Abstract: A method of modulating information on pressure fluctuations transmitted via a tubular string can include applying pressure to a piston, thereby axially displacing the piston, axially displacing and rotating an intermediate sleeve in response to the piston displacement, rotating an output member in response to the axial displacement and rotation of the intermediate sleeve, and rotating a variable flow restrictor rotor relative to a stator, the rotor being connected to the output member. A mud pulser can include a variable flow restrictor, and an actuator which operates the flow restrictor and modulates information on pressure fluctuations produced by the flow restrictor, the actuator including a piston which displaces axially in response to a pressure differential, an intermediate sleeve which is both rotated and displaced axially by the piston, and an output member which is rotated by both rotation and axial displacement of the intermediate sleeve.

Abstract: A downhole assembly including a turbine to be disposed within a wellbore and a rotating array. The rotating array includes magnetic material and is coupled to the turbine. The downhole assembly also includes a magnetostrictive material coupled to the rotating array to strain the magnetostrictive material to induce an electric current in a conductor coupled to the magnetostrictive material.

Abstract: A downhole assembly including a turbine to be disposed within a wellbore and a rotating array. The rotating array includes magnetic material and is coupled to the turbine. The downhole assembly also includes a magnetostrictive material coupled to the rotating array to strain the magnetostrictive material to induce an electric current in a conductor coupled to the magnetostrictive material.

Abstract: A downhole assembly including a turbine to be disposed within a wellbore and a rotating array. The rotating array includes magnetic material and is coupled to the turbine. The downhole assembly also includes a magnetostrictive material coupled to the rotating array to strain the magnetostrictive material to induce an electric current in a conductor coupled to the magnetostrictive material.

Abstract: A method of modulating information on pressure fluctuations transmitted via a tubular string can include applying pressure to a piston, thereby axially displacing the piston, axially displacing and rotating an intermediate sleeve in response to the piston displacement, rotating an output member in response to the axial displacement and rotation of the intermediate sleeve, and rotating a variable flow restrictor rotor relative to a stator, the rotor being connected to the output member. A mud pulser can include a variable flow restrictor, and an actuator which operates the flow restrictor and modulates information on pressure fluctuations produced by the flow restrictor, the actuator including a piston which displaces axially in response to a pressure differential, an intermediate sleeve which is both rotated and displaced axially by the piston, and an output member which is rotated by both rotation and axial displacement of the intermediate sleeve.

Abstract: A downhole assembly including a turbine to be disposed within a wellbore and a rotating array. The rotating array includes magnetic material and is coupled to the turbine. The downhole assembly also includes a magnetostrictive material coupled to the rotating array to strain the magnetostrictive material to induce an electric current in a conductor coupled to the magnetostrictive material.

Abstract: A downhole assembly including a turbine to be disposed within a wellbore and a rotating array. The rotating array includes magnetic material and is coupled to the turbine. The downhole assembly also includes a magnetostrictive material coupled to the rotating array to strain the magnetostrictive material to induce an electric current in a conductor coupled to the magnetostrictive material.

Abstract: A downhole assembly including a turbine to be disposed within a wellbore and a rotating array. The rotating array includes magnetic material and is coupled to the turbine. The downhole assembly also includes a magnetostrictive material coupled to the rotating array to strain the magnetostrictive material to induce an electric current in a conductor coupled to the magnetostrictive material.

Abstract: An inductive coupling system including a mandrel and an inner sleeve and outer housing that surround and rotate relative to the mandrel the system also includes a mandrel electronics system and a housing electronics system that communicate electronically using a mandrel inductive coupler and a housing inductive coupler. The mandrel electronics system may also communicate with equipment on the surface. Alternatively, the system may include a mandrel and first and second mandrel electronics systems in different mandrel sections. The first and second mandrel electronics systems communicate electronically using a mandrel inductive coupler. Also alternatively, the system may include a mandrel and an inner sleeve and outer housing that surround and rotate relative to the mandrel. The system also includes a mandrel electronics system and a housing electronics system that communicate electronically using a housing inductive coupler.

Abstract: An apparatus including a drill collar having an outer surface, an assembly for interaction with an earth formation coupled to the drill collar, the assembly including a first member to extend beyond the drill collar outer surface and a second member to extend beyond the first member and toward the earth formation to receive formation fluids. An apparatus including an MWD tool having an outer surface, a formation testing assembly coupled to the MWD tool, the formation testing assembly recessed beneath the outer surface in a first position and including a piston to extend beyond the outer surface to a second position and an inner sampling member to extend beyond the piston to a third position.

Abstract: A downhole, extendable apparatus and methods of use are described and claimed herein. In one embodiment, the extendable apparatus includes a piston that extends toward a borehole wall, the piston having an inner sampling member that is also extendable. The sampling member may be further extended to engage the borehole wall and penetrate the formation. The sampling member may also include a screen and an inner scraper or wiper that frictionally engages the screen and reciprocates to remove debris from the screen. The piston may comprise a seal pad having an internal cavity for receiving a volume of fluid. In another embodiment, the extendable apparatus comprises multiple, concentric pistons for extending the sampling member further toward the borehole wall than is possible with a single piston. The extendable apparatus may also include a retraction contact switch and position indicator.

Abstract: A formation testing tool is described herein, including a formation probe assembly having an extendable sampling probe surrounded by a cylindrical sleeve. The sleeve is configured to engage a metal skirt having an elastomeric seal pad coupled thereto. The skirt and seal are configured to be field replaceable. The elastomeric pad has a non-planar outer surface which engages a borehole wall in preparation for formation testing. The seal pad may be donut-shaped, having an aperture through the middle of the seal pad. The seal pad and its surface may include numerous different embodiments, including having a curved profile. The seal pad may also include numerous different embodiments of means for coupling the seal pad to the metal skirt. The formation testing tool also includes formation probe assembly anti-rotation means, a deviated non-circular flowbore, and at least one closed hydraulic fluid chamber for balancing fluid pressures.