VORRICHTUNG ZUR VORNAHME VON MESSUNGEN WAEHREND DES BOHRENS UND SCHLAMMDRUCKSIGNALVENTIL

摘要

A measuring and transmitting apparatus for use in a drill string of a well drilling rig has an elongated tubular member functioning as a drill collar in a drill string. This apparatus includes an instrument having transducers that measure lithological and geophysical parameters in the borehole and derive from them data that is encoded into pressure pulsations of the mud flow of the drill string by a modulated signal generator. The modulated signal generator has a valve assembly that selectively restricts the mud flow to introduce the data. The valve is constructed with a movable valve element that is displaced into an orifice located in the mud flow stream. The movable valve element is mounted in a pressure balanced and an area balanced configuration in order that it can be displaced between extended and retracted positions by a valve actuator without regard to the mud pressure either within the drill string or in the borehole annulus around the drill string.