Abstract: 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.

Abstract: A sidewall coring device includes a housing (12) which is operable to be disposed on the end of a drill string. A core tube (18) is disposed on one side of the housing on the interior thereof with an opening (20) provided for receiving core material. A coring mechanism (24) is provided that tilts outward from the housing with blades (26) engaging the sidewall. A passageway (14) allows mud to flow from the drill string downward therethrough to provide a hydraulic force to a hydraulic mechanism (32) to drive saw blades (26). The stabilizing mechanism (32) is provided for forcing the housing (12) against the sidewall of the bore to bore hole (10). The drill string imparts a downward force onto the coring blades (26) to form core segments (40) which are diverted into the core tube (18) by a diverter mechanism (22).