| 摘要 |
A drilling system comprises a tool body including a drilling motor; a drill bit mounted on the tool body to be rotated by the drilling motor, a mechanism for applying weight to the bit when drilling and a control system for controlling the rate of rotation of the bit (RPM) and the weight applied to the bit (WOB) during drilling. The control system has a first mode in which RPM and WOB are controlled to maintain the power on bit at a predetermined maximum and a second mode in which RPM and WOB are controlled to maintain a predetermined depth of cut (DOC). In use, the control system switches between the first and second modes depending on drilling conditions. Sensors may be included to measure vibrations and the inclination and azimuth of the drilling system as well as the gamma ray count from the formation being drilled. |
