2. n. [Well Testing]
The theoretical flow capacity of gas wells if the bottomhole pressure could be reduced to atmospheric pressure. Test procedures to determine the AOF (Atmospheric Open-Flow) potential were often prescribed by law and enforced by state agencies. The open-flow potential capacity of the well was then used to determine the maximum rate that the gas well would be allowed to produce into a pipeline. During that period when there was an excessive amount of gas available for sale, this approach allowed an orderly method of allocating production rights to operators. The methodology is still used in some areas. The test required use of multiple rates, usually three or four, with measurement or calculation of the bottomhole pressure at the end of each flow period. The values of the difference between the square of the average reservoir pressure and the square of the bottomhole pressure were computed for each flow rate. These values were then plotted on the y-axis of a log-log plot versus the rate on the x-axis. The value of the open-flow potential is obtained by extrapolating the best straight line to the value of the average reservoir pressure squared minus atmospheric pressure squared, and then reading the corresponding rate off the x-axis.