Measuring micro stalls and stick slips in mud motors using fiber optic sensors

摘要

A fiber optic sensor is disposed in the elastomer of the stator of the mud motor in order to sense elastomer strain while drilling. The frequencies of micro stalls and stick slips are measured from the fiber optic sensor data by classification using thresholds or by converting time-domain measurements from the fiber optic sensor data to frequencies. For example, the frequencies are produced by accumulating a histogram over an interval of time or by computing a Discrete Fourier Transform over an interval of time. A plurality of fiber optic sensors also can sense angular position of the rotor of the mud motor for correlation of the micro stalls and stick slips with the angular position. The measurements of the micro stalls and stick slips are used to select remedial action such as changes in drilling parameters.