Study On Piezoelectric Dynamometer For Torque Real-time Monitoring Of Drilling Rigs

With the deep development of ?13th Five-Year Plan?,the national economy has developed rapidly,and the oil and gas resources are hugely consumed.While developing the new energy industry,expanding the development of marine and deep crustal oil and gas resources is also important to alleviate the current energy shortage.Drilling a few kilometers deep involves many aspects of knowledge,one of which is to accurately detect the change of the resistance moment at the drill bit.Timely adjustment of drilling parameters,and then ensuring the production safety is more realistic.A new kind of piezoelectric torque measuring instrument is developed,which is used to measure the torque of oil drilling rigs.The problems of multi sensors arrangement torque measurement,signal conditioning,wireless transmission and power supply are solved.It can achieve real-time measurement and wireless transmission for the large range of torque in the absence of external power.Firstly,based on the idea of torque equal to ?force×force arm?,"force × force arm" torque measurement mathematical model of multi-sensor circumferential arrangement is built.And based on the comprehensive measurement,assembly and other factors,two groups of sensors are used.To refer to torque measurement range,dynamometer space layout size,and quartz crystal mechanical parameters,the geometrical dimensions of the force sensing elements are calculated and determined.The mechanical structure of the dynamometer is designed,and its 3D model is established.The dynamometer is checked at full scale by the finite element analysis.Secondly,according to Miller effect and Kirchhoff's second law,the theoretical expression of the charge quantity of the piezoelectric sensor is deduced,and the relation between quasi-static performance and the time constant is clarified.The principle of charge transfer chip with high impedance and stability is established.Finally,the output signal conditioning circuit of piezoelectric sensor is designed with high magnification and low lower cutoff frequency.Compared to the standard charge amplifier,its performance meets the piezoelectric sensor measurement requirements.On the premise that the charge signal can be converted into voltage signal by the signal conditioning circuit,the Bluetooth transmission protocol is used,and the sender and receiver of the specific implementation of the program is given.The voltage signal of torque can achieve wireless transmission through the cooperation of software and hardware.Driven by the rotation of the drilling rig,and based on the principle of electromagnetic induction,a three-phase AC generator is designed,and the working voltage acquisition path of "three-phase AC-rectification-regulator – stable DC" is determined.The three-phase electric mathematical model is established,and the rectification principle of full-wave bridge rectifier circuit is analyzed.In the allowed input voltage range of the selected chip,single-phase electric potential is calculated reversely.Then the specific parameters of generator are determined by establishing the mapping relationship between single-phase electromotive force and speed range of drilling rig.Finally,after assembling the components of each part of the dynamometer,and packaging the signal conditioning circuit and the wireless transmission circuit,the static calibration is performed on the multidimensional force calibration table.By applying the equal step force on both sides of the dynamometer,the standard torque of different sizes is simulated.The experimental results show that the non-linearity of the dynamometer is about 1% and the repeatability is less than 0.5%,which satisfies the requirement of real-time monitoring of deep drilling rig torque.