Apparatus and method for transmitting downhole conditions to the surface

Claim 1

A measuring while drilling mud-pulse telemetry system for use while drilling a borehold in the earth, the system comprising: (a) an elongate, hollow tubular member adapted to be connected in a drill string; (b) constriction means in said tubular member for creating a sequence of pressure pulses in drilling fluid circulated through the drill string; (c) a mud pulser sub mounted within said hollow tubular member and extending into a length a drill pipe in the drill string for producing pressure pulses in the drilling fluid, said mud pulser sub including a rod member having a plurality of spaced peaks and valleys formed along a lower portion of said rod member; (d) a closed hydraulic fluid system for modulating downward movement of said rod member of said mud pulser sub; (e) sensor means responsive to a variable of interest in the borehole for forming a signal indicative of a value of the variable of interest; (f) switch means operatively connected to said sensor means, said switch means being engageable with said lower portion of said mud pulser sub and being actuable upon downward movement of said rod member of said mud pulser sub; and (g) battery means operatively connected to said sensor means for operation thereof.