Drilling system

Claim 1

A drilling system, comprising a hollow drill pipe and a cutting means located within said drill pipe, said cutting means including drill bits so formed as to be capable of passing through said drill pipe, said cutting means also including reaming bits capable of opening outwardly of said drill pipe and capable of closing inwardly thereof, said cutting means further including locking means comprising an inner cylinder and an outer cylinder surrounding said inner cylinder, said cylinders being axially interconnected when said cutting means is locked in place within said drill pipe, and said cylinders being slightly movable in an axial direction relative to each other when said cutting means is disengaged from said drill pipe, said outer cylinder having window openings therein and latches being mounted on said inner cylinder for projection out of said window openings from a position inwardly thereof, each said latch being pivotally mounted at one end on a pin at the drill bit side of said cutting means, recesses located within said inner cylinder for the reception of said latches in their inward positions, said latches in their outwardly projected position engaging said outer cylinder and notches provided at the inner surface of said drill pipe for locking said cutting means in place, and said latches being so arranged that, upon movement of said outer cylinder relative to said inner cylinder, said latches are disengaged, hydraulic motor means for rotating said drill bits and said reaming bits, said rotating means comprising a turbine or the like having a rotor with which said drill bits and said reaming bits or said cutting means are connected and a stator integral with said inner cylinder, said hydraulic motor means having a torque-generating water passage located between said rotor and said stator and having also a bypass water passage leading to said bits in communication with said inner cylinder without passing through said torque-generating water passage, a valve means provided for switching water to either of said two passages, said latches of said locking means being engaged with said outer cylinder by the interengagement of an upper end of each said window opening and an end of each said latch opposite said one end thereof, said valve means being so disposed as to prevent water fed at a first predetermined pressure from flowing into said bypass water passage during said interengagement, and a spearhead having means for engaging with a pulling-up machine and further being operatively connected to said locking means in such a manner that, when said spearhead is pulled up by the machine, said outer and inner cylinders are axially moved relative to one another so as to unlock said latches whereby only said cutting means may be pulled up.