There is provided a wire line core drilling apparatus including an elongated assembly which is hydraulically propelled along the interior of a drill string to a desired location adjacent the bit end of the drill string under the influence of a moving pressurized liquid within the drill string, characterized in that said elongated assembly is provided with an annular cup seal having a flexible annular lip thereon which expands radially outwardly under the influence of liquid pressure thereon to substantially prevent by-pass of the pressurized liquid between the elongated assembly and the interior wall of the drill string and which annular lip is capable of expanding and contracting as said assembly moves along the drill string interior to accommodate reasonable fluctuations in drill string interior diameter which may be encountered.
The drilling apparatus includes a safety sub mountable to the drill string outer end to retain the combination of an overshot assembly and an overshot adaptor extending within the drill string outer end during a drilling operation and preventing the drilling tool moving out of the drill string until the sub is removed. The overshot assembly has a fluid seal between the overshot tube and the drill string and a fluid bypass channel with/a valve for blocking axial outward flow through the channel when the overshot adaptor is separated from the overshot assembly and when connected thereto, retaining the valve in an open condition. When the overshot adaptor is removed from the overshot assembly, the overshot assembly is fluidly propellable to the bit end. A disconnect tool facilitates the removal of the adaptor from the sub.
The invention concerns a core barrel, in particular for oil exploration, comprising a string, an external tube (2) fixed at the front end of the string, a core bit mounted on a front section (3A) of the external tube, and an internal tube assembly (8) mounted in the external tube and comprising hydrodynamic means transforming a core sampling line pressure into a load thrusting said assembly towards the core barrel front, the front section of the external tube being mounted axially sliding, limited by front and rear stop elements (12A, 12P), in a rear section (3P) of the same external tube to project therefrom longitudinally, the assembly comprising a support stop (14) arranged to thrust selectively forward the front section of the external tube, means being arranged between the inner tube (9) proper and said front section such that the latter can be driven in rotation about its longitudinal axis independently of said internal tube, a motor (7) capable of driving the core bit in rotation relative to the string.
The drilling apparatus includes a wire line core barrel head assembly that has a latch body seatable on a drill string landing shoulder and retained in a latch seated position by a latch assembly spring urged to a latch seated position, fluid seals on the latch body to facilitate fluidly propelling the head assembly in an upward direction, valve mechanism in a latch body bypass channel to restrict fluid flow therethrough to provide a signal of the latch body seating on the landing shoulder and then opening together with being retractable to an open position by a latch retractor prior to the latch body being retracted and second valve mechanism to block axial outward flow in the bypass channel. The fluid seals are mounted to a latch body adaptor that may be removed to convert from an up-hole to a down-hole assembly.
