Downhole turbine rotary drilling device

Claim 1

In a gas turbine drilling device for use in a borehole forming operation wherein means are provided for compressing and injecting gas into a drill string with drill collars attached to the downhole portion thereof, the improvement comprising: a heat exchanger comprising an oil reservoir, said heat exchanger is housed in a collar and adapted to be removably attached to the downhole portion of the drill collars; a gas turbine connected in underlying relationship respective to said heat exchanger; a reduction gear means operably connected to the gas actuated turbine to thereby achieve a reduction in revolutions per minute between the output of the gas turbine and the final output of the gear reduction system, said gear reduction system being housed within a drill collar configuration and adapted to be attached to the output portion of the gas turbine; a bit sub means removably attached to the output of said gear reduction system for operably connecting the output of said gear reduction system to a standard drill bit; a gas passage means provided through said oil reservoir in said heat exchanger, said gas turbine engine, said gear reduction system, and said bit sub means to provide passage for gases through the system when all parts are operably connected together; said oil reservoir in said heat exchanger contains lubricating oil and includes means for urging lubricating oil retained within said oil reservoir to flow to the working parts of the gas turbine engine and the reduction gearing system when the drilling system is operably connected; means for returning the lubricating oil from the gas turbine and the reduction gearing system to the oil reservoir so as to provide continuous circulation of lubricating oil throughout the gas turbine and reduction gearing system; and valve means responsive to gas pressure for precluding flow of oil until the pressure at said gas passage means reaches a predetermined magnitude.