METHOD AND SYSTEM FOR THE EARLY DETECTION OF THE JAMMING OF A CORE SAMPLING DEVICE IN AN EARTH BOREHOLE, AND FOR TAKING REMEDIAL ACTION RESPONSIVE THERETO

摘要

A drill string having a core sampling device at its lower end is suspended in an earth borehole by a rotary drilling rig at the earth's surface. Drilling fluid pulsations are monitored in the drilling fluid standpipe to generate characteristic signatures of normal coring operations and a precursor, abnormal, signature when the core sampling device first begins to jam, before catastrophic jamming has occurred. Responsive to the abnormal signature, remedial action is commenced, such as reducing WOB, RPM, or terminating the coring operation. The system is also used to determine that an activatable downhole tool has one or more of its parts moved from a first position to a second position.