The eccentric reamer drill is an overburden drilling system designed for conditions where a cased hole is required. Collapsing holes tend to make overburden drilling expensive, with lost drilling equipment and down time.
The eccentric-designed bit rotates outward and drills a larger diameter hole than the casing, avoiding cave-ins, wash-outs, and other problems common in normal drilling operations in soft and gravel-type strata or loose rock. Since 90% of the world's overburden drilling is in loose strata, potential utilization is enormous.
After reaching the designated depth, the reamer-bit is retracted by reversing the direction of the rotation and by applying tension on the reamer-bit, which has a taper and will retract into the casing for easy removal of the entire drill-string. This leaves the casing in place for other applications or for removal at a later date. The method is designed for use with flush joint threaded pipe or welded-type casing and provides a bit size for a wide variety of different casing wall thicknesses.
