Design And Research Of Crude Oil Moisture Measurement System Based On Quartz Crystal Resonator

In the oilfield development process,the exploration,drilling,oil recovery,transportation and other production chains are inseparable from the accurate measurement of the crude oil moisture content.Nowadays,the crude oil moisture content has become a key measurement parameter in the oilfield development process.In the measurement of moisture content,the indirect measurement has the advantages of high test efficiency and good accuracy,and is the main direction of research on moisture content measuring instruments at home and abroad.The indirect measurement method includes conductivity method,capacitance method,radio frequency method,short wave method,microwave method,ray method and density method.Among them,The density method has the problems of insufficient and low resolution in the measurement of crude oil moisture content.which makes it unsuitable for measuring crude oil with moisture content below 20%.Aiming at the above problems,a design scheme of crude oil moisture content measurement system based on quartz crystal resonance principle is proposed.The program uses the experimental method to calibrate the parameters of the theoretical formula of moisture content,and then calculates the moisture content of the crude oil sample through the measurement system,which can solve the problem of low accuracy and low resolution to some extent.The main work of the thesis includes:1.A theoretical derivation was made for the measurement of the moisture content of crude oil.According to the principle of calculating the moisture content of crude oil according to the density,combined with the theoretical knowledge of the density of crude oil measured by quartz crystal resonator,the calculation formula of the moisture content of crude oil with respect to the resonant frequency of quartz crystal is derived.According to the principle of calculating the moisture content of crude oil according to the density,combined with the theoretical knowledge of the density of crude oil measured by quartz crystal resonator,the theoretical formula of the moisture content of crude oil with respect to the resonant frequency of quartz crystal is derived.2.The measurement scheme of the moisture content measurement system was designed,the experimental platform was built,and the sensor selection experiment and result analysis were carried out.The lock-in amplifier is the core of the measurement system,and the measurement system is built.A quartz tuning fork crystal with a resonant frequency of 32.768 kHz,a quartz crystal oscillator of 5 MHz,and a quartz beam crystal of 4 MHz were measured.Through the analysis of the result,a 4 MHz quartz beam crystal was finally selected as thesensor of the measuring system.3.Nine sets of standard solutions were configured,and the theoretical formula of moisture content measurement was calibrated,and the results after calibration were verified.According to the theoretical formula of the crude moisture content of the crude oil with respect to the resonant frequency of the quartz crystal,the parameters were calibrated by experimental methods;The theoretical formula after the parameter calibration is experimentally verified,and the measurement result is compared with the actual result of the distillation method.The results show that the measured moisture content has a high correlation with the actual moisture content,and the error is also small,indicating the feasibility of the measurement system.4.The crude oil samples of an oilfield branch were measured and compared with the test results of the distillation method.The results show that the measurement system has higher accuracy in the range of 0~99.65% moisture content,and also has higher resolution for crude oil with moisture content below 20%.5.According to the constructed moisture content measurement system,the measurement steps of the oil well site are simulated,the moisture content change curve is drawn,and the error caused by the gas and sand content in the crude oil is qualitatively analyzed.The crude oil samples taken from a single oil well were tested,and the moisture content change curve of the oil well was fitted and compared with the artificial test results.The results showed that:The measurement results of the crude oil moisture content measurement system based on the quartz crystal resonator are more accurate,and the fitted moisture content change curve is more gradual,which can play a better role in predicting the crude oil production in the oil field.