System for logging highly deviated earth boreholes utilizing auxiliary sinker bar assembly

Abstract

A conventional logging instrument is adapted to traverse a slanted or deviated earth borehole on the end of a conventional logging cable. A heavy, streamlined sinker bar is adapted to be fitted over the cable and to slide freely thereon. Upper and lower stop clamps, separated by approximately 100 feet of cable, are provided on the cable with the lower stop clamp being located approximately 200 feet above the logging instrument. The sinker bar is adapted to slide freely between the upper and lower stop clamps. Since it is unlikely that the logging tool and the sinker bar will become stuck at the same time in a highly deviated borehole, one of two things can happen. If the sinker bar becomes stuck, the cable passes freely through the center of the sinker bar without impeding the logging tool until the upper clamp reaches the limit of its travel. If at that point the logging instrument is descending freely, it can dislodge the sinker bar with a gravitational force. If the logging instrument becomes stuck while the sinker bar is free, the sinker bar will rest on the lower clamp and push on the logging cable to impel it downward. By the concerted action of the sinker bar and logging tool, the probability of reaching greater depths within the deviated borehole is increased. A spring or other such shock absorber is affixed to each of the clamps to prevent transfer of excessive inertial force during the operation of the system.

Dependencies are inferred from the claim text.