An internal temperature field inversion method and system for heavy oil thermal recovery experiment

Abstract

The present application belongs to the technical field of oil and natural gas exploitation, and relates to an internal temperature field inversion method and system for heavy oil thermal recovery experiment, comprising the following steps: collecting data of a quartz glass plate; determining a two-dimensional temperature matrix of the outer surface of the quartz glass plate; constructing a one-dimensional non-steady-state heat conduction control model along the thickness direction; obtaining the temperature field of the inner surface of the quartz glass plate; obtaining the corrected temperature field of the inner surface of the quartz glass plate; and quantitatively reconstructing the temperature field of the heavy oil thermal recovery experiment. The present application obtains a continuous and reliable temperature field of the inner surface of the quartz glass plate through parameter collection of the quartz glass plate, correction of high-temperature abnormal points and inversion of the one-dimensional non-steady-state heat conduction control model, realizes high-precision quantitative reconstruction of the internal temperature field of the heavy oil thermal recovery experiment, reduces the nonlinear deviation in the characterization process of the steam cavity development range, temperature transition zone position and thermal front advance speed, and significantly improves the refinement and accuracy of the analysis of the steam cavity evolution law.

Description

Technical Field

[0001] This invention belongs to the field of oil and gas extraction technology, and relates to an internal temperature field inversion method and system for heavy oil thermal recovery experiments. Background Technology

[0002] In heavy oil thermal recovery and steam-assisted gravity drainage (SAGD) development, the development pattern of the steam cavity and the heat transfer process are the core basis for optimizing development parameters and improving oil recovery. Two-dimensional visualization physical simulation experiments can intuitively reflect the expansion morphology and microscopic displacement characteristics of the steam cavity, and have become an important means of studying the thermal recovery mechanism. Such experiments typically consist of a temperature-controlled chamber, a two-dimensional visualization model, and a fluid injection and production device. By injecting hot steam and combining it with visualization observation, the interaction law between steam, oil, and rock is analyzed. During the steam displacement process, the internal temperature field exhibits strong unsteady-state and spatiotemporally non-uniform distribution characteristics. The steam cavity region is a high-temperature zone, the unaffected area is a low-temperature zone, and there is a clear temperature transition zone in between. This temperature distribution directly determines the expansion path of the steam cavity and the oil displacement efficiency. Therefore, accurately obtaining the internal temperature field of the model is crucial for the study of the thermal recovery mechanism and process optimization.

[0003] Currently, for acquiring the temperature field in two-dimensional visualization experiments, infrared thermal imagers are mainly used to record the temperature distribution on the outer surface of a quartz glass plate. During the experiment, the thermal imaging device continuously collects the temperature matrix of the model's outer surface and uses this outer surface temperature as the main basis for judging the development degree of the steam cavity, the range of heat transfer, and the characteristics of the temperature field distribution. Because infrared thermal imaging technology can achieve non-contact large-area temperature measurement and is easy to synchronize with the visualization image in the spatiotemporal dimension, it is widely used in surface temperature monitoring of various physical simulation experiments.

[0004] However, due to the certain thickness, thermal diffusivity, and boundary thermal resistance of the quartz glass plate, and the nonlinear phase lag and amplitude attenuation between its outer surface temperature and the actual internal temperature of the model, there are significant deviations in the characterization of the steam cavity development range, the position of the temperature transition zone, and the advancing speed of the thermal front. This makes existing experiments mainly limited to qualitative observation of external surface phenomena, making it difficult to quantitatively reconstruct the internal temperature field and the dynamic evolution process of the steam cavity. This restricts the precision of the analysis of the steam cavity evolution law and weakens the reliability of the experimental basis for SAGD process parameter optimization research. Summary of the Invention

[0005] The purpose of this invention is to provide an internal temperature field inversion method and system for heavy oil thermal recovery experiments, which can reduce the nonlinear deviation between external measurements and actual internal temperatures, realize quantitative reconstruction of the internal temperature field, improve the precision of steam cavity evolution law analysis, and enhance the reliability of experimental basis for SAGD process parameter optimization research.

[0006] To achieve the above objectives, the technical solution provided by the present invention is as follows: An internal temperature field inversion method for heavy oil thermal recovery experiments includes: The thickness, thermal conductivity, density, specific heat capacity, and initial temperature of the quartz glass plate were collected, as well as the temperature field data of the outer surface of the quartz glass plate. Based on the thickness, thermal conductivity, density and specific heat capacity of the quartz glass plate, the thermal diffusivity of the quartz glass plate is determined, and the two-dimensional temperature matrix of the outer surface of the quartz glass plate as a function of time is determined based on the temperature field data of the outer surface of the quartz glass plate. The high-temperature abnormality points in the two-dimensional temperature matrix of the outer surface of the quartz glass plate are corrected to obtain the corrected two-dimensional temperature matrix of the outer surface of the quartz glass. Based on the geometric characteristics of quartz glass plates where the dimensions in the planar direction are much larger than their thickness, and combined with the thermal diffusivity of quartz glass plates, a one-dimensional unsteady thermal conduction control model along the thickness direction is constructed. Using the modified two-dimensional temperature matrix of the outer surface of the quartz glass as the outer boundary condition of the one-dimensional unsteady thermal conduction control, the one-dimensional unsteady thermal conduction control model is inverted according to the thermal diffusion process to obtain the temperature field of the inner surface of the quartz glass plate that is quantitatively reconstructed for the temperature field of the heavy oil thermal recovery experiment.

[0007] The invention is further characterized by: When inverting the one-dimensional unsteady thermal conduction control model based on the thermal diffusion process, if the thermal diffusion depth is less than the full thickness of the quartz glass plate, the error function relationship under the assumption of a semi-infinite flat plate is used to invert the one-dimensional unsteady thermal conduction control.

[0008] The one-dimensional unsteady heat conduction control is inverted using the error function relationship under the assumption of a semi-infinite plate. The resulting temperature field on the inner surface of the quartz glass plate is determined by the following formula: , In the formula, T (x,y, z , τ k ( ) represents the temperature field on the inner surface of the quartz glass plate. T 0 represents the initial temperature of the quartz glass plate. T in (x,y, τ k ( ) represents the two-dimensional temperature of the inner surface of the quartz glass plate. δ The thickness of the quartz glass plate. a The thermal diffusivity of the quartz glass plate. z Let be the coordinates along the thickness direction of the quartz glass plate. τ k For the first k A moment in a historical time step (k =1,2,…,n), T in (x,y, τ k ( ) represents the two-dimensional temperature of the inner surface of the quartz glass plate. T s (x,y, τ k ) is a two-dimensional temperature matrix of the outer surface of a quartz glass plate.

[0009] When inverting the one-dimensional unsteady thermal conduction control model based on the thermal diffusion process, if the thermal diffusion depth is greater than the full thickness of the quartz glass plate, the one-dimensional unsteady thermal conduction control model of a finite-thickness flat plate or the numerical difference method is used to invert and solve the one-dimensional unsteady thermal conduction control model.

[0010] When inverting the one-dimensional unsteady thermal conductivity control model based on the thermal diffusion process, if the temperature of the outer surface of the quartz glass plate changes continuously with time, the temperature history is discretized into several step temperature rises. Based on the linear superposition principle of the one-dimensional unsteady thermal conductivity control model, the temperature response corresponding to each step is accumulated piecewise for inversion.

[0011] The temperature field of the inner surface of the quartz glass plate is output in one or more of the following image formats: a two-dimensional temperature distribution map of the inner surface of the quartz glass, an isotherm map of the inner surface of the quartz glass, a temperature curve in the thickness direction of the quartz glass plate, a vapor chamber outline recognition map, and a comparative analysis result map under different steam injection rates.

[0012] When correcting the high-temperature abnormal temperature points in the two-dimensional temperature matrix of the outer surface of the quartz glass plate, the mirror-inverse distance weighted interpolation method is used.

[0013] An internal temperature field inversion system for heavy oil thermal recovery experiments includes: The data acquisition module is used to collect the thickness, thermal conductivity, density, specific heat capacity and initial temperature of the quartz glass plate, and to collect the temperature field data of the outer surface of the quartz glass plate. The data processing module determines the thermal diffusivity of the quartz glass plate based on its thickness, thermal conductivity, density, and specific heat capacity, and determines the two-dimensional temperature matrix of the outer surface of the quartz glass plate as it changes over time based on the temperature field data of the outer surface of the quartz glass plate. The anomaly correction module is used to correct the high-temperature anomaly points in the two-dimensional temperature matrix of the outer surface of the quartz glass plate, and obtain the corrected two-dimensional temperature matrix of the outer surface of the quartz glass. The thermal conductivity model building module is used to construct a one-dimensional unsteady thermal conductivity control model along the thickness direction based on the geometric feature that the size of the quartz glass plate in the planar direction is much larger than its thickness, and combined with the thermal diffusivity of the quartz glass plate. The thermal conductivity inversion module is used to invert the one-dimensional unsteady thermal conductivity control by using the modified two-dimensional temperature matrix of the outer surface of the quartz glass as the outer boundary condition of the one-dimensional unsteady thermal conductivity control. Based on the thermal diffusion process, the one-dimensional unsteady thermal conductivity control model is inverted to obtain the temperature field of the inner surface of the quartz glass plate that is quantitatively reconstructed from the temperature field of the heavy oil thermal recovery experiment.

[0014] The internal temperature field inversion method and system for heavy oil thermal recovery experiments of the present invention has the following advantages: This invention obtains a continuous and reliable temperature field on the inner surface of a quartz glass plate through data acquisition, high-temperature anomaly correction, and inversion using a one-dimensional unsteady-state thermal conduction control model. This enables high-precision quantitative reconstruction of the internal temperature field in heavy oil thermal recovery experiments, effectively avoiding numerical distortion caused by directly using the external surface temperature to characterize the internal temperature field. This significantly improves the continuity and uniformity of the temperature field on the inner surface of the quartz glass plate, weakens the interference of local high-temperature noise on the overall temperature field distribution, reduces nonlinear deviations in characterizing the steam cavity development range, temperature transition zone position, and thermal front advancement speed, and significantly improves the refinement and accuracy of the steam cavity evolution law analysis. This provides more stable, realistic, and quantifiable experimental data support for the matching and optimization of SAGD process parameters in heavy oil thermal recovery. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the overall process of the present invention.

[0016] Figure 2 This is a schematic diagram of the two-dimensional theoretical model in this invention.

[0017] Figure 3 This is a temperature field block diagram of the outer surface of the quartz glass plate in this invention.

[0018] Figure 4 This is a block diagram of the temperature field on the inner surface of the quartz glass plate in this invention.

[0019] Figure 5 This is an isotherm diagram of the temperature field on the inner surface of the quartz glass plate in this invention.

[0020] Figure 6 This is a comparison diagram of the temperature fields on the inner and outer surfaces of the Y=7.14 quartz glass in this invention.

[0021] Figure 7 This is a comparison diagram of the temperature fields on the inner and outer surfaces of the Y=10 quartz glass in this invention. Detailed Implementation

[0022] The technical solutions of the present invention will now be described clearly and in detail with reference to the accompanying drawings. In the description of the embodiments of the present invention, unless otherwise stated, " / " indicates "or," for example, A / B can mean A or B. "And / or" in the text is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A alone, A and B simultaneously, and B alone. Furthermore, in the description of the embodiments of the present invention, "multiple" refers to two or more. The terms "first" and "second" are used for descriptive purposes only and should not be construed as implying or suggesting relative importance or implicitly indicating the number of indicated technical features. Therefore, a feature defined with "first" or "second" may explicitly or implicitly include one or more of that feature.

[0023] like Figure 1 , Figure 2 As shown, this invention provides a method for inverting the internal temperature field in heavy oil thermal recovery experiments, comprising the following steps: The thickness, thermal conductivity, density, specific heat capacity, and initial temperature of the quartz glass plate were collected, as well as the temperature field data of the outer surface of the quartz glass plate.

[0024] Based on the thickness, thermal conductivity, density, and specific heat capacity of the quartz glass plate, the thermal diffusivity of the quartz glass plate is determined, and the two-dimensional temperature matrix of the outer surface of the quartz glass plate as a function of time is determined based on the temperature field data of the outer surface of the quartz glass plate.

[0025] The high-temperature anomaly points in the two-dimensional temperature matrix of the outer surface of the quartz glass plate are corrected to obtain the corrected two-dimensional temperature matrix of the outer surface of the quartz glass.

[0026] Based on the geometric characteristics of quartz glass plates where the dimensions in the planar direction are much larger than their thickness, and combined with the thermal diffusivity of quartz glass plates, a one-dimensional unsteady thermal conduction control model along the thickness direction is constructed.

[0027] Using the modified two-dimensional temperature matrix of the outer surface of the quartz glass as the outer boundary condition of the one-dimensional unsteady thermal conduction control, the one-dimensional unsteady thermal conduction control model is inverted according to the thermal diffusion process to obtain the temperature field of the inner surface of the quartz glass plate that is quantitatively reconstructed for the temperature field of the heavy oil thermal recovery experiment.

[0028] In summary, this invention obtains a continuous and reliable temperature field on the inner surface of a quartz glass plate through data acquisition, high-temperature anomaly correction, and inversion using a one-dimensional unsteady-state thermal conduction control model. This enables high-precision quantitative reconstruction of the internal temperature field in heavy oil thermal recovery experiments, effectively avoiding numerical distortion caused by directly using the external surface temperature to characterize the internal temperature field. This significantly improves the continuity and uniformity of the temperature field on the inner surface of the quartz glass plate, weakens the interference of local high-temperature noise on the overall temperature field distribution, reduces nonlinear deviations in characterizing the steam cavity development range, temperature transition zone position, and thermal front advancement speed, and significantly improves the refinement and accuracy of the steam cavity evolution law analysis. This provides more stable, realistic, and quantifiable experimental data support for the matching and optimization of SAGD process parameters in heavy oil thermal recovery.

[0029] Infrared thermal imaging was used to collect temperature field data on the outer surface of the quartz glass plate. This method allows for non-contact, large-area temperature measurement without interfering with the development of the vapor chamber and fluid transport processes within the model.

[0030] In this process, when collecting temperature field data on the outer surface of the quartz glass plate, high-definition video equipment was used to simultaneously acquire images of the steam cavity development and fluid transport process. After time synchronization and spatial registration, the temperature field data of the outer surface of the quartz glass plate and the images of the steam cavity development and fluid transport process were established to establish a correspondence between thermal field changes and steam cavity morphological evolution. By synchronizing and spatially registering the temperature field data with the visualized images, a direct correspondence between thermal field changes and steam cavity morphological evolution can be established, providing an intuitive morphological verification basis for the temperature inversion results.

[0031] like Figure 2 As shown, to facilitate the description of the heat transfer and seepage process of the two-dimensional visualization experimental device in this invention, the experimental model is abstracted along the thickness direction into a two-dimensional theoretical model composed of two quartz glass plates on both sides, a porous medium filling area, and a fluid inlet channel. During the experiment, quartz glass plates with a thickness of 30 mm are placed on both sides of the two-dimensional theoretical model, and porous medium particles are filled in the middle to simulate the reservoir medium structure. Fluid is injected into the two-dimensional theoretical model through the side inlet and undergoes seepage, heat transfer, and thermal displacement processes in the porous medium. Since the porous medium particle channel is 0.8 mm to 1 mm thick and the quartz glass plate is 30 mm thick, it can be approximately regarded as a semi-infinite plate.

[0032] The thermal diffusivity of the quartz glass plate is determined by the following formula: .

[0033] In the formula, a The thermal diffusivity of the quartz glass plate. δThe thickness of the quartz glass plate ranges from 3mm to 8mm. λ The thermal conductivity of the quartz glass plate is... ρ The density of the quartz glass plate, c p The specific heat capacity of the quartz glass plate is given above. All the physical parameters of the quartz glass plate can be given by the material handbook or obtained by pre-experimental calibration.

[0034] The one-dimensional unsteady heat conduction control model is as follows: .

[0035] In the formula, a The thermal diffusivity of the quartz glass plate. T The temperature field variable represents the temperature at a specific location within the quartz glass plate at a specific moment. τ The variable is time, representing the time taken for the heat conduction process. z is the coordinate along the thickness direction of the quartz glass plate, and represents the position coordinate along the thickness direction of the quartz glass plate.

[0036] In the inversion of the one-dimensional unsteady thermal conduction control model based on the thermal diffusion process, if the thermal diffusion depth is less than the full thickness of the quartz glass plate, the error function relationship under the assumption of a semi-infinite flat plate is used to invert the one-dimensional unsteady thermal conduction control. Using the error function relationship under the assumption of a semi-infinite flat plate for inversion allows the establishment of an analytical mapping relationship between the outer and inner surface temperatures before the thermal disturbance penetrates the full thickness of the glass, avoiding calculation errors caused by numerical discretization.

[0037] The temperature field on the inner surface of the quartz glass plate is determined by inverting the one-dimensional unsteady heat conduction control using the error function relationship under the assumption of a semi-infinite plate, and the result is: .

[0038] In the formula, T (x,y, z , τ k ( ) represents the temperature field on the inner surface of the quartz glass plate. T 0 represents the initial temperature of the quartz glass plate. T in (x,y, τ k ( ) represents the two-dimensional temperature of the inner surface of the quartz glass plate. δ The thickness of the quartz glass plate. a The thermal diffusivity of the quartz glass plate. z Let be the coordinates along the thickness direction of the quartz glass plate. τ k For the first k A moment in a historical time step (k =1,2,…,n), T in (x,y, τ k ( ) represents the two-dimensional temperature of the inner surface of the quartz glass plate. T s (x,y, τ k ) represents the two-dimensional temperature matrix of the outer surface of the quartz glass plate, and erfc is the error function.

[0039] In the inversion of the one-dimensional unsteady thermal conduction control model based on the thermal diffusion process, if the thermal diffusion depth is greater than the full thickness of the quartz glass plate, a finite-thickness plate unsteady thermal conduction model or a numerical difference method is used to solve the one-dimensional unsteady thermal conduction control model. Using a finite-thickness plate unsteady thermal conduction model or a numerical difference method for correction can compensate for the deviation of the semi-infinite assumption when thermal disturbances penetrate the full thickness of the glass, improving the accuracy of temperature inversion in the later stages of the experiment.

[0040] In the inversion of a one-dimensional unsteady-state thermal conductivity control model based on the thermal diffusion process, if the outer surface temperature of the quartz glass plate changes continuously over time, the temperature history is discretized into several step temperature rises. Relying on the linear superposition principle of the one-dimensional unsteady-state thermal conductivity control model, the temperature responses corresponding to each step are accumulated piecewise for inversion. When using the piecewise step discretization and linear superposition method, the variable boundary conditions can adapt to the continuous changes in the outer surface temperature during steam displacement, improving the accuracy of temperature inversion under unsteady-state conditions.

[0041] The temperature process is discretized into multiple step temperature rises, denoted as . ΔT in,j The temperature distribution at any location inside the quartz glass plate is as follows: , .

[0042] In the formula, T ( z , τ n The interior of the quartz glass plate is at a certain time. τ n Thickness direction coordinates z Temperature at location T 0 represents the initial temperature of the quartz glass plate. ΔT in,j For the first j At time step 1, the temperature of the inner surface of the quartz glass plate relative to the initial temperature T 0 increment temperature rise, δ The thickness of the quartz glass plate. a The thermal diffusivity of the quartz glass plate. zLet be the coordinates along the thickness direction of the quartz glass plate. τ j For the first j A moment in a historical time step ( j =1,2,…,n), where erfc is the error function.

[0043] Based on the inversion solution of the temperature field at arbitrary depths on the inner surface of the quartz glass plate, the temperature field is visualized and quantitatively extracted through image reconstruction, grid block division and pixel recognition analysis, and the expansion of the vapor chamber and the dynamic change law of the experiment are correlated.

[0044] In summary, this invention establishes a physical mapping relationship between "outer surface temperature - glass internal temperature - glass inner surface temperature - model boundary temperature characterization" by using the two-dimensional temperature matrix determined by the outer surface temperature measured by the infrared thermometer as the time-varying boundary input, combined with the exact solution of the error function of the semi-infinite plate and the correction of the finite thickness plate. This relationship can be used to draw the temperature distribution map inside the equipment glass, and when the contact thermal resistance is negligible or corrected, it provides a reference for subsequent vapor cavity boundary identification and internal thermal front analysis.

[0045] The temperature field of the inner surface of the quartz glass plate is output in one or more of the following image formats: a two-dimensional temperature distribution map of the inner surface of the quartz glass, an isotherm map of the inner surface of the quartz glass, a temperature curve along the thickness direction of the quartz glass plate, a steam cavity outline recognition map, and a comparative analysis result map under different steam injection rates. Outputting the corrected inner surface temperature field in multiple image formats allows for the presentation of the internal thermal state from multiple dimensions, including spatial distribution, gradient changes, thickness profiles, and process comparisons, providing a more comprehensive visualization basis for the evolution analysis of the steam cavity.

[0046] Specifically, when correcting the high-temperature anomaly points in the two-dimensional temperature matrix of the outer surface of the quartz glass plate, the mirror-inverse distance weighted interpolation method is used. This method effectively eliminates anomalies caused by thermal radiation interference from the heating zone while preserving the spatial continuity of the temperature field, thus avoiding misleading identification of the steam cavity boundary due to abnormal temperatures.

[0047] The present invention also provides an internal temperature field inversion system for heavy oil thermal recovery experiments, comprising: The data acquisition module is used to collect the thickness, thermal conductivity, density, specific heat capacity, and initial temperature of the quartz glass plate, as well as the temperature field data of the outer surface of the quartz glass plate.

[0048] The data processing module determines the thermal diffusivity of the quartz glass plate based on its thickness, thermal conductivity, density, and specific heat capacity, and determines the two-dimensional temperature matrix of the outer surface of the quartz glass plate as it changes over time based on the temperature field data of the outer surface of the quartz glass plate.

[0049] The anomaly correction module is used to correct the high-temperature anomaly points in the two-dimensional temperature matrix of the outer surface of the quartz glass plate, so as to obtain the corrected two-dimensional temperature matrix of the outer surface of the quartz glass.

[0050] The thermal conductivity model building module is used to construct a one-dimensional unsteady thermal conductivity control model along the thickness direction based on the geometric characteristics of the quartz glass plate, where the size in the planar direction is much larger than its thickness, and in combination with the thermal diffusivity of the quartz glass plate.

[0051] The thermal conductivity inversion module is used to invert the one-dimensional unsteady thermal conductivity control by using the modified two-dimensional temperature matrix of the outer surface of the quartz glass as the outer boundary condition of the one-dimensional unsteady thermal conductivity control. Based on the thermal diffusion process, the one-dimensional unsteady thermal conductivity control model is inverted to obtain the temperature field of the inner surface of the quartz glass plate that is quantitatively reconstructed from the temperature field of the heavy oil thermal recovery experiment.

[0052] Example 1 Taking the two-dimensional visualization SAGD experiment as an example, a two-dimensional visualization model with a planar visualization range of 20cm×20cm was used, and the thickness of the quartz glass plate was... δ =30mm, the theoretical maximum temperature of injected steam is 180℃, initial temperature T 0 = 25℃. The specific steps are as follows:

[0053] 1) such as Figure 3 As shown, an infrared thermal imaging device is used to continuously collect temperature field data of the outer surface of a quartz glass plate, with a sampling time interval of 1 second, to obtain a two-dimensional temperature matrix of the outer surface of the quartz glass plate that changes over time. This embodiment uses a 7×7 two-dimensional temperature matrix of the outer surface of the quartz glass plate at a certain moment as an example, as shown in Table 1 below.

[0054] Table 1. 7×7 two-dimensional temperature matrix of the outer surface of a quartz glass plate at a certain moment (unit: °C) In Table 1, some temperature values ​​exceed the theoretical maximum temperature of injected steam by 180℃ (such as 199℃, 235.3℃, 181.9℃, 224.2℃, 220.2℃, etc.). These abnormal values ​​are pseudo-high temperature anomalies caused by thermal radiation interference from the heating zone, and are not the actual heat transfer results of the outer surface of the quartz glass plate.

[0055] 2) The high-temperature anomaly points in the two-dimensional temperature matrix of the outer surface of the quartz glass plate are corrected using the mirror-inverse distance weighted interpolation method. Taking the temperature value of 199℃ in the fifth column of the first row as an example, the location of this point is denoted as (…). i , j = (1,5), since 199>180, it is determined to be an abnormal block.

[0056] First, with the central axis of symmetry X Based on 10, the mirror column number of the outlier about the central symmetry axis is... j =8-5=3, the mirror block is located at (1,3), and its temperature is 139.6℃, which is used as the symmetrical reference temperature for this anomaly point. T mirror .

[0057] Secondly, a valid neighborhood set was formed by selecting all normal blocks within a 5×5 neighborhood of the anomaly point that do not exceed 180℃, including (1,3), (1,4), (2,3), (2,7), (3,3), (3,4), (3,5), (3,6), and (3,7), with corresponding temperatures of 139.6℃, 172.8℃, 159.7℃, 130.5℃, 154.7℃, 176.9℃, 155.7℃, 118.4℃, and 115.4℃, respectively.

[0058] Calculate the grid distance and weight between each normal block and the abnormal block. The weight is defined as the reciprocal of the square of the grid distance between the normal block and the abnormal block. For example, (1,3) has a distance of 2 and a weight of 0.25. Similarly, (1,4) has a distance of 1 from the abnormal block, so its weight is 1; the distances between (2,3) and (2,7) are both √5, so their weights are both 0.2; the distances between (3,3) and (3,7) are both √8, so their weights are both 0.125; the distances between (3,4) and (3,6) are both √5, so their weights are both 0.2; and the distance between (3,5) is 2, so its weight is 0.25. The calculated numerator of each weight multiplied by its corresponding temperature is 397.4875, and the sum of all weights is 2.55. The local inverse distance weighted interpolation temperature is 397.4875 ÷ 2.55 = 155.9℃. Taking the symmetry constraint weight as 0.3, the final corrected temperature of the anomalous block is 0.3×139.6+0.7×155.9=150.9℃. Similarly, the other anomalous temperature points in Table 1 are corrected one by one to obtain the corrected 7×7 two-dimensional temperature matrix of the outer surface of the quartz glass plate at a certain moment, as shown in Table 2 below.

[0059] Table 2. 7×7 two-dimensional temperature matrix of the outer surface of the quartz glass plate at a certain moment (unit: °C) 3) Based on the geometric characteristics that the size of the quartz glass plate in the planar direction is much larger than its thickness, and combined with the thermal diffusivity of the quartz glass plate, the heat transfer along the thickness direction is approximated as a one-dimensional unsteady-state heat conduction process.

[0060] 4) The error function relationship under the assumption of a semi-infinite plate is used for inversion. The temperature of each point in Table 2 is substituted into the formula of the temperature field of the inner surface of the quartz glass plate to obtain the 7×7 temperature field of the inner surface of the quartz glass plate at a certain moment, as shown in Table 3 below.

[0061] Table 3. Temperature field of the inner surface of the quartz glass plate at a certain moment (7×7). 5) Using the 7×7 temperature field of the inner surface of the quartz glass plate at a certain moment as shown in Table 3, the internal temperature field of the heavy oil thermal recovery experiment was quantitatively reconstructed, and a temperature field map of the inner surface of the quartz glass plate was plotted using the temperature field data in Table 3, as shown below. Figure 4 As shown, the figure exhibits a clear spatial non-uniform distribution characteristic, with high-temperature areas concentrated in locations heavily affected by steam heat, and temperatures gradually decreasing in the peripheral areas; further, corresponding temperature contour maps are drawn, such as... Figure 5 As shown, the density of contour lines can be used to identify the boundaries of high-temperature zones, temperature transition zones, and low-temperature zones. Dense contour lines correspond to thermal fronts with larger temperature gradients, while sparse contour lines correspond to regions with gentler temperature changes.

[0062] like Figure 6 , Figure 7 As shown, by selecting two cross-sections, Y=7.14 and Y=10, the temperature difference between the inner and outer surfaces of the quartz glass plate was compared. Figure 6 This is a comparison diagram of the temperature fields on the inner and outer surfaces of a quartz glass plate at Y=7.14. Figure 6 The figures show a comparison of the temperature fields on the inner and outer surfaces of the quartz glass plate in the Y=10 section. It can be seen that in both sections, the temperature fields on both the inner and outer surfaces of the quartz glass plate exhibit a distribution pattern of high temperature in the middle and low temperature on both sides, with the peak positions being basically consistent. This indicates that the inversion results of the inner surface are in good agreement with the measured results of the outer surface. In contrast, the overall temperature of the outer surface is lower than that of the inner surface, reflecting a significant attenuation of heat during the transfer of heat along the thickness of the quartz glass plate. Meanwhile, the overall temperature level and the concentrated high-temperature characteristics in the middle of the Y=7.14 section are stronger than those of the Y=10 section, indicating that the former is closer to the main heat-affected area of ​​the vapor chamber, while the latter is in a transitional region where heat gradually weakens.

[0063] The internal temperature field inversion method and system for heavy oil thermal recovery experiments of the present invention have the following other advantages: First, this invention focuses on the core objective of "inverting the temperature field of the inner surface of a quartz glass plate from the temperature field of the outer surface of a two-dimensional visualized experimental sample," and establishes an inversion relationship from the two-dimensional temperature matrix of the outer surface measured by infrared thermography to the temperature field of the inner surface. Based on the error function relationship under the assumption of a semi-infinite flat plate, the inner surface temperature of the quartz glass plate, which cannot be directly measured during the experiment, is transformed into a calculable, reconstructable, and identifiable result. Furthermore, high-temperature anomalies in the inner surface temperature field that may be affected by thermal radiation from the heating zone are corrected using a mirror-inverse distance weighted interpolation method, thereby obtaining the corrected inner surface temperature field of the quartz glass plate and realizing the quantitative reconstruction of the internal temperature field of the heavy oil thermal recovery experiment.

[0064] Secondly, this invention can achieve non-contact inversion of the temperature field on the inner surface of a quartz glass plate without damaging the original two-dimensional visualization experimental device structure, thus avoiding interference from the insertion of internal sensors on the seepage field and the development morphology of the vapor chamber.

[0065] Third, by introducing the error function relationship under the assumption of a semi-infinite plate, the piecewise step discretization and linear superposition method, and the unsteady heat conduction model or numerical difference correction strategy for a finite-thickness plate, this invention improves the physical rationality and accuracy of temperature inversion under unsteady conditions.

[0066] Fourth, the present invention can convert the measured outer surface temperature field of infrared thermal imaging into a quantitative characterization of the inner surface temperature field of a quartz glass plate, thereby more accurately identifying the location of the steam cavity boundary, high temperature zone, low temperature zone and temperature transition zone.

[0067] Fifth, this invention can output two-dimensional temperature distribution maps, isotherm maps, thickness-direction temperature curve maps, steam cavity outline identification maps, and comparative analysis results maps under different steam injection rate conditions on the inner surface of quartz glass, providing a data basis for analyzing the development law of steam cavity under different steam injection rates.

[0068] Sixth, this invention has good compatibility with existing infrared thermal imaging equipment, high-definition camera equipment and two-dimensional visualization experimental procedures, low implementation cost, strong engineering operability, and is easy to promote and apply on existing experimental platforms.

[0069] Seventh, this invention possesses both good versatility and scalability. It is not only applicable to the reconstruction of the temperature field of a two-dimensional visualized SAGD steam cavity under quartz glass observation window conditions, but can also be extended to other thermal recovery physics simulation experiments with transparent observation walls or thin-plate thermally conductive boundaries. By jointly analyzing the temperature field of the inner surface of the quartz glass plate obtained by this invention with images of steam cavity development and fluid transport processes synchronously acquired by high-definition camera equipment, the precision of experimental interpretation can be improved, providing experimental basis for optimizing steam injection process parameters, studying the development law of steam cavities, and analyzing the mechanism of heavy oil thermal recovery.

[0070] It is understood that this invention has been described through some embodiments, and those skilled in the art will recognize that various changes or equivalent substitutions can be made to these features and embodiments without departing from the spirit and scope of this invention. Furthermore, under the teachings of this invention, these features and embodiments can be modified to adapt to specific situations and materials without departing from the spirit and scope of this invention. Therefore, this invention is not limited to the specific embodiments disclosed herein, and all embodiments falling within the scope of the claims of this invention are within the protection scope of this invention.

Claims

1. A method for inverting the internal temperature field in heavy oil thermal recovery experiments, characterized in that, include: The thickness, thermal conductivity, density, specific heat capacity, and initial temperature of the quartz glass plate were collected, as well as the temperature field data of the outer surface of the quartz glass plate. Based on the thickness, thermal conductivity, density and specific heat capacity of the quartz glass plate, the thermal diffusivity of the quartz glass plate is determined, and the two-dimensional temperature matrix of the outer surface of the quartz glass plate as a function of time is determined based on the temperature field data of the outer surface of the quartz glass plate. The high-temperature abnormality points in the two-dimensional temperature matrix of the outer surface of the quartz glass plate are corrected to obtain the corrected two-dimensional temperature matrix of the outer surface of the quartz glass. Based on the geometric characteristics of quartz glass plates where the dimensions in the planar direction are much larger than their thickness, and combined with the thermal diffusivity of quartz glass plates, a one-dimensional unsteady thermal conduction control model along the thickness direction is constructed. Using the modified two-dimensional temperature matrix of the outer surface of the quartz glass as the outer boundary condition of the one-dimensional unsteady thermal conduction control, the one-dimensional unsteady thermal conduction control model is inverted according to the thermal diffusion process to obtain the temperature field of the inner surface of the quartz glass plate that is quantitatively reconstructed for the temperature field of the heavy oil thermal recovery experiment.

2. The internal temperature field inversion method for heavy oil thermal recovery experiments according to claim 1, characterized in that, When inverting the one-dimensional unsteady thermal conduction control model based on the thermal diffusion process, if the thermal diffusion depth is less than the full thickness of the quartz glass plate, the error function relationship under the assumption of a semi-infinite flat plate is used to invert the one-dimensional unsteady thermal conduction control.

3. The method for inverting the internal temperature field in a heavy oil thermal recovery experiment according to claim 2, characterized in that, The temperature field on the inner surface of the quartz glass plate is determined by inverting the one-dimensional unsteady heat conduction control using the error function relationship under the assumption of a semi-infinite plate, and the result is: ， In the formula, T (x,y, z , τ k ( ) represents the temperature field on the inner surface of the quartz glass plate. T 0 represents the initial temperature of the quartz glass plate. T in (x,y, τ k ( ) represents the two-dimensional temperature of the inner surface of the quartz glass plate. δ The thickness of the quartz glass plate. a The thermal diffusivity of the quartz glass plate. z Let be the coordinates along the thickness direction of the quartz glass plate. τ k For the first k A moment in a historical time step ( k =1,2,…,n), T in (x,y, τ k ( ) represents the two-dimensional temperature of the inner surface of the quartz glass plate. T s (x,y, τ k ) is a two-dimensional temperature matrix of the outer surface of a quartz glass plate.

4. The method for inverting the internal temperature field in a heavy oil thermal recovery experiment according to claim 1, characterized in that, When inverting the one-dimensional unsteady thermal conduction control model based on the thermal diffusion process, if the thermal diffusion depth is greater than the full thickness of the quartz glass plate, the one-dimensional unsteady thermal conduction control model can be solved by inverting the model using a finite-thickness flat plate unsteady thermal conduction model or a numerical difference method.

5. The method for inverting the internal temperature field in a heavy oil thermal recovery experiment according to claim 1, characterized in that, When inverting a one-dimensional unsteady thermal conductivity control model based on the thermal diffusion process, if the temperature of the outer surface of the quartz glass plate changes continuously with time, the temperature history is discretized into several step temperature rises. Based on the linear superposition principle of the one-dimensional unsteady thermal conductivity control model, the temperature response corresponding to each step is accumulated piecewise for inversion.

6. The method for inverting the internal temperature field in a heavy oil thermal recovery experiment according to claim 1, characterized in that, The temperature field of the inner surface of the quartz glass plate is output in one or more of the following image formats: a two-dimensional temperature distribution map of the inner surface of the quartz glass, an isotherm map of the inner surface of the quartz glass, a temperature curve in the thickness direction of the quartz glass plate, a vapor chamber outline recognition map, and a comparative analysis result map under different steam injection rate conditions.

7. The method for inverting the internal temperature field in a heavy oil thermal recovery experiment according to claim 1, characterized in that, When correcting the high-temperature abnormality points in the two-dimensional temperature matrix of the outer surface of the quartz glass plate, the mirror-inverse distance weighted interpolation method is used.

8. An internal temperature field inversion system for heavy oil thermal recovery experiments, characterized in that, The method described in any one of claims 1 to 7 includes: The data acquisition module is used to collect the thickness, thermal conductivity, density, specific heat capacity and initial temperature of the quartz glass plate, and to collect the temperature field data of the outer surface of the quartz glass plate. The data processing module determines the thermal diffusivity of the quartz glass plate based on its thickness, thermal conductivity, density, and specific heat capacity, and determines the two-dimensional temperature matrix of the outer surface of the quartz glass plate as it changes over time based on the temperature field data of the outer surface of the quartz glass plate. The anomaly correction module is used to correct the high-temperature anomaly points in the two-dimensional temperature matrix of the outer surface of the quartz glass plate, and obtain the corrected two-dimensional temperature matrix of the outer surface of the quartz glass. The thermal conductivity model building module is used to construct a one-dimensional unsteady thermal conductivity control model along the thickness direction based on the geometric feature that the size of the quartz glass plate in the planar direction is much larger than its thickness, and combined with the thermal diffusivity of the quartz glass plate. The thermal conductivity inversion module is used to invert the one-dimensional unsteady thermal conductivity control by using the modified two-dimensional temperature matrix of the outer surface of the quartz glass as the outer boundary condition of the one-dimensional unsteady thermal conductivity control. Based on the thermal diffusion process, the one-dimensional unsteady thermal conductivity control model is inverted to obtain the temperature field of the inner surface of the quartz glass plate that is quantitatively reconstructed from the temperature field of the heavy oil thermal recovery experiment.

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