Patent ID: 7431347
Filing Date: 2008-10-07
Classification: E21B

Abstract:
1. An elongated drive string assembly comprising a plurality of hollow sucker rods and connecting elements with an axis, connected together and between a drive head located at the surface of an oil well and a rotary pump located deep down hole in an oil well, wherein each hollow sucker rod has at least a first end comprising an internal female threaded surface engaging an external male threaded surface on a connecting element, wherein said threads are frustro-conical, non-symmetrical but differential in diametral taper to each other; the first end of each hollow sucker rod further comprising an annular torque shoulder engaging an annular torque shoulder on a connecting element, and being characterized in that, for an outside diameter of the connecting element (DEN), an internal diameter (DIN1) of the connecting element, and a diameter of the torque shoulder on the connecting element (DHT1), the following ratios are maintained: