EARTH DRILLING METHOD AND APPARATUS USING MULTIPLE HYDRAULIC FORCES

摘要

A drilling system in which hydraulic forces are applied against a drillhead at the forward end of a drilling pipe to pull a pipe into underground formation. A pushing force also is applied from the rearward end using sliding seals and a closed rearward end of the drill string against which fluid pressure is applied, or (b) by providing a dead weight to the rearward end.