Analysis of ''Slug Test'' Or DST Flow Period Data

In recent years, there has been a great interest in the "slug test" which involves the instantaneous removal of a specific quantity of fluid from a wellbore and measurement of the resulting pressure-time response. Although a skin effect term was introduced by Jaeger, most recent studies have not considered a skin effect in analyzing slug test data. A new approach to conventional well-test analysis by Earlougher and Kersch was used to prepare type curves for the slug tech which include the skin effect. This study includes: results presented in both tabular and graphical form to aid application, a new material on the radius investigated and the time of duration of slug test, and the presentation of field example illustrating the application and important limitations of the method, as well as limitations of conventional DST analyses. The main application of the slug test method is in the analysis of pressure data for cases wherein the fluid influx into the drill pipe tends to kill the flow (sometimes even before the tester valve is closed). On the other hand, many field test have been observed wherein the phenomena of critical (acoustic velocity) flow destroys the application of the method. The slug test, as currently developed, does not consider critical flow.