Patent ID: 6764108
Filing Date: 2004-07-20
Classification: E21B,F16L

Abstract:
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 the 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 frusto-conical and 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 the connecting element, and being characterized in that, for an outside diameter of the connecting element (DEN), an internal diameter (DIN) of the connecting element, and a starting diameter of the torque shoulder on the connecting element (DHT), the following ratios are maintained:RangeDiameter RatiosMin.Max.DHT/DEN0.600.98DIN/DEN0.150.90DIN/DHT0.25â€‰0.92.