John G. Svinos, Theta Enterprises
A "smart" predictive computer program called RODSTAR has been developed that combines expert rod pumping knowledge with state-of- the-art wave equation and pumping unit modeling algorithms. With this computer program one can get optimized system designs in minutes by asking the program to calculate the strokes per minute, plunger size, and rod string design for a desired production rate. RODSTAR also helps the user select the pumping unit size and warns him about bad designs, pump or rods that are too big for the tubing, or pumping speed that is too high. The program's capability to automatically design steel or fiberglass rod strings ensures minimum rod loading and lowest rod string cost. In addition to the expert features of its design algorithms, the program calculates rod stresses at the top and bottom of each rod section to help avoid rod compression, and recommends prime mover size for NEMA D, gas engines, or ultra high slip motors. It also calculates prime mover energy consumption, monthly electricity bill, overall system efficiency, and the effect of prime mover speed variation and unit inertia on net gearbox torque. It can simulate full pump, fluid pound, or gas interference, and any pumping unit geometry including non-beam pumping units.