Patent ID: 6851490
Filing Date: 2005-02-08
Classification: E21B

Abstract:
1. In a large diameter drill for placing a corresponding large diameter casing, the combination comprising: a large diameter drill head including a stationary casing attached to the leading end of the large diameter casing, an articulating portion for steering the drill head; a pump for evacuating drilling mud and tailings, and a rotating cutting head; a large diameter casing attached to the large diameter drill head; a drilling mud supply line for supplying drilling mud under pressure to the drilling head threaded through the large diameter casing; a drilling mud removal line for receiving exhausted drilling mud and tailings and removing the exhausted drilling mud and tailings from the drilling head threaded through the large diameter casing; a mud driven motor in the vicinity of the large diameter drill head for receiving drilling mud under pressure and providing a rotational output, the mud driven motor having exhaust at least to the rotating cutting head; at least one hydraulic driven pump for receiving the rotational output from the mud driven motor and providing pressurized hydraulic output through a control manifold to a plurality of closed loop hydraulic circuits contained in the cutting head; a remote connect between the manifold and the plurality of hydraulic circuits for individually controlling the rate of hydraulic fluid flow to the hydraulic circuits; at least one hydraulic circuit connected to the rotating cutting head for rotating the cutting head at a variable and controlled speed; at least one hydraulic circuit connected to the pump for the evacuation of the drilling mud and tailings for operating the pump for drilling mud and tailings at a variable and controlled rate, the pump for the evacuation of drilling mud and tailing connected to the drilling mud removal line; at least one hydraulic circuit connected to articulating portion of the drill head for the controlled varying of the articulating portion for steering the drill head for steering the drill head.