dib hole(в скважине); settling pond; dia hole(в скважине); drill sump; rat hole(Islet); rathole(опережающая скважина малого диаметра; A small-diameter pilot-type hole drilled a short distance ahead of a larger diameter hole to stabilize a smaller diameter bit and core barrel when used to core a limited portion of the borehole. After core drilling is completed, the rathole is reamed out and the larger size hole advanced, usually by some noncoring method. See edu.trwordfiend); drilling sump(Climber)
