Diamond drilling for core sampling

Abstract

The drilling for, and recovery of core samples from the earth's crust, sometimes at distances of up to 3 km from the surface, is subject to many practical problems. One of these problems involves the jamming of core samples inside the recovery cylinder during drilling. There is a need to analyse the forces involved when the recovery cylinder is sliding over the core. Several simple mechanisms associated with naturally occurring variations in rock and soil structure were suggested as possible causes of jamming. The results suggest that the simplest mechanisms are not the cause of the problem, but combinations of these simple mechanisms might well be the cause. The results and discussion indicate some experiments that would be useful in a further study of the problem, and data from the drilling operations that should be kept for further analysis.