FIELD: drilling of soil or rock.
SUBSTANCE: group of inventions relates to preventing the sticking of downhole tools. Downhole-adjusting impact apparatus (DAIA) is mechanically coupled between opposing first and second portions of a tool string, wherein the tool string is conveyable within a wellbore extending between a wellsite surface and a subterranean formation. First tool string portion comprises a first electrical conductor in electrical communication with surface equipment located at the wellsite surface; DAIA comprises a second electrical conductor in electrical communication with the first electrical conductor. DAIA is operable to detect an electrical characteristic of the second electrical conductor, impart a first impact force on the second tool string portion, when the electrical characteristic is detected, and impart a second impact force on the second tool string portion when the electrical characteristic is not detected. Second impact force is substantially greater than the first impact force.
EFFECT: more effective prevention of sticking.
30 cl, 25 dwg
