Patent ID: 6714138
Filing Date: 2004-03-30
Classification: E21B

Abstract:
A method for transmitting information from a portion of a drill string operating at a down hole location in a well bore to a location proximate the surface of the earth, a drilling fluid flowing through said drill string through a flow path thereof having a rotor disposed therein, comprising the steps of:a) generating a sequence of pressure pulses in the drilling fluid at said down hole location that propagate to said surface location, said sequence of pressure pulses generated by operating a drive train that drives said rotor so as to create rotational oscillations in said rotor that alternately block and unblock at least a portion of said drill string flow path by a predetermined amount, said sequence of pressure pulses being encoded with said information to be transmitted, said sequence of pressure pulses having an amplitude defined by the difference between the maximum and minimum values of the pressure of said drilling fluid; and b) controlling said amplitude of said generated encoded sequence of pressure pulses in situ at said down hole location by operating said drive train so as to vary the magnitude of said rotational oscillations of said rotor thereby varying said amount by which said portion of said flow path is alternately blocked and unblocked.