Short-Time Well Test Data Interpretation in the Presence of Skin Effect and Wellbore Storage

Short-time data are defined as data obtained before a conventional straight line is reached, during well testing (drawdown or buildup). Some of the factors that effect the short-time data are the effects of well-bore storage, perforations, partial penetration, and well stimulation, such as fracturing or acidizing. Although the effects of such factors are generally known, the duration and importance have not been clearly defined in all cases--particularly when these effects are combined in a well test. However, recent studies have revealed a great deal of potentially useful information concerning the analysis of short-time well test data. The purpose of this study is to illustrate the interpretation of short-time well test data through presentation of field examples. Factors to be considered include well-bore storage, well damage, and fractured wells. The log-log type-curve described shows clearly the presence of linear flow due to fracturing. It can be used to obtain quantitatively the information normally obtained from pressure buildup analyses and to identify the proper straight line in pseudoradial flow for a fractured well. (14 refs.)