The Study And Design On MWD Collection Joint Of Downhole Engineerning Parameters

With the development of modern drilling technology, MWD has been applied more and more commonly. In geological survey and oil drilling, especially in the directional drillings and extended-reach horizontal wells, MWD is an indispensable tool for continuous monitoring of drilling trajectory and timely correction. Therefore, MWD is important to the theoretical study of drilling engineering and improvement of drilling efficiency.At the beginning, this paper was mainly focused on the theoretical analysis of twisting and pressure on the drilling collar by Mechanics of Materials, in order to establish the paste way of strain gauge and electric bridge of measurement. The position error of strain gauge by man-made was studied, the scope of the maximum allowable error from deviation angle was given, which was the theoretical basis for the following experiment.Secondly, according to theoretical calculations and system design requirements for the hardware, the signal conditioning circuit and CPU control circuit has been designed. Against the harsh downhole environment and low-power requirements, the corresponding chips were selected carefully, the signal conditioning circuit board and software programming was developped.Finally, the experiment with the model was done in order to simulate drill collar force in this paper, then, WOB and torque signals were imposed on the model separately. The outputs of strain gauge bridge were amplified by the corresponding conditioning circuit and compared with the results of theoretical calculations. The result was that WOB signals coincided with the corresponding theoretical data, while the torque signals didn't. The source of the error in the results of torque measurement and the error correction method were analyzed. In the end, the decoupling formula of twisting and pressure on the drill collar were established at the same time.