A stator compound including an acrylonitrile butadiene isoprene rubber (NBIR) terpolymer elastomeric base.

A method of lining an inner surface of a tubular with a polymer, includes positioning a polymer injecting head within the tubular, forming an annular space between the injecting head and an inner surface of the tubular, injecting polymer through the injecting head into the annular space, and moving the polymer injecting head longitudinally relative to the tubular while injecting polymer.

A valve (11) for controlling the flow of a drilling fluid through a down-hole tool (10) positionable in a wellbore penetrating a subterranean formation. The down-hole tool has a housing with a drilling motor therein and a drill bit (1) at an end thereof. The drilling motor (9) has a housing with a rotor (206) rotationally movable in a rotor channel (204) as the drilling fluid passes through a rotor channel between the housing and the rotor. The rotor has a bypass channel therethrough for bypassing a portion of the drilling fluid therethrough. The valve includes a valve plate positionable upstream of the motor. The valve plate (200) has at least one flow passage (226) and at least one bypass passage (220) therethrough. The flow passage is in fluid communication with the rotor channel for passing the drilling fluid therethrough. The bypass passage is in selective fluid communication with the bypass channel when the rotor rotates about the housing and moves the bypass channel into alignment with at least a portion of the bypass passage for bypassing a portion of the drilling fluid therethrough whereby a hammering effect is generated on the bit.

A valve (11) for controlling the flow of a drilling fluid through a down-hole tool (10) positionable in a wellbore penetrating a subterranean formation. The down-hole tool has a housing with a drilling motor therein and a drill bit (1) at an end thereof. The drilling motor (9) has a housing with a rotor (206) rotationally movable in a rotor channel (204) as the drilling fluid passes through a rotor channel between the housing and the rotor. The rotor has a bypass channel therethrough for bypassing a portion of the drilling fluid therethrough. The valve includes a valve plate positionable upstream of the motor. The valve plate (200) has at least one flow passage (226) and at least one bypass passage (220) therethrough. The flow passage is in fluid communication with the rotor channel for passing the drilling fluid therethrough. The bypass passage is in selective fluid communication with the bypass channel when the rotor rotates about the housing and moves the bypass channel into alignment with at least a portion of the bypass passage for bypassing a portion of the drilling fluid therethrough whereby a hammering effect is generated on the bit.

Rotary positive displacement machines can include a rotor having a teardrop-shaped profile that undergoes planetary motion relative to a stator having an elliptical or near-elliptical profile. In some embodiments, these rotary positive displacement machines can be used for a variety of applications including as positive displacement pumps. In some embodiments the rotor and stator are helical. In some embodiments the rotor comprises a dynamic seal. Aspects of the machine geometry can be selected to provide operational and/or durability benefits.