Patent ID: 6152231
Filing Date: 2000-11-28
Classification: E21B,F04C,F05B

Abstract:
For use with a pumping system in which a downhole pump has a rotor which is rotated by the bottom end of a rod string of which the top end is in turn rotated by torque energy derived from a prime mover, and in which twist energy is stored in the rod string during operation,a braking mechanism for avoiding a too sudden release of said twist energy in the rod string on shut down or power failure, the mechanism comprising:a) a rotary member mounted so that it rotates at a consistent speed ratio and direction with respect to the top end of the rod string,b) a fluid pump,c) a reservoir containing a fluid,d) an input conduit communicating the fluid in the reservoir with the intake of said fluid pump,e) an output conduit communicating the fluid in the reservoir with the output of said fluid pump,f) an adjustable flow-control valve located in one of said conduits, andg) an over-running clutch operatively associated with the fluid pump such that, when the top end of the rod string rotates in the direction corresponding to normal operation of the downhole pump, no pumping work is done by the fluid pump, but when the top end of the rod string rotates in the direction opposite that corresponding to normal operation of the downhole pump, the fluid pump does the work of pumping the fluid out of and then back to said reservoir against a resistance determined by the setting of the valve,whereby if the stored energy in the rod string is suddenly released, the energy is dissipated in a controlled manner.