Fetkovich’s Approximation

Vogel’s correlation, normalizing q_o by q_o,max, is frequently not in close accordance with field data. Fetkovich (1973) suggested a normalization with , and in a flow equation of the form

the relationship becomes

Equation (3-63) requires the determination of two unknowns, the absolute open flow potential, q_o,max, and the exponent n. Both of them are characteristic of a specific well and therefore a test at two stabilized flow rates can allow the calculation of the corresponding p_wf and therefore can lead to the determination of q_o,max and n.

Equations (3-55) and (3-62) are both empirical fits and thus should be used accordingly.