CN-121678490-B - Core displacement fluid in-situ dynamic inversion method and system based on multi-frequency resistance and capacitive coupling tomography

CN121678490BCN 121678490 BCN121678490 BCN 121678490BCN-121678490-B

Abstract

The invention relates to the technical field of oilfield reservoir research, in particular to a core displacement fluid in-situ dynamic inversion method and system based on multi-frequency resistance and capacitive coupling tomography, which comprises the steps of performing capacitive mode detection and resistive mode detection in the current time step by utilizing multi-frequency signal synchronous excitation in displacement simulation to obtain corresponding bimodal electrical signals; the method comprises the steps of carrying out fusion on bimodal electrical signals according to modal optimization conditions, obtaining corresponding oil/water/gas three-dimensional saturation distribution inversion data based on a saturation inversion model, carrying out fitting based on errors between oil/water/gas three-dimensional saturation distribution calculation data and inversion data, and outputting fitting phase seepage results. The invention constructs the core displacement fluid in-situ dynamic inversion method integrating multi-mode detection, modal optimization, saturation inversion and phase permeability fitting, has low cost, small volume and high response frequency, realizes the capacitive modal detection and the resistive modal detection, and inversion based on a saturation inversion model, and is not limited by application environment.

Inventors

TAN YAWEN
MU ZONGJIE
Chai Jiangdao
ZHANG PANPAN
TIAN SHOUCENG
Sheng mao
DAI JIACHENG
ZHOU RONGHAO
XU PENG

Assignees

中国石油大学(北京)克拉玛依校区

Dates

Publication Date: 20260505
Application Date: 20260212

Claims (10)

1. A core displacement fluid in-situ dynamic inversion method based on multi-frequency resistance and capacitive coupling tomography is characterized by comprising the following steps: Performing displacement simulation on a core sample clamped in a core clamping device, and performing capacitive mode detection and resistive mode detection at the current time by utilizing multi-frequency signal synchronous excitation in the displacement simulation to obtain corresponding bimodal electrical signals, wherein the bimodal electrical signals comprise a resistive signal and a capacitive signal; fusing the bimodal electrical signals according to modal preference conditions, wherein the modal preference conditions include: At either the gas saturation > set point or the water saturation < set point in the displacement simulation, In the other cases, the first and second heat exchangers, ; Wherein the method comprises the steps of Are all the weight coefficients of the two-dimensional space model, R is a resistance signal; Inputting the effective porosity of the core sample, the permeability of the core sample in the oil-water fully saturated state and the flow field data pre-calculated by the Darcy equation as priori knowledge of a saturation inversion model, and inputting the fused bimodal electrical signals as raw data of the saturation inversion model to obtain corresponding oil/water/gas three-dimensional saturation distribution inversion data; And calculating oil/water/gas three-dimensional saturation distribution calculation data of the current time step according to the relative permeability of each phase of the previous time step, fitting based on errors between the oil/water/gas three-dimensional saturation distribution calculation data and oil/water/gas three-dimensional saturation distribution inversion data, and outputting a fitting infiltration result and an oil/water/gas three-dimensional saturation distribution result.
2. The method for in-situ dynamic inversion of core displacement fluid based on multi-frequency resistive and capacitive coupling tomography according to claim 1, wherein the process for constructing the saturation inversion model comprises the following steps: obtaining a plurality of samples, and dividing the samples into a training sample set and a testing sample set according to a proportion, wherein each sample comprises identification information of oil/water/gas three-dimensional saturation distribution, core effective porosity of a historical core sample, permeability of the historical core sample in a fully saturated state and flow field data pre-calculated by a Darcy equation, and fused bimodal electrical signals corresponding to a certain time step in displacement simulation of the historical core sample; Training an initial model by using a training sample set, introducing a loss function during training, ending training when the value of the loss function is stable, and obtaining a saturation inversion model, wherein the initial model is a double-channel U-Net network introducing residual connection and attention mechanism, and comprises a double channel, a feature fusion module, an encoder, a physical constraint module and a decoder, wherein the double channel comprises a priori knowledge input channel and an original data input channel which are parallel and are respectively used for inputting the priori knowledge and the fused bimodal electrical signal, the feature fusion module performs feature fusion and tensor construction on the priori knowledge and the fused bimodal electrical signal, the encoder performs 4-level downsampling on the input fusion features, reserves microscopic boundary features through residual connection, performs physical constraint by using the physical constraint module in the encoding process, and the decoder performs feature recovery on the encoded fusion features; and respectively testing the saturation inversion model by using the test sample set, optimizing model parameters of the saturation inversion model, and outputting the saturation inversion model meeting the test evaluation requirement.
3. The method for dynamic inversion of core displacement fluid in situ based on multi-frequency resistive and capacitive coupling tomography according to claim 1 or 2, wherein calculating oil/water/gas three-dimensional saturation distribution calculation data of a current time step according to relative permeability of each phase of a previous time step, fitting based on errors between the oil/water/gas three-dimensional saturation distribution calculation data and the oil/water/gas three-dimensional saturation distribution inversion data, and outputting fitting infiltration results and oil/water/gas three-dimensional saturation distribution results, comprises: Judging whether the error between the oil/water/gas three-dimensional saturation distribution calculation data and the oil/water/gas three-dimensional saturation distribution inversion data in the current time step is larger than a set value or not; Judging whether the error between the oil/water/gas three-dimensional saturation distribution calculation data and the oil/water/gas three-dimensional saturation distribution inversion data in the current time step is larger than a set value or not; Responding to the response, randomly adjusting the relative permeability of each phase of the previous time step in a set adjusting interval, and returning to redetermine the oil/water/gas three-dimensional saturation distribution calculation data of the current time step; and if not, outputting the relative permeability of each phase of the previous time step as a fitting phase permeability result, and using the corresponding oil/water/gas three-dimensional saturation distribution inversion data as an oil/water/gas three-dimensional saturation distribution result.
4. The core displacement fluid in-situ dynamic inversion method based on multi-frequency resistance and capacitive coupling tomography according to claim 1 or 2, wherein the core clamping device comprises a clamping body and two end covers, the two end covers are respectively arranged at the front end and the rear end of the clamping body, fluid inlets/outlets are respectively arranged on the two end covers, the clamping body comprises a clamping sleeve and a multi-mode sensing array sleeve, the multi-mode sensing array sleeve is sleeved in the clamping sleeve, the multi-mode sensing array sleeve comprises 5 layers of multi-mode sensing array measuring layers which are sequentially arranged from top to bottom, each multi-mode sensing array measuring layer is of a hollow cylindrical structure and comprises measuring rings and 2 insulating rubber sleeves with the same size, the 2 insulating rubber sleeves are respectively arranged at the left end and the right end of each measuring ring, each measuring ring comprises 16 groups of resistance electrodes and 16 insulating rubber sleeve blocks, the resistance electrodes and the insulating rubber sleeve blocks are arranged at intervals to form a closed measuring ring, the middle part of each insulating rubber sleeve block is provided with an opening groove with an upward opening, and 1 group of capacitance electrodes are arranged in the opening groove.
5. The multi-frequency resistive and capacitive coupling tomography-based core displacement fluid in-situ dynamic inversion method of claim 4, wherein the performing displacement simulation on the core sample held in the core holding device, and performing capacitive mode detection and resistive mode detection at the current time step by using multi-frequency signal synchronous excitation in the displacement simulation, to obtain a corresponding bimodal electrical signal, comprises: processing the core into a core sample; placing a core sample in a multi-modal sensing array sleeve, placing the multi-modal sensing array sleeve in a clamping sleeve, filling insulating silicone oil between the clamping sleeve and the multi-modal sensing array sleeve through an external pump, compacting the core sample into the multi-modal sensing array sleeve while providing confining pressure for the core sample, and enabling a resistance electrode on the multi-modal sensing array sleeve to be in full contact with the core sample; And performing displacement simulation on a core sample clamped in the core clamping device in a mode of setting displacement or constant pressure, and performing capacitance mode detection and resistance mode detection by utilizing multi-frequency signal synchronous excitation based on a multi-mode sensing electrode array in the core clamping device in the displacement process, so as to measure the bimodal electrical signal of the current time step in real time, wherein the bimodal electrical signal comprises a capacitance signal and a resistance signal.
6. The method for in-situ dynamic inversion of core displacement fluid based on multi-frequency resistive and capacitive coupling tomography according to claim 5, wherein the capacitive mode detection process comprises: Injecting high-frequency excitation signals into adjacent capacitance electrode pairs in the multi-mode sensing array measuring layer, measuring corresponding capacitance signals, and traversing all adjacent capacitance electrodes; And cycling the steps, traversing all the multi-mode sensing array measuring layers to obtain capacitance signals of the current time step, and setting the traversing period to be a fixed value.
7. The multi-frequency resistive and capacitive coupling tomography-based core displacement fluid in-situ dynamic inversion method as claimed in claim 5 or 6, wherein the resistive modal detection process comprises: Injecting a low-frequency excitation signal into the diagonal resistance electrode pair in the multi-mode sensing array measuring layer, measuring a voltage gradient along the axial direction of the core, and calculating to obtain an equivalent resistance value; and (3) circulating the steps, sequentially applying current layer by layer, and determining the equivalent resistance of each multi-mode sensing array measuring layer.
8. A core displacement fluid in-situ dynamic inversion system based on multi-frequency resistive and capacitive coupling tomography using the method of any one of claims 1 to 7, comprising a displacement execution detection section and a fluid in-situ dynamic inversion section; The displacement execution detection part comprises a core clamping device and a dual-channel excitation and detection device, wherein the core clamping device clamps a core sample, the dual-channel excitation and detection device executes multi-frequency signal synchronous excitation on the core clamping device in displacement simulation on the core sample clamped in the core clamping device, and performs capacitance mode detection and resistance mode detection at the current time step to obtain corresponding bimodal electrical signals, wherein the bimodal electrical signals comprise resistance signals and capacitance signals; The fluid in situ dynamic inversion section includes: And a mode preference unit for fusing the bimodal electrical signals according to mode preference conditions, wherein the mode preference conditions comprise: At either the gas saturation > set point or the water saturation < set point in the displacement simulation, In the other cases, the first and second heat exchangers, ; Wherein the method comprises the steps of Are all the weight coefficients of the two-dimensional space model, R is a resistance signal; The dynamic inversion unit inputs the core effective porosity of the core sample, the permeability of the oil water in a fully saturated state and the flow field data pre-calculated by the Darcy equation as priori knowledge of a saturation inversion model, and inputs the fused bimodal electrical signals as raw data of the saturation inversion model to obtain corresponding oil/water/gas three-dimensional saturation distribution inversion data; And the phase permeability fitting unit is used for calculating oil/water/gas three-dimensional saturation distribution calculation data of the current time step according to the relative permeability of each phase of the previous time step, fitting the oil/water/gas three-dimensional saturation distribution calculation data and the oil/water/gas three-dimensional saturation distribution inversion data based on errors between the oil/water/gas three-dimensional saturation distribution calculation data, and outputting a fitting phase permeability result and an oil/water/gas three-dimensional saturation distribution result.
9. The core displacement fluid in-situ dynamic inversion system based on multi-frequency resistance and capacitive coupling tomography according to claim 8, wherein the core clamping device comprises a clamping body and two end covers, the two end covers are respectively arranged at the front end and the rear end of the clamping body, fluid inlets/outlets are respectively arranged on the two end covers, the clamping body comprises a clamping sleeve and a multi-mode sensing array sleeve, the multi-mode sensing array sleeve is sleeved in the clamping sleeve, the multi-mode sensing array sleeve comprises 5 layers of multi-mode sensing array measuring layers which are sequentially arranged from top to bottom, each multi-mode sensing array measuring layer is of a hollow cylindrical structure and comprises measuring rings and 2 insulating rubber sleeves with the same size, the 2 insulating rubber sleeves are respectively arranged at the left end and the right end of each measuring ring, each measuring ring comprises 16 groups of resistance electrodes and 16 insulating rubber sleeve blocks, the resistance electrodes and the insulating rubber sleeve blocks are arranged at intervals to form a closed measuring ring, the middle part of each insulating rubber sleeve block is provided with an opening groove with an upward opening, and 1 group of capacitance electrodes are arranged in the opening groove; or/and the combination of the two, The dual-channel excitation and detection device comprises a dual-channel excitation source module and a multi-mode detection module; The dual-channel excitation source module is provided with independent dual-channel output and comprises a high-frequency capacitance excitation channel, a low-frequency resistance excitation channel, a high-frequency resistance excitation channel and a core axial and radial resistance gradient measurement, wherein the high-frequency capacitance excitation channel outputs a sine wave signal of 1-10MHz, the power is less than or equal to 1W, and the frequency switching time is less than 10 mu s; the multi-mode detection module comprises a resistance gradient measurement module and a capacitance measurement module, and performs capacitance mode detection and resistance mode detection respectively.
10. The core displacement fluid in-situ dynamic inversion system based on multi-frequency resistive and capacitive coupling tomography according to claim 8 or 9, further comprising a model building unit for building a saturation inversion model, comprising: The sample acquisition module is used for acquiring a plurality of samples, and dividing the samples into a training sample set and a testing sample set according to a proportion, wherein each sample comprises identification information of oil/water/gas three-dimensional saturation distribution, core effective porosity of a historical core sample, permeability in an oil-water full saturated state and flow field data pre-calculated by a Darcy equation, and fused bimodal electrical signals corresponding to a certain time step in displacement simulation of the historical core sample; the system comprises a training module, a characteristic fusion module, an encoder, a physical constraint module and a decoder, wherein the training module is used for training an initial model by using a training sample set, introducing a loss function during training, ending training when the value of the loss function is stable, obtaining a saturation inversion model, wherein the initial model is a dual-channel U-Net network introducing residual connection and an attention mechanism, the dual-channel U-Net network comprises a dual-channel, a characteristic fusion module, an encoder, a physical constraint module and the decoder, the dual-channel U-Net network comprises a priori knowledge input channel and an original data input channel which are parallel, the priori knowledge input channel and the original data input channel are respectively used for inputting the priori knowledge and the fused bimodal electrical signal, the characteristic fusion module is used for carrying out characteristic fusion and tensor construction on the priori knowledge and the fused bimodal electrical signal, the encoder is used for carrying out 4-level downsampling on the input fusion characteristics, and reserving microscopic boundary characteristics through residual connection, and carrying out physical constraint by the decoder in the encoding process; the testing module is used for testing the saturation inversion model respectively by using the testing sample set, optimizing model parameters of the saturation inversion model and outputting the saturation inversion model meeting the testing evaluation requirement.

Description

Core displacement fluid in-situ dynamic inversion method and system based on multi-frequency resistance and capacitive coupling tomography Technical Field The invention relates to the technical field of oilfield reservoir research, in particular to a core displacement fluid in-situ dynamic inversion method and system based on multi-frequency resistance and capacitance coupling tomography. Background The relative permeability is an important parameter for the development of the oil and gas reservoir, and the relative permeability is obtained rapidly and accurately, which is important for the formulation of the development scheme of the oil and gas reservoir. Currently, core displacement experiments are the primary route to relative permeability, calculated by the "j.b.n." method, mainly by metering the outlet fluid during displacement. The method has the following problems: (1) The outlet fluid metering directly affects the calculation result, for example, when gas is driven, the expansion and high flow rate of outlet gas can obviously affect the gas metering result, and meanwhile, the outlet fluid separation, the formation of oil-water emulsion, the dead volume of an outlet pipeline and the like can affect the metering result; (2) In the later stage of the experiment, after outlet gas breaks through or water is taken in, the oil phase in the outlet fluid can be rapidly reduced, so that the phase permeability curve is calculated at the high water content and high gas content stage, the data points are fewer, and the data precision is insufficient; (3) The unconventional rock core has extremely small pore permeation, extremely long displacement period, needs days or even weeks, and has low success rate; (4) The relative permeability is essentially the representation of the flow capacity of oil, gas and water under certain saturation, and the distribution state of the fluid in the core is inverted by the outlet flow data, so that the systematic error in the calculation process is increased. In order to solve the problems, an in-situ fluid inversion technology based on the displacement process is developed, and the method has the advantages that the distribution of fluid in the core is directly recorded, the fluid in the core keeps the set temperature and pressure conditions, so that the data is more accurate, and the error caused by the change of the outlet temperature and pressure is reduced. The conventional core displacement in-situ fluid distribution inversion comprises two modes of CT and nuclear magnetic imaging, wherein the resolution of the CT mode is high, the refreshing frequency is about 10min/fps, the data points are few at the later stage of displacement and are insufficient for obtaining the complete displacement process, the nuclear magnetic imaging can achieve 2s/fps, the resolution is low, the nuclear magnetic imaging has requirements on the polarity of fluid, the application range is limited to a certain extent, the experimental cost of the CT mode and the nuclear magnetic imaging mode is high, the cost of the CT mode and the nuclear magnetic imaging mode can reach millions, and due to the limitations of CT and nuclear magnetic equipment, high-temperature and high-pressure displacement is difficult to carry out. Existing core displacement in situ fluid distribution inversion methods, for example: The method comprises the steps of S1, obtaining original stratum pressure and temperature of a gas reservoir, S2, obtaining core, testing physical property data of the core, then performing nuclear magnetic testing on the core, S3, saturating stratum water of the core, then performing nuclear magnetic testing on the core, S4, performing gas-driven water seepage testing on the core according to the data of S1, obtaining water output, S5, performing nuclear magnetic testing on the core after failure, S6, obtaining core bound water saturation after failure according to the core physical property data, water output and core bound water saturation after failure, S7, obtaining core total bound water saturation according to the core physical property data, the water output and core bound water saturation after failure, and the device comprises an oven, a first container, a second container, a core holder, a surrounding pressure pump, a displacement pump, a back pressure component, a receiving container and an electronic balance. The invention can improve the accuracy of fluid saturation measurement. The nuclear magnetic testing method has high cost, and an impedance-capacitance bimodal dynamic compensation mechanism cannot be constructed through the combination of capacitance modal detection, resistance modal detection and modal optimization, so that a capacitance dominant mode or a resistance dominant mode cannot be automatically switched according to modal optimization conditions, further, the signal reliability in the full displacement stage cannot be ensured, and the saturation inversion accuracy is aff