Patent ID: 8083499
Filing Date: 2011-12-27
Classification: E21B,F04B,F15B,Y10S

Abstract:
1. A system for pumping fluid comprising: a hydraulic pump; a down hole pump; a rod, piston and cylinder assembly, the piston located about an end of the rod in the cylinder, the rod slideably mounted to the cylinder in a radially offset position, the rod including a central axis offset from, and parallel to, a centerline of the cylinder to impede a rotation of the piston about the rod, the rod configured to reciprocate up and down with respect to the cylinder according to a hydraulic pressure supplied by the hydraulic pump to control an operation of the down hole pump, the piston having two sides and the cylinder on each side of the piston being hydraulically connected with the cylinder on the other side of the piston and the hydraulic pressure in the cylinder being approximately equalized on both sides of the piston, a hydraulic force not acting directly against the piston but against the end of the rod, causing the rod to raise or lower within the cylinder as the pressure is modulated; and a sensor mounted within the cylinder and spaced apart from the rod, the central axis offset of the rod protecting the sensor from damage by piston rotation, the sensor configured to measure a rod position within the cylinder to provide feedback to a hydraulic system controller.