Abstract: An acoustic transmitter for borehole logging includes a flexure disc acoustic source affixed to one end of an open-ended pipe. A rubber boot surrounds the pipe and flexure disc source and fluidly isolates them from the surrounding borehole fluid. Oil fills the rubber boot and pipe, such that the borehole fluid pressure is transmitted through the rubber boot to the oil. The flexure disc source is electrically excited to cause the transmitter to generate acoustic energy tube waves at one of the resonances of the flexure disc source within the seismic frequency range.

Abstract: Apparatus is provided for measuring weight and torque on the drill bit in a logging-while-drilling system. The upper end of the drill bit is adapted for slidable engagement with the lower end of the drill collar. Transducers are mounted with a cavity formed between the drill collar and drill bit when they are in slidable engagement. The transducers measure axial and rotational motions of the drill bit which represent weight and torque on the drill bit, respectively.