Fracturing-temporary plugging-sand adding whole-process physical simulation experiment device and method

Abstract

The invention discloses a fracturing-temporary plugging-sand adding whole-process physical simulation experiment device and method.The fracturing-temporary plugging-sand adding whole-process physical simulation experiment device comprises an experiment rock sample, a sand adding device, a sand adding device, a sand adding device, a sand adding device and a sand adding device, the large-scale rock sample stress loading system comprises a true triaxial pressure chamber and a hydraulic servo control system, an experimental rock sample is arranged in the true triaxial pressure chamber, and three-way hydraulic stress is applied to the experimental rock sample through the hydraulic servo control system to simulate a ground stress environment of a target reservoir; the multi-stage fluid injection system comprises a fracturing fluid injection unit, a temporary plugging agent injection unit, a sand-carrying fluid injection unit and a full-scale fracturing pump vehicle set, the full-scale fracturing pump vehicle set is connected with the experimental rock sample in series through a sleeve, and the fracturing fluid injection unit, the temporary plugging agent injection unit and the sand-carrying fluid injection unit are communicated with the full-scale fracturing pump vehicle set in a switching mode. The device is used for a physical simulation experiment of the whole process of fracturing-temporary plugging-sand adding.

Description

Technical Field

[0001] The present invention relates to the technical field of oil and gas field development, and in particular to a physical simulation experimental device and method for the entire process of fracturing, temporary plugging and sand addition. Background Art

[0002] In the development of unconventional oil and gas resources, hydraulic fracturing technology is the core means to improve reservoir permeability and recovery rate, and the coordinated optimization of temporary plugging and diversion and proppant sand addition technology is the key link to form a complex fracture network and improve the fracturing effect. However, the existing physical simulation experimental methods have significant limitations: Traditional experiments mostly use small-sized rock samples, which make it difficult to truly reflect the crack expansion laws of industrial-grade fracturing, the dynamic sealing efficiency of temporary plugging agents, and the distribution characteristics of proppants in cracks. Due to the size effect, the stress field distribution and crack morphology of small rock samples deviate significantly from the actual field conditions.

[0003] In addition, existing research usually separates the fracturing, temporary plugging and sand addition links. For example, only independent experiments are used to evaluate the crack expansion, temporary plugging agent plugging ability or proppant conductivity, and there is a lack of integrated collaborative simulation of the entire "fracturing-temporary plugging-sand addition" process. As a result, experimental data is difficult to guide the optimization of key parameters such as temporary plugging timing and sand addition concentration in industrial-grade fracturing design.

[0004] At the same time, traditional detection methods rely on single parameters such as pressure and flow to indirectly evaluate the plugging effect. They are unable to directly obtain multi-dimensional data on the three-dimensional morphology of fractures, the distribution of temporary plugging agents, and the concentration of proppant placement through technologies such as acoustic imaging, CT scanning, or three-dimensional conductivity testing. Especially under high temperature and high pressure or heterogeneous reservoir conditions, the stability of temporary plugging agents and the settlement patterns of proppant are likely to deviate from the actual working conditions, further exacerbating the unreliability of experimental conclusions.

[0005] In recent years, large-scale physical modeling experimental technology has made progress in reducing reservoir heterogeneity and fracture propagation behavior by adopting large-scale rock samples and high-precision environmental control systems (temperature, confining pressure, and stress field) that match actual reservoirs. However, existing equipment still focuses on a single process link, and there is still a gap between the rock sample size and the industrial-grade fracturing scale. There is a lack of systematic experimental verification of the induction mechanism of new fractures after temporary plugging agents are blocked and the migration and sedimentation law of proppants in complex fracture networks.

[0006] Therefore, there is an urgent need for an industrial-scale integrated physical simulation experimental device and method for fracturing and temporary plugging. By integrating large-scale rock samples, coordinated control of the entire process of fracturing, temporary plugging and sanding, and multi-dimensional detection technology, a full-chain high-precision simulation of fracturing crack expansion, dynamic plugging and steering of temporary plugging agents, and efficient laying of proppants can be achieved, providing a reliable experimental basis for the fracturing design of complex reservoirs and promoting the development of temporary plugging fracturing technology towards efficiency and precision.

[0007] In view of this, the present invention is proposed. Summary of the Invention

[0008] In order to solve the above problems, the present invention proposes a full-process physical simulation experimental device and method for fracturing-temporary plugging-sand adding, which breaks through the scale distortion limitations of traditional small-scale experiments and aims to solve the problems of traditional physical simulation devices being unable to truly reflect the three-dimensional expansion law of industrial-grade fracturing cracks, the difficulty in quantitatively evaluating the temporary plugging and diversion effect, the lack of verification of proppant laying efficiency, and parameter inaccuracy caused by multi-link fracturing simulation.

[0009] Specifically, the following technical solutions are adopted: A physical simulation experimental device for the entire process of fracturing, temporary plugging and sand addition, comprising: Experimental rock samples, wherein the experimental rock samples are large-scale physical model rock samples with a size of one meter or more; A large-scale rock sample stress loading system includes a true triaxial pressure chamber and a hydraulic servo control system. The experimental rock sample is placed in the true triaxial pressure chamber. The hydraulic servo control system applies triaxial hydraulic stress to the experimental rock sample to simulate the in-situ stress environment of the target reservoir. A multi-stage fluid injection system includes a fracturing fluid injection unit, a temporary plugging agent injection unit, a sand-carrying fluid injection unit, and a full-scale fracturing pump unit. The full-scale fracturing pump unit is connected in series with the experimental rock sample through a casing. The fracturing fluid injection unit, the temporary plugging agent injection unit, and the sand-carrying fluid injection unit are switched and connected to the full-scale fracturing pump unit for conducting a physical simulation experiment of the entire process of fracturing-temporary plugging-sand addition. The temporary plugging agent injection unit includes an intelligent control module, which supports the switching injection of granular, fiber-type and degradable composite temporary plugging agents. The dynamic adjustment range of the temporary plugging agent concentration of the intelligent control module is 5-40%, and the intelligent control module supports pulsed / continuous injection modes.

[0010] As an optional embodiment of the present invention, the fracturing fluid injection unit of the present invention includes a slick water tank and a fracturing fluid tank, and the slick water tank and the fracturing fluid tank are switchably connected to the full-scale fracturing pump truck; The temporary plugging agent injection unit includes a temporary plugging agent tank, which is switchably connected to the full-scale fracturing pump vehicle group; The sand-carrying fluid injection unit includes a sand-carrying fluid tank, which is switchably connected to the full-scale fracturing pump truck group.

[0011] As an optional embodiment of the present invention, a full-process physical simulation experimental device of fracturing-temporary plugging-sand addition of the present invention includes a fracture dynamic monitoring system, wherein the fracture dynamic monitoring system includes distributed optical fiber sensors, which are embedded along the surface and inside of the experimental rock sample to monitor the fracture width, fracture extension length and fracture extension speed in real time; The dynamic crack monitoring system includes an acoustic emission three-dimensional positioning device to locate the crack extension trajectory and measure the angle of branch cracks, accurately capturing the temporary plugging agent plugging position and secondary cracking direction.

[0012] The present invention also provides an experimental method for the physical simulation experimental device of the whole process of fracturing-temporary plugging-sand addition, comprising: Placing the experimental rock sample in a true triaxial pressure chamber of the large-scale rock sample stress loading system, and applying triaxial hydraulic stress to the experimental rock sample through the hydraulic servo control system of the large-scale rock sample stress loading system to simulate the in-situ stress environment of the target reservoir; The fracturing fluid injection unit, temporary plugging agent injection unit, and sand-carrying fluid injection unit are controlled to switch and connect with the full-scale fracturing pump truck group to conduct a physical simulation experiment of the entire process of fracturing-temporary plugging-sand addition.

[0013] As an optional embodiment of the present invention, in an experimental method of a full-process physical simulation experimental device for fracturing-temporary plugging-sand addition of the present invention, controlling the switching connection between the fracturing fluid injection unit, the temporary plugging agent injection unit, and the sand-carrying fluid injection unit and the full-scale fracturing pump vehicle group to conduct a full-process physical simulation experiment of fracturing-temporary plugging-sand addition includes: Controlling the connection between the slickwater tank and the full-scale fracturing pump truck to inject slickwater into the experimental rock sample to perform the initial fracturing stage; During the initial fracturing stage, the main fracture extension length monitored by the distributed optical fiber sensor is obtained. When it is determined that the main fracture extension length reaches a preset fracture length value, the temporary plugging agent injection stage is automatically triggered, and the temporary plugging agent tank is controlled to be connected to the full-scale fracturing pump vehicle group to inject the temporary plugging agent in a pulsed manner. During the temporary plugging agent injection stage, the plugging effect is determined in real time by the acoustic emission three-dimensional positioning device. When it is determined that the temporary plugging agent has successfully plugged the main crack, the secondary fracturing and sand addition stage is automatically triggered, the fracturing fluid tank and the sand-carrying fluid tank are controlled to be connected to the full-scale fracturing pump truck, the fracturing fluid is injected to generate a redirected crack, and the sand-carrying fluid is simultaneously injected to support the new crack.

[0014] As an optional embodiment of the present invention, in an experimental method of a full-process physical simulation experimental device of fracturing-temporary plugging-sanding of the present invention, during the temporary plugging agent injection stage, the crack width after temporary plugging is monitored in real time by the distributed optical fiber sensor. If the crack width is reduced by less than 50%, the temporary plugging agent concentration is automatically increased and the single temporary plugging agent injection time is extended.

[0015] As an optional embodiment of the present invention, in the experimental method of a full-process physical simulation experimental device of fracturing-temporary plugging-sanding of the present invention, in the primary fracturing stage and the secondary fracturing and sanding stage, a crack extension velocity model is constructed based on the acoustic emission data monitored by the acoustic emission three-dimensional positioning device and Darcy's law. , where v is the fracture extension velocity, ΔP is the pressure gradient, w is the fracture width, μ is the fluid viscosity, and L represents the distance from the fracture center (or injection point) to the fracture tip. The predicted fracture length error is ≤5%, allowing for early optimization of fracturing parameters.

[0016] As an optional embodiment of the present invention, an experimental method of a full-process physical simulation experimental device of fracturing-temporary plugging-sand addition of the present invention includes quantitatively evaluating the temporary plugging effect based on monitoring data of the full-process physical simulation experiment of fracturing-temporary plugging-sand addition, and the quantitative evaluation of the temporary plugging effect includes: Plugging efficiency: Through the quantification of the hole friction increase rate and the number of branch cracks, the quantitative acceptance of temporary plugging efficiency is achieved; Steering success rate: The ratio of crack steering angles located by the acoustic emission three-dimensional positioning device is ≥ the preset angle value, realizing the quantitative acceptance of the temporary plugging steering success rate.

[0017] As an optional embodiment of the present invention, an experimental method of a full-process physical simulation experimental device of fracturing-temporary plugging-sanding of the present invention includes verifying the proppant laying efficiency based on the monitoring data of the full-process physical simulation experiment of fracturing-temporary plugging-sanding, inverting the fracture conductivity based on the monitoring data of the distributed optical fiber sensor and Darcy's law, and three-dimensionally reconstructing the proppant filling rate to verify the proppant laying efficiency.

[0018] Compared with the prior art, the present invention has the following beneficial effects: The present invention provides a full-process physical simulation experimental device for fracturing-temporary plugging-sanding: by constructing a large-scale rock sample stress loading system for a 2m×2m×1m large-scale experimental rock sample equivalent to an actual reservoir, the full-process physical simulation of fracturing, temporary plugging and proppant placement is achieved. The device aims to overcome the limitation that traditional small-scale experiments cannot reflect the law of industrial-grade crack expansion, establish a visual characterization method for the dynamic extension of cracks under a real stress environment, and solve the problems in the existing technology of difficult to accurately control the timing of temporary plugging agent injection, inaccurate prediction of secondary crack morphology after temporary plugging, and insufficient verification of the effect of proppant migration and placement.

[0019] The present invention provides a full-process physical simulation experimental device for fracturing-temporary plugging-sanding: by integrating a multi-stage fluid injection system, intelligent control of temporary plugging agents and a real-time fracture monitoring system, it provides a basis for optimizing the design of fracturing parameters for the development of unconventional reservoirs such as shale oil and gas and tight oil and gas, improves the efficiency of complex fracture network construction and reservoir transformation volume, and reduces field test costs and construction risks.

[0020] The experimental method of the present invention is a physical simulation experimental device for the whole process of fracturing-temporary plugging-sand addition: Industrial-scale reproduction: 2m×2m×1m experimental rock samples and true triaxial pressure chamber simulate the on-site fracturing stress field and crack scale, solving the problem of scale distortion in small-scale experiments.

[0021] Temporary plugging-support coordinated regulation of the entire process: integrated "fracturing-temporary plugging-sand addition" closed-loop control, achieving dynamic linkage through multi-channel fluid switching and intelligent algorithms.

[0022] Multimodal data fusion monitoring: Distributed optical fiber + acoustic emission quantifies crack expansion and temporary plugging effects in real time, improving the accuracy of conductivity prediction by 40%. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 A structural schematic diagram of a physical simulation experimental device for the entire process of fracturing, temporary plugging, and sand addition according to an embodiment of the present invention; Figure 2 A flow chart of an experimental method for a full-process physical simulation experimental device for fracturing-temporary plugging-sand addition according to an embodiment of the present invention. DETAILED DESCRIPTION

[0024] To make the purpose, technical solutions and advantages of the embodiments of the present invention more clear, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them.

[0025] Therefore, the following detailed description of the embodiments of the present invention is not intended to limit the scope of the claimed invention, but merely represents some embodiments of the present invention. All other embodiments derived by persons of ordinary skill in the art based on the embodiments of the present invention without creative effort shall fall within the scope of protection of the present invention.

[0026] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features and technical solutions therein may be combined with each other.

[0027] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, it does not need to be further defined or explained in subsequent drawings.

[0028] In the description of the present invention, it should be noted that the terms "upper" and "lower" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, or the orientations or positional relationships in which the inventive product is typically placed when in use, or the orientations or positional relationships commonly understood by those skilled in the art. Such terms are intended solely to facilitate the description of the present invention and simplify the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, be constructed, or operate in a specific orientation. Therefore, they should not be construed as limitations on the present invention. Furthermore, the terms "first" and "second" and the like are used solely for distinction and should not be construed as indicating or implying relative importance.

[0029] See also Figure 1 As shown, a physical simulation experimental device for the whole process of fracturing-temporary plugging-sand addition in this embodiment includes: An experimental rock sample 100, which is a large-scale model rock sample with a size of more than one meter; A large-scale rock sample stress loading system 200 includes a true triaxial pressure chamber and a hydraulic servo control system. The experimental rock sample 100 is placed in the true triaxial pressure chamber. The hydraulic servo control system applies triaxial hydraulic stress to the experimental rock sample to simulate the in-situ stress environment of the target reservoir. A multi-stage fluid injection system includes a fracturing fluid injection unit 901, a temporary plugging agent injection unit 902, a sand-carrying fluid injection unit 903 and a full-scale fracturing pump truck group 400. The full-scale fracturing pump truck group 400 is connected in series with the experimental rock sample 100 through a casing 300. The fracturing fluid injection unit 901, the temporary plugging agent injection unit 902, and the sand-carrying fluid injection unit 903 are switched and connected to the full-scale fracturing pump truck group 400 for conducting a full-process physical simulation experiment of fracturing-temporary plugging-sand addition.

[0030] A physical simulation experimental device for the whole process of fracturing-temporary plugging-sand addition in this embodiment: By constructing a large-scale rock sample stress loading system 200 for a 2m×2m×1m large-scale experimental rock sample equivalent to the actual reservoir, a full-process physical simulation of fracturing, temporary plugging and diversion, and proppant placement is achieved. This aims to overcome the limitation of traditional small-scale experiments that cannot reflect the laws of industrial-level crack expansion, establish a visual representation method for the dynamic extension of cracks under real stress environments, and solve problems in existing technologies such as the difficulty in accurately controlling the timing of temporary plugging agent injection, inaccurate prediction of secondary fracture morphology after temporary plugging, and insufficient verification of the proppant migration and placement effect.

[0031] By integrating a multi-stage fluid injection system, intelligent control of temporary plugging agents, and a real-time fracture monitoring system, it provides a basis for optimized fracturing parameter design for the development of unconventional reservoirs such as shale oil and gas, tight oil and gas, etc., improves the efficiency of complex fracture network construction and reservoir transformation volume, while reducing field test costs and construction risks.

[0032] Furthermore, in a physical simulation experimental device for the full process of fracturing-temporary plugging-sanding in this embodiment, the fracturing fluid injection unit 901 includes a slick water tank and a fracturing fluid tank, which are switchably connected to the full-scale fracturing pump truck 400; The temporary plugging agent injection unit 902 includes a temporary plugging agent tank, which is switchably connected to the full-scale fracturing pump vehicle assembly 400; The sand-carrying fluid injection unit 903 includes a sand-carrying fluid tank, which is switchably connected to the full-scale fracturing pump truck 400.

[0033] The present embodiment is a physical simulation experiment device for the whole process of fracturing-temporary plugging-sanding, which realizes the physical simulation experiment of the whole process of fracturing-temporary plugging-sanding through the fracturing fluid injection unit 901, the temporary plugging agent injection unit 902, and the sand-carrying fluid injection unit 903.

[0034] In a full-process physical simulation experimental device for fracturing, temporary plugging, and sanding in this embodiment, the temporary plugging agent injection unit 902 includes an intelligent control module that supports switching injection of granular, fibrous, and degradable composite temporary plugging agents. The intelligent control module has a dynamic adjustment range of temporary plugging agent concentration of 5-40%, and supports both pulsed and continuous injection modes.

[0035] In a full-process physical simulation experimental device for fracturing-temporary plugging-sanding of this embodiment, the fracturing fluid injection unit 901 includes a high-pressure plunger pump (displacement 0.1-5.0 m³ / min, pressure range 0-60 MPa), which supports dynamic switching between slick water (viscosity 1-5 mPa•s) and linear glue (viscosity 50-100 mPa•s).

[0036] In a physical simulation experimental device for the full process of fracturing, temporary plugging, and sand addition in this embodiment, the sand-carrying fluid injection unit 903 includes a spiral sand mixer (rotation speed 50-300 rpm) linked to a double-cylinder plunger pump. The proppant (quartz sand / ceramsite, particle size 20-100 mesh) concentration is 0-40%, and the sand ratio error is ≤±2%.

[0037] The present embodiment provides a full-process physical simulation experimental device for fracturing, temporary plugging, and sand addition, including a dynamic fracture monitoring system 800. The dynamic fracture monitoring system 800 includes distributed optical fiber sensors 600, which are embedded along the surface and inside of the experimental rock sample 100 to monitor the fracture width, fracture extension length, and fracture extension speed in real time. The dynamic crack monitoring system 800 includes an acoustic emission three-dimensional positioning device 700, which can locate the crack extension trajectory and measure the angle of branch cracks, and accurately capture the temporary plugging agent plugging position and secondary cracking direction.

[0038] This embodiment is a physical simulation experimental device for the entire process of fracturing-temporary plugging-sand addition. The fracture dynamic monitoring system 800 includes a pressure sensor and a flow meter 500 to monitor the pressure and flow rate during the fracturing process.

[0039] This embodiment provides a full-process physical simulation experimental device for fracturing, temporary plugging, and sanding, and a large-scale rock sample stress loading system 200 (breaking through the bottleneck of laboratory-level simulation). It includes a true triaxial pressure chamber: the internal effective space dimensions are 2.2m×2.2m×1.2m (more than 50 times the volume of existing rock samples), made of high-strength alloy steel, equipped with a hydraulic servo control system, supporting serial loading of multiple groups of experimental rock samples, with a maximum horizontal stress of 0-60MPa, a vertical stress of 0-50MPa, a stress loading rate of 0.1MPa / s, and a pressure stabilization error of ≤±0.3MPa, accurately reproducing the in-situ stress environment of a reservoir buried at a depth of 3500m.

[0040] Rock sample preparation: A 2m×2m×1m natural sandstone or artificially cast rock sample (industrial scale) was selected. A perforating gun with an 8mm aperture and a density of 16 holes / meter was used to simulate the staged fracturing parameters of a horizontal well. Perforation holes 101 were formed in the experimental rock sample 100, authentically recreating the on-site perforating process.

[0041] See also Figure 2 As shown, this embodiment also provides an experimental method for the physical simulation experimental device of the whole process of fracturing-temporary plugging-sand addition, including: Placing the experimental rock sample in a true triaxial pressure chamber of the large-scale rock sample stress loading system, and applying triaxial hydraulic stress to the experimental rock sample through the hydraulic servo control system of the large-scale rock sample stress loading system to simulate the in-situ stress environment of the target reservoir; The fracturing fluid injection unit, temporary plugging agent injection unit, and sand-carrying fluid injection unit are controlled to switch and connect with the full-scale fracturing pump truck group to conduct a physical simulation experiment of the entire process of fracturing-temporary plugging-sand addition.

[0042] In the experimental method of a full-process physical simulation experimental device for fracturing-temporary plugging-sand addition in this embodiment, controlling the switching connection between the fracturing fluid injection unit, the temporary plugging agent injection unit, and the sand-carrying fluid injection unit and the full-scale fracturing pump vehicle assembly to conduct the full-process physical simulation experiment for fracturing-temporary plugging-sand addition includes: Controlling the connection between the slickwater tank and the full-scale fracturing pump truck to inject slickwater into the experimental rock sample to perform the initial fracturing stage; During the initial fracturing stage, the main fracture extension length monitored by the distributed optical fiber sensor is obtained. When it is determined that the main fracture extension length reaches a preset fracture length value, the temporary plugging agent injection stage is automatically triggered, and the temporary plugging agent tank is controlled to be connected to the full-scale fracturing pump vehicle group to inject the temporary plugging agent in a pulsed manner. During the temporary plugging agent injection stage, the plugging effect is determined in real time by the acoustic emission three-dimensional positioning device. When it is determined that the temporary plugging agent has successfully plugged the main crack, the secondary fracturing and sand addition stage is automatically triggered, the fracturing fluid tank and the sand-carrying fluid tank are controlled to be connected to the full-scale fracturing pump truck, the fracturing fluid is injected to generate a redirected crack, and the sand-carrying fluid is simultaneously injected to support the new crack.

[0043] In the experimental method of a full-process physical simulation experimental device for fracturing-temporary plugging-sand addition of this embodiment, during the temporary plugging agent injection stage, the crack width after temporary plugging is monitored in real time by the distributed optical fiber sensor. If the crack width is reduced by less than 50%, the temporary plugging agent concentration is automatically increased and the single temporary plugging agent injection time is extended.

[0044] In the experimental method of a full-process physical simulation experimental device for fracturing-temporary plugging-sanding of this embodiment, in the primary fracturing stage and the secondary fracturing and sanding stage, a crack extension velocity model is constructed based on the acoustic emission data monitored by the acoustic emission three-dimensional positioning device and Darcy's law. , where v is the fracture extension velocity, ΔP is the pressure gradient, w is the fracture width, μ is the fluid viscosity, and L represents the distance from the fracture center (or injection point) to the fracture tip, where: v (crack extension velocity) Physical meaning: The distance the crack front extends forward per unit time, usually expressed in m / s or mm / s.

[0045] Function: Characterizes the speed of dynamic development of fractures and is a key indicator for evaluating reservoir transformation efficiency or geological disaster risks.

[0046] ΔP (pressure gradient) Physical meaning: pressure difference between the fluid inside and outside the fracture (Pinside - Poutside), unit is Pa or MPa.

[0047] Effect: Pressure difference is the main driving force for crack extension. When ΔP increases, v increases linearly.

[0048] w (crack width) Physical meaning: The average opening width of the crack perpendicular to the extension direction, in m or mm.

[0049] Function: The larger the width, the smoother the fluid flow channel, the smaller the crack extension resistance, and the higher the velocity v.

[0050] μ (fluid viscosity) Physical meaning: Friction resistance coefficient within the fluid, unit is Pa·s or mPa·s.

[0051] Effect: The higher the viscosity, the greater the fluid flow resistance, and the lower the crack extension velocity v.

[0052] L represents the distance from the crack center (or injection point) to the crack tip.

[0053] This formula combines Darcy's law (fluid flow velocity is proportional to pressure gradient and permeability, and inversely proportional to viscosity) with fracture geometry to derive the fracture propagation velocity. Its core assumption is that fracture propagation is driven by fluid and that acoustic emission data can indirectly reflect fracture dynamics (e.g., through event location to determine L or w).

[0054] In this embodiment, a crack extension velocity model is constructed , the error of predicted crack length is ≤5%, and the fracturing parameters are optimized in advance.

[0055] An experimental method for a full-process physical simulation experimental device for fracturing, temporary plugging, and sand addition in this embodiment includes quantitatively evaluating the temporary plugging effect based on monitoring data from the full-process physical simulation experiment for fracturing, temporary plugging, and sand addition. The quantitative evaluation of the temporary plugging effect includes: Plugging efficiency: Through the quantification of the hole friction increase rate and the number of branch cracks, the quantitative acceptance of temporary plugging efficiency is achieved; Steering success rate: The ratio of crack steering angles located by the acoustic emission three-dimensional positioning device is ≥ the preset angle value, realizing the quantitative acceptance of the temporary plugging steering success rate.

[0056] The present embodiment provides an experimental method for a full-process physical simulation experimental device for fracturing-temporary plugging-sanding, including verifying proppant placement efficiency based on monitoring data from the full-process physical simulation experiment for fracturing-temporary plugging-sanding, inverting fracture conductivity based on the monitoring data of the distributed optical fiber sensor and Darcy's law, and three-dimensionally reconstructing the proppant filling rate to verify the proppant placement efficiency.

[0057] As a specific embodiment of the present invention's full-process physical simulation experimental device and experimental method for fracturing-temporary plugging-sand addition, the specific technical solution is as follows: 1. Experimental setup and system composition (1) Large-scale rock sample stress loading system At least three independent stress loading units are set up in the true triaxial pressure chamber. Each stress loading unit can accommodate an experimental rock sample with a size of 2m×2m×1m, supporting differentiated environmental simulation.

[0058] Each stress loading unit independently controls the maximum horizontal stress (0-60MPa), vertical stress (0-50MPa) and temperature (20-200℃). The stress loading error is ≤±0.2MPa and the temperature control accuracy is ±2℃.

[0059] Thermal and pressure insulation barriers are set between each stress loading unit to support the coordinated injection of high temperature and high pressure (150℃ / 50MPa), low temperature and low pressure (30℃ / 10MPa) and gas-water-sand multiphase fluids.

[0060] The experimental rock samples were prepared using natural sandstone or artificial casting materials (cement-quartz sand mixture ratio 1:3), with pre-perforation clusters (aperture diameter 8 mm, hole density 16 holes / m) on the surface and distributed optical fiber sensors embedded inside (spacing 10 cm).

[0061] (2) Multi-stage fluid injection system fracturing fluid injection unit: high-pressure plunger pump (displacement 0.1-5.0 m³ / min, pressure 0-60 MPa), supporting dynamic switching between slick water (viscosity 1-5 mPa•s) and linear glue (viscosity 50-100 mPa•s); Temporary plugging agent injection unit: intelligent control module, supports on-demand mixing of granular (0.1-5mm), fiber (5-20mm), and nano self-assembled temporary plugging agents (mixing ratio error ≤±0.5%), and concentration adaptive adjustment range of 5-40%; Sand-carrying fluid injection unit: A spiral sand mixer (rotation speed 50-300rpm) is linked to a double-cylinder plunger pump, with real-time feedback control of sand ratio (0-50%), and a proppant (quartz sand / ceramsite, 20-100 mesh) distribution uniformity ≥ 95%.

[0062] (3) Distributed fiber optic array of the crack dynamic monitoring system: deployed along the surface and inside the rock sample (density 10 points / m²), real-time monitoring of crack width (resolution 0.05mm) and extension speed (accuracy ±0.03m / s); Acoustic emission three-dimensional positioning device: 64-channel acoustic emission probe network, locates the crack propagation trajectory (spatial error ≤ 1cm) and the angle of branch crack formation; Micro CT scanning module: integrated in the pressure chamber, it generates a three-dimensional crack morphology and a temporary plugging agent distribution thermal map every 30 seconds, supporting dynamic visual analysis.

[0063] (4) AI dynamic optimization platform Based on the reinforcement learning algorithm, it receives optical fiber, acoustic emission and CT data in real time, dynamically adjusts the stress field, injection parameters and temporary plugging strategy of each sample, and realizes closed-loop control of the entire process of "fracturing-temporary plugging-support"; Through cross-validation of multiple sample data, a global optimal parameter set (such as displacement, sand ratio, and temporary plugging agent type) is generated, and the sample operation strategy for unfinished experiments is reversely regulated.

[0064] 2. Experimental Procedure and Control Methods (1) Differentiated loading of multiple specimens Different stress combinations are applied to the three rock samples: Specimen A: high stress inhomogeneity (maximum horizontal stress 55 MPa, vertical 45 MPa); Specimen B: low stress homogeneous (maximum horizontal stress 40 MPa, vertical 30 MPa); Specimen C: dynamic stress fluctuation (horizontal stress 40-55 MPa periodically changes); The loading rate was 0.1 MPa / s, and the pressure was maintained for 30 minutes until the stress fluctuation was ≤±0.2 MPa.

[0065] (2) Fracturing-temporary plugging-support coordinated operation Sample A: Using the "high-pressure fracturing rate (2.5 m³ / min) + low sand ratio (20%)" strategy, AI dynamically increases the sand ratio to 45% based on the crack propagation rate; Sample B: Pulsed injection of nano self-assembled temporary plugging agent (concentration 25%), combined with dynamic stress adjustment, to induce multi-branched cracks (target ≥ 5); Sample C: simulates a high temperature environment of 150°C to verify the half-life of the degradable temporary plugging agent and the settlement law of the proppant.

[0066] (3) Dynamic feedback and intelligent control Temporary plugging agent enhancement: If the CT scan shows that the temporary plugging agent bridging coverage is less than 70%, it will automatically switch to a fiber-type temporary plugging agent and increase the concentration to 30%; Crack propagation prediction: Based on the acoustic emission energy distribution and Darcy's law, a crack extension velocity model is constructed (Formula: , where v is the fracture extension velocity, ΔP is the pressure gradient, w is the fracture width, μ is the fluid viscosity, and L represents the distance from the fracture center or injection point to the fracture tip). The prediction error is ≤3%; Sand plugging risk warning: Real-time displacement adjustment is triggered by pressure fluctuations (±0.5MPa) to avoid construction interruptions.

[0067] 3. Multi-scale performance evaluation and verification (1) Quantification of the effect of temporary blocking and diversion Plugging efficiency: Calculate the temporary plugging agent coverage rate by combining the CT thermal map and friction change (target improvement ≥80%); Steering success rate: The proportion of crack steering angles ≥40° determined by acoustic emission positioning (target ≥85%).

[0068] (2) Verification of proppant placement efficiency Conductivity: Based on optical fiber strain data and Darcy's law inversion, the target value is ≥150D•cm, with an error of ≤5%; 3D Filling Rate: Quantify the uniformity of proppant distribution through CT scanning (target ≥90%).

[0069] The core innovation of the present invention's full-process physical simulation experimental device and experimental method for fracturing-temporary plugging-sand addition is: Multi-sample parallel comparative experiment: Supports simultaneous experiments on three industrial-grade rock samples (2m×2m×1m), independently controls stress, temperature, and fluid parameters, and enables rapid comparison of complex reservoir conditions, improving experimental efficiency by 40%.

[0070] AI-driven closed-loop control: Introducing a reinforcement learning algorithm to optimize parameters in real time and reversely regulate experimental strategies, reducing the use of temporary plugging agents by 30%.

[0071] Real-time 3D imaging and thermal map analysis: integrated micro-CT module dynamically captures the temporary plugging agent bridging process, with a plugging efficiency quantification error of ≤5%.

[0072] Intelligent switching of multiple types of temporary plugging agents: supports on-demand mixing of granular, fiber and nano-temporary plugging agents to adapt to complex fracture networks.

[0073] High-temperature, high-pressure, multiphase environment simulation: The pressure chamber unit has independent temperature control (up to 200°C), supports gas-water-sand coordinated injection, and accurately simulates deep reservoirs. Example

[0074] This embodiment provides an experimental method for a full-process physical simulation experimental device of fracturing-temporary plugging-sanding, which realizes the construction of a complex fracture network in a shale reservoir.

[0075] 1. Experimental Objectives Verify the steering control ability of temporary plugging agents on multi-branch fractures in shale reservoirs, optimize the matching of a 2mm-sized degradable temporary plugging agent and a proppant combination (40-mesh ceramsite), and target a fracture network complexity index ≥3.0.

[0076] 2. Device and parameters Rock sample: 2m×2m×1m shale (TOC ≥ 4%, compressive strength 60MPa), pre-perforated cluster (aperture 10mm, perforation density 18 holes / m).

[0077] Stress loading: maximum horizontal stress 55MPa, vertical stress 45MPa, simulated reservoir depth 3500m.

[0078] Fluid injection: The fracturing fluid is slick water (viscosity 3 mPa•s) with a displacement of 1.5 m³ / min.

[0079] Temporary plugging agent: degradable particles (particle size 2 mm, concentration 25%), pulse injection (single 15s, interval 25s).

[0080] Sand-carrying liquid: sand ratio 35%, expanded clay 40 mesh.

[0081] 3. Experimental Procedure Initial fracturing: Slick water was injected until the main fracture length reached 1.7 m (the fracture extension speed was monitored by distributed optical fiber and was ≥ 0.1 m / s), with a fracture pressure of 32 MPa.

[0082] Stop fracturing and wait for the crack to stabilize.

[0083] Temporary plugging and diversion phase: When the fiber optic monitoring detects a main fracture width of 6mm or greater, a temporary plugging agent injection command is triggered. Pulsed injection of the temporary plugging agent seals three perforation clusters, with the fracture tip pressure rising at a rate of 1.8 MPa / s (acoustic emission signals confirm successful plugging).

[0084] Secondary fracturing and sand support: Slick fracturing fluid (1.8 m³ / min) is reinjected, and diverted fractures are generated using acoustic emission positioning. Sand-carrying fluid (35% sand ratio) is switched to and continuously injected until the pressure in the fracture stabilizes (pressure fluctuation ≤ ±0.5 MPa).

[0085] 4. Dynamic Optimization Sand ratio adjustment: Based on the number of branch cracks (5) monitored by real-time acoustic emission, the sand ratio was dynamically increased to 40% using the Bayesian algorithm to avoid the risk of sand blockage.

[0086] Temporary plugging agent enhancement: If the optical fiber shows that the branch crack turning angle does not reach 40°, increase the temporary plugging agent concentration to 28%.

[0087] 5. Effect Verification Crack network complexity: Acoustic emission positioning generated 6 branch cracks (steering angle ≥ 40°), with a complexity index of 3.5 (traditional method ≤ 2.0).

[0088] Conductivity: Based on the optical fiber strain data and Darcy's law inversion, the conductivity is 135D•cm, which is 50% higher than that of the experiment without temporary plugging.

[0089] Economical: The amount of temporary plugging agent is reduced by 20%, and the proppant prediction error is reduced from ±25% to ±8%. Example

[0090] This embodiment provides an experimental method for a full-process physical simulation experimental device of fracturing-temporary plugging-sanding, which realizes the optimization of high-sand ratio fracturing of dense sandstone.

[0091] 1. Experimental Objectives The effect of a fiber-type temporary plugging agent (15 mm in length) on the migration path of proppant with a high sand ratio (45%) in tight sandstone was verified, with the target proppant filling rate ≥90% and fracture conductivity ≥150 D•cm.

[0092] 2. Device and parameters Rock sample: 2m×2m×1m dense sandstone (permeability 0.1mD, compressive strength 55MPa), perforation cluster aperture 8mm.

[0093] Stress loading: maximum horizontal stress 50MPa, vertical stress 40MPa.

[0094] Fluid injection: The fracturing fluid is linear gel (viscosity 60mPa•s), with a displacement of 1.2m³ / min; Temporary plugging agent: fiber type (length 15mm, concentration 18%), continuous injection mode; Sand-carrying fluid: sand ratio 45%, quartz sand 30 mesh.

[0095] 3. Experimental Procedure Initial fracturing: Linear glue was injected to form a main fracture of 1.6m (fracture pressure 28MPa), and the crack width was monitored to be 5mm through distributed optical fiber.

[0096] Stop fracturing and wait for the crack to stabilize.

[0097] Temporary plugging and diversion stage: triggering the injection of fiber temporary plugging agent to form a mesh bridging structure, and the hole friction resistance increases from 0.6MPa to 1.8MPa (real-time feedback from the pressure sensor).

[0098] Secondary fracturing and sand support: Linear gel fracturing fluid was re-injected (displacement rate 2.0m³ / min), and acoustic emission positioning showed the generation of three branch fractures.

[0099] Switch to sand-carrying fluid (sand ratio 45%) and dynamically adjust the displacement to 1.5m³ / min (PID control is triggered by pressure fluctuation of ±0.8MPa).

[0100] 4. Dynamic Optimization Displacement control: Reduce the displacement to 1.5m³ / min in real time according to pressure fluctuations (±0.8MPa) to prevent sand blockage.

[0101] Temporary plugging agent enhancement: The concentration of fiber temporary plugging agent is dynamically adjusted from 18% to 22% through the PID algorithm to enhance the plugging stability.

[0102] 5. Effect Verification Proppant distribution: 3D reconstruction shows a filling rate of 93%, with local sand-free areas accounting for ≤5%.

[0103] Conductivity: The conductivity measured by Darcy test is 160D•cm, with an error of ≤6%.

[0104] Adaptability: The distribution deviation of fiber temporary plugging agent in the 0.1-10mD permeability layer is ≤12%, which is better than that of granular temporary plugging agent (deviation ≥25%).

[0105] The above embodiments are only used to illustrate the present invention and are not intended to limit the technical solutions described in the present invention. Although this specification has described the present invention in detail with reference to the above embodiments, the present invention is not limited to the above specific implementation methods. Therefore, any modification or equivalent replacement of the present invention; and all technical solutions and improvements thereof that do not depart from the spirit and scope of the invention are included in the scope of the claims of the present invention.

Claims

1. A physical simulation experimental device for the whole process of fracturing-temporary plugging-sand adding, characterized in that: include: Experimental rock samples, wherein the experimental rock samples are large-scale physical model rock samples with a size of one meter or more; A large-scale rock sample stress loading system includes a true triaxial pressure chamber and a hydraulic servo control system. The experimental rock sample is placed in the true triaxial pressure chamber. The hydraulic servo control system applies triaxial hydraulic stress to the experimental rock sample to simulate the in-situ stress environment of the target reservoir. A multi-stage fluid injection system includes a fracturing fluid injection unit, a temporary plugging agent injection unit, a sand-carrying fluid injection unit, and a full-scale fracturing pump unit. The full-scale fracturing pump unit is connected in series with the experimental rock sample through a casing. The fracturing fluid injection unit, the temporary plugging agent injection unit, and the sand-carrying fluid injection unit are switched and connected to the full-scale fracturing pump unit for conducting a physical simulation experiment of the entire process of fracturing-temporary plugging-sand addition. The temporary plugging agent injection unit includes an intelligent control module, which supports the switching injection of granular, fiber-type and degradable composite temporary plugging agents. The dynamic adjustment range of the temporary plugging agent concentration of the intelligent control module is 5-40%, and the intelligent control module supports pulsed / continuous injection modes.

2. A full-process physical simulation experimental device for fracturing-temporary plugging-sand addition according to claim 1, characterized in that: The fracturing fluid injection unit includes a slick water tank and a fracturing fluid tank, which are switchably connected to the full-scale fracturing pump truck; The temporary plugging agent injection unit includes a temporary plugging agent tank, which is switchably connected to the full-scale fracturing pump vehicle group; The sand-carrying fluid injection unit includes a sand-carrying fluid tank, which is switchably connected to the full-scale fracturing pump truck group.

3. A physical simulation experimental device for the whole process of fracturing-temporary plugging-sand addition according to any one of claims 1-2, characterized in that: It includes a dynamic crack monitoring system, which includes distributed optical fiber sensors embedded along the surface and inside of the test rock sample to monitor the crack width, crack extension length and crack extension speed in real time; The dynamic crack monitoring system includes an acoustic emission three-dimensional positioning device to locate the crack extension trajectory and measure the angle of branch cracks, accurately capturing the temporary plugging agent plugging position and secondary cracking direction.

4. An experimental method for the full-process physical simulation experimental device of fracturing-temporary plugging-sand addition according to any one of claims 1 to 3, characterized in that: include: Placing the experimental rock sample in a true triaxial pressure chamber of the large-scale rock sample stress loading system, and applying triaxial hydraulic stress to the experimental rock sample through the hydraulic servo control system of the large-scale rock sample stress loading system to simulate the in-situ stress environment of the target reservoir; The fracturing fluid injection unit, temporary plugging agent injection unit, and sand-carrying fluid injection unit are controlled to switch and connect with the full-scale fracturing pump truck group to conduct a physical simulation experiment of the entire process of fracturing-temporary plugging-sand addition.

5. The experimental method of a full-process physical simulation experimental device for fracturing-temporary plugging-sand addition according to claim 4 is characterized in that: The controlling of switching and connecting the fracturing fluid injection unit, the temporary plugging agent injection unit, and the sand-carrying fluid injection unit with the full-scale fracturing pump vehicle group to conduct a physical simulation experiment of the whole process of fracturing-temporary plugging-sand addition includes: Controlling the connection between the slickwater tank and the full-scale fracturing pump truck to inject slickwater into the experimental rock sample to perform the initial fracturing stage; During the initial fracturing stage, the main fracture extension length monitored by the distributed optical fiber sensor is obtained. When it is determined that the main fracture extension length reaches a preset fracture length value, the temporary plugging agent injection stage is automatically triggered, and the temporary plugging agent tank is controlled to be connected to the full-scale fracturing pump vehicle group to inject the temporary plugging agent in a pulsed manner; During the temporary plugging agent injection stage, the plugging effect is determined in real time by an acoustic emission three-dimensional positioning device. When it is determined that the temporary plugging agent has successfully plugged the main crack, the secondary fracturing and sand addition stage is automatically triggered. The fracturing fluid tank and the sand-carrying fluid tank are controlled to be connected to the full-scale fracturing pump truck group, and the fracturing fluid is injected to generate a redirected crack, and the sand-carrying fluid is simultaneously injected to support the new crack.

6. The experimental method of a full-process physical simulation experimental device for fracturing-temporary plugging-sand addition according to claim 5 is characterized in that: During the temporary plugging agent injection stage, the distributed optical fiber sensor monitors the crack width after temporary plugging in real time. If the crack width is reduced by less than 50%, the temporary plugging agent concentration is automatically increased and the single temporary plugging agent injection time is extended.

7. The experimental method of the full-process physical simulation experimental device of fracturing-temporary plugging-sand addition according to claim 5 is characterized in that: During the primary fracturing stage and the secondary fracturing and sand adding stage, a crack extension velocity model is constructed based on the acoustic emission data monitored by the acoustic emission three-dimensional positioning device and Darcy's law. , where v is the fracture extension velocity, ΔP is the pressure gradient, w is the fracture width, μ is the fluid viscosity, and L represents the distance from the fracture center or injection point to the fracture tip; the predicted fracture length error is ≤5%, and the fracturing parameters are optimized in advance.

8. The experimental method of a full-process physical simulation experimental device for fracturing-temporary plugging-sand addition according to claim 4 is characterized in that: The method includes quantitatively evaluating the temporary plugging effect based on the monitoring data of the physical simulation experiment of the whole process of fracturing-temporary plugging-sand addition, and the quantitative evaluation of the temporary plugging effect includes: Plugging efficiency: Through the quantification of the hole friction increase rate and the number of branch cracks, the quantitative acceptance of temporary plugging efficiency is achieved; Steering success rate: The ratio of crack steering angles located by the acoustic emission three-dimensional positioning device is ≥ the preset angle value, realizing the quantitative acceptance of the temporary plugging steering success rate.

9. The experimental method of a full-process physical simulation experimental device for fracturing-temporary plugging-sand addition according to claim 4, characterized in that: This includes verifying the proppant placement efficiency based on the monitoring data of the physical simulation experiment of the entire process of fracturing-temporary plugging-sanding, inverting the fracture conductivity based on the monitoring data of the distributed optical fiber sensor and Darcy's law, and three-dimensionally reconstructing the proppant filling rate to verify the proppant placement efficiency.

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