Cementing operation cement slurry density monitoring method based on double closed loop cooperative control

Abstract

The application provides a cementing operation cement slurry density monitoring method based on double closed-loop cooperative control, relates to the cement slurry density monitoring field and specifically comprises the following steps: collecting sensor original signals and driver original signals; storing and shifting the sensor signals and the driver signals; judging whether the signals pass zero points; if yes, calculating the amplitudes of the sensor signals and the driving signals in a period, calculating the frequency of the sensor signals and the phases of the two signals; calculating the phase of the driving gain increment signal and the driving signal; generating a composite driving signal fusing frequency, phase and amplitude information; through quadratic polynomial fitting of a density-frequency model, the measured cement slurry density is calculated online by using the extracted fundamental frequency. The technical scheme of the application overcomes the problems in the prior art that the cement slurry density calculation error increases, resonance drift caused by working condition changes cannot be coped with, the measurement pipe vibration is unstable, and the measurement precision is further affected.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of cement slurry density monitoring, in particular to a cementing operation cement slurry density monitoring method based on double closed-loop cooperative control. BACKGROUND

[0002] Cementing operation is a key process of oil and gas exploitation, and cement slurry density is a core parameter that determines the quality of cementing and the safety of wellbore. Whether it can be accurately and timely monitored directly relates to the safety of the operation and the long-term stability of oil and gas wells. If the density is too low, it is easy to cause blowout, annular channeling and other serious accidents, and if the density is too high, it may fracture the formation and cause insufficient annular filling, resulting in huge economic losses. The traditional offline density measurement method (such as specific gravity bottle and laboratory densimeter) has a measurement period of more than 10 minutes, which cannot cope with the dynamic fluctuations of cement slurry density in deep well and ultra-deep well operations, and is easy to miss the control window; radioactive density instruments have radiation safety risks and complex maintenance, which are difficult to meet the continuous operation requirements of cementing operation.

[0003] The vibrating tube density meter (VTD) is based on the inherent coupling relationship between the measurement tube's natural vibration frequency and the density, realizes online measurement of fluid density, and has the core advantages of simple structure, high measurement accuracy and non-contact measurement, which is an ideal technical solution for real-time monitoring of cement slurry density in cementing operation. However, the cementing wellhead working condition is extremely harsh: the cement slurry viscosity is as high as 500~2000mPa・s, the solid particle content is more than 20%, and it is also faced with 10~120MPa high pressure, strong mechanical vibration (piping vibration caused by mud pump) and electromagnetic interference, which poses a severe challenge to the stability and adaptability of the VTD driving system.

[0004] The existing VTD driving system has certain limitations: on the one hand, the signal processing accuracy is insufficient, the traditional time / frequency domain analysis method is easily affected by speed fluctuation and environmental interference, and it is difficult to accurately extract the frequency, amplitude and phase difference of the vibration signal, which leads to an increase in density calculation error; on the other hand, the control strategy is single, most driving systems only use simple amplitude control, lack of accurate compensation for phase difference, and cannot cope with the resonance drift caused by working condition changes, which leads to unstable vibration of the measurement tube and further affects the measurement accuracy. In addition, the analog driving system has inherent defects such as difficult start and weak anti-electromagnetic interference ability, and the existing digital driving system has insufficient cooperation between the parameter extraction algorithm and the control strategy, and limited working condition adaptability.

[0005] Therefore, there is a need for a cementing operation cement slurry density monitoring method based on double closed-loop cooperative control, which can accurately extract parameters under complex working conditions and has high density measurement accuracy. SUMMARY

[0006] The main objective of this invention is to provide a method for monitoring the density of cement slurry in cementing operations based on dual closed-loop collaborative control, in order to solve the problems in the prior art where it is difficult to accurately extract key parameters such as frequency, amplitude and phase difference of vibration signals, which leads to increased density calculation errors; and the inability to cope with resonance drift caused by changes in operating conditions, which leads to unstable vibration of the measuring tube and further affects the measurement accuracy.

[0007] To achieve the above objectives, this invention provides a method for monitoring the density of cement slurry during cementing operations based on dual closed-loop collaborative control, specifically including the following steps:

[0008] S1, after the measuring tube vibrates, acquire the original signals from the sensor and the driver, and remove outliers.

[0009] S2, store and shift the sensor signal and driver signal, and determine whether the signal has crossed zero based on the changes before and after the signal. If yes, calculate the amplitude of the sensor signal and driver signal within one cycle, calculate the frequency of the sensor signal and the phase difference between the two signals, and then execute step S3. If no, continue to collect the sensor signal and driver signal at the next point, and continue to execute step S2 until the signal is detected to have crossed zero.

[0010] S3, based on the sensor signal amplitude, calculates the incremental drive gain signal according to the PID calculation law; based on the phase difference between the sensor and the driver, calculates the phase compensation amount according to the PID calculation law.

[0011] S4 transmits the extracted frequency and phase difference to the direct digital synthesizer (DDS), and transmits the drive amplitude gain and the sinusoidal signal with specified frequency and phase generated by the DDS to the multiplicative digital-to-analog converter (MDAC) to generate a composite drive signal that integrates frequency, phase and amplitude information.

[0012] S5 uses a quadratic polynomial to fit a density-frequency model and calculates the density of the cement slurry online using the extracted fundamental frequency.

[0013] Furthermore, step S1 specifically includes the following steps:

[0014] S1.1, data collection Raw signal from time sensor With the original signal of the driver .

[0015] S1.2, Eliminate abnormal values ​​in sensor signals:

[0016] ;

[0017] in, for Sensor signal values ​​after outlier removal, initial value , is the upper limit value of the sensor signal.

[0018] S1.3, eliminate abnormal values of the driver signal:

[0019] ;

[0020] wherein, is the abnormal value of the driver signal at the moment, and the initial value is 0 V. , is the upper limit value of the driver signal.

[0021] Further, step S2 specifically comprises the following steps:

[0022] S2.1, perform storage shift of the sensor signal:

[0023] ; ; ; ;

[0024] wherein, is the sensor signal value at the moment, and the initial value is 0 V. is the sensor signal value at the moment, and the initial value is 0 V. is the sensor signal value at the moment, and the initial value is 0 V. is the sensor signal value at the moment, and the initial value is 0 V.

[0025] S2.2, perform storage shift of the driver signal:

[0026] ; ; ; ;

[0027] wherein, is the driver signal value at the moment, and the initial value is 0 V. is the driver signal value at the moment, and the initial value is 0 V. is the driver signal value at the moment, and the initial value is 0 V. is the driver signal value at the moment, and the initial value is 0 V.

[0028] S2.3, update the maximum value of the sensor signal :​​​​​​​​​

[0029] ;

[0030] wherein, is a maximum function.

[0031] S2.4, update the minimum value of the sensor signal :

[0032] ;

[0033] wherein, is a minimum function.

[0034] Further, step S2 further comprises the following steps:

[0035] S2.5, if the sensor signal satisfies the condition , then calculate the number of zero-crossing points of the sensor signal :

[0036] ;

[0037] wherein, the initial value of is set to 0.

[0038] Calculate the sampling count value corresponding to the previous zero-crossing time of the sensor :

[0039] ;

[0040] wherein, the initial value of is set to 0.

[0041] Calculate the sampling count value corresponding to the current zero-crossing time of the sensor :

[0042] ;

[0043] wherein, the initial value of is set to 0.

[0044] S2.6, calculate the number of sampling points between the adjacent two zero-crossing points of the sensor signal :

[0045] ;

[0046] Calculate the interpolation correction value corresponding to the current zero-crossing time of the sensor :

[0047] ;

[0048] wherein, the initial value is set to 0.

[0049] assigning the interpolated correction value corresponding to the current zero-crossing of the sensor to the interpolated correction value corresponding to the previous zero-crossing of the sensor

[0050]

[0051] wherein the initial value is set to 0.

[0052] S2.7, updating the sensor signal frequency value

[0053]

[0054] wherein is the signal sampling frequency.

[0055] S2.8, updating the driver signal and sensor signal phase difference value

[0056]

[0057] wherein is the sampling period; the initial value of is set to 0;

[0058] if then normalizing to [-180°, 180°].

[0059] S2.9, updating the sensor signal amplitude value

[0060]

[0061] calculating the amplitude deviation is the set value for the amplitude of the vibrating tube.

[0062] Further, the step S3 comprises the following steps:

[0063] S3.1, calculating the current time phase difference deviation:

[0064]

[0065] wherein the initial value is set to 0°; is the set value for the phase difference, set to 0°.

[0066] assigning the current time phase difference deviation to the previous time phase difference of the driver and the sensor: ​​​​​​​​​​

[0067] ;

[0068] wherein, the initial value is set to 0°;

[0069] The PI controller is used to generate the phase compensation amount :

[0070] ;

[0071] wherein, , are the proportional and integral coefficients of the phase difference PI controller, respectively;

[0072]

[0073] wherein, and are the upper and lower limit values of the phase compensation amount, respectively.

[0074] The phase compensation amount at the current time is assigned to the phase compensation amount at the previous time :

[0075] ;

[0076] wherein, is the phase compensation amount at the current time, the initial value is set to 0°, the initial value is set to 0°.

[0077] S3.2, according to , match different proportional coefficients and integral coefficients :

[0078] ;

[0079] wherein, and are the high and low threshold values of the amplitude deviation, respectively, , are the high deviation proportional and integral coefficients of the amplitude PI controller, respectively; , are the medium deviation proportional and integral coefficients of the amplitude PI controller, respectively; are the low deviation proportional and integral coefficients of the amplitude PI controller, respectively.

[0080] S3.3, calculate the driving gain increment signal:

[0081] ;

[0082] wherein, is the amplitude deviation of the current time, and the initial value is set to 0V; is the amplitude deviation of the previous time, and the initial value is set to 0V; is the amplitude gain increment.

[0083] assign the amplitude deviation of the current time to the amplitude deviation of the previous time :

[0084] .

[0085] S3.4, calculate the driving amplitude gain :

[0086] ;

[0087] wherein, and are the upper and lower limit values of the driving gain, respectively.

[0088] S3.5, if the sensor signal does not satisfy the condition , then step S4 is executed.

[0089] Further, step S4 specifically includes the following steps:

[0090] update the DDS phase based on the fusion frequency and the phase compensation amount to generate a sinusoidal signal :

[0091] ;

[0092] calculate the sinusoidal signal output by the DDS at :

[0093] . multiply the DDS output signal by the amplitude gain to synthesize the driving signal at

[0094] : ;

[0095] amplify the MDAC output signal to obtain the driving signal

[0096] :

[0097] ;

[0098] wherein, is the amplification factor of the power amplifier.

[0099] Further, step S5 is specifically:

[0100] ​​Computing sampling time Density of the model :

[0101] ;

[0102] wherein, 、 、 are model coefficients.

[0103] The present application has the following beneficial effects:

[0104] The present application aims to provide an integrated digital driving system of "signal processing-double closed-loop collaborative control-density calculation", through the collaborative design of high-precision signal processing algorithm and double closed-loop control strategy, to improve the parameter extraction accuracy, vibration stability and density measurement accuracy of the vibrating tube densitometer under complex cementing working conditions, and to meet the real-time online monitoring requirements of cement slurry density. BRIEF DESCRIPTION OF DRAWINGS

[0105] In order to more clearly illustrate the specific embodiments of the present application or the technical solutions in the prior art, the drawings needed to be used in the specific embodiments or prior art description will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present application, and those skilled in the art can also obtain other drawings according to these drawings without creative labor. In the drawings:

[0106] Figure 1 The figure shows the principle diagram of the vibrating tube densitometer digital driving system based on double closed-loop collaborative control of the second embodiment of the present application. DETAILED DESCRIPTION

[0107] The technical solutions of the present application will be described below in conjunction with the drawings, obviously, the described embodiments are part of the embodiments of the present application, not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0108] Embodiment one

[0109] A monitoring method for cementing operation cement slurry density based on double closed-loop collaborative control, defines the sensor and driver signal sampling frequency as (unit: Hz) (example value Hz), the sampling period , is the discrete sampling time, represents the initial time. From the sampling time k=1, the following steps are executed, specifically including the following steps:

[0110] S1, after measuring the vibration of the pipe, collect the original signals of the sensor and the driver, and eliminate abnormal values; wherein the driver is used to drive the resonant motion of the measuring pipe (vibration pipe) of the densimeter.

[0111] S2, store and shift the sensor signals and the driver signals, and respectively judge whether the signals pass zero point according to the changes before and after the signals; if yes, calculate the amplitudes of the sensor signals and the driver signals within one period, calculate the frequency of the sensor signals and the phase difference between the two signals, and then execute step S3; if not, continue to collect the sensor signals and the driver signals of the next point, and continue to execute step S2 until the signal passes zero point.

[0112] S3, according to the amplitude of the sensor signal, calculate the driving gain increment signal according to the PID operation rule; according to the phase difference between the sensor and the driver, calculate the phase compensation according to the PID operation rule.

[0113] S4, transmit the extracted frequency and phase difference to the direct digital synthesizer DDS, and transmit the driving amplitude gain and the sine signal with specified frequency and phase generated by the DDS to the multiplying digital-to-analog converter MDAC. The DDS generates a sine signal with specified frequency and phase; the MDAC multiplies the analog input signal (i.e. the output signal of the DDS) and the digital input signal (i.e. the amplitude gain) to generate a composite driving signal that integrates the frequency, phase and amplitude information. The composite signal is amplified by a power amplifier and used to drive the vibration of the measuring pipe.

[0114] S5, by fitting the density-frequency model with a quadratic polynomial, calculate the density of the measured cement slurry online using the extracted fundamental frequency.

[0115] Specifically, the step S1 specifically comprises the following steps:

[0116] S1.1, collect the sensor original signal at time t and the driver original signal at time t .

[0117] S1.2, eliminate the abnormal values of the sensor signal:

[0118] ;

[0119] wherein, the sensor signal value after eliminating abnormal values at time t is the initial value , is the upper limit value of the sensor signal, and exceeding this range is determined as abnormal (for example: 5v).

[0120] S1.3, Eliminate abnormal values ​​in the driver signal:

[0121] ;

[0122] in, for Driver signal for constantly removing outliers (unit: V), initial value , This is the upper limit value of the driver signal; values ​​exceeding this range are considered abnormal (e.g., 5V).

[0123] Specifically, step S2 includes the following steps:

[0124] S2.1, Perform sensor signal storage shifting:

[0125] ; ; ; ;

[0126] in, for The initial value of the time sensor signal is set to 0V. for The initial value of the time sensor signal is set to 0 V. for The sensor signal value is set to 0 V initially. for The sensor signal value is set to 0 V initially.

[0127] S2.2, Perform driver signal storage shift:

[0128] ; ; ; ;

[0129] in, for Set the time driver signal value, initially set to 0V; for Set the time driver signal value, initially set to 0 V; for Set the time driver signal value, initially set to 0 V; for The time driver signal value is initialized to 0 V.

[0130] S2.3, Update the maximum value of the sensor signal. :

[0131] ;

[0132] wherein, is the max function, The initial value is set to 0.1 V.

[0133] S2.4, update the minimum value of the sensor signal :

[0134] ;

[0135] wherein, is the min function, The initial value is set to -0.1 V.

[0136] Specifically, step S3 specifically comprises the following steps:

[0137] S2.5, if the sensor signal satisfies the condition , then calculate the number of times of zero-crossing of the sensor signal :

[0138] ;

[0139] wherein, The initial value of is set to 0.

[0140] Calculate the sampling count value corresponding to the previous zero-crossing time of the sensor :

[0141] ;

[0142] wherein, The initial value of is set to 0; (dimensionless)

[0143] Calculate the sampling count value corresponding to the current zero-crossing time of the sensor :

[0144] ;

[0145] wherein, The initial value of is set to 0; (dimensionless)

[0146] S2.6, calculate the number of sampling points between the adjacent two zero-crossing points of the sensor signal :

[0147] .

[0148] Calculate the interpolation correction value corresponding to the current zero-crossing time of the sensor :

[0149] ;

[0150] wherein, Initial value is set to 0 (dimensionless, range [0, 1]).

[0151] Assign the interpolated correction value corresponding to the current zero-crossing of the sensor to the interpolated correction value corresponding to the previous zero-crossing of the sensor :

[0152] ;

[0153] wherein, Initial value is set to 0 (dimensionless, range [0, 1]).

[0154] S2.7, Update sensor signal frequency value (unit Hz):

[0155] ;

[0156] wherein, is the signal sampling frequency.

[0157] S2.8, Update driver signal and sensor signal phase difference value (unit °):

[0158] ;

[0159] wherein, is the sampling period; Initial value of is set to 0.

[0160] If , let Normalize to [-180°, 180°].

[0161] S2.9, Update sensor signal amplitude value (unit V):

[0162] ;

[0163] Calculate amplitude deviation ; is the vibration tube amplitude set value.

[0164] In particular, step S3 comprises the following steps:

[0165] S3.1, Calculate the current time phase difference deviation:

[0166] ;

[0167] wherein, Initial value is set to 0°, is the difference between the phase difference set value and the actual phase difference; Set the phase difference value as 0°.

[0168] Assign the current time phase difference deviation to the phase deviation of the last time driver and sensor (i.e. driver phase minus sensor phase):

[0169] ;

[0170] Wherein, The initial value is set as 0°, and the difference between the phase difference set value and the actual phase difference.

[0171] Generate the phase compensation amount by using the PI controller :

[0172] ;

[0173] Wherein, , The proportional coefficient and the integral coefficient of the phase difference PI controller are respectively set as 0.3 and 0.1 in the embodiment.

[0174]

[0175] Wherein, and The upper limit and the lower limit value of the phase compensation amount are respectively set as 0° and -0°.

[0176] Assign the current time phase compensation amount to the phase compensation amount of the last time :

[0177] ;

[0178] Wherein, The current time phase compensation amount is set as 0°, and is used to adjust the phase of the driving signal to match the sensor signal. The initial value is set as 0°, and is used to adjust the phase of the driving signal to match the sensor signal.

[0179] S3.2, according to The size, match different proportional coefficients and integral coefficients :

[0180] ;

[0181] Wherein, and The high and low threshold values of the amplitude deviation are respectively set as 5 and 2; , The high deviation proportional coefficient and the integral coefficient of the amplitude PI controller are respectively set as 5 and 2 in the embodiment. , S3.2, calculate the amplitude PI controller's mid-bias proportional and integral coefficients, which are respectively set to 3 and 1 in the embodiment; S3.2, calculate the amplitude PI controller's mid-bias proportional and integral coefficients, which are respectively set to 3 and 1 in the embodiment;

[0182] S3.3, calculate the drive gain increment signal:

[0183] ;

[0184] wherein, is the current time amplitude bias, the initial value is set to 0V, and is the difference between the preset amplitude and the actual amplitude; is the last time amplitude bias, the initial value is set to 0V, and is the difference between the preset amplitude and the actual amplitude; is the amplitude gain increment, the initial value is set to 0, and is used to update the amplitude gain.

[0185] assign the current time amplitude bias to the previous time amplitude bias for next iteration calculation:

[0186] .

[0187] S3.4, calculate the drive amplitude gain :

[0188] ;

[0189] wherein, and are the upper and lower limit values of the drive gain, respectively; the initial value is set to 1.0 (dimensionless), which is used to adjust the amplitude of the drive signal.

[0190] S3.5, if the sensor signal does not satisfy the condition , then execute step S4.

[0191] Specifically, step S4 specifically includes the following steps:

[0192] update the DDS phase based on the fusion frequency and the phase compensation amount to generate a sinusoidal signal :

[0193] ;

[0194] wherein, is the phase of the DDS at time k (unit: rad).

[0195] calculate the sinusoidal signal output by the DDS at time :

[0196] ​ ;

[0197] Non-dimensional, range [-1, 1].

[0198] The DDS output signal is multiplied by the amplitude gain to synthesize The time moment driving signal :

[0199] ;

[0200] The MDAC output signal is amplified to obtain the driving signal :

[0201] ;

[0202] Wherein, The power amplifier amplification factor is used to amplify the driving signal.

[0203] Specifically, step S5 is specifically:

[0204] The density of the sampling time moment :

[0205] ;

[0206] Wherein, , , The model coefficient.

[0207] In the field test of the vibration pipe densitometer matched with the cementing pump in an oilfield, the method provided by the application is used for online monitoring of the cement slurry density, and the experimental conditions and results are as follows:

[0208] 1. Experimental conditions

[0209] Environmental conditions: normal temperature (25±1℃);

[0210] Test medium: 6 kinds of media covering the density range of commonly used cementing cement slurry, including seawater (1.02 g / cm³), low-density cementing cement slurry (LD-LC1: 1.18 and LD-LC2: 1.21 g / cm³), medium-density cementing cement slurry (MD-LC1: 1.38 and MD-LC2: 1.45 g / cm³), and high-density cementing cement slurry (HD-LC: 1.90 g / cm³);

[0211] System parameters: sensor sampling frequency 16 kHz, DDS 16 bits (frequency resolution 0.01 Hz), and MDAC 12 bits (to ensure the accuracy of gain adjustment). ​​

[0212] 2. Test results

[0213] Signal extraction accuracy: frequency extraction error ≤ ± 0.01 Hz, amplitude extraction steady-state error ≤ ± 0.01 V, phase difference steady-state fluctuation ≤ ± 0.1°;

[0214] Closed-loop control performance: when the test medium is switched (such as seawater → low-density cementing slurry → high-density cementing slurry), the phase difference is restored to the set value within 1s, the amplitude fluctuation range is ≤ ± 0.1V, and the frequency tracking response time is ≤ 1s (without overshoot);

[0215] Density measurement accuracy: as shown in Table 1, the absolute error of the density measurement of the cementing slurry is all ≤ 0.005 g / cm³, meeting the density monitoring accuracy requirement of cementing operations.

[0216] Table 1: Density measurement values and errors

[0217]

[0218] Working condition adaptability: in the test of simulating high-viscosity (1500 mPa·s) and high-solid-phase (20% particle content) cementing slurry, the system can still operate stably, the density measurement error does not increase significantly, and the anti-interference ability is significantly better than that of the traditional driving system.

[0219] The method provided by the application shows excellent parameter extraction accuracy, closed-loop control stability and density measurement accuracy in field tests, can adapt to complex working conditions of cementing operations, effectively solves the technical bottleneck of the traditional driving system, provides a reliable technical solution for real-time online monitoring of cement slurry density, and has been successfully applied to cementing operations of three deep wells, with a cumulative operation time of more than 1000 hours, without any problem of downtime or measurement accuracy exceeding the standard.

[0220] Example two

[0221] As Figure 1As shown, the application also provides a double closed-loop cooperative control based digital driving system for vibrating tube density meter. The working principle of the system is as follows: after the measurement tube is vibrated, the sensor signal is collected and the signal amplitude, frequency and driver-sensor phase difference are extracted online through signal processing algorithm. The frequency signal is mapped to the corresponding density value through the density-frequency model; the amplitude signal is fed back to the adaptive amplitude controller to generate the driving amplitude gain, ensuring that the measurement tube maintains stable vibration at the preset amplitude set value; the phase difference signal is fed back to the phase difference controller to match the phase of the driving output and the sensor signal, ensuring that the driving signal can maintain the resonance of the measurement tube with the highest energy efficiency and avoid vibration attenuation or instability caused by phase mismatch. Finally, the extracted frequency and the compensation phase output by the phase difference controller are transmitted to the direct digital synthesizer (DDS), and the amplitude gain is transmitted to the multiplication digital-to-analog converter (MDAC). The DDS generates a sine signal with specified frequency and phase; the MDAC multiplies the analog input signal (i.e. the DDS output signal) and the digital input signal (i.e. the amplitude gain) to generate a composite driving signal that integrates frequency, phase and amplitude information. After being amplified by the power amplifier, the composite signal is used to drive the measurement tube to vibrate.

[0222] Of course, the above description is not a limitation of the application, and the application is not limited to the above examples. Changes, modifications, additions or substitutions made by those skilled in the art within the scope of the application should also be within the scope of the application.

Claims

1. A method for monitoring cement slurry density in cementing operation based on double closed-loop cooperative control, characterized in that, Specifically comprising the following steps: S1, after measuring the pipe vibration, collecting the sensor original signal and the driver original signal, and eliminating abnormal values; S2, storing and shifting the sensor signal and the driver signal, and judging whether the signal is zero point according to the changes before and after the signal respectively; if yes, calculating the amplitude of the sensor signal and the driving signal within a period, calculating the frequency of the sensor signal and the phase difference of the two signals, and then executing step S3; if not, continue to collect the sensor signal and the driver signal of the next point, and continue to execute step S2 until the signal zero point is detected; S3, according to the sensor signal amplitude, calculating the driving gain increment signal according to the PID operation rule; according to the phase difference between the sensor and the driver, calculating the phase compensation according to the PID operation rule; S4, transmitting the extracted frequency and phase difference to the direct digital synthesizer DDS, transmitting the driving amplitude gain and the sine signal with specified frequency and phase generated by DDS to the multiplication digital analog converter MDAC, and generating the composite driving signal integrating the frequency, phase and amplitude information; S5, through the quadratic polynomial fitting density-frequency model, the extracted base frequency is used to calculate the measured cement slurry density online; Step S3 comprises the following steps: S3.1, calculating the phase difference deviation at the current time: ； wherein The initial value is set to 0°. The value for the phase difference is set to 0°. Assigning the phase difference deviation at the current time to the phase deviation of the driver and the sensor at the last time: ； wherein, Initial value is set to 0°; Generating phase compensation with a pi controller : ； wherein, , P, I are the proportional, integral coefficients of the phase difference PI controller, respectively. ； wherein and are the upper and lower limit values of the phase compensation, respectively; assigning a current time phase compensation amount to a previous time phase compensation amount : ； wherein, is the phase compensation amount for the current time instant, the initial value is set to 0°, the initial value is set to 0°; S3.2, according to size, match different scale factors with integral coefficients : ； wherein, and are high, low amplitude deviation thresholds, respectively, , are high deviation proportional, integral coefficients of the amplitude PI controller, respectively; , are medium deviation proportional, integral coefficients of the amplitude PI controller, respectively; are low deviation proportional, integral coefficients of the amplitude PI controller, respectively; S3.3, calculating the driving gain increment signal: ； wherein, is the amplitude value deviation at the current time, and the initial value is set to 0V; is the amplitude value deviation at the previous time, and the initial value is set to 0V; is the amplitude gain increment. assigning the amplitude deviation of the current time instant to the amplitude deviation of the previous time instant : ； S3.4, compute drive amplitude gain : ； wherein and are the upper and lower drive gain limits, respectively; S3.5, if the sensor signal does not satisfy the condition then step S4 is performed.

2. The method of claim 1, wherein the method is characterized by, Step S1 specifically comprises the following steps: S1.1, acquisition time sensor raw signal with driver raw signal ; S1.2, eliminating the abnormal values of the sensor signal: ； wherein is the sensor signal value after removing outliers at the moment, initial value , is the upper limit value of the sensor signal; S1.3, eliminating the abnormal values of the driver signal: ； wherein, is the initial value of the driver signal , is the upper limit value of the driver signal.

3. The method of claim 1, wherein the method is characterized by: Step S2 specifically comprises the following steps: S2.1, storing and shifting the sensor signal: ; ; ; ； wherein, is the sensor signal value at the time instant, the initial value being 0 V; is the sensor signal value at the time instant, the initial value being 0 V; is the sensor signal value at the time instant, the initial value being 0 V; is the sensor signal value at the time instant, the initial value being 0 V; S2.2, storing and shifting the driver signal: ; ; ; ; wherein, is the driver signal value at time t, with an initial value of 0 V; is the driver signal value at time t, with an initial value of 0 V; is the driver signal value at time t, with an initial value of 0 V; is the driver signal value at time t, with an initial value of 0 V; S2.3, update sensor signal maximum value : ； wherein is a max function; S2.4, update sensor signal minimum value : ; wherein is the minimum function.

4. The method according to claim 3, wherein, Step S2 further comprises the following steps: S2.5, if the sensor signal satisfies the condition then calculate the number of zero-crossings of the sensor signal : ； wherein, the initial value of is set to 0; Computing a sampling count value corresponding to a previous zero-crossing time of the sensor : ； wherein, the initial value of is set to 0; calculating a sampling count value corresponding to a current zero-crossing time of the sensor : ； wherein, the initial value of is set to 0; S2.6, calculate the number of sampling points between two adjacent zero-crossings of the sensor signal : ； calculating an interpolated correction value corresponding to a current zero-crossing time of the sensor : ； wherein, Initial value is 0; assigning the interpolation correction value corresponding to the current zero-crossing time of the sensor to the interpolation correction value corresponding to the previous zero-crossing time of the sensor : ； wherein Initial value is 0; S2.7, updating the sensor signal frequency value : ； wherein is the signal sampling frequency; S2.8, updating the drive signal and sensor signal phase difference value : ； wherein is a sampling period; is initialized to 0; If then let normalize to [-180°, 180°]; S2.9, update sensor signal amplitude : ； Calculate amplitude deviation ; Set the amplitude value for the vibrating tube.

5. The method of claim 1, wherein the method is characterized by: Step S4 specifically comprises the following steps: Updating the DDS phase based on the fusion frequency and phase compensation amount to generate a sinusoidal signal : ； Computing the sine signal outputted by the DDS at the moment : ； The DDS output signal is multiplied by an amplitude gain to synthesize the moment driving signal : ； The MDAC output signal Amplification to obtain a drive signal : ； wherein PAM is the power amplifier multiplication factor.

6. The method of claim 1, wherein the method is characterized by: Step S5 is specifically: Computing the sampling instants Density of the instants : ; wherein , , are model coefficients.

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