Abstract

A new approach to hyperbolic decline curve analysis has been developed which is efficient and timesaving and has made it possible to determine the hyperbolic b exponents characterized by thousands of wells. After extensive use of the technique the authors have concluded that the range of the b exponent as prescribed by Arps is too narrow.

Introduction

The extrapolation of decline curves is a valuable yet often misused· tool for predicting the future production rate and ultimate recovery of a producing well. Despite all the evidence as to the common applicability of hyperbolic curves to the extrapolation of historical production performance, many engineers continue to use only the constant percentage type decline analysis. A major contributing factor to this circumstance is the difficulty historically associated with use of the hyperbolic curve. While some engineers may use a french curve or a series of constant percentage declines with sequentially decreasing decline rates as an attempt to compensate for the conservative results of the constant percentage decline assumption, these procedures have neither the experience nor the theoretical background documentation available for hyperbolic declines.

This discussion emphasizes several circumstances, among many observed throughout the U.S., where the production curve exhibits a decline exponent, b, greater than 1.0, and demonstrates the ease with which engineers may use hyperbolic decline curves by using overlays in estimating future production rate and ultimate recovery. Relatively high b exponent values make the correct use of the hyperbolic curve more essential than ever before. When using this overlay technique to match the history of a producing well, the engineer acquires a visual perception of the uniqueness of the solution which is not readily apparent in a computer's numerical solution.

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