Device and method for measuring fluid conductivity at high temperature and high pressure

Abstract

The invention discloses a device and a method for measuring fluid conductivity at high temperature and high pressure, and relates to the technical field of physical property measurement. The device for measuring the conductivity of the fluid at the high temperature and the high pressure comprises a pyrophyllite pressure transmission assembly, a heater, a lower electrode plate, an upper electrode plate and a polytetrafluoroethylene sample cavity, and can measure the conductivity of the fluid at different temperatures and pressures by combining with a multi-surface jacking press; the polytetrafluoroethylene sample cavity is arranged, and the characteristics of low cost and high chemical stability of polytetrafluoroethylene are applied, so that the measurement of the fluid conductivity under the high-temperature and high-pressure environment can be realized at lower cost, and the measurement of the fluid conductivity under the high-temperature and high-pressure environment in the earth can be simulated.

Description

Technical Field

[0001] The present application relates to the technical field of physical property measurement, and in particular to a device and method for measuring the electrical conductivity of a fluid under high temperature and high pressure. Background Art

[0002] Fluids have many unique properties under high temperature and high pressure, such as strong oxidation, high solubility, and high ionization. These properties of fluids have wide applications in many fields (such as materials science, analytical chemistry, environmental governance, etc.), and have received high attention in the chemical and engineering communities. In the field of earth science, the physical and chemical properties of fluids under high temperature and high pressure have also been widely studied. Fluids in the earth's internal environment not only have an important influence on the properties of geophysical fields (conductivity, seismic waves, viscosity, thermal conductivity, etc.), but also play an extremely important role in many geological processes such as the migration of mineralizing elements, geological structural evolution, earthquake incubation, magma generation and eruption. The existence of fluids may be an important reason why the earth has a different evolutionary history from other terrestrial planets. The high conductivity and low wave velocity anomalies commonly seen in magnetotelluric and seismic tomography observations are considered to be the presence of water-rich fluids in the earth's interior, due to the high conductivity and low wave velocity characteristics of the fluids. However, since these geophysical methods have many uncertainties in inverting the composition of the Earth's interior, it is extremely important to simulate the high temperature and high pressure environment inside the Earth to conduct research on the electrical properties of fluids. This can help constrain the results of geophysical inversion, provide key evidence for the existence of fluids inside the Earth, and help to deeply understand the material composition, structural characteristics and dynamic processes of the deep Earth. Summary of the invention

[0003] The purpose of this application is to provide a device and method for measuring fluid conductivity under high temperature and high pressure, so as to realize the measurement of fluid conductivity under high temperature and high pressure, and further realize the measurement of fluid conductivity under high temperature and high pressure environment simulating the earth's interior.

[0004] To achieve the above objectives, this application provides the following solutions.

[0005] In a first aspect, the present application provides a device for measuring the conductivity of a fluid under high temperature and high pressure, the device comprising: a pyrophyllite pressure transmission component, a heater, a lower electrode sheet, an upper electrode sheet and a polytetrafluoroethylene sample chamber;

[0006] The polytetrafluoroethylene sample chamber is arranged inside the pyrophyllite pressure transmission component, the heater is arranged between the polytetrafluoroethylene sample chamber and the pyrophyllite pressure transmission component, the lower electrode sheet is arranged at the bottom of the polytetrafluoroethylene sample chamber, and the upper electrode sheet covers the top of the polytetrafluoroethylene sample chamber;

[0007] During measurement, a multi-faceted press applies pressure to the pyrophyllite pressure transmission component, and the circulating water inwardly of the multi-faceted press and the heater are used to adjust the temperature of the liquid to be measured in the polytetrafluoroethylene sample chamber; the lower electrode sheet and the upper electrode sheet are used to draw out the impedance signal of the liquid to be measured, and the impedance signal is used to calculate the conductivity of the liquid to be measured.

[0008] In a second aspect, the present application provides a method for measuring fluid conductivity under high temperature and high pressure, comprising the following steps:

[0009] Assemble the above-mentioned device for measuring fluid conductivity under high temperature and high pressure, and inject the liquid to be measured;

[0010] A device for measuring fluid conductivity under high temperature and high pressure is arranged in a multi-faceted top press, and a lower electrode sheet and an upper electrode sheet are connected to an impedance spectrometer through measuring lines;

[0011] Using a multi-faceted top press to apply pressure to the pyrophyllite pressure transmission component, and using the circulating water inwardly of the multi-faceted top press and the heater to adjust the temperature of the liquid to be tested in the polytetrafluoroethylene sample chamber, and obtaining the impedance of the liquid to be tested at different pressures and temperatures through an impedance spectrometer;

[0012] According to the impedance of the liquid to be tested at different pressures and temperatures, the conductivity of the liquid to be tested at different pressures and temperatures is calculated.

[0013] According to the specific embodiments provided in this application, this application has the following technical effects.

[0014] The present application provides a device and method for measuring the electrical conductivity of a fluid under high temperature and high pressure. The device for measuring the electrical conductivity of a fluid under high temperature and high pressure of the present application comprises: a pyrophyllite pressure transmission component, a heater, a lower electrode sheet, an upper electrode sheet and a polytetrafluoroethylene sample chamber. The measuring device of the present application is combined with a multi-faceted top press to realize the measurement of the electrical conductivity of the fluid under different temperatures and pressures. The setting of the polytetrafluoroethylene sample chamber of the present application utilizes the characteristics of low cost and high chemical stability of polytetrafluoroethylene, and can realize the measurement of the electrical conductivity of the fluid under a high temperature and high pressure environment at a relatively low cost, thereby realizing the measurement of the fluid conductivity under a high temperature and high pressure environment simulating the interior of the earth. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0016] Figure 1A schematic diagram of the structure of a device for measuring fluid conductivity under high temperature and high pressure provided in one embodiment of the present application.

[0017] Figure 2 A flow chart of a method for measuring fluid conductivity under high temperature and high pressure provided in one embodiment of the present application.

[0018] Figure 3 An experimental flow chart for measuring fluid conductivity under high temperature and high pressure provided in one embodiment of the present application.

[0019] Figure 4 This is a graph of impedance characteristics obtained by measurement according to an embodiment of the present application.

[0020] Figure 5 The conductivity of the NaCl solution and its calibration curve obtained by impedance fitting provided in one embodiment of the present application.

[0021] Figure 6 A comparison chart of the conductivity of the NaCl solution provided in one embodiment of the present application and prior art data.

[0022] Description of reference numerals:

[0023] 1. Pyrophyllite pressure transmission assembly; 2. Heater; 3. Lower electrode sheet; 4. Upper electrode sheet; 5. K-type thermocouple; 6. Polytetrafluoroethylene sample chamber; 7. Measuring line. DETAILED DESCRIPTION

[0024] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0025] In order to make the above-mentioned objects, features and advantages of the present application more obvious and easy to understand, the present application is further described in detail below with reference to the accompanying drawings and specific implementation methods.

[0026] In an exemplary embodiment, a device for measuring fluid conductivity under high temperature and high pressure is provided, such as Figure 1As shown, the device for measuring the electrical conductivity of a fluid under high temperature and high pressure comprises: a pyrophyllite pressure transmission component 1, a heater 2, a lower electrode sheet 3, an upper electrode sheet 4 and a polytetrafluoroethylene sample chamber 6; the polytetrafluoroethylene sample chamber 6 is arranged inside the pyrophyllite pressure transmission component 1, the heater 2 is arranged between the polytetrafluoroethylene sample chamber 6 and the pyrophyllite pressure transmission component 1, the lower electrode sheet 3 is arranged at the bottom of the polytetrafluoroethylene sample chamber 6, and the upper electrode sheet 4 covers the top of the polytetrafluoroethylene sample chamber 6; during measurement, a multi-faceted top press applies pressure to the pyrophyllite pressure transmission component 1, and the circulating water inwardly of the multi-faceted top press and the heater 2 are used to adjust the temperature of the liquid to be measured in the polytetrafluoroethylene sample chamber 6; the lower electrode sheet 3 and the upper electrode sheet 4 are used to draw out the impedance signal of the liquid to be measured, and the impedance signal is used to calculate the electrical conductivity of the liquid to be measured.

[0027] At present, in the relevant technical field, the conductivity measurement experiments of fluids under high temperature and high pressure conditions mainly use cold-sealed autoclaves, hydrothermal diamond pressure chambers, and piston-cylinder devices. These experimental devices usually use precious metals such as Pt-Rh and Au-Pd as sample cavity materials. However, these precious metals are not only expensive, but also difficult to make sample cavities of specific shapes according to experimental requirements during actual processing, which limits the flexibility and efficiency of the experiment to a certain extent.

[0028] More importantly, the large cavity press is the most widely used high-pressure device in many disciplines such as geology, chemistry, physics, and materials, which has greatly promoted the research progress under high-pressure conditions in various fields. However, up to now, the measurement of the conductivity of pure fluids in large cavity presses is still a blank.

[0029] This application aims to solve two major problems currently faced in the field of fluid conductivity measurement under high temperature and high pressure conditions: first, to solve the problems of high cost and difficult flexible processing of sample cavity materials in the measurement process; second, to change the current situation that large cavity presses are widely used in related fields but have not been used for pure fluid conductivity measurement. Based on this, this application uses polytetrafluoroethylene materials to prepare sample cavities, and provides a low-cost device for measuring the conductivity of fluids under high temperature and high pressure conditions on large cavity presses. In addition, the device also has the potential to measure water-rock interactions and wave velocity.

[0030] In another exemplary embodiment, the above-mentioned device for measuring fluid conductivity under high temperature and high pressure further includes a K-type thermocouple 5; the K-type thermocouple 5 passes through the pyrophyllite pressure transmission component 1, the heater 2 and the polytetrafluoroethylene sample cavity 6, and extends to the interior of the polytetrafluoroethylene sample cavity 6; the K-type thermocouple 5 is used to measure the temperature of the environment in which the liquid to be measured is located. Specifically, the K-type thermocouple 5 is installed close to the polytetrafluoroethylene sample cavity 6, 1 mm away from the liquid to be measured.

[0031] In another exemplary embodiment, the polytetrafluoroethylene sample chamber 6 in the above embodiment is a cylindrical cup-shaped structure, a first thermocouple hole is provided in the middle position of the side wall of the cylindrical cup-shaped structure, a first lower electrode hole is provided at the bottom of the cylindrical cup-shaped structure, the upper electrode sheet 4 covers the top opening of the cylindrical cup-shaped structure, a polytetrafluoroethylene gasket is also provided on the upper part of the upper electrode sheet 4, and the first upper electrode hole is provided on the polytetrafluoroethylene gasket. The polytetrafluoroethylene sample chamber 6 is made of polytetrafluoroethylene material with high chemical stability and low cost, and the measurement of fluid conductivity under high temperature and high pressure conditions is achieved at low cost. The contact between the polytetrafluoroethylene gasket and the polytetrafluoroethylene sample chamber 6 and the pyrophyllite pressure transmission component is compacted and sealed under pressure to prevent liquid leakage and external interference.

[0032] In another exemplary embodiment, the pyrophyllite pressure transmission component 1 in the above embodiment is used to transmit pressure to the polytetrafluoroethylene sample chamber 6 and other components inside it under the action of a multi-faceted top press, and the pressure value is accurately determined based on the pre-calibrated oil pressure. The pyrophyllite pressure transmission component 1 includes a pyrophyllite block with a cylindrical cavity, a first pyrophyllite plug and a second pyrophyllite plug, the first pyrophyllite plug and the second pyrophyllite plug are respectively arranged at both ends of the cylindrical cavity; the pyrophyllite block is provided with a second thermocouple hole, a second lower electrode hole and a second upper electrode hole, the second thermocouple hole is opposite to the first thermocouple hole, the second lower electrode hole is opposite to the first lower electrode hole, and the second upper electrode hole is opposite to the first upper electrode hole.

[0033] In another exemplary embodiment, the heater 2 in the above embodiment is a stainless steel frame heater, which is arranged in contact with the talc pressure transmission component 1 and is connected to the top hammer on the multi-sided top press, and cooperates with the circulating water on the multi-sided top press to adjust the temperature, and the temperature adjustment is controlled by the operating console.

[0034] The stainless steel heater is formed by staggered stacking of multiple stainless steel sheets. The stainless steel frame heater is provided with a third thermocouple hole, a third lower electrode hole and a third upper electrode hole. The third thermocouple hole is opposite to the first thermocouple hole, the third lower electrode hole is opposite to the first lower electrode hole, and the third upper electrode hole is opposite to the first upper electrode hole.

[0035] Among them, the first thermocouple hole, the second thermocouple hole and the third thermocouple hole are used to extend the K-type thermocouple 5 to the interior of the polytetrafluoroethylene sample cavity 6, the first lower electrode hole, the second lower electrode hole and the third lower electrode hole are used to lead out the measurement line 7 connected to the lower electrode sheet 3, and the first upper electrode hole, the second upper electrode hole and the third upper electrode hole are used to lead out the measurement line 7 connected to the upper electrode sheet 4.

[0036] The measuring line 7 connected to the lower electrode sheet 3 and the measuring line 7 connected to the upper electrode sheet 4 are connected to an impedance spectrometer; the impedance spectrometer is used to measure and display the impedance of the liquid to be measured. The upper electrode sheet 4 and the lower electrode sheet 3 are used to draw out the electrical signal in the liquid to be measured, and transmit the signal to the impedance spectrometer through the measuring line 7. Shielding measures are taken when wiring through the measuring line 7 to reduce signal interference.

[0037] In another exemplary embodiment, the liquid to be tested is a single or multi-component fluid at a temperature lower than the melting point of polytetrafluoroethylene. The above-mentioned temperature and pressure controls are all for the sample chamber, and the fluid conductivity measurement is only for the experimental liquid to be tested. The pressure is provided by the anvil on the multi-faceted top press, and the pressure on the sample chamber is controlled and determined by the oil pressure control panel on the operation panel. The temperature is achieved by the circulating water on the multi-faceted top press and the stainless steel heater in contact with the top hammer. The temperature monitoring is completed by the K-type thermocouple 5, and the specific temperature value is set through the temperature control panel on the operating table. The pressure range that the above-mentioned measuring device can withstand is 0-1GPa, and the temperature range that the above-mentioned measuring device can withstand is 0-598K.

[0038] Exemplarily, the impedance spectrometer can select a 1260 impedance spectrometer, which is used to apply an AC excitation signal to the sample within a suitable frequency and voltage range. The test solution generates an electrical signal response to the AC excitation signal applied by the 1260 impedance spectrometer. After the sample responds to the excitation signal, it is presented in the form of an impedance spectrum in the Zview software. The impedance spectrum of the fluid under two continuous heating and cooling cycles under the conditions of 0.5-1.0GPa and 323-598K is collected. By fitting and analyzing the impedance spectrum and based on the formula "conductivity = conductivity cell constant / resistance", the conductivity of the fluid under different temperature and pressure conditions is measured.

[0039] The conductivity of the liquid to be tested is calculated using the following formula:

[0040] σ=K cell / R;

[0041] Among them, σ is the conductivity of the liquid to be measured, R is the impedance of the liquid to be measured, K cell To correct the conductivity cell constant, the Redlich-Kwong equation is used to correct the conductivity cell constant K. 0 Correction is performed to obtain K 0 =L / S, L is the distance between the lower electrode sheet and the upper electrode sheet, and S is the bottom area of ​​the liquid to be tested in the polytetrafluoroethylene sample chamber.

[0042] In an exemplary embodiment, a method for measuring fluid conductivity under high temperature and high pressure is provided, such as Figure 2 As shown, the process includes the following steps 101 to 104.

[0043] Step 101, assemble the above-mentioned device for measuring fluid conductivity under high temperature and high pressure, and inject the liquid to be measured.

[0044] Step 102 , a device for measuring fluid conductivity under high temperature and high pressure is arranged in a multi-faceted top press, and the lower electrode sheet 3 and the upper electrode sheet 4 are connected to an impedance spectrometer through a measuring line 7 .

[0045] Step 103, using a multi-faceted press to apply pressure to the talc pressure transmission component 1, and using the circulating water inwardly of the multi-faceted press and the heater 2 to adjust the temperature of the liquid to be tested in the polytetrafluoroethylene sample chamber 6, and obtaining the impedance of the liquid to be tested at different pressures and temperatures through an impedance spectrometer.

[0046] Step 104, calculating the conductivity of the liquid to be tested at different pressures and temperatures according to the impedance of the liquid to be tested at different pressures and temperatures.

[0047] In another exemplary embodiment, the above step 101 specifically includes the following steps 201 to 207.

[0048] Step 201, attach the stainless steel heater to the inside of the pyrophyllite pressure transmission component so that its top end protrudes a little distance beyond the pyrophyllite pressure transmission component 1 to ensure good contact with the top hammer of the multi-faceted top press to provide heating.

[0049] Step 202, place the polytetrafluoroethylene sample chamber 6 in the middle of the pyrophyllite pressure transmission component 1 to ensure a quasi-hydrostatic pressure environment, and align the first thermocouple hole on the polytetrafluoroethylene sample chamber 6 with the second thermocouple hole on the pyrophyllite pressure transmission component 1 to facilitate the installation of the K-type thermocouple 5.

[0050] Step 203 , install the K-type thermocouple 5 , and place its probe near the middle of the polytetrafluoroethylene sample cavity 6 and 1 mm away from the liquid to be tested to ensure that the temperature can be accurately detected later. At the same time, the position of the polytetrafluoroethylene sample cavity 6 is fixed by installing the K-type thermocouple 5 .

[0051] Step 204: use a pipette to put the liquid to be tested into the polytetrafluoroethylene sample chamber 6 under a microscope.

[0052] Step 205, the upper electrode sheet 4 is placed so as to be in full contact with the liquid to be tested in the polytetrafluoroethylene sample chamber 6. Subsequently, a polytetrafluoroethylene gasket is covered on the upper electrode sheet 4, which can not only fix the position of the upper electrode sheet 4, but also play a good sealing role under high pressure to prevent liquid leakage and external interference.

[0053] Step 206, installing the measuring line 7 and the pyrophyllite plug.

[0054] Step 207, use a reasonable wiring method to connect the electrode sheet to the 1260 impedance spectrometer through the electrode wire, and take shielding measures.

[0055] In another exemplary embodiment, in the above step 102, the assembled measuring device is placed on a multi-faceted press, the measuring line 7 is connected to the 1260 impedance spectrometer, and the thermocouple line is connected to the operating table.

[0056] In another exemplary embodiment, the above step 103 specifically includes the following steps 301 and 302.

[0057] Step 301, the pressure is increased to a set value at a pressure increase rate of 0.5 GPa / hr. After the pressure reaches the set value, the pressure is increased to an initial temperature value at a rate of 30 K / min.

[0058] Step 302, the frequency and AC voltage of the excitation signal are set to 104-107 Hz and 500 mV respectively. The high frequency AC voltage is conducive to reducing the error caused by the polarization effect, and the AC impedance spectrum is collected.

[0059] In another exemplary embodiment, the above step 104 specifically includes, according to the AC impedance spectrum characteristics of the liquid to be tested, selecting a suitable equivalent circuit to fit the collected impedance spectrum to obtain the resistance value.

[0060] According to the formula K 0 =L / S, calculate the conductivity cell constant.

[0061] Among them, K 0 is the conductivity cell constant, in m -1 ; L is the distance between the lower electrode and the upper electrode, in m; S is the bottom area of ​​the liquid to be tested in the polytetrafluoroethylene sample chamber, in m 2 .

[0062] Since the increase of temperature and pressure will cause the polytetrafluoroethylene sample chamber 6 to deform, thus affecting the conductivity cell constant, the conductivity cell constant under high temperature and high pressure can be calculated by the density of the solution. The density of the NaCl solution is approximately equal to the density of water. Therefore, the density of the NaCl solution under different temperatures and pressures can be calculated according to the Redlich-Kwong equation, and the conductivity cell constant can be corrected according to the volume change corresponding to these density changes.

[0063] The calibration process is as follows:

[0064]

[0065] Where P is the gas pressure, R is the universal gas constant, T is the absolute temperature, V mis the molar volume of the gas, and a and b are constants related to the type of gas. The above formula can be used to calculate the volume of the solution under high temperature and high pressure. Assume that the force on the sample is equal in all directions under high temperature and high pressure, that is, the sample cavity is uniformly deformed in all directions. Taking a simple cube as an example, assuming that the side length before compression is "α" and the side length after compression is "β", the volume relationship before and after deformation is obtained:

[0066]

[0067] Where V 0 , L, S, K 0 They represent the volume of the sample cavity before deformation, the distance between the lower electrode sheet and the upper electrode sheet, the bottom area of ​​the liquid to be tested in the polytetrafluoroethylene sample cavity, and the conductivity cell constant. 1 , L', S', K cell They represent the volume of the sample cavity after deformation, the distance between the lower electrode and the upper electrode, the bottom area of ​​the liquid to be tested in the polytetrafluoroethylene sample cavity, and the corrected conductivity cell constant. cell / R calculates the fluid conductivity.

[0068] Where, σ is the conductivity of the liquid to be measured, in S / m, R is the impedance of the liquid to be measured, in Ω, K cell is the corrected conductivity cell constant, in m -1 .

[0069] In another exemplary embodiment, the embodiment of the present application can repeatedly measure the conductivity of the solution to be tested at each concentration and analyze its error.

[0070] In an exemplary embodiment, in order to illustrate the technical effect of the present application, a specific example is provided, which mainly uses the method of AC impedance spectroscopy based on a multi-faceted top press to measure the conductivity of a fluid under high temperature and high pressure conditions. Specifically, the conductivity of NaCl solutions with concentrations of 0.01 mol / L, 0.1 mol / L, and 1 mol / L at 25-325°C and 0.5-1.0 GPa is used for explanation.

[0071] Figure 3 The experimental flow chart given in the embodiment of the present application is presented, which includes the following steps: preparation before the experiment, assembly of samples, measurement of conductivity under high temperature and high pressure, and data processing.

[0072] The preparation work before the experiment includes two parts: solution configuration and consumables preparation.

[0073] The solution preparation includes the following steps:

[0074] According to the required salinity (0.058, 0.58, 5.63wt%), the corresponding mass of sodium chloride (purity of 99.99wt%) is accurately weighed with the help of a weighing balance. Subsequently, the weighed sodium chloride is placed in a clean beaker, ultrapure water (conductivity ≤ 0.01mS / m at room temperature) is added, and the mixture is placed on a magnetic stirrer and stirred thoroughly until the sodium chloride particles are completely dissolved. Next, the sodium chloride solution is transferred to a volumetric flask, and the beaker is washed with ultrapure water at the same time, and the washing liquid is transferred to a volumetric flask, and then diluted with ultrapure water to the required salinity. Finally, the volumetric flask is gently shaken to fully mix the solution, thereby preparing 0.01, 0.1, and 1mol / L NaCl solutions.

[0075] The steps for preparing consumables are as follows:

[0076] In the pyrophyllite block (size 32.5×32.5×32.5mm 3 ) was drilled with a 13 mm diameter hole at the center of the pyrophyllite block, and then the pyrophyllite block and the pyrophyllite plug (i.e., the first pyrophyllite plug and the second pyrophyllite plug, with a diameter of d = 12 mm) were placed in a muffle furnace at 800°C for 8 hours to prevent the pyrophyllite from dehydrating and interfering with the experiment. After the firing was completed, it was placed in a muffle furnace at 150°C for standby use.

[0077] Prepare gold electrode sheets; use laser punching technology to punch out discs with diameters of 6 mm and 4 mm respectively on a gold foil sheet with a thickness of 0.05 mm, wherein the 4 mm disc is used as the lower electrode sheet 3 and the 6 mm disc is used as the upper electrode sheet 4.

[0078] Processing polytetrafluoroethylene sample cavity 6 and polytetrafluoroethylene gasket; on a precision CNC lathe, the polytetrafluoroethylene plate is processed into a specific shape, that is, a cylindrical cup-shaped structure with an outer diameter of 12mm, a height of 10mm, an inner diameter of 4mm, and a height of 9mm, and a hole (first thermocouple hole) with a length of 4mm and a diameter of 2.5mm is drilled in the middle position thereof for inserting a thermocouple; at the same time, a polytetrafluoroethylene gasket with a diameter of 12mm and a thickness of 1mm is processed. A hole with a diameter of 0.02mm is drilled at the bottom of the polytetrafluoroethylene sample cavity 6 and in the middle of the polytetrafluoroethylene gasket, and a 0.02mm platinum wire is passed through the hole, and is respectively coiled into a circle at the bottom of the lower electrode sheet 3 and the upper part of the upper electrode sheet 4 to facilitate the extraction of the electrical signal of the liquid to be tested. Afterwards, the first electrode sheet with a diameter of 4mm is placed inside the polytetrafluoroethylene sample cavity 6, and is pushed to the bottom using a needle gauge wiped with alcohol. Before the test, the polytetrafluoroethylene sample cavity 6 and the polytetrafluoroethylene gasket were placed in a clean beaker, and a NaCl solution with the same concentration as the sample was poured in to completely immerse them, and then placed in an ultrasonic cleaner for cleaning.

[0079] In terms of the preparation of thermocouples, the multi-faceted top press usually uses K-type thermocouple 5 (NiCr-NiAl). The specific operation is to insert two thermocouple wires into a two-hole ceramic insulating tube (the insulating tube also protects the thermocouple from being squeezed off), and let the thermocouple wires extend about two millimeters, and then use pliers to twist the two extended thermocouple wires into a twist shape. The two wires at the other end of the thermocouple are connected to the transformer, and the thermocouple is inserted into a sodium chloride conductive solution. Generally, a voltage of 145V is selected. After power is turned on, the two thermocouple wires will melt and connect into a ball shape to form the K-type thermocouple 5.

[0080] The preparation of the stainless steel heater is as follows: cut the stainless steel sheet into a rectangle of about 42 mm in length and 34 mm in height, and group three stainless steel sheets into a group.

[0081] The stainless steel heater is installed by placing three layers of stainless steel sheets in a staggered manner in the cylindrical cavity of the pyrophyllite block, and using the first pyrophyllite plug and the second pyrophyllite plug to plug the two ends of the cylindrical cavity to prevent the stainless steel sheet from deforming. Then, holes are punched on a lathe, and the diameters of the holes are 2 mm, 2 mm, and 2.5 mm, respectively, for inserting two measuring wires 7 and a thermocouple.

[0082] At one end of the cylindrical cavity of the pyrophyllite block, the first pyrophyllite plug, the measuring line 7 connected to the lower electrode sheet 3, and the polytetrafluoroethylene gasket are placed in sequence. The first thermocouple hole on the polytetrafluoroethylene sample cavity 6 is aligned with the second thermocouple hole on the pyrophyllite block, and the sample is placed in the cylindrical cavity. The end where the pyrophyllite plug is not placed is illuminated by the light of a mobile phone, and the second thermocouple hole on the pyrophyllite block is observed. After ensuring that the first thermocouple on the polytetrafluoroethylene sample cavity 6 is aligned with the second thermocouple hole on the pyrophyllite block, the thermocouple is inserted.

[0083] Under a microscope, use a pipette to transfer the NaCl solution into the polytetrafluoroethylene sample chamber 6 until the liquid surface is flush with the edge of the polytetrafluoroethylene sample chamber 6. Then, cover the upper electrode sheet 4 with a diameter of 6 mm on the polytetrafluoroethylene sample chamber 6, and then put the polytetrafluoroethylene gasket, the measuring wire 7 and the second pyrophyllite plug in sequence.

[0084] Figure 4 The present invention is demonstrated to be applied in practice based on the above assembly, measuring the real part Z′ and imaginary part Z″ of the impedance spectrum of the sample at different frequencies, and the equivalent circuit used for fitting the resistance; wherein R 1 and C 1 Respectively represent the resistance and capacitance of the solution; R 2 , W o1 and CPE 2 They represent the charge transfer resistance, the open Warburg element, and the electrochemical double layer capacitance simulated by the constant phase element, respectively. Figure 5The conductivity of the NaCl solution and its correction result obtained by fitting the impedance spectrum obtained by the embodiment of the present application are presented. Figure 5 (a) is the conductivity of 0.01 mol / L NaCl solution during continuous heating and cooling; Figure 5 (b) is the conductivity of NaCl solution with different concentrations before and after correction at high temperature; at the same time, Figure 6 A comparison is given between the conductivity of the NaCl solution measured in the embodiment of the present application based on the assembly and the previous experimental data, and the good consistency fully demonstrates that the measuring device can accurately measure the conductivity of the fluid under high temperature and high pressure conditions on the multi-faceted top press.

[0085] The technical features of the above embodiments may be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0086] This article uses specific examples to illustrate the principles and implementation methods of this application. The description of the above embodiments is only used to help understand the method and core ideas of this application. At the same time, for those skilled in the art, according to the ideas of this application, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as limiting this application.

Claims

1. A device for measuring fluid conductivity under high temperature and high pressure, characterized in that: The device for measuring fluid conductivity under high temperature and high pressure comprises: a pyrophyllite pressure transmission component, a heater, a lower electrode sheet, an upper electrode sheet and a polytetrafluoroethylene sample chamber; The polytetrafluoroethylene sample chamber is arranged inside the pyrophyllite pressure transmission component, the heater is arranged between the polytetrafluoroethylene sample chamber and the pyrophyllite pressure transmission component, the lower electrode sheet is arranged at the bottom of the polytetrafluoroethylene sample chamber, and the upper electrode sheet covers the top of the polytetrafluoroethylene sample chamber; During measurement, a multi-faceted press applies pressure to the pyrophyllite pressure transmission component, and the circulating water inwardly of the multi-faceted press and the heater are used to adjust the temperature of the liquid to be measured in the polytetrafluoroethylene sample chamber; the lower electrode sheet and the upper electrode sheet are used to draw out the impedance signal of the liquid to be measured, and the impedance signal is used to calculate the conductivity of the liquid to be measured.

2. The device for measuring fluid conductivity under high temperature and high pressure according to claim 1, characterized in that: The device for measuring the conductivity of fluid under high temperature and high pressure also includes a K-type thermocouple; The K-type thermocouple passes through the pyrophyllite pressure transmission component, the heater and the polytetrafluoroethylene sample cavity, and extends to the interior of the polytetrafluoroethylene sample cavity; the K-type thermocouple is used to measure the temperature of the environment in which the liquid to be measured is located.

3. The device for measuring fluid conductivity under high temperature and high pressure according to claim 2, characterized in that: The polytetrafluoroethylene sample cavity is a cylindrical cup-shaped structure, a first thermocouple hole is opened in the middle position of the side wall of the cylindrical cup-shaped structure, a first lower electrode hole is opened at the bottom of the cylindrical cup-shaped structure, the upper electrode sheet covers the top opening of the cylindrical cup-shaped structure, a polytetrafluoroethylene gasket is also arranged on the upper part of the upper electrode sheet, and a first upper electrode hole is opened on the polytetrafluoroethylene gasket.

4. The device for measuring fluid conductivity under high temperature and high pressure according to claim 3, characterized in that: The pyrophyllite pressure transmission component comprises a pyrophyllite block with a cylindrical cavity, a first pyrophyllite plug and a second pyrophyllite plug, wherein the first pyrophyllite plug and the second pyrophyllite plug are respectively arranged at two ends of the cylindrical cavity; The pyrophyllite block is provided with a second thermocouple hole, a second lower electrode hole and a second upper electrode hole, the second thermocouple hole is opposite to the first thermocouple hole, the second lower electrode hole is opposite to the first lower electrode hole, and the second upper electrode hole is opposite to the first upper electrode hole.

5. The device for measuring fluid conductivity under high temperature and high pressure according to claim 4, characterized in that: The heater is a stainless steel frame heater, which is formed by a plurality of stainless steel sheets being staggered and stacked. The stainless steel frame heater is provided with a third thermocouple hole, a third lower electrode hole and a third upper electrode hole. The third thermocouple hole is opposite to the first thermocouple hole, the third lower electrode hole is opposite to the first lower electrode hole, and the third upper electrode hole is opposite to the first upper electrode hole.

6. The device for measuring fluid conductivity under high temperature and high pressure according to claim 5, characterized in that: The first thermocouple hole, the second thermocouple hole and the third thermocouple hole are used to extend the K-type thermocouple to the interior of the polytetrafluoroethylene sample cavity, the first lower electrode hole, the second lower electrode hole and the third lower electrode hole are used to lead out the measurement line connected to the lower electrode sheet, and the first upper electrode hole, the second upper electrode hole and the third upper electrode hole are used to lead out the measurement line connected to the upper electrode sheet.

7. The device for measuring fluid conductivity under high temperature and high pressure according to claim 6, characterized in that: The measuring line connected to the lower electrode sheet and the measuring line connected to the upper electrode sheet are connected to an impedance spectrometer; The impedance spectrometer is used to measure and display the impedance of the liquid to be tested; The conductivity of the liquid to be tested is calculated using the following formula: σ=K cell / R; Among them, σ is the conductivity of the liquid to be measured, R is the impedance of the liquid to be measured, K cell To correct the conductivity cell constant, the Redlich-Kwong equation is used to correct the conductivity cell constant K0 to obtain K0=L / S, L is the distance between the lower electrode sheet and the upper electrode sheet before the sample cavity is deformed, and S is the bottom area of ​​the liquid to be measured in the polytetrafluoroethylene sample cavity before the sample cavity is deformed.

8. A method for measuring fluid conductivity under high temperature and high pressure, characterized in that: The steps include: Assemble the device for measuring fluid conductivity under high temperature and high pressure as described in any one of claims 1 to 7, and inject the liquid to be measured; A device for measuring fluid conductivity under high temperature and high pressure is arranged in a multi-faceted top press, and a lower electrode sheet and an upper electrode sheet are connected to an impedance spectrometer through a measuring line; Using a multi-faceted top press to apply pressure to the pyrophyllite pressure transmission component, and using the circulating water inwardly of the multi-faceted top press and the heater to adjust the temperature of the liquid to be tested in the polytetrafluoroethylene sample chamber, and obtaining the impedance of the liquid to be tested at different pressures and temperatures through an impedance spectrometer; According to the impedance of the liquid to be tested at different pressures and temperatures, the conductivity of the liquid to be tested at different pressures and temperatures is calculated.

9. The method for measuring fluid conductivity under high temperature and high pressure according to claim 8, characterized in that: The assembly method of the device for measuring fluid conductivity under high temperature and high pressure is as follows: The heater is attached to the inside of the pyrophyllite pressure transmission component so that the top of the heater exceeds the preset distance of the pyrophyllite pressure transmission component; Place the polytetrafluoroethylene sample chamber in the middle of the pyrophyllite pressure transmission component; Place the lower electrode sheet at the bottom of the polytetrafluoroethylene sample chamber; Use a pipette to load the liquid to be tested into the polytetrafluoroethylene sample chamber; Place the upper electrode sheet so that it contacts the liquid to be tested in the polytetrafluoroethylene sample chamber; The upper electrode sheet is covered with a polytetrafluoroethylene gasket and a pyrophyllite plug.

10. The method for measuring fluid conductivity under high temperature and high pressure according to claim 9, characterized in that: After the polytetrafluoroethylene sample chamber is placed in the middle of the pyrophyllite pressure transmission assembly, the following further comprises: Adjust the polytetrafluoroethylene sample cavity so that the first thermocouple hole on the polytetrafluoroethylene sample cavity is aligned with the second thermocouple hole on the pyrophyllite pressure transmission component; Install a K-type thermocouple and place the probe of the K-type thermocouple in the middle of the polytetrafluoroethylene sample cavity and 1 mm away from the liquid to be tested.

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