American Institute of Mining, Metallurgical, and Petroleum Engineers, Inc.
The actual production performance of a number of wells have been compared to predictions made by the McKinley afterflow analysis of drill stem test and short time production test data on these wells.
Many formations are tested for short time periods that do not give sufficient or periods that do not give sufficient or conclusive data for reservoir analysis by conventional methods thereby necessitating use of an afterflow method.
The example wells in this study show low permeability, wellbore damage, two zones permeability, wellbore damage, two zones with a large contrast in permeability, artificial stimulation and naturally occurring fracture systems with a tight matrix.
Example plotted curve shapes of the above conditions are illustrated along with a discussion of how to recognize and use each. Limitations as well as the applications of the McKinley afterflow method are discussed.
The most important use of the McKinley After-flow Method is the ability to predict the tight matrix production rate of a well after a stimulated wellbore area has been depleted. Comparison of drill stem test analysis before completion with production test analysis after completion on the same well give comparable answers.
Data on a group of wells selected from South Texas, the Permian Basin and Rocky Mountain areas have been furnished by the industry and the results are shown in Table 3. Illustrations of D.S.T. charts, Horner plots, McKinley plots and production decline curves are shown plots and production decline curves are shown for most examples.
The conclusions reached from this study show the McKinley afterflow method gives reliable predictions of reservoir performance when predictions of reservoir performance when conventional analysis methods cannot be used.
