Abstract: A mud pulser system for use in a wellbore includes a pulser assembly disposed in a drill string and through which drilling fluid is metered in order to generate pressure pulses in the drilling fluid. The pulser assembly includes a pulser body having an inlet and an exit. Included in the pulser body is a rotary member having multiple ports formed through the member. The rotary member can be spherically shaped. The ports are formed so that selectively rotating the rotary member registers opposing ends of a one of the ports with the inlet and exit in the body to provide communication between the inlet and exit. An actuator couples with the rotary member for its selective rotation.

Abstract: A rotary steerable drilling tool with an electromagnetic steering system can include a drill collar, a bit shaft, an orientation control module, a mud tube, a mud tube coupler, a universal joint, a mud sealing device, and a drill bit. The bit shaft can be mechanically coupled to the drill collar through the universal joint and the orientation control module and rotate about the universal joint. The orientation and the inclination angle of the bit shaft against the drill collar can be controlled by the orientation control module with the electromagnetic steering system. The orientation control module can include an array of electromagnets, an array of permanent magnets, a rotor, and a set of bearings. The orientation control module can be coupled to the bit shaft through the rotor. The movement of the rotor can be driven by the interaction between the array of electromagnets and the array of permanent magnets.

Abstract: An oil-based mud formation imaging tool for measuring electrical properties of surrounding formation includes at least one base plate, a first port and a second port deployed on the base plate, surface conductors covering both sides of the base plate, and inside conductors deployed in the first port and the second ports and with gaps from the edges of the first and second ports. The first port is fed with electromagnetic signals by a waveguide and a coupling is formed between the imaging tool and the surrounding formation accordingly. Resonance signals are induced at the second port to be used to compute corresponding formation resistivity and dielectric constant. A corresponding imaging method is also provided.