Method for drilling under rivers and other obstacles

摘要

A method of drilling under barriers (rivers, highways and the like) is set out. The horizontal drilling system mounts a guidance tool on the end of the drill string just behind the drill bit. The guidance tool includes a pair of right angle accelero meters and a 3-axis mounted gyro. The gyro furnishes data in a plane at right angles to the z-axis. This defines four data streams to the CPU enabling determination of drill bit location and pathway.