| Dynamic measurement of downhole engineering parameters is to measure the dynamic parameters such as drilling pressure,torque,bending moment and vibration of bottom drilling tools.It is also an important technical basis for realizing drilling optimization,drilling tool optimization,bit optimization,drilling automation,informationization and intellectualization.In recent years,a large number of oil suits around the world have been invested in research.At present,the utilization of engineering parameters in China mainly focuses on real-time early warning of static measurement data,and there is a lack of dynamic measurement instruments for engineering parameters.In this paper,the key technology of dynamic measuring instrument for engineering parameters is analyzed from two aspects of instrument design theory and test equipment development.For the theory of instrument design,this paper first invents an engineering algorithm of complex surface strain,and analyses the calculation accuracy of the algorithm.The algorithm uses finite element analysis software to calculate the triaxial principal strain of each node on the target surface when the model is loaded.The core of the algorithm is to calculate the vector synthesis of the principal strain by calculating the contribution of the principal strain in the direction of the target,and then to calculate the vector synthesis results in batches by matrix operation software,so as to quickly obtain the strain response on the target surface when the instrument structure model is loaded.Comparing with the results of surface strain calculation based on the first principle,the accuracy of the algorithm is determined.Because it is not limited to surface shape,this algorithm greatly increases the design method of instrument structure,improves the calculation efficiency,and provides the technical basis for instrument design and optimization.Then,this paper studies the coupling phenomenon of the measurement of drilling pressure and torque,analyses the reasons of coupling,analyses the influence of instrument structure,the precision of strain gauge sticking and the length of strain gauge on the coupling phenomenon one by one,finds out the main influencing factors,and designs a low-coupling measurement structure of drilling pressure and torque on this basis,which enhances the measurement accuracy and measurement of the instrument from the angle of decoupling quantitative stability.Finally,the measurement performance of the instrument is discussed in terms of the linearity and dynamic characteristics of the measurement system,and the highest effective measurement frequency of the instrument is found.For the development of test equipment,this paper analyzed the shortcomings of the current calibration device.Through a large number of tests of the current device,it was found that there were some problems in the transformation of the old device,such as unstable pressure supply of hydraulic pumps,serious electromagnetic interference of sensors and so on.In this paper,a digital filter method for the sensor of the device is designed,which can not only eliminate the high-frequency electromagnetic interference,but also truly reflect the fluctuation of the pressure of the hydraulic pump.In the aspect of control,firstly,the system identification of the device is carried out,and the second-order model of the system is obtained by using multiple excitation signals,and the identification results are verified by the correlation of residuals.Then,a control method is designed according to the self-stability characteristics of the device,that is,internal model control is used to eliminate the influence of hydraulic pump fluctuation in low frequency band,and self-stability of the device is used in high frequency band to achieve fast sinusoidal excitation stability.This research has reference value for the final development of dynamic measuring instrument for underground engineering parameters. |
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