DOWNHOLE APPARATUS, SYSTEM AND METHOD

摘要

An example apparatus for generating downhole fluid pressure pulses includes a tubular housing defining an internal fluid flow passage and providing a housing wall having an internal surface and an external surface. The apparatus also includes a device for selectively generating a fluid pressure pulse, the device being mounted in an aperture defined in the housing wall and being movable between a retracted position, where the device is seated within the aperture, and a radially extended position, where the device extends at least partially beyond the external surface.