Multi-frequency broadband full-size core water-containing porosity local measurement method and system

Abstract

A method and system for localized measurement of water-bearing porosity in multi-frequency broadband full-size core samples. The measurement method includes the following steps: (1) Preparation: Divide the core sample into m axial regions and p radial regions, each radial region being a coaxial ring from the inside out; (2) Measure the corresponding parameters: ① Measure the diameter and temperature of each axial region to obtain the diameter φ of the i-th axial region. i and temperature T i ; ② Pass the core through each sensor in sequence without contact and perform response tests on each sensor; (3) Local inversion of the complex dielectric constant of the core; (4) Local inversion of the water-bearing porosity and pore water salinity of the core. The measurement system includes a core propulsion device, a core diameter measuring device, a temperature recorder, a sensor group, a microwave multiplexer, a microwave scattering parameter sweep frequency measuring device, and a main control computer. This invention can realize localized, step-by-step fully automatic measurement of the dielectric properties of full-size cores, which can improve the accuracy and efficiency of core analysis at the well site.

Description

Technical Field

[0001] This invention relates to a localized measurement system and method for water-bearing porosity and mineralization in rock cores, belonging to the field of rock electrical property testing and analysis technology. Background Technology

[0002] The dielectric constant in the microwave band has been proven to be one of the important parameters characterizing formation properties, playing a crucial role in various applications such as reservoir logging inversion, remote sensing, and geotechnical engineering. As a key rock physics parameter, the dielectric constant has historically been used to quantify water content. Establishing an accurate and robust relationship between the dielectric constant and geophysical parameters is a fundamental prerequisite for dielectric logging inversion and microwave remote sensing data interpretation. The dielectric properties of rock samples can be studied through laboratory or field testing. Rapid testing of the dielectric properties of freshly drilled full-size cores at the well site can obtain key geological information such as water-bearing porosity, pore water salinity, and mud intrusion, closely resembling the original state of the formation.

[0003] Currently, there are various methods for testing the dielectric properties and water content of rocks. For example, CN117571798A discloses "A Method and System for In-situ Acquisition of Rock Water Content Using Frequency Domain Reflectometry," which uses probe reflection technology to monitor the water content of surface rocks in the field. CN114252926A discloses "A Core Dielectric Property Measurement Device," which draws on the design concept of downhole instruments and is applicable to the dielectric measurement of large-sized core samples in laboratory and other field environments. CN116660328A discloses "A Method and Device for Obtaining Rock Volumetric Water Content Through Rock Dielectric Constant," which obtains the dielectric constant and thus the rock volumetric water content by drilling holes in the rock surface. CN109444174A discloses "A High-Frequency Rock Dielectric Constant Measurement Method and Measuring Fixture," which utilizes transmission and reflection characteristics to measure the high-frequency dielectric constant after drilling holes in the core sample. CN105699787A discloses a "Method for Measuring the Dielectric Constant of Coal and Rock Based on Impedance Analyzer," which uses an impedance analyzer and a parallel plate capacitor to measure the dielectric constant of coal mixed with rock. CN1064548 discloses an "Automatic Measurement System for the Dielectric Constant of Rock," which uses a closed resonant cavity as a sensor to achieve the testing of the dielectric constant of liquids loaded in small-sized rock cores and containers.

[0004] The problem with the above-mentioned disclosed technology is that it either requires contact with the rock core for measurement or measurement after the rock core has been damaged (drilling). It cannot achieve localized measurement of axial / radial water content (water porosity) and mineralization of a full-size rock core without contacting or damaging the rock core, nor can it achieve axial localized measurement and radial localized measurement at the same time. Summary of the Invention

[0005] This invention addresses the shortcomings of existing full-size core microwave dielectric properties and water content (water porosity) measurement technologies by providing an automated measurement method capable of localized measurement of water porosity and mineralization in full-size cores over a wide frequency band, and also provides the measurement system for this system.

[0006] The multi-frequency broadband full-size core water-bearing porosity local measurement method of the present invention includes the following steps:

[0007] (1) Preparations:

[0008] ① Divide the core into m axial regions of equal length, m≥1; divide each axial region into p radial regions, each radial region being a coaxial ring from the inside out, p≥1;

[0009] ② Set up n sensors, n≥1. The sensors are open resonant cavity sensors (cylindrical resonant cavities with hollow structures and openings on both bottom surfaces). The sensors work simultaneously in the TM010 resonant mode, which is sensitive to the internal region of the core, and the TM110 resonant mode, which is sensitive to the surface region of the core.

[0010] (2) Measure and obtain the corresponding parameters:

[0011] ① Measure the diameter and temperature of each axial region to obtain the diameter φ of the i-th axial region. i and temperature T i ;

[0012] ② The core sample is passed through each sensor in a non-contact manner to test the response of each sensor; each sensor operates sequentially, and the frequency shift Δf of each sensor in the two resonant modes is obtained respectively. ij-1 and △f ij-2 And the relative change in the reciprocal of the quality factor (Q value) Δ1 / Q ij-1 and △1 / Q ij-2 , where △f ij-1 and △f ij-2 These represent the frequency shifts (Δ1 / Q) of the j-th sensor in the i-th axial region under two resonance modes (TM010 mode and TM110 mode). ij-1 and △1 / Q ij-2 These represent the relative changes in the reciprocals of the quality factor for the j-th sensor in the i-th axial region under the two resonance modes, respectively.

[0013] ③ Advance the core to an axial region and repeat the diameter, temperature, and sensor response tests from step ② to step ④ until the m-th region has been detected by the n-th sensor, thus completing the measurement steps of the core microwave response and other parameters.

[0014] (3) Local inversion of complex permittivity of core;

[0015] ①Based on the frequency offset Δf of the j-th sensor ij-1 and △f ij-2 And the relative change in the reciprocal of the quality factor, Δ1 / Q ij-1 and △1 / Q ij-2 Obtain the apparent complex permittivity ε of the i-th axial region. * ij-1 and ε * ij-2 ;

[0016] ② For the i-th axial region, divide it into p radial regions and construct the complex permittivity ε of each radial region. * ip A system of p-variable linear equations relating the 2n apparent complex permittivity of region i;

[0017] ③ Solve for the complex permittivity ε of the i-th axial region and p radial regions. * i1 to ε * ip This continues until the complex permittivity of all m axial regions and p radial regions has been solved.

[0018] (4) Localized inversion of core water porosity and pore water salinity:

[0019] ① To obtain the water porosity and pore water salinity information of the i-th axial region, the complex permittivity ε of the water at the resonant frequencies of n sensors in the i-th axial region is first calculated based on the temperature Ti of the i-th axial region. * werter-ni-1 and ε * werter-ni-2 ;

[0020] ② Combining the complex permittivity ε of the p radial regions of the i-th axial region * i1 to ε * ip The Effective Medium Theory (EMT) model was applied to analyze the ε values ​​in various axial and radial regions. * ip Modeling and fitting were performed to obtain information on water-bearing porosity and pore water salinity.

[0021] ③ Repeat steps ① and ② above to obtain spatial distribution information of water-bearing porosity and pore water salinity in other axial regions.

[0022] In step (2)②, the frequency shift Δf between the two resonant modes ij-1 and △f ij-2The difference between the unloaded resonant frequency and the actual sample resonant frequency in the two resonant modes is given by the resonant frequency S21, which is calculated from the point of maximum amplitude in that resonant mode, i.e., Δf. ij-1 =f 1空 -f ij-1 , △f ij-2 =f 2空 -f ij-2 The relative change in the reciprocal of the quality factor, Δ1 / Q ij-1 and △1 / Q ij-2 , is the difference between the unloaded resonance quality factor and the actual sample resonance quality factor in the two resonance modes. The quality factor is determined based on the 3dB frequency range Δf of the amplitude at the resonance frequency point S21. ij-1-3dB and △f ij-2-3dB and resonant frequency f ij-1 and f ij-2 The calculation determines, that is, Q. ij-1 =f ij-1 / △f ij-1-3dB and Q ij-2 =f ij-2 / △f ij-2-3dB .

[0023] The acquisition of the apparent complex permittivity in step (3)① is based on the response curves of the complex permittivity of the sample under two resonant modes of the sensor, where ε * ij-1 =ε' ij-1 +jε” ij-1 and ε * ij-2 =ε' ij-2 +jε” ij-2 The response curve is fitted with an s-order polynomial, where s ≥ 2, as shown in the following equation:

[0024] ε' ij-1 =C0+C1(△f ij-1 ) 1 +C2(△f ij-1 ) 2 +…+C s (△f ij-1 ) s ,

[0025] ε” ij-1 =D0+D1(△1 / Q) ij-1 ) 1 +D2(△1 / Q ij-1 ) 2 +…+D s (△1 / Q ij-1 ) s ,

[0026] ε'ij-1 =E0+E1(△f ij-1 ) 1 +E2(△f ij-1 ) 2 +…+E s (△f ij-1 ) s ,

[0027] ε” ij-2 =F0+F1(△1 / Q) ij-2 ) 1 +F2(△1 / Q ij-2 ) 2 +…+F s (△1 / Q ij-2 ) s ,

[0028] The coefficient matrix of each s-order polynomial is C0 / C1 / C2…C… s D0 / D1 / D2…D s E0 / E1 / E2…E s F0 / F1 / F2…F s The coefficient matrix of the above-mentioned s-order polynomial is obtained by determining the value through electromagnetic field numerical simulation, or by manufacturing a calibration piece with the same diameter as the core using a standard material (such as polytetrafluoroethylene, polyvinyl chloride, silicon, etc.) with known real and imaginary parts of the dielectric constant, and then performing s-order polynomial fitting.

[0029] In step (3)②, for the i-th axial region, a total of n sensors obtain 2n apparent complex permittivity ε. * ij-1 and ε * ij-2 , j≤n, p radial regions correspond to p regions of unsolved permittivity ε * i1 to ε * ip Given that p ≤ 2n, construct a system of p linear equations as shown below:

[0030] ε * i1 =A 1-1 ε * i1-1 +A 1-2 ε * i2-1 …+A 1-n ε * in-1 +B 1-1 ε * i1-2 +B 1-2 ε * i2-2 …+B1-n ε * in-2 ,

[0031] ε * i2 =A 2-1 ε * i1-1 +A 2-2 ε * i2-1 …+A 2-n ε * in-1 +B 2-1 ε * i1-2 +B 2-2 ε * i2-2 …+B 2-n ε * in-2 ,

[0032] ...

[0033] ε * ip =A p-1 ε * i1-1 +A p-2 ε * i2-1 …+A p-n ε * in-1 +B p-1 ε * i1-2 +B p-2 ε * i2-2 …+B p-n ε * in-2 ,

[0034] The coefficient matrix of the equation system is determined by electromagnetic field numerical simulation or by simulation experiments using layered artificial rock cores.

[0035] In step (4)①, the complex permittivity ε of water * werter-ni-1 and ε * werter-ni-2 ; is given through the Debye or Cole-Cole model, that is or Where ε s ε ∞τ, α, ω, and j represent the zero-frequency dielectric constant, optical-frequency dielectric constant, Debye relaxation time, Cole-Cole factor, test angular frequency, and imaginary sign, respectively, where ω = 2πf, and f is the test frequency. The zero-frequency dielectric constant, optical-frequency dielectric constant, and Debye relaxation angular frequency can be established relative to the core temperature T. i For example, ε s =A1+B1×T i ε ∞ =A² + B² × T i τ=A3+B3×T i The linear relationship is obtained by referring to publicly available experimental materials or laboratory-controlled temperature calibration.

[0036] In step (4)②, the effective medium theory model can be a negative refractive index model or a Maxwell-Wagner model, but is not limited to the above models.

[0037] The system for implementing the above-mentioned multi-frequency broadband full-size core water aquifer porosity local measurement method adopts the following technical solution:

[0038] The system includes a core propulsion device, a core diameter measuring device, a temperature recorder, a sensor group, a microwave multiplexer, a microwave scattering parameter sweep frequency measuring device, and a main control computer. The core propulsion device, the core diameter measuring device, and the sensor group are arranged sequentially. The sensor group includes n sensors, where n ≥ 1 (if n ≠ 1, then the n sensors operate at different frequencies). Each sensor is connected to the microwave multiplexer, which is connected to the microwave scattering parameter sweep frequency measuring device. The core propulsion device, the core diameter measuring device, the temperature recorder, the microwave multiplexer, and the microwave scattering parameter sweep frequency measuring device are all connected to the main control computer.

[0039] The core propulsion device is used to push the core along the axial direction in a stepping motion. It can adopt existing technologies, such as the "Core Pushing Device" disclosed in CN213205610U.

[0040] The core diameter measuring device is used to achieve real-time measurement of the core diameter, obtaining the diameter φ at a specific axial position of the core. Existing technologies can be used to measure the diameter of the axial region through optical, ultrasonic, or other physical methods, such as a laser diameter gauge.

[0041] The temperature recorder contacts the core via an external resistance temperature detector (RTD) or thermocouple sensor to measure the core temperature T, or acquires and records the temperature T at a specific axial position of the core in real time via non-contact measurement (infrared, colorimetric, etc.).

[0042] The sensor is an open resonant cavity sensor with a hollow structure. The open resonant cavity sensor is a cylindrical resonant cavity with openings on both bottom surfaces, and it operates simultaneously in both the TM010 mode, which is sensitive to the internal region of the core, and the TM110 mode, which is sensitive to the surface region of the core.

[0043] The sensor has two ports, which are respectively connected to the moving ends of two microwave multiplexing devices (connected via coaxial phase-stable cables); the stationary ends of the two microwave multiplexing devices are respectively connected to the two ports of the microwave scattering parameter scanning measurement device (connected via coaxial phase-stable cables).

[0044] The microwave multiplexing device is a single-pole multi-throw structure, equipped with one fixed end and n free ends. The fixed end connects to only one free end at a time and is isolated from the other free ends. Each free end is connected to one port of a sensor via a coaxial phase-stabilized cable. The free ends of the second microwave multiplexing device are connected to the other ports of the n open resonant cavity sensors via coaxial phase-stabilized cables. The fixed ends of both microwave multiplexing devices are connected to two ports of the microwave scattering parameter sweep frequency measurement device via coaxial phase-stabilized cables.

[0045] The microwave scattering parameter sweep frequency measurement device adopts existing technology and can be a vector network analyzer. It needs to have the ability to acquire the amplitude and phase of forward transmission (S11), forward reflection (S21) or reverse transmission (S12), reverse reflection (S22) in the two-port microwave scattering parameter matrix.

[0046] The core propulsion device pushes a full-size core sequentially through the core diameter measuring device and sensor array. Before entering the sensors, the core diameter is measured by the core diameter measuring device, and the data is transmitted to the computer. Then, the core passes non-contactly through the hollow portion of the sensor. Each resonant cavity sensor can operate in two transverse magnetic modes: TM010 and TM110. A temperature recorder collects and records the core temperature in real time via an external resistance temperature detector (RTD) or thermocouple, or through non-contact temperature measurement. The main control computer can be a programmable logic controller (PLC) to automatically control the open resonant cavity sensors, microwave scattering parameter sweep frequency measuring device, microwave multiplexing device, core propulsion device, and core diameter measuring device. It also collects monitoring data from each device, analyzes and processes the data, and calculates pore water information.

[0047] This invention achieves axial localized measurement of water content (water content porosity) and mineralization in a step-by-step manner through a combination of sensors without contacting or damaging the core. Different sensors test different sensitive areas, establishing a quantitative correlation between water content porosity, mineralization, and sensor response in a fixed axial region of the core, thus achieving radial localized measurement. Finally, through standard materials and artificial core calibration, a quantitative mapping is established between water content porosity, mineralization, etc., and instrument response and apparent dielectric constant of the core, ultimately achieving localized measurement of axial / radial water content (water content porosity) and mineralization in full-size cores.

[0048] During testing, the core is pushed stepwise through various sensors by a propulsion device. Changes in geological parameters such as water-bearing porosity and mineralization of the core cause differences in the sensor resonance parameters, resulting in changes in the resonance frequency and quality factor (Q value) of its two modes, TM010 and TM110. The amplitude and phase information of the transmission and reflection coefficients are obtained by a microwave scattering parameter sweep frequency measurement device. Combined with standard material calibration parts, the system response compensation calibration is completed. By utilizing the differences in electric field distribution and penetration depth of different sensors and different working modes, a quantitative correlation is established between the water-bearing porosity and mineralization of the core in a fixed axial region and the sensor resonance frequency and quality factor (Q value).

[0049] This invention enables localized, step-by-step, fully automated measurement of dielectric properties of full-size core samples, and compensates for core diameter interference. It can meet the needs of full-size core well site analysis, eliminate the influence of mud intrusion, and obtain information on the water-bearing porosity and mineralization of the original formation, thereby improving the accuracy and efficiency of on-site core analysis. Attached Figure Description

[0050] Figure 1 This is a schematic diagram of the structural principle of the multi-frequency broadband full-size core water porosity localization measurement system of the present invention.

[0051] Figure 2 This is a schematic diagram of the working modes of an open resonant cavity sensor; where (a) is the TM010 mode and (b) is the TM110 mode.

[0052] Figure 3 This is a flowchart of the measurement process of the multi-frequency broadband full-size core water porosity localization measurement system in this invention.

[0053] Figure 4 This is a schematic diagram showing the division of the axial and radial regions of the core sample.

[0054] In the figure: 1. Core propulsion device, 2. Core diameter measuring device, 3. Temperature recorder, 4. Sensor group, 5. Microwave multiplexer, 6. Microwave scattering parameter sweep frequency measuring device, 7. Main control computer. Detailed Implementation

[0055] like Figure 1 As shown, the multi-frequency broadband full-size core water-bearing porosity localization measurement system of the present invention includes a core propulsion device 1, a core diameter measuring device 2, a temperature recorder 3, a sensor group 4, a microwave multiplexer 5, a microwave scattering parameter sweep measurement device 6, and a main control computer 7. The sensor group 4 includes multiple open resonant cavity sensors operating at different frequencies. The open resonant cavity sensors have a hollow design, with each sensor having two reserved ports, which are respectively connected to different moving ends of the two microwave multiplexers 5 via coaxial phase-stabilized cables. The two ports of the microwave scattering parameter sweep measurement device 6 are respectively connected to the stationary ends of the two microwave multiplexers 5 via coaxial phase-stabilized cables. The core propulsion device 1 realizes the function of pushing the core along the axial direction in a stepping motion. The core diameter measuring device 2 is used to realize the real-time measurement of the core diameter, which can measure the diameter of the axial region through optical, ultrasonic, or other physical methods to obtain the diameter φ at a specific axial position of the core. Temperature recorder 3 measures the core temperature T by contacting the core with an external resistance temperature detector (RTD) or thermocouple sensor, or by acquiring and recording the temperature T at a specific axial position of the core in real time using non-contact measurement principles such as infrared or colorimetry. Core propulsion device 1, core diameter measuring device 2, temperature recorder 3, microwave multiplexer 5, and microwave scattering parameter sweep frequency measuring device 6 are all connected to the main control computer 7.

[0056] The number of open-cavity sensors can be n (n≥1), which are cylindrical resonant cavities with openings on both bottom surfaces (see...). Figure 1 The sensor is excited by a magnetic loop antenna, which is connected to a coaxial phase-stabilized cable via RF interfaces soldered to both sides of the sensor. It can operate simultaneously in both TM010 and TM110 modes (see [link]). Figure 2 ),in Figure 2 In (a), the electric field energy of the TM010 mode is concentrated in a circular region centered on the core, and is sensitive to the internal region of the core. Figure 2 (b) TM110 converges in two semi-circular regions symmetrical about the center line of the resonant cavity cross section, and is sensitive to the surface region of the core.

[0057] There are two sets of microwave multiplexing devices 5, which are single-pole multi-throw structures. Each set is equipped with one fixed end and n free ends. The fixed end is connected to only one free end at a time and is isolated from the other free ends. The free ends are connected to one port of each of the n open resonant cavity sensors through coaxial phase-stabilized cables. The free ends of the second microwave multiplexing device 5 are connected to the other port of each of the n open resonant cavity sensors through coaxial phase-stabilized cables. The fixed ends of the two sets of microwave multiplexing devices 5 are connected to the two ports of the microwave scattering parameter sweep frequency measurement device 6 through coaxial phase-stabilized cables.

[0058] The number of microwave scattering parameter sweep frequency measurement devices 6 is 1. It needs to be able to acquire the amplitude and phase of forward transmission (S11), forward reflection (S21) or reverse transmission (S12), reverse reflection (S22) in the two-port microwave scattering parameter matrix. It can be a vector network analyzer.

[0059] The full-size core is propelled through the hollow section non-contactly by the core propulsion device 1. Before entering the sensor, the core passes through the core diameter measuring device 2, which is installed in series with the sensor. The main control computer 7 can be a programmable logic controller (PLC) to automatically control the microwave scattering parameter sweep measurement device 6, the microwave multiplexing device 5, the core propulsion device 1, and the core diameter measuring device 2, and to collect monitoring data from each device, analyze and process the data, and calculate pore water information.

[0060] The process of the above system realizing localized measurement of water-bearing porosity in multi-frequency broadband full-size core samples is as follows: Figure 3 As shown, the specific steps include:

[0061] (1) Setting test parameters, initializing calibration and test preparation

[0062] ① Set test parameters, including but not limited to test frequency range, frequency resolution, sampling interval, intermediate frequency bandwidth, test signal power, etc.;

[0063] ② Select the calibration type and set the reference surface measured by the microwave scattering parameter sweep frequency measurement device 6 at the moving end of the microwave multiplexer 5;

[0064] ③ Initialize and calibrate the microwave scattering parameter sweep measurement device 6;

[0065] ④ For example Figure 4 As shown, the core is divided into m axial regions and p radial regions, where m ≥ 1. The lengths of each axial region are equal, and each radial region is a coaxial ring from the inside to the outside.

[0066] (2) Complete the measurement of the core microwave response and other parameters.

[0067] ① Place the core on the core propulsion device 1, with the first axial region located at the center of the diameter measuring device;

[0068] ② The core diameter measuring device 2 obtains the diameter φ of the i-th axial region. i ;

[0069] ③ Temperature recorder 3 records the temperature T of the i-th axial region. i ;

[0070] ④ The main control computer 7 operates the microwave multiplexing device 5 to make n sensors work sequentially, and the microwave scattering parameter sweep frequency measurement device 6 obtains the frequency offset Δf of each sensor in the two resonant modes TM010 and TM110 respectively. ij-1 and △f ij-2 The relative change of the reciprocal of the quality factor Δ1 / Q ij-1 and △1 / Q ij-2 Among them, △f ij-1 and △f ij-2 These represent the frequency offsets (Δ1 / Q) of the first and second operating modes (TM010 and TM110) of the j-th sensor in the i-th axial region, respectively. ij-1 and

[0071] △1 / Q ij-2 These represent the relative changes in the reciprocals of the quality factor for the j-th sensor in the i-th axial region under the first and second operating modes, respectively.

[0072] Frequency shift Δf between the two resonant modes ij-1 and △f ij-2 The value is the difference between the unloaded resonant frequency and the actual sample resonant frequency in the two resonant modes. The resonant frequency is calculated from the point of maximum amplitude of S21 in that resonant mode, i.e., Δf. ij-1 =f 1空 -f ij-1 , △f ij-2 =f 2空 -f ij-2 The relative change in the reciprocal of the quality factor, Δ1 / Q ij-1 and △1 / Q ij-2 , is the difference between the unloaded resonance quality factor and the actual sample resonance quality factor in the two resonance modes. The quality factor is determined based on the 3dB frequency range Δf of the amplitude at the resonance frequency point S21. ij-1-3dB and △f ij-2-3dB and resonant frequency f ij-1 and f ij-2 The calculation determines, that is, Q. ij-1 =f ij-1 / △f ij-1-3dB and Q ij-2 =f ij-2 / △f ij-2-3dB .

[0073] ⑤ Determine whether the m-th region has been detected by the n-th sensor. If the result is no, the propulsion device 1 will advance the core forward by one axial region (in one direction). Repeat the diameter, temperature and sensor response tests from step ② to step ④ until the result is yes. Complete the measurement steps of the core microwave response and other parameters, and proceed to the next step.

[0074] (3) Local inversion of complex permittivity of core

[0075] ① Store the relative changes in frequency offset Δf and reciprocal of quality factor Δ1 / Q for all m axial regions and n sensors in two modes;

[0076] ②Based on the frequency offset Δf of the j-th sensor ij-1 , △f ij-2 The relative change of the reciprocal of the quality factor Δ1 / Q ij-1 △1 / Q ij-2 Obtain the apparent complex permittivity ε of the i-th axial region. * ij-1 and ε * ij-2 ;

[0077] The apparent complex permittivity was obtained based on the response curves of the sample's complex permittivity under two sensor operating modes, where ε * ij-1 =ε' ij-1 +jε” ij-1 and ε * ij-2 =ε' ij-2 +jε” ij-2 The response curve is fitted with an s-order polynomial (s≥2), as shown in the following equation:

[0078] ε' ij-1 =C0+C1(△f ij-1 ) 1 +C2(△f ij-1 ) 2 +…+C s (△f ij-1 ) s ,

[0079] ε” ij-1 =D0+D1(△1 / Q) ij-1 ) 1 +D2(△1 / Q ij-1 ) 2 +…+D s (△1 / Q ij-1 ) s ,

[0080] ε' ij-1 =E0+E1(△f ij-1 ) 1 +E2(△f ij-1 ) 2 +…+E s (△f ij-1 ) s ,

[0081] ε” ij-2 =F0+F1(△1 / Q) ij-2 ) 1 +F2(△1 / Q ij-2 ) 2 +…+F s (△1 / Q ij-2 ) s ,

[0082] The coefficient matrix of each s-order polynomial is C0 / C1 / C2…C… s D0 / D1 / D2…D s E0 / E1 / E2…E s F0 / F1 / F2…F s The coefficient matrix of the above-mentioned s-order polynomial can be obtained by numerical simulation of electromagnetic fields, or by manufacturing a calibration piece with the same diameter as the core using a standard material with known real and imaginary parts of dielectric constants, such as polytetrafluoroethylene, polyvinyl chloride, or silicon, and then fitting it with an s-order polynomial.

[0083] ③ For the i-th axial region, divide it into p radial regions and construct the complex permittivity ε of each radial region. * ip A system of p-variable linear equations relating the 2n apparent complex permittivity of region i;

[0084] For the i-th axial region, a total of n sensors obtain 2n apparent complex permittivity ε. * ij-1 and ε * ij-2 , j≤n, such as Figure 4 As shown, the p radial regions correspond to the p regions' unsolved permittivity ε. * i1 to ε * ip Given that p ≤ 2n, a system of p linear equations can be constructed as shown in the following equation:

[0085] ε * i1 =A 1-1 ε * i1-1 +A 1-2 ε * i2-1 …+A 1-n ε * in-1 +B 1-1 ε * i1-2 +B 1-2 ε * i2-2 …+B 1-n ε *in-2

[0086] ε * i2 =A 2-1 ε * i1-1 +A 2-2 ε * i2-1 …+A 2-n ε * in-1 +B 2-1 ε * i1-2 +B 2-2 ε * i2-2 …+B 2-n ε * in-2

[0087] ...

[0088] ε * ip =A p-1 ε * i1-1 +A p-2 ε * i2-1 …+A p-n ε * in-1 +B p-1 ε * i1-2 +B p-2 ε * i2-2 …+B p-n ε * in-2

[0089] The coefficient matrix of the equation system can be determined by electromagnetic field numerical simulation or by simulation experiments using layered artificial rock cores.

[0090] ④ Solve for the complex permittivity ε of the i-th axial region and p radial regions. * i1 to ε * ip This continues until the complex permittivity of all m axial regions and p radial regions has been solved.

[0091] (4) Local inversion of core water porosity and pore water salinity

[0092] ① To obtain the water porosity and pore water salinity information for the i-th axial region, first calculate the complex permittivity ε of the water at the resonant frequencies of n sensors in the i-th axial region based on Ti. *werter-ni-1 and ε * werter-ni-2 .

[0093] The complex permittivity ε of water * werter-ni-1 and ε * werter-ni-2 ; is given through the Debye or Cole-Cole model, that is or Where ε s ε ∞ τ, α, ω, and j represent the zero-frequency dielectric constant, optical-frequency dielectric constant, Debye relaxation time, Cole-Cole factor, test angular frequency, and imaginary sign, respectively, where ω = 2πf, and f is the test frequency. The zero-frequency dielectric constant, optical-frequency dielectric constant, and Debye relaxation angular frequency can be established relative to the core temperature T. i For example, ε s =A1+B1×T i ε ∞ =A² + B² × T i τ=A3+B3×T i The linear relationship is such that the coefficients A1, A2, A3, B1, B2, and B3 can be obtained by referring to publicly available experimental materials or by laboratory temperature control calibration.

[0094] ② Combining the complex permittivity ε of the p radial regions of the i-th axial region * i1 to ε * ip The Effective Medium Theory (EMT) model was applied to analyze the ε values ​​in various axial and radial regions. * ip Modeling and fitting were performed to obtain information on water-bearing porosity and pore water salinity;

[0095] The effective medium theory model can be a negative refractive index model or a Maxwell-Wagner model, but is not limited to the above models.

[0096] ③ If spatial distribution information of water-bearing porosity and pore water salinity is required in other axial regions, steps ① and ② can be repeated.

Claims

1. A method for localized measurement of water-bearing porosity in multi-frequency broadband full-size core samples, characterized in that, Includes the following steps: (1) Preparations: ① Divide the core into m axial regions of equal length, m≥1; divide each axial region into p radial regions, each radial region being a coaxial ring from the inside out, p≥1; ② Set up n sensors, n≥1; the sensors are open resonant cavity sensors, and the sensors work simultaneously in the TM010 resonant mode which is sensitive to the internal region of the core and the TM110 resonant mode which is sensitive to the surface region of the core. (2) Measure and obtain the corresponding parameters: ① Measure the diameter and temperature of each axial region to obtain the diameter φ of the i-th axial region. i and temperature T i ; ② The core sample is passed through each sensor in a non-contact manner to test the response of each sensor; each sensor operates sequentially, and the frequency shift Δf of each sensor in the two resonant modes is obtained respectively. ij-1 and △f ij-2 And the relative change in the reciprocal of the quality factor, Δ1 / Q ij-1 and △1 / Q ij-2 , where △f ij-1 and △f ij-2 These represent the frequency shifts of the j-th sensor in the i-th axial region under the two resonant modes, Δ1 / Q ij-1 and △1 / Q ij-2 These represent the relative changes in the reciprocals of the quality factor for the j-th sensor in the i-th axial region under the two resonance modes, respectively. ③ Advance the core to an axial region and repeat the diameter, temperature, and sensor response tests from step ② to step ④ until the m-th region has been detected by the n-th sensor, thus completing the measurement steps of the core microwave response and other parameters. (3) Local inversion of complex permittivity of core; ①Based on the frequency offset Δf of the j-th sensor ij-1 and △f ij-2 And the relative change in the reciprocal of the quality factor, Δ1 / Q ij-1 and △1 / Q ij-2 Obtain the apparent complex permittivity ε of the i-th axial region. * ij-1 and ε * ij-2 ; ② For the i-th axial region, divide it into p radial regions and construct the complex permittivity ε of each radial region. * ip A system of p-variable linear equations relating the 2n apparent complex permittivity of region i; ③ Solve for the complex permittivity ε of the i-th axial region and p radial regions. * i1 to ε * ip This continues until the complex permittivity of all m axial regions and p radial regions has been solved. (4) Localized inversion of core water porosity and pore water salinity: ① To obtain the water porosity and pore water salinity information of the i-th axial region, the complex permittivity ε of the water at the resonant frequencies of n sensors in the i-th axial region is first calculated based on the temperature Ti of the i-th axial region. * werter-ni-1 and ε * werter-ni-2 ; ② Combining the complex permittivity ε of the p radial regions of the i-th axial region * i1 to ε * ip The effective medium theory model was applied to the ε values ​​in various axial and radial regions. * ip Modeling and fitting were performed to obtain information on water-bearing porosity and pore water salinity. ③ Repeat steps ① and ② above to obtain spatial distribution information of water-bearing porosity and pore water salinity in other axial regions.

2. The method for localized measurement of water-bearing porosity in multi-frequency broadband full-size cores according to claim 1, characterized in that, In step (2)②, the frequency shift Δf between the two resonant modes ij-1 and △f ij-2 The difference between the unloaded resonant frequency and the actual sample resonant frequency in the two resonant modes is given by the resonant frequency S21, which is calculated from the point of maximum amplitude in that resonant mode, i.e., Δf. ij-1 =f 1空 -f ij-1 , △f ij-2 =f 2空 -f ij-2 The relative change in the reciprocal of the quality factor, Δ1 / Q ij-1 and △1 / Q ij-2 , is the difference between the unloaded resonance quality factor and the actual sample resonance quality factor in the two resonance modes. The quality factor is determined based on the 3dB frequency range Δf of the amplitude at the resonance frequency point S21. ij-1-3dB and △f ij-2-3dB and resonant frequency f ij-1 and f ij-2 The calculation determines, that is, Q. ij-1 =f ij-1 / △f ij-1-3dB and Q ij-2 =f ij-2 / △f ij-2-3dB .

3. The method for localized measurement of water-bearing porosity in multi-frequency broadband full-size cores according to claim 1, characterized in that, The acquisition of the apparent complex permittivity in step (3)① is based on the response curves of the complex permittivity of the sample under two resonant modes of the sensor, where ε * ij-1 =ε' ij-1 +jε” ij-1 and ε * ij-2 =ε' ij-2 +jε” ij-2 The response curve is fitted with an s-order polynomial, where s ≥ 2, as shown in the following equation: e' ij-1 =C0+C1(△f ij-1 ) 1 +C2(△f ij-1 ) 2 +…+C s (△f ij-1 ) s , ε” ij-1 =D0+D1(△1 / Q ij-1 ) 1 +D2(△1 / Q ij-1 ) 2 +…+D s (△1 / Q ij-1 ) s , ε' ij-1 =E0+E1(△f ij-1 ) 1 +E2(△f ij-1 ) 2 +…+E s (△f ij-1 ) s , ε” ij-2 =F0+F1(△1 / Q ij-2 ) 1 +F2(△1 / Q ij-2 ) 2 +…+F s (△1 / Q ij-2 ) s , The coefficient matrix of each s-order polynomial is C0 / C1 / C2…C… s D0 / D1 / D2…D s E0 / E1 / E2…E s F0 / F1 / F2…F s The coefficient matrix of the above-mentioned s-order polynomial is obtained by determining the coefficient matrix through electromagnetic field numerical simulation, or by manufacturing a calibration piece with the same diameter as the core using a standard material with a known real and imaginary part of the dielectric constant, and then fitting it with an s-order polynomial.

4. The method for localized measurement of water-bearing porosity in multi-frequency broadband full-size core samples according to claim 1, characterized in that, In step (3)②, for the i-th axial region, a total of n sensors obtain 2n apparent complex permittivity ε. * ij-1 and ε * ij-2 , j≤n, p radial regions correspond to p regions of unsolved permittivity ε * i1 to ε * ip Given that p ≤ 2n, construct a system of p linear equations as shown below: e * i1 =A 1-1 e * i1-1 +A 1-2 e * i2-1 …+A 1-n e * in-1 +B 1-1 e * i1-2 +B 1-2 e * i2-2 …+B 1-n e * in-2 , e * i2 =A 2-1 e * i1-1 +A 2-2 e * i2-1 …+A 2-n e * in-1 +B 2-1 e * i1-2 +B 2-2 e * i2-2 …+B 2-n e * in-2 , …… e * ip =A p-1 e * i1-1 +A p-2 e * i2-1 …+A p-n e * in-1 +B p-1 e * i1-2 +B p-2 e * i2-2 …+B p-n e * in-2 , The coefficient matrix of the equation system is determined by electromagnetic field numerical simulation or by simulation experiments using layered artificial rock cores.

5. The method for localized measurement of water-bearing porosity in multi-frequency broadband full-size cores according to claim 1, characterized in that, In step (4)①, the complex permittivity ε of water * werter-ni-1 and ε * werter-ni-2 It is given through the Debye or Cole-Cole model, that is... or Where ε s ε ∞ τ, α, ω, and j represent the zero-frequency dielectric constant, optical-frequency dielectric constant, Debye relaxation time, Cole-Cole factor, test angular frequency, and imaginary sign, respectively, where ω = 2πf, and f is the test frequency. The zero-frequency dielectric constant, optical-frequency dielectric constant, and Debye relaxation angular frequency can be established relative to the core temperature T. i For example, ε s =A1+B1×T i ε ∞ =A² + B² × T i τ=A3+B3×T i The linear relationship is obtained by referring to publicly available experimental materials or laboratory-controlled temperature calibration.

6. The method for localized measurement of water-bearing porosity in multi-frequency broadband full-size cores according to claim 1, characterized in that, In step (4)②, the effective medium theoretical model is either the negative refractive index model or the Maxwell-Wagner model.

7. A system for implementing the multi-frequency broadband full-size core water-bearing porosity local measurement method according to any one of claims 1-6, characterized in that: It includes a core propulsion device, a core diameter measuring device, a temperature recorder, a sensor group, a microwave multiplexer, a microwave scattering parameter sweep frequency measuring device, and a main control computer; the core propulsion device, the core diameter measuring device, and the sensor group are arranged sequentially; the sensor group includes n sensors, n≥1, each sensor is connected to the microwave multiplexer, the microwave multiplexer is connected to the microwave scattering parameter sweep frequency measuring device, and the core propulsion device, the core diameter measuring device, the temperature recorder, the microwave multiplexer, and the microwave scattering parameter sweep frequency measuring device are all connected to the main control computer.

8. The system for localized measurement of water-bearing porosity in multi-frequency broadband full-size cores according to claim 7, characterized in that: The sensor is an open resonant cavity sensor with a hollow structure; the open resonant cavity sensor is a cylindrical resonant cavity with openings on both bottom surfaces, and it operates simultaneously in the TM010 mode, which is sensitive to the internal region of the core, and the TM110 mode, which is sensitive to the surface region of the core.

9. The system for localized measurement of water-bearing porosity in multi-frequency broadband full-size cores according to claim 7, characterized in that: The sensor has two ports, which are respectively connected to the moving ends of two microwave multiplexing devices; The stationary ends of the two microwave multiplexing devices are respectively connected to the two ports of the microwave scattering parameter scanning measurement device.

10. The system for localized measurement of water-bearing porosity in multi-frequency broadband full-size cores according to claim 7, characterized in that: The microwave multiplexing device is configured with one fixed end and n free ends. The fixed end is connected to only one free end at a time and is isolated from the other free ends. The free ends are respectively connected to one port of the sensor through a coaxial phase-stabilized cable. The free ends of the second microwave multiplexing device are respectively connected to the other port of the n open resonant cavity sensors through coaxial phase-stabilized cables. The fixed ends of the two microwave multiplexing devices are connected to the two ports of the microwave scattering parameter sweep frequency measurement device via coaxial phase-stable cables.

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