MULTIPLE LATERAL HYDRAULIC DRILLING APPARATUS AND METHOD

摘要

Hydraulic drilling apparatus and method in which a hole is formed with a series of drilling heads (26) and strings (42) of successively smaller diameter. After each section of the hole is formed, the drill head is withdrawn back through the string, leaving the string in place in the hole as a casing for the well. The next smaller size drill head and string are then introduced through the strings which have already been placed, and the process is repeated until the hole has reached the desired length. The course of the hole can be changed, e.g. from vertical to horizontal, without interruption of the drilling process by selective application of the drilling fluid to the nozzles in the drill head to steer the advancing string. Multiple laterals (53a-53d) are formed by introducing a module (51) having a plurality of extensible drilling tubes (53) with drill heads (56) at the distal ends thereof into the string and applying the pressurized drilling fluid to the module to advance the tube from the string.