Design Of A Measuring Instrument For Wireless MWD System

The MWD (Measurement While Drilling) technology requires drilling rigs to continuously detect the geological information in the vicinity of the drill bit and transmit the required information to the ground by wireless transmission for drilling engineers to control drilling at any time. Trajectory, is applied to the oil drilling process in an advanced technology. With the oil and gas resources continue to be developed, the formation of the environment is also complicated, drilling on the performance requirements of measuring instruments will be more and more high. Therefore, this paper designed a three-axis acceleration sensor and three-axis fluxgate sensor wireless MWD measuring instrument, to meet the domestic logging technology services (domestic and foreign) Market demand, has important value.This paper analyzes the development status and trends of MWD measurement technology at home and abroad, studies the measurement mechanism based on gravity acceleration sensor and fluxgate sensor, and elaborates the calculation model of the inclination angle, azimuth angle and tool face angle of the well. The derivation of mathematical expressions. The measurement errors of the MWD are mainly the measurement error of the sensor itself and the installation error of the sensor. The error of the installation is corrected by the mathematical space geometry method, and the temperature drift of the sensor is eliminated by means of the average method.The paper mainly designs the downhole measuring instrument of the MWD measurement system.The hardware circuit of the measuring instrument mainly includes: sensor selection, filter module, AD conversion module and MCU Control module. The use of high-temperature, self-temperature compensation function of the sensor; control circuit MCU selected a low-power, high temperature, high temperature, low temperature, The use of analog multiplexer to select the sensor seven-way signal; in order to ensure accuracy and ability to high temperature and high pressure, using 24-bit AD converter. The choice of components used in all high temperature, high pressure and strong vibration and other harsh environment devices. The software work flow and data acquisition program of the underground probe are mainly designed. In order to extract the low frequency signal of 0?1Hz, the second order Butterworth filter is designed and verified by MATLAB. At last, rolling test and high temperature test are carried out to test the accuracy, reliability and stability.The test results show that the measurement accuracy of the system well angle is 0.1 d egrees, and the measurement accuracy of the azimuth angle is within 1.5 degrees. Its max imum operating temperature can reach 125 degrees Celsius, can adapt to the high tempera ture environment.