Predicting the deliverability of a gas well is normally accomplished by conducting a four-point backpressure test, an isochronal test or a modified isochronal test. All of these methods require testing a well at a minimum of four flow rates. Several researchers have worked to advance the theory of predicting gas well deliverability using a one-point test. Their research focused on the development of dimensionless IPR curves for gas wells similar to Vogel's curve for oil wells.

This paper describes a method for predicting the deliverability of a gas well that requires only pressure build-up or draw-down test data. The method utilizes new dimensionless IPR curves that were developed specifically for hydraulically fractured gas wells. The curves may also be applied to unfractured wells by converting the apparent skin factor obtained from a pressure transient test to an equivalent ratio of external drainage radius to fracture half-length (xe/xf) using the apparent wellbore radius concept. Using the new curves or their general equation, an IPR curve can be constructed. In its simplest application, the new method allows an engineer to predict the AOF of a gas well which, when plotted on log-log paper along with the single stabilized point obtained from the pressure build-up or draw-down test, permits the construction of the stabilized deliverability curve and the determination of its equation.

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