Abstract: Downhole wellbore tools are actuated by electrically controllable fluids energized by a magnetic field, for example. When energized, the viscosity state of the fluid may be increased by a degree depending on the fluid formulation. Reduction of the controllable fluid viscosity by terminating a magnetic field acting upon the fluid may permit in situ wellbore pressure to actuate a downhole device, such as a wellbore packer.

Abstract: Sealing elements for well packers and bridgeplugs may be constructed with magnetorheological elastomers or foams disposed about electromagnet windings set in an internal mandrel. The elastomer or foam stiffness properties are formulated for a low setting force compliance in the absence of a magnetic field. After deployment, the tool winding is energized to engage the magnetic field and raise the stiffness properties of the elastomer or foam. When the magnetic field is activated, the packer or bridgeplug has greater structural resistance to unwanted pressure displacement. When the field is de-energized, the sealing element relaxes to permit resetting or removal.

Abstract: Downhole wellbore tools are actuated by electrically controllable fluids that are energized by a magnetic field. When energized, the viscosity state of the fluid may be increased by a degree depending on the fluid formulation. Reduction of the controllable fluid viscosity by terminating a magnetic field acting upon the fluid may permit in situ wellbore pressure to displace a tool actuating piston. When the field is de-energized, the controllable fluid viscosity quickly falls thereby permitting the fluid to flow through an open orifice into a low pressure receiving volume. In an alternative embodiment of the invention, an expandable volume fluid may be used against a slip actuating element in the same manner as a fluid pressure motor.