, the above-mentioned device may include more or fewer components than illustrated, or combine some components, or split some components, or arrange different components, which can be determined according to the actual application scenario and is not limited here. Figure 6 The components shown can be implemented in hardware, software, or a combination of both.

[0183] Figure 7 This is a schematic diagram of a device for predicting the perforation performance of fracturing fluid provided in an embodiment of this application. Please refer to... Figure 7 The fracturing fluid perforation performance prediction device 700 includes an acquisition module 701, a calculation module 702, and a determination module 703, wherein:

[0184] The acquisition module 701 acquires upstream and downstream samples of the fracturing fluid under various experimental conditions in the same test section during the testing process of the fracturing fluid to be tested; different experimental conditions are used at least for the orifice plate indicating different orifice geometric parameters in the test section; the upstream sample is taken from the upstream of the orifice plate, and the downstream sample is taken from the downstream of the orifice plate; the test section is used to simulate wellbore orifices.

[0185] The calculation module 702 calculates the viscosity loss rate for each experimental condition based on the viscosity of the upstream sample before the through-hole and the viscosity of the downstream sample after the through-hole.

[0186] Module 703 is used to determine the variation law of the perforation performance of the fracturing fluid under different experimental conditions based on the viscosity loss rate.

[0187] Optionally, module 701 is used specifically for:

[0188] Different experimental conditions are also used to indicate at least one of the following: the discharge rate of the fracturing fluid to be tested through the orifice plate in the test section, and the number of times the fracturing fluid to be tested passes through the orifice plate in the test section.

[0189] Optionally, module 701 is used specifically for:

[0190] Displacement switches between multiple displacement gradients, and orifice geometry switches between multiple roughnesses.

[0191] Optionally, module 701 is used specifically for:

[0192] Under the same experimental conditions, N parallel groups of upstream and downstream samples were obtained; where N is any positive integer greater than 1.

[0193] Calculate the viscosity loss rate based on the viscosity before and after the via, including:

[0194] Calculate the viscosity loss rate for each parallel group separately, and take the average viscosity loss rate of each parallel group as the viscosity loss rate under the experimental conditions.

[0195] Optionally, module 703 is specifically used for:

[0196] Obtain the initial molecular weight distribution and the molecular weight distribution after perforation of the fracturing fluid to be tested in order to determine the molecular weight fracture ratio;

[0197] Based on the correlation between molecular weight fracture ratio and multiple viscosity loss rates, a molecular weight viscosity degradation prediction model for the fracturing fluid under test is established; wherein, the molecular weight viscosity degradation prediction model is used to characterize the quantitative relationship between viscosity loss and molecular chain fracture of the fracturing fluid under test.

[0198] Optionally, after determining the variation law of the perforation performance of the fracturing fluid under different experimental conditions based on multiple viscosity loss rates, the above device also includes a storage module, specifically used for:

[0199] The viscosity loss rate under multiple experimental conditions is stored in the system experimental database;

[0200] Using a preset allowable viscosity loss rate as a constraint, construction parameter optimization suggestions are generated based on the system's experimental database.

[0201] This embodiment provides a device for predicting the perforation performance of fracturing fluid, which can perform the method provided in the above-described method embodiment. Its implementation principle and technical effect are similar, and will not be described in detail here.

[0202] Figure 8 This is a schematic diagram of a device for predicting the perforation performance of fracturing fluid, provided as an embodiment of this application. Please refer to... Figure 8 The diagram illustrates a structural schematic of a fracturing fluid perforation performance prediction device 800 suitable for implementing this embodiment. The fracturing fluid perforation performance prediction device may include, but is not limited to, mobile terminals such as laptops, personal digital assistants (PDAs), and portable Android devices (PADs), as well as fixed terminals such as digital TVs and desktop computers. Figure 8 The fracturing fluid perforation performance prediction device shown is merely an example and should not impose any limitation on the functionality and scope of use of the embodiments of this application.

[0203] like Figure 8 As shown, the fracturing fluid perforation performance prediction device 800 may include a processing unit (e.g., a central processing unit, a graphics processing unit, etc.) 801, which can perform various appropriate actions and processes according to a program stored in a read-only memory (ROM) 802 or a program loaded from a storage device 808 into a random access memory (RAM) 803. The RAM 803 also stores various programs and data required for the operation of the fracturing fluid perforation performance prediction device 800. The processing unit 801, the ROM 802, and the RAM 803 are interconnected via a bus 804. An input / output (I / O) interface 805 is also connected to the bus 804.

[0204] Typically, the following devices can be connected to I / O interface 805: input devices 806 including, for example, touchscreens, touchpads, keyboards, mice, cameras, microphones, accelerometers, gyroscopes, etc.; output devices 807 including, for example, liquid crystal displays (LCDs), speakers, vibrators, etc.; storage devices 808 including, for example, magnetic tapes, hard disks, etc.; and communication devices 809. Communication device 809 allows the fracturing fluid perforation performance prediction device 800 to communicate wirelessly or wiredly with other devices to exchange data. Although Figure 8 A predictive device 800 for fracturing fluid perforation performance is shown, but it should be understood that implementation or possession of all the devices shown is not required. More or fewer devices may be implemented alternatively.

[0205] Specifically, according to embodiments of this application, the processes described above with reference to the flowcharts can be implemented as computer software programs. For example, embodiments of this application include a computer program product comprising a computer program carried on a computer-readable medium, the computer program containing program code for performing the methods shown in the flowcharts. In such embodiments, the computer program can be downloaded and installed from a network via a communication device 809, or installed from a storage device 808, or installed from a read-only memory 802. When the computer program is executed by the processing device 801, it performs the functions defined in the methods of the embodiments of this application.

[0206] It should be noted that the computer-readable medium described above in this application can be a computer-readable signal medium or a computer-readable storage medium, or any combination of the two. A computer-readable storage medium can be, for example,—but not limited to—an electrical, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or any combination thereof. More specific examples of a computer-readable storage medium may include, but are not limited to: an electrical connection having one or more wires, a portable computer disk, a hard disk, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM or flash memory), optical fiber, portable compact disk read-only memory (CD-ROM), optical storage device, magnetic storage device, or any suitable combination thereof. In this application, a computer-readable storage medium can be any tangible medium containing or storing a program that can be used by or in conjunction with an instruction execution system, apparatus, or device. In this application, a computer-readable signal medium can include a data signal propagated in baseband or as part of a carrier wave, carrying computer-readable program code. Such propagated data signals can take various forms, including but not limited to electromagnetic signals, optical signals, or any suitable combination thereof. A computer-readable signal medium can be any computer-readable medium other than a computer-readable storage medium, which can send, propagate, or transmit a program for use by or in connection with an instruction execution system, apparatus, or device. The program code contained on the computer-readable medium can be transmitted using any suitable medium, including but not limited to: wires, optical fibers, RF (radio frequency), etc., or any suitable combination thereof.

[0207] The aforementioned computer-readable medium may be included in the aforementioned fracturing fluid perforation performance prediction device; or it may exist independently and not assembled into the fracturing fluid perforation performance prediction device.

[0208] The aforementioned computer-readable medium carries one or more programs that, when executed by the fracturing fluid perforation performance prediction device, cause the fracturing fluid perforation performance prediction device to perform the method shown in the above embodiments.

[0209] This application provides a computer-readable storage medium storing computer-executable instructions. When a processor executes the computer-executable instructions, it implements various methods that may be involved in the above embodiments.

[0210] This application provides a computer program product, including a computer program that, when executed by a processor, implements various methods that may be involved in the above embodiments.

[0211] Computer program code for performing the operations of this application can be written in one or more programming languages ​​or a combination thereof, including object-oriented programming languages ​​such as Java, Smalltalk, and C++, as well as conventional procedural programming languages ​​such as "C" or similar programming languages. The program code can be executed entirely on the user's computer, partially on the user's computer, as a standalone software package, partially on the user's computer and partially on a remote computer, or entirely on a remote computer or server. In cases involving remote computers, the remote computer can be connected to the user's computer via any type of network—including a Local Area Network (LAN) or a Wide Area Network (WAN)—or can be connected to an external computer (e.g., via the Internet using an Internet service provider).

[0212] The flowcharts and block diagrams in the accompanying drawings illustrate the architecture, functionality, and operation of possible implementations of systems, methods, and computer program products according to various embodiments of this application. In this regard, each block in a flowchart or block diagram may represent a module, segment, or portion of code containing one or more executable instructions for implementing a specified logical function. It should also be noted that in some alternative implementations, the functions indicated in the blocks may occur in a different order than those indicated in the drawings. For example, two consecutively indicated blocks may actually be executed substantially in parallel, and they may sometimes be executed in reverse order, depending on the functions involved. It should also be noted that each block in the block diagrams and / or flowcharts, and combinations of blocks in the block diagrams and / or flowcharts, can be implemented using a dedicated hardware-based system that performs the specified function or operation, or using a combination of dedicated hardware and computer instructions.

[0213] The functions described above in this document can be performed at least in part by one or more hardware logic components. For example, exemplary types of hardware logic components that can be used, without limitation, include: field-programmable gate arrays (FPGAs), application-specific integrated circuits (ASICs), application-specific standard products (ASSPs), system-on-a-chip (SoCs), complex programmable logic devices (CPLDs), and so on.

[0214] In the context of this application, a machine-readable medium can be a tangible medium that may contain or store a program for use by or in conjunction with an instruction execution system, apparatus, or device. A machine-readable medium can be a machine-readable signal medium or a machine-readable storage medium. Machine-readable media can be, but is not limited to, electronic, magnetic, optical, electromagnetic, infrared, or semiconductor systems, apparatus, or devices, or any suitable combination of the foregoing. More specific examples of machine-readable storage media include electrical connections based on one or more wires, portable computer disks, hard disks, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM or flash memory), optical fibers, portable compact disk read-only memory (CD-ROM), optical storage devices, magnetic storage devices, or any suitable combination of the foregoing.

[0215] It should be noted that the terms "a" and "a plurality of" used in this application are illustrative rather than restrictive, and those skilled in the art should understand that, unless otherwise expressly indicated in the context, they should be understood as "one or more".

[0216] The above description is merely a preferred embodiment of this application and an explanation of the technical principles employed. Those skilled in the art should understand that the scope of disclosure in this application is not limited to technical solutions formed by specific combinations of the above-described technical features, but should also cover other technical solutions formed by arbitrary combinations of the above-described technical features or their equivalents without departing from the above-described concept. For example, technical solutions formed by substituting the above features with (but not limited to) technical features with similar functions disclosed in this application.

[0217] Finally, it should be noted that other embodiments of the invention will readily occur to those skilled in the art upon consideration of the specification and practice of the invention disclosed herein. This invention is intended to cover any variations, uses, or adaptations of the invention that follow the general principles of the invention and include common knowledge or customary techniques in the art not disclosed herein, and is not limited to the precise structures described above and shown in the accompanying drawings, and various modifications and changes can be made without departing from its scope.

Claims

1. A method for predicting the perforation performance of fracturing fluid, characterized in that, include: During the testing of the fracturing fluid to be tested, upstream and downstream samples of the fracturing fluid to be tested under various experimental conditions in the same test section are obtained; Different experimental conditions are used to indicate at least different orifice geometric parameters in the test section; the upstream sample is taken from the upstream of the orifice plate, and the downstream sample is taken from the downstream of the orifice plate; the test section is used to simulate wellbore orifices; For each of the aforementioned experimental conditions, the viscosity loss rate is calculated based on the viscosity of the upstream sample before the via and the viscosity of the downstream sample after the via. Based on the viscosity loss rate, the variation law of the perforation performance of the fracturing fluid under different experimental conditions is determined.

2. The method according to claim 1, characterized in that, Different experimental conditions are also used to indicate at least one of the following: the discharge rate of the fracturing fluid to be tested through the orifice plate in the test section, and the number of times the fracturing fluid to be tested passes through the orifice plate in the test section.

3. The method according to claim 2, characterized in that, The displacement switches between multiple displacement gradients, and the orifice geometry switches between multiple roughnesses.

4. The method according to any one of claims 1 to 3, characterized in that, The acquisition of upstream and downstream samples of the fracturing fluid under various experimental conditions in the same test section includes: Under the same experimental conditions, N parallel groups of upstream and downstream samples are obtained; where N is any positive integer greater than 1. The step of calculating the viscosity loss rate based on the viscosity after the via and the viscosity before the via includes: The viscosity loss rate of each of the parallel groups was calculated separately, and the average viscosity loss rate of each of the parallel groups was taken as the viscosity loss rate under the experimental conditions.

5. The method according to any one of claims 1 to 3, characterized in that, The step of determining the variation law of the perforation performance of the fracturing fluid under different experimental conditions based on the viscosity loss rate includes: The initial molecular weight distribution and the molecular weight distribution after perforation of the fracturing fluid to be tested are obtained in order to determine the molecular weight fracture ratio; Based on the correlation between the molecular weight fracture ratio and multiple viscosity loss rates, a molecular weight viscosity degradation prediction model for the fracturing fluid under test is established; wherein, the molecular weight viscosity degradation prediction model is used to characterize the quantitative relationship between viscosity loss and molecular chain fracture of the fracturing fluid under test.

6. The method according to any one of claims 1 to 3, characterized in that, After determining the variation law of the perforation performance of the fracturing fluid under different experimental conditions based on the viscosity loss rate, the method further includes: The viscosity loss rates under multiple experimental conditions are stored in the system experimental database; With a preset allowable viscosity loss rate as a constraint, construction parameter optimization suggestions are generated based on the system's experimental database.

7. A closed-loop experimental system, characterized in that, For performing the method as described in any one of claims 1 to 6, the closed-loop experimental system comprises: Mixing tank, used to hold the fracturing fluid to be tested; A pumping device is connected to the outlet of the mixing tank, and the pumping device is used to drive the fracturing fluid to be tested to circulate. A test section for simulating wellbore perforations, wherein the inlet of the test section is connected to the outlet of the pumping device, and the test section is provided with a main pipe of the same size as the mine casing and a perforation plate set on the main pipe, wherein the perforation plate is machined with perforation holes that are consistent with the perforation parameters of the mine. A bypass circuit, the inlet of which is connected between the outlet of the pumping device and the inlet of the test section, and the outlet of which is connected to the inlet of the mixing tank, the bypass circuit being used to allow the fracturing fluid to be tested to bypass the test section during the pre-circulation stage; A sealed receiving chamber is provided on the outlet side of the perforation plate for collecting fracturing fluid after passing through the perforation hole; A sampling device, comprising a first sampling port disposed upstream of the perforated plate and a second sampling port disposed within the sealed receiving cavity, for simultaneously sampling upstream and downstream of the perforated plate; The return liquid pipeline has its inlet connected to the outlet of the sealed receiving chamber and its outlet connected to the inlet of the mixing tank. The return liquid pipeline, together with the pumping device and the test section, forms a closed-loop circulation circuit.

8. The closed-loop experimental system according to claim 7, characterized in that, Also includes: A proppant supply device is disposed above the mixing tank for quantitatively adding proppant into the mixing tank; A concentration monitoring device is installed at the outlet pipeline of the mixing tank to monitor the proppant concentration in the fracturing fluid to be tested in real time. A control device is connected to the proppant supply device and the concentration monitoring device respectively, and is used to control the sand addition rate of the proppant supply device according to the feedback signal of the concentration monitoring device.

9. The closed-loop experimental system according to claim 7, characterized in that, The perforated plate can be replaced on the main pipe.

10. A device for predicting the perforation performance of fracturing fluid, characterized in that, include: A processor, and a memory communicatively connected to the processor; The memory stores computer-executed instructions; The processor executes computer execution instructions stored in the memory to implement the method as described in any one of claims 1 to 6.

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