Method for measuring viscosity of underground polymer and viscometer

Abstract

The invention relates to an underground polymer viscosity measuring method and a viscometer. The viscosity measuring method comprises the following steps: placing a motor, a magnetic coupling inner rotor and a first Hall sensor in a first space; the motor drives the magnetic coupling inner rotor to rotate; the first Hall sensor is used for receiving a phase signal of the magnetic coupling inner rotor; the magnetic coupling outer rotor and the second Hall sensor are arranged in the second space; the second Hall sensor is used for receiving a phase signal of the magnetic coupling outer rotor; the second space and the first space are not communicated and are only integrally connected; the magnetic coupling outer rotor rotates along with the magnetic coupling inner rotor; the second space is provided with a plurality of openings which are communicated with the inner cavity and serve as sampling ports of a to-be-detected polymer; after the polymer solution is injected into the second space, the rotation resistance in the fluid is changed, so that phase difference is generated between phase signals of the magnetic coupling inner rotor and the magnetic coupling outer rotor; coupling magnetic pole phase difference signals received by the first Hall sensor and the second Hall sensor are subjected to a standard liquid calibration experiment, and a viscosity and phase difference mapping mathematical model is established; and substituting the coupling magnetic pole phase difference signal into the viscosity and phase difference mapping mathematical model to determine the viscosity of the underground polymer solution. By means of the scheme, the viscosity of the polymer solution at the bottom of the well can be directly measured, and the production cost in the actual oil extraction process is effectively reduced.

Description

Technical Field

[0001] The present disclosure relates to the field of solution viscosity measurement, and in particular to a method and a device that can be directly placed in an oil field polymer injection well to measure downhole polymer viscosity. Background Art

[0002] With the annual decrease in oil reserves in high-water-content oil fields, ensuring stable and increased oil production is crucial to meet my country's crude oil consumption. After decades of development, the water content in the old oil fields is now getting higher and higher. Compound flooding technology has also experienced years of development, especially polymer flooding technology. Existing numerical simulation technology and field test technology have shown that most blocks in high-water-content oil fields are very conducive to polymer flooding oil production. In the development of polymer flooding oil production technology, in order to further master the dynamic and static data of polymer injection wells and improve polymer flooding technology, it is necessary to carry out research on downhole stratified viscosity testing technology for polymer injection wells. However, the existing measurement technology can only measure static viscosity on the ground, such as Chinese patent CN202211083956.3, a method for determining the polymer concentration in a solution after static adsorption using a capillary viscometer, and Chinese patent CN202220557370.5, a detachable polymer online viscometer, which cannot break through the limitation of leaving the ground and cannot directly measure the viscosity of the bottom hole polymer solution. Summary of the invention

[0003] In order to solve the technical problems existing in the background technology, the present disclosure proposes a downhole polymer viscosity measurement method and a viscometer. In this technical solution, a magnetically coupled inner rotor is used to drive an outer rotor. Under the condition of constant speed, torque balance is achieved. As the dynamic viscosity of the polymer solution changes, the rotational resistance in the fluid changes, resulting in a change in the coupling magnetic pole phase difference. A Hall sensor is used to receive the coupling magnetic pole phase difference, and a standard liquid calibration experiment is performed to establish a viscosity and phase difference mapping mathematical model. Then, through experiments, the relationship curve between the concentration and viscosity of the polymer solution at different temperatures is obtained, and finally the viscosity model is corrected. The viscometer obtained by applying this solution can be directly placed in the polymer injection well of the oil field, which can directly measure the viscosity of the polymer solution in the high-pressure environment of the polymer injection well, and save the mechanical rotating seal, avoiding the risk of polymer leakage.

[0004] The present disclosure first provides a method for measuring downhole polymer viscosity, comprising:

[0005] The motor, the inner magnetic pole, the inner rotor and the first Hall sensor are placed in the first space, the inner magnetic pole and the inner rotor constitute a magnetically coupled inner rotor; the first Hall sensor is fixed at the middle position of the corresponding inner magnetic pole; the motor drives the magnetically coupled inner rotor to rotate; the first Hall sensor is used to receive a phase signal of the magnetically coupled inner rotor;

[0006] The outer magnetic pole, the outer rotor and the second Hall sensor are placed in the second space, the outer magnetic pole and the outer rotor constitute a magnetically coupled outer rotor; the second Hall sensor is fixed at the middle position of the corresponding outer magnetic pole; the second Hall sensor is used to receive the phase signal of the magnetically coupled outer rotor;

[0007] The second space is not connected to the first space but is connected as an integral whole; the magnetic coupling outer rotor can be coupled to the magnetic coupling inner rotor and rotate with the magnetic coupling inner rotor;

[0008] The second space is provided with a plurality of openings leading to the inner cavity, serving as sampling ports for the polymer to be tested;

[0009] The outer rotor is driven by the magnetically coupled inner rotor to achieve torque balance under the condition of constant speed;

[0010] After the polymer solution is injected into the second space, the rotational resistance in the fluid changes, resulting in a phase difference between the phase signals of the magnetically coupled inner and outer rotors;

[0011] The coupled magnetic pole phase difference signals received by the first and second Hall sensors are subjected to a standard liquid calibration experiment to establish a viscosity and phase difference mapping mathematical model;

[0012] The viscosity of the downhole polymer solution is determined by substituting the coupled magnetic pole phase difference signals received by the first and second Hall sensors into the viscosity and phase difference mapping mathematical model.

[0013] Furthermore, the standard liquid calibration experiment is used to establish a viscosity and phase difference mapping mathematical model, which is carried out in the following way:

[0014] The speed of the motor-driven magnetically coupled inner rotor is set to be controlled at n (r / min), the first Hall sensor detects the N-pole position of the magnetic pole of the magnetically coupled inner rotor, and the second Hall sensor detects the N-pole position of the magnetic pole of the magnetically coupled outer rotor. When the inner and outer rotors are in phase, the phase difference detected by the Hall sensor is zero;

[0015] The polymer solution enters the second space, and after the torque is balanced, the phase difference between the outer magnetic pole and the inner magnetic pole changes. The phase difference between the inner and outer magnetic poles is converted into a time signal t1 (microseconds), and a corresponding mathematical relationship is established, that is, by calibrating the standard liquid, the physical quantity of dynamic viscosity, the measurement range (0-100, mPa·s) is converted into a phase difference, and further converted into a time signal, the range (0-T, s), and a polynomial curve fitting of n is performed using m pairs of data points;

[0016] The polynomial curve fitting adopts the least square curve fitting viscosity model coefficient, that is,

[0017] m for a given point (x i ,yi )(i=1,2,…,m), (x is time, y is viscosity), find an approximate curve, requiring the function With data y i ,error The sum of squares is the minimum as shown in formula 1;

[0018]

[0019] Furthermore, N standard solutions are selected, with time as the horizontal axis and viscosity as the vertical axis, and N pairs of data are fitted to obtain the n-order polynomial fitting formula of time-converted viscosity:

[0020]

[0021] Among them, t is the time detected by the Hall sensor; A0 is the intercept when time is zero, which is used to adjust the zero-point migration of viscosity; A1…A n is the model weight coefficient;

[0022] Using the matrix solution, there are m samples, each sample has n-dimensional features, and all sample points are substituted into the model:

[0023]

[0024] Let t 0 =1, the above equation is expressed in matrix as:

[0025]

[0026] in, is an m×1 vector representing the theoretical value of the model, A is an n×1 vector, X is an m×n dimensional matrix, m represents the number of samples, and n represents the number of features of the samples, so the target loss function is expressed as a matrix:

[0027]

[0028] Where Y is the output vector of samples, with dimension m×1

[0029] Substitute all N groups of data into the n-order polynomial fitting formula and fit it using the least squares formula; The value of converges to 10 -6 Then the value of n is obtained as the output result.

[0030] Furthermore, the viscosity and phase difference mapping mathematical model is corrected using the relationship curve between the concentration and viscosity of the polymer solution at different temperatures.

[0031] Furthermore, the relationship curve between the concentration and viscosity of the polymer solution at different temperatures is obtained according to the following path:

[0032] (1) using polyacrylamide to prepare a mother solution, using a stirrer to fully stir under the preparation condition that the ratio of water to polyacrylamide is 1000:1, to prepare polymer solutions of different concentrations, and controlling the concentration range to be between 50-1500 mg / L;

[0033] (2) Use a thermostat to control the temperature between 20-50°C and keep it constant. Choose a suitable thermostatic water bath to ensure that the temperature control accuracy reaches ±0.1°C.

[0034] (3) Ensure that the maximum flow rate does not exceed 1.5 m / s, and use a viscometer to measure the viscosity of polymer solutions of different concentrations under constant temperature conditions;

[0035] (4) Record the temperature and viscosity of each measurement;

[0036] (5) changing the concentration and temperature of the polymer, repeating the above steps, and obtaining multiple sets of data on the relationship between the concentration and viscosity of the polymer solution at different temperatures;

[0037] (6) Process the collected data and plot the coordinate points of the viscosity relationship of polymer solutions at different temperatures at the same concentration.

[0038] Furthermore, when the relationship curve between the concentration and viscosity of the polymer solution at different temperatures is obtained, a secondary calibration correction is performed for the viscosity corresponding to different temperatures at the same concentration;

[0039] For the temperature correction coefficient, we first experimentally verified that the temperature range was between 20°C and 50°C. We recorded data every time the temperature increased by 1°C from 20°C to 50°C, and used Origin software to fit all the data. After fitting, we obtained the temperature formula:

[0040]

[0041] in It is the viscosity at 20°C. When the temperature is higher than 20°C, the viscosity is corrected by adding the coefficient B multiplied by the temperature (z-20). When the temperature increases, the viscosity of the polymer decreases, and the coefficient of general temperature is a negative number.

[0042] Another aspect of the present disclosure provides a downhole polymer viscometer for use in any of the aforementioned measurement methods, comprising an upper cylinder, a lower cylinder, and an intermediate separator, wherein:

[0043] The upper cylinder, the lower cylinder and the middle separator are connected as one body; the middle separator is used to separate the upper cylinder and the lower cylinder so that the two are not connected;

[0044] The upper cylinder is built with a control unit, a data communication module, a motor, and a magnetically coupled inner rotor;

[0045] The middle partition is provided with a first Hall sensor and a second Hall sensor; the first Hall sensor is used to detect the square wave state of the high and low levels of the magnetically coupled inner rotor, and to return the phase value of the magnetically coupled inner rotor to the control unit; the second Hall sensor is used to detect the square wave state of the high and low levels of the magnetically coupled outer rotor and to return the phase value of the magnetically coupled outer rotor to the control unit;

[0046] The lower cylinder has a magnetically coupled outer rotor built in, and a plurality of openings leading to the inner cavity are opened on the cylinder wall to serve as sampling ports for the polymer to be tested;

[0047] The magnetic coupling inner rotor is coaxially connected to the motor; the magnetic coupling outer rotor can rotate with the magnetic coupling inner rotor under the action of magnetic coupling;

[0048] The upper and lower end surfaces of the intermediate separator are respectively provided with rotor coupling magnetic pole fixing grooves with the same central axis, which are respectively used to place the magnetic coupling inner rotor and the magnetic coupling outer rotor; the intermediate separator is made of a material with good magnetic conductivity;

[0049] The control unit has a built-in program that can substitute the received phase difference between the magnetically coupled inner and outer rotors into the viscosity and phase difference mapping mathematical model to calculate and obtain a viscosity value.

[0050] Furthermore, the data communication module communicates with ground data processing equipment through Manchester code, and transmits the viscosity data measured in real time to the ground for display and recording.

[0051] Furthermore, a temperature sensor and a pressure sensor are arranged in the upper cylinder, and the obtained temperature signal and pressure signal are sent to the control unit; under the control of a built-in program, the control unit corrects the viscosity and phase difference mapping mathematical model according to the temperature parameter.

[0052] At least one of the above technical solutions adopted in one or more embodiments of this specification can achieve the following beneficial effects:

[0053] First, the technical solution provided by the present disclosure replaces the mechanical seal bearing of the traditional rotational viscometer with a magnetic coupling drive, and drives the magnetic poles of the outer rotor with the magnetic poles of the inner rotor, so that the spaces where the inner rotor and the outer rotor are located are independent of each other. The space where the outer rotor is located can be used as a sampler for the downhole solution, avoiding direct contact between the downhole solution and the measuring unit. The viscometer can be directly placed in the polymer injection well of the oil field, which can directly measure the viscosity of the polymer solution in the high-pressure environment of the polymer injection well, and eliminate the mechanical rotating seal, avoiding the risk of polymer leakage. The combination of the sensor unit, the STM32 control unit, the magnetically coupled inner and outer rotors, the Hall sensor and the data communication module provides a high-precision and real-time polymer measurement solution.

[0054] Secondly, during the optimization implementation, the sensor unit is configured on the downhole rotational viscometer to sense the motion characteristics of the polymer; the STM32 control unit, with integrated processor and memory, is used to receive, process and store the data acquired by the sensor unit; the data communication module communicates with the ground data processing equipment using Manchester code to achieve real-time data transmission and remote monitoring.

[0055] Again, the STM32 control unit runs the preset viscosity calculation algorithm, and calculates the phase difference of the polymer in real time based on the phase difference data measured by the magnetically coupled Hall sensor. The data communication module communicates with the ground data processing equipment through Manchester code, and transmits the real-time measured viscosity data to the ground for display and recording. The communication between the downhole rotary viscometer and the host computer adopts Manchester coding communication. Manchester coding is a linear code that represents data bits by changes in signal levels. Because it relies on level changes rather than absolute levels, Manchester coding has strong resistance to noise and interference, and is very suitable for communication needs in complex underground environments.

[0056] In addition, the single-core steel pipe cable can be used to power the downhole rotational viscometer and realize signal coding communication transmission. Furthermore, in specific implementation, the delay time parameters can be adaptively adjusted according to the change in the cable downhole depth and the change in the cable capacitance effect. Different cables correspond to different capacitance delay parameters. When the length of the cable changes after it goes downhole, the communication is disturbed. At this time, the cable capacitance effect changes, and the communication delay time parameters are adjusted accordingly. For this reason, the host computer makes adaptive adjustments, and manual parameter settings are no longer required.

[0057] In addition, the present disclosure proposes a two-stage modeling method. The first stage is to calibrate the standard liquid to obtain a basic model. The second stage is to obtain the relationship curve between the concentration and viscosity of the polymer solution at different temperatures through experiments. Finally, the viscosity model is corrected, thereby improving the measurement accuracy of the viscosity of the downhole polymer fluid at a certain flow rate.

[0058] It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the present disclosure.

[0059] Further features and aspects of the present disclosure will become apparent from the following detailed description of exemplary embodiments with reference to the attached drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0060] The drawings herein are incorporated into the specification and constitute a part of the specification. These drawings illustrate embodiments consistent with the present disclosure and are used to illustrate the technical solutions of the present disclosure together with the specification.

[0061] Figure 1It is a schematic diagram of the component units of the downhole polymer viscometer described in the present disclosure.

[0062] Figure 2 The overall system structure diagram of the downhole polymer viscometer disclosed in the present invention.

[0063] Figure 3 The present invention discloses a schematic diagram of the mechanical structure of the downhole polymer viscometer probe.

[0064] Figure 4 The figure is a curve diagram showing the relationship between the concentration and viscosity of a polymer solution obtained in a specific implementation.

[0065] In the figure: 1-temperature sensor; 2-pressure sensor; 3-sealing groove; 4-pressure sensor sampling hole; 5-motor; 6-inner rotor; 7-inner coupling magnetic pole; 8-first Hall sensor; 9-second Hall sensor; 10-outer coupling magnetic pole; 11-sampling hole; 12-outer rotor; 13-sampler. DETAILED DESCRIPTION

[0066] Various exemplary embodiments, features and aspects of the present disclosure will be described in detail below with reference to the accompanying drawings. The same reference numerals in the accompanying drawings represent elements with the same or similar functions. Although various aspects of the embodiments are shown in the accompanying drawings, the drawings are not necessarily drawn to scale unless otherwise specified.

[0067] In addition, in order to better illustrate the present disclosure, numerous specific details are given in the following specific embodiments. It should be understood by those skilled in the art that the present disclosure can also be implemented without certain specific details. In some examples, methods and means well known to those skilled in the art are not described in detail in order to highlight the main purpose of the present disclosure.

[0068] First, the present disclosure provides a method for measuring downhole polymer viscosity, comprising:

[0069] The motor, the magnetically coupled inner rotor and the first Hall sensor are placed in the first space; the motor drives the magnetically coupled inner rotor to rotate; the first Hall sensor is used to receive the phase signal of the magnetically coupled inner rotor;

[0070] The magnetically coupled outer rotor and the second Hall sensor are placed in the second space; the second Hall sensor is used to receive the phase signal of the magnetically coupled outer rotor;

[0071] The second space is not connected to the first space but is connected as an integral whole; the magnetic coupling outer rotor can be coupled to the magnetic coupling inner rotor and rotate with the magnetic coupling inner rotor;

[0072] The second space is provided with a plurality of openings leading to the inner cavity, serving as sampling ports for the polymer to be tested;

[0073] The outer rotor is driven by the magnetically coupled inner rotor to achieve torque balance under the condition of constant speed;

[0074] After the polymer solution is injected into the second space, the rotational resistance in the fluid changes, resulting in a phase difference between the phase signals of the magnetically coupled inner and outer rotors;

[0075] The coupled magnetic pole phase difference signals received by the first and second Hall sensors are subjected to a standard liquid calibration experiment to establish a viscosity and phase difference mapping mathematical model;

[0076] The viscosity of the downhole polymer solution is determined by substituting the coupled magnetic pole phase difference signals received by the first and second Hall sensors into the viscosity and phase difference mapping mathematical model.

[0077] The conception principle of this method is as follows:

[0078] Magnetic coupling enables the inner rotor of the motor to drive the outer rotor and transfer kinetic energy. The outer rotor contacts the polymer solution and rotates at a constant speed. The phase difference signal is fed back through the Hall sensor and converted into a time difference for viscosity calibration.

[0079] When the voltage is stable, the inner rotor drives the outer rotor to rotate at the same speed under the action of magnetic coupling, transferring kinetic energy. Due to the liquid friction resistance generated when the outer rotor contacts the polymer solution,

[0080]

[0081] Where M is the shear force on the rotor; h is the height of the rotor; ω is the angular velocity; and R is the radius of the rotor.

[0082] At this time, the motor of the outer rotor and the motor of the inner rotor produce a phase difference θ. Two Hall sensors are installed at the connection between the inner rotor and the outer rotor. One detects the square wave state of the high and low levels of the inner rotor, and the other detects the square wave state of the high and low levels of the outer rotor. The time difference reflected by the two square waves can be indirectly converted into a viscosity formula.

[0083] The calculation formula is:

[0084] θ=ωt

[0085] In the formula, θ is the phase difference; ω is the angular velocity; t is the time

[0086] in:

[0087]

[0088] Where, n--motor speed

[0089] Since the voltage is stable, the speed setting values ​​of the inner rotor and outer rotor motors are the same and unchanged, so the angular velocity ω is fixed. Therefore, when the phase difference and angular velocity are known, the time t can be recorded. The time t is converted into viscosity through a function, and the viscosity value can be read.

[0090] Using this method, the motor, magnetically coupled rotor, magnetic poles and Hall sensor can measure viscosity in the high-pressure environment of polymer injection wells, eliminating the need for mechanical rotating seals and avoiding the risk of leakage failure. The magnetically coupled inner rotor drives the outer rotor to achieve torque balance under constant speed. As the dynamic viscosity of the polymer solution changes, the rotational resistance in the fluid changes, resulting in a change in the phase difference of the coupled magnetic poles. The Hall sensor is used to receive the phase difference of the coupled magnetic poles, and a mathematical model for mapping viscosity and phase difference is established through standard liquid calibration experiments. The relationship curve between the concentration and viscosity of the polymer solution at different temperatures is then obtained through experiments. Finally, the viscosity model is corrected to improve the accuracy of measuring the viscosity of downhole polymer fluids at a certain flow rate.

[0091] The above standard liquid calibration experiment is used to establish a mathematical model for viscosity and phase difference mapping, which is carried out as follows:

[0092] The speed of the inner rotor driven by the motor is controlled at n (r / min). Hall sensor 1 detects the N-pole position of the inner rotor magnetic pole, and Hall sensor 2 detects the N-pole position of the outer rotor magnetic pole. When the inner and outer rotors are in phase, the phase difference detected by Hall sensors 1 and 2 is zero. When the polymer solution enters the sampler, the outer rotor is subjected to the viscosity resistance of the polymer. After the torque is balanced, the phase difference between the outer and inner magnetic poles changes. The phase difference between the inner and outer magnetic poles is converted into a time signal t1 (microseconds) to establish a corresponding mathematical relationship. Therefore, by calibrating the standard liquid, the physical quantity of dynamic viscosity, measuring range (0-100, mPa·s) is converted into a phase difference, and further converted into a time signal, range (0-T, s). Then, m pairs of data points can be used to fit an n-order polynomial curve.

[0093] The viscosity model coefficient is obtained by the least squares curve fitting method. Curve fitting is a commonly used smoothing method. Its outstanding feature is that it can reduce the prior information of the model or measurement and reduce the sensitivity of the initial value. However, for strong maneuvering targets, the fitting accuracy and effect are not ideal when the order is low. When the order is large, the fitting accuracy and effect are ideal, but it is easy to make the solution of the normal equation complicated, the robustness of the fitting curve deteriorate, and the random fluctuation has a greater impact.

[0094] Curve fitting is the method of fitting m to a given point (x i ,y i )(i=1,2,…,m), (x is time, y is viscosity), find an approximate curve, that is, according to a certain function type Finding the best function To fit the given data (t i ,y i ). The least squares curve fit requires the function With data y i ,error The sum of squares (see the following formula) is the smallest.

[0095]

[0096] We selected 5 standard liquids. The first standard liquid was numbered GBW(E)130201, with a dynamic viscosity of 4.087 mPa·s and a viscometer calibration time of 443μs. The second standard liquid was numbered GBW(E)130202, with a dynamic viscosity of 8.459 mPa·s and a viscometer calibration time of 497μs. The third standard liquid was numbered GBW(E)130203, with a dynamic viscosity of 16.83 mPa·s and a viscometer calibration time of 573μs. The fourth standard liquid was numbered GBW(E)130204, with a dynamic viscosity of 43.17 mPa·s and a viscometer calibration time of 757μs. The fifth standard liquid was numbered GBW(E)130205, with a dynamic viscosity of 105.82 mPa·s and a viscometer calibration time of 967μs. Using time as the horizontal axis and viscosity as the vertical axis, these five pairs of data are fitted to obtain the n-order polynomial fitting formula of time-converted viscosity:

[0097]

[0098] Among them, t is the time detected by the Hall sensor;

[0099] Among them, A0 is the intercept at time zero, which is used to adjust the zero-point migration of viscosity;

[0100] Among them, A1…A n The model weight coefficient calculated by the algorithm;

[0101] Using the matrix solution, assume that there are m samples, each with n-dimensional features, and substitute all sample points into the model:

[0102]

[0103] For the convenience of matrix representation, let t 0 =1, the above equation can be expressed in matrix as:

[0104]

[0105] in, is an m×1 vector representing the theoretical value of the model, A is an n×1 vector, X is an m×n dimensional matrix, m represents the number of samples, and n represents the number of features of the samples, so the target loss function is expressed as a matrix:

[0106]

[0107] Where Y is the output vector of samples, with dimension m×1

[0108] Substitute all five sets of data into the fitting formula:

[0109] 4.087=A0+A1*443 1 +A2*443 2 +A3*443 3 +…+A n *443 n

[0110] 8.459=A0+A1*497 1 +A2*497 2 +A3*497 3 +…+A n *497 n

[0111] 16.83=A0+A1*573 1 +A2*573 2 +A3*573 3 +…+A n *573 n

[0112] 43.17=A0+A1*757 1 +A2*757 2 +A3*757 3 +…+A n *757 n

[0113] 105.82=A0+A1*967 1 +A2*967 2 +A3*967 3 +…+A n *967 n

[0114] After fitting with the least squares formula, we get Figure 4 Results shown.

[0115] Will The value of converges to 10 -6 The result is:

[0116]

[0117] The coefficient above the cube is 0, so we conclude that n=3.

[0118] Furthermore, the viscosity and phase difference mapping mathematical model is corrected using the relationship curve between the concentration and viscosity of the polymer solution at different temperatures.

[0119] The specific process of obtaining the relationship curve between polymer solution concentration and viscosity at different temperatures is as follows:

[0120] (1) Prepare a mother solution of polyacrylamide, stir the mixture with a stirrer at a ratio of 1000:1 between water and polyacrylamide, prepare polymer solutions of different concentrations, and control the concentration range to be between 50 and 1500 mg / L; (2) Use a thermostat to control the temperature range to be between 20 and 50°C and keep it constant, select a suitable constant temperature water bath device, and ensure that the temperature control accuracy reaches ±0.1°C; (3) Ensure that the maximum flow rate does not exceed 1.5 m / s, and measure the viscosity of polymer solutions of different concentrations using a viscometer under constant temperature conditions; (5) Use a data acquisition system to record the temperature and viscosity of each measurement; (6) Repeat the above steps to conduct experiments by changing the concentration and temperature of the polymer to obtain multiple sets of data on the relationship between the concentration and viscosity of the polymer solution at different temperatures.

[0121] Data analysis: Process the collected data, plot the coordinate points of the viscosity relationship of the polymer solution at different temperatures at the same concentration, and make secondary calibration corrections for the viscosity at different temperatures at the same concentration.

[0122] For the temperature correction coefficient, we first experimentally verified that the temperature range was between 20℃ and 50℃. We recorded data every time the temperature increased by 1℃ from 20℃ to 50℃, and used Origin software to fit all the data. The fitting function is that when measuring the polymer at a certain temperature in the future, the system will directly give the specific viscosity through the algorithm. After fitting, we get the temperature formula:

[0123]

[0124] T(z)=-40.924+10.523t-0.175t 2 +0.00098t 3 -0.49*(z-20)

[0125] in It is the viscosity at 20°C. When the temperature is higher than 20°C, the viscosity is corrected by adding the coefficient B multiplied by the temperature (z-20). When the temperature increases, the viscosity of the polymer decreases, so the coefficient of general temperature is a negative number.

[0126] The following table compares the data obtained using this method with the data obtained using a Brookfield viscometer.

[0127]

[0128] This data is the result of ground measurement by two different viscometers. When the concentration value is not high, the Brookfield viscometer can maintain stable data measurement. When the concentration increases, the Brookfield measurement value is not stable. At this time, the stable measurement of the downhole rotary viscometer shows its advantages. The Brookfield viscometer is only suitable for ground measurement and is not sufficient to withstand pressure to enter the well.

[0129] In order to implement the above method, a downhole polymer viscometer is constructed, including an upper cylinder, a lower cylinder and an intermediate separator. The schematic diagram of its component units is shown in FIG. Figure 1 As shown in the figure, it includes: lower-level single-chip microcomputer, power management module, magnetic coupling rotor, Hall sensor, temperature and pressure sensor, and sampler. The power management module adopts an efficient and stable power management system to ensure continuous power supply under high temperature and high pressure environment. The lower-level single-chip microcomputer is responsible for data acquisition, processing, transmission and storage. The temperature and pressure sensors monitor the downhole environment in real time and provide accurate downhole temperature data.

[0130] The upper cylinder, the lower cylinder and the middle partition are connected as one body; the middle partition is used to separate the upper cylinder and the lower cylinder so that the two are not connected.

[0131] The upper cylinder is provided with a control unit, a data communication module, a motor 5, a magnetically coupled inner rotor consisting of an inner rotor 6 and an inner coupling magnetic pole 7, and a first Hall sensor 8;

[0132] The intermediate partition body is provided with a first Hall sensor 8 and a second Hall sensor 9. The first Hall sensor is used to detect the square wave state of the high and low levels of the magnetically coupled inner rotor, and to feed back the phase value of the magnetically coupled inner rotor to the control unit; the second Hall sensor is used to detect the square wave state of the high and low levels of the magnetically coupled outer rotor, and to feed back the phase value of the magnetically coupled outer rotor to the control unit.

[0133] The lower cylinder has a magnetic coupling outer rotor composed of an outer rotor 12 and an outer coupling magnetic pole 10. The lower cylinder is a sampler 13, and after being lowered into the well, the polymer solution flows into it.

[0134] The magnetic coupling inner rotor is coaxially connected to the motor; the magnetic coupling outer rotor can rotate with the magnetic coupling inner rotor under the action of magnetic coupling.

[0135] The upper and lower end surfaces of the intermediate separator are respectively provided with rotor coupling magnetic pole fixing grooves with the same central axis, which are respectively used to place the magnetic coupling inner rotor and the magnetic coupling outer rotor; the intermediate separator is made of a material with good magnetic conductivity.

[0136] The control unit has a built-in program that can substitute the received phase difference between the magnetically coupled inner and outer rotors into the viscosity and phase difference mapping mathematical model to calculate and obtain a viscosity value.

[0137] The data communication module communicates with the ground data processing equipment through a single-core steel pipe cable, and communicates with the ground data processing equipment through the Manchester code method, and transmits the real-time measured viscosity data to the ground for display and recording. Through the built-in program, according to the change of the cable downhole depth and the change of the cable capacitance effect, the delay time parameters can be adaptively adjusted to adaptively adjust the long-distance single-core steel pipe cable communication parameters. The ground host computer maintains data connection with the downhole viscometer through Manchester coding communication technology to ensure efficient and reliable data transmission. The host computer is equipped with data processing and display functions, which can receive and analyze the data sent by the downhole viscometer in real time, and provide operators with detailed fluid viscosity, temperature and pressure information. These data are clearly displayed through the human-computer interface, which is convenient for immediate monitoring and decision-making.

[0138] Manchester coding is a linear code that represents data bits by changes in signal levels. Since it relies on level changes rather than absolute levels, Manchester coding is highly resistant to noise and interference and is very suitable for communication needs in complex underground environments.

[0139] The steps for upward communication of underground signals are as follows:

[0140] (1) The STM32-based integrated microcontroller built into the rotational viscometer is responsible for collecting the fluid pressure and viscosity data fed back by the sensor and motor parts and performing preliminary processing.

[0141] (2) Manchester encoding is performed on the collected data to convert it into a signal format suitable for transmission.

[0142] (3) The encoded data is sent to the surface via downhole communication cables.

[0143] The steps for the ground part to accept and display viscosity data are as follows:

[0144] (1) Reception: Receive the Manchester coded signal transmitted from underground.

[0145] (2) Decoding: Decode the Manchester encoded signal into the original viscosity data.

[0146] (3) Processing and display: The decoded data is transmitted to the host computer for further analysis and processing, and the viscosity of the downhole fluid is finally displayed on the monitoring interface.

[0147] The upper cylinder is provided with a temperature sensor 1 and a pressure sensor 2, and the obtained temperature signal and pressure signal are sent to the control unit; the control unit corrects the viscosity and phase difference mapping mathematical model according to the temperature parameter under the control of the built-in program. The temperature sensor 1 and the pressure sensor 2 are configured on the downhole rotation viscometer, and the pressure parameters of the polymer solution are obtained through the pressure sensor sampling hole 4. The temperature sensor is used to collect the polymer temperature parameters of the downhole environment and dynamically correct the viscosity measurement. The control unit adopts an STM32 control unit with an integrated processor and memory, which is used to receive, process and store the data obtained by the sensor unit.

[0148] Preferably, an O-ring is placed in the sealing groove 3 to achieve high pressure resistance and enable direct measurement into the target layer underground.

[0149] The above is only a preferred specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed by the present invention should be included in the protection scope of the present invention. It can be understood by a person of ordinary skill in the art that various modifications can be made in form and details without departing from the spirit and scope of the present invention defined in the appended claims.

Claims

1. A method for measuring downhole polymer viscosity, comprising: The motor, the inner magnetic pole, the inner rotor and the first Hall sensor are placed in the first space, wherein the inner magnetic pole and the inner rotor form a magnetically coupled inner rotor; The first Hall sensor is fixed at the middle position of the corresponding inner magnetic pole; the motor drives the magnetically coupled inner rotor to rotate; the first Hall sensor is used to receive the phase signal of the magnetically coupled inner rotor; The outer magnetic pole, the outer rotor and the second Hall sensor are placed in the second space, the outer magnetic pole and the outer rotor constitute a magnetically coupled outer rotor; the second Hall sensor is fixed at the middle position of the corresponding outer magnetic pole; the second Hall sensor is used to receive the phase signal of the magnetically coupled outer rotor; The second space is not connected to the first space but is connected as an integral whole; The magnetic coupling outer rotor can be coupled to the magnetic coupling inner rotor and rotate along with the magnetic coupling inner rotor; The second space is provided with a plurality of openings leading to the inner cavity, serving as sampling ports for the polymer to be tested; The outer rotor is driven by the magnetically coupled inner rotor to achieve torque balance under the condition of constant speed; After the polymer solution is injected into the second space, the rotational resistance in the fluid changes, resulting in a phase difference between the phase signals of the magnetically coupled inner and outer rotors; The coupled magnetic pole phase difference signals received by the first and second Hall sensors are subjected to a standard liquid calibration experiment to establish a viscosity and phase difference mapping mathematical model; The viscosity of the downhole polymer solution is determined by substituting the coupled magnetic pole phase difference signals received by the first and second Hall sensors into the viscosity and phase difference mapping mathematical model.

2. A method for measuring downhole polymer viscosity according to claim 1, characterized in that: The standard liquid calibration experiment is used to establish a viscosity and phase difference mapping mathematical model, which is carried out according to the following path: The speed of the motor-driven magnetically coupled inner rotor is set to be controlled at n (r / min), the first Hall sensor detects the N-pole position of the magnetic pole of the magnetically coupled inner rotor, and the second Hall sensor detects the N-pole position of the magnetic pole of the magnetically coupled outer rotor. When the inner and outer rotors are in phase, the phase difference detected by the Hall sensor is zero; The polymer solution enters the second space, and after the torque is balanced, the phase difference between the outer magnetic pole and the inner magnetic pole changes. The phase difference between the inner and outer magnetic poles is converted into a time signal t1 (microseconds), and a corresponding mathematical relationship is established, that is, by calibrating the standard liquid, the physical quantity of dynamic viscosity, the measurement range (0-100, mPa·s) is converted into a phase difference, and further converted into a time signal, the range (0-T, s), and a polynomial curve fitting of n is performed using m pairs of data points; The polynomial curve fitting adopts the least square curve fitting viscosity model coefficient, that is, m for a given point (x i ,y i )(i=1,2,…,m), (x is time, y is viscosity), find an approximate curve, requiring the function With data y i ,error The sum of squares is the minimum as shown in formula 1; 3. A method for measuring downhole polymer viscosity according to claim 2, characterized in that: Select N standard solutions, use time as the horizontal axis and viscosity as the vertical axis, and fit N pairs of data to obtain the n-order polynomial fitting formula of time-converted viscosity: Among them, t is the time detected by the Hall sensor; A0 is the intercept when time is zero, which is used to adjust the zero-point migration of viscosity; A1…A n is the model weight coefficient; Using the matrix solution, there are m samples, each sample has n-dimensional features, and all sample points are substituted into the model: Let t 0 =1, the above equation is expressed in matrix as: in, is an m×1 vector representing the theoretical value of the model, A is an n×1 vector, X is an m×n dimensional matrix, m represents the number of samples, and n represents the number of features of the samples, so the target loss function is expressed as a matrix: Where Y is the output vector of samples, with dimension m×1 Substitute all N groups of data into the n-order polynomial fitting formula and fit it using the least squares formula; The value of converges to 10 -6 Then the value of n is obtained as the output result.

4. A method for measuring downhole polymer viscosity according to claim 3, characterized in that: The viscosity and phase difference mapping mathematical model is corrected using the relationship curve between polymer solution concentration and viscosity at different temperatures.

5. A downhole polymer viscosity measurement method according to claim 4, characterized in that: The relationship curve between the concentration and viscosity of the polymer solution at different temperatures is obtained by the following path: (1) using polyacrylamide to prepare a mother solution, using a stirrer to fully stir the mixture under the condition that the ratio of water to polyacrylamide is 1000:1, to prepare polymer solutions of different concentrations, and controlling the concentration range to be between 50-1500 mg / L; (2) Use a thermostat to control the temperature between 20-50°C and keep it constant. Choose a suitable thermostatic water bath to ensure that the temperature control accuracy reaches ±0.1°C. (3) Ensure that the maximum flow rate does not exceed 1.5 m / s, and use a viscometer to measure the viscosity of polymer solutions of different concentrations under constant temperature conditions; (4) Record the temperature and viscosity of each measurement; (5) changing the concentration and temperature of the polymer, repeating the above steps, and obtaining multiple sets of data on the relationship between the concentration and viscosity of the polymer solution at different temperatures; (6) Process the collected data and plot the coordinate points of the viscosity relationship of polymer solutions at different temperatures at the same concentration.

6. A downhole polymer viscosity measurement method according to claim 5, characterized in that: When obtaining the relationship curve between the concentration and viscosity of the polymer solution at different temperatures, a secondary calibration correction is performed for the viscosity corresponding to different temperatures at the same concentration; For the temperature correction coefficient, we first experimentally verified that the temperature range was between 20°C and 50°C. We recorded data every time the temperature increased by 1°C from 20°C to 50°C, and used the Origin software to fit all the data. After fitting, we obtained the temperature formula: in It is the viscosity at 20°C. When the temperature is higher than 20°C, the viscosity is corrected by adding the coefficient B multiplied by the temperature (z-20). When the temperature increases, the viscosity of the polymer decreases, and the coefficient of general temperature is a negative number.

7. A downhole polymer viscometer for implementing any one of the measurement methods of claims 1 to 6, comprising an upper cylinder, a lower cylinder and an intermediate separator, characterized in that: The upper cylinder, the lower cylinder and the middle separator are connected as one body; the middle separator is used to separate the upper cylinder and the lower cylinder so that the two are not connected; The upper cylinder is built with a control unit, a data communication module, a motor, and a magnetically coupled inner rotor; The middle partition is provided with a first Hall sensor and a second Hall sensor; the first Hall sensor is used to detect the square wave state of the high and low levels of the magnetically coupled inner rotor, and to return the phase value of the magnetically coupled inner rotor to the control unit; the second Hall sensor is used to detect the square wave state of the high and low levels of the magnetically coupled outer rotor and to return the phase value of the magnetically coupled outer rotor to the control unit; The lower cylinder has a magnetically coupled outer rotor built in, and a plurality of openings leading to the inner cavity are opened on the cylinder wall to serve as sampling ports for the polymer to be tested; The magnetic coupling inner rotor is coaxially connected to the motor; the magnetic coupling outer rotor can rotate with the magnetic coupling inner rotor under the action of magnetic coupling; The upper and lower end surfaces of the intermediate separator are respectively provided with rotor coupling magnetic pole fixing grooves with the same central axis, which are respectively used to place the magnetic coupling inner rotor and the magnetic coupling outer rotor; the intermediate separator is made of a material with good magnetic conductivity; The control unit has a built-in program that can substitute the received phase difference between the magnetically coupled inner and outer rotors into the viscosity and phase difference mapping mathematical model to calculate and obtain a viscosity value.

8. A downhole polymer viscometer according to claim 7, characterized in that: The data communication module communicates with the ground data processing equipment through Manchester code, and transmits the viscosity data obtained by real-time measurement to the ground for display and recording.

9. A downhole polymer viscometer according to claim 8, characterized in that: The upper cylinder is provided with a temperature sensor and a pressure sensor, and the obtained temperature signal and pressure signal are sent to the control unit; the control unit corrects the viscosity and phase difference mapping mathematical model according to the temperature parameter under the control of the built-in program.

Images