An Assessment of the Huntley (2000) Baildown Tests Data Analysis Method

Abstract

Introduction Oil baildown tests are routinely conducted in practice for determining oil conductivity in aquifers. The commonly used approach, in practice, is to adapt the existing slug test data analysis methods even though there are more sophisticated approaches based on numerical models (e.g., Zhu et al. 1993). Unfortunately, there are some controversial issues in applying especially the existing slug test data analysis methods to drawdown data for oils in aquifers and these are the main reasons for this commentary. Over 10 years ago, Huntley (2000) published a method under the title “Analytic Determination of Hydrocarbon Transmissivity from Baildown Tests.” This method is also included in the American Petroleum Institute (API) Interactive Guide (2002, Version 2.0, Release 2.04) based on Beckett and Lyverse (2002). Huntley presents his method mainly by applying the Bouwer and Rice (1976) slug test data analysis method with some modification to oil baildown tests by including a density correction factor. The same API Interactive Guide also includes the Lundy and Zimmerman Method (Lundy 2002), which is also based on the same modification on the Bouwer and Rice (1976) slug test data analysis method (Lundy 2002). Most importantly, the Lundy and Zimmerman method does not use a density correction factor as the case is for the Huntley method. The Bouwer and Rice slug test data analysis method is based on the Thiem equation (Thiem 1906), which predicts the drawdown in a confined aquifer under steady-state conditions. Therefore, the aforementioned modification by Huntley, and Lundy and Zimmerman imply that, in reality, the Thiem equation is modified.