Comparison of Oil Transmissivity Methods Using Bail‐Down Test Data

Abstract

This paper evaluates the results from three methods commonly used to estimate oil transmissivity: the modified Cooper solution (Beckett and Lyverse 2002), the modified Bouwer and Rice method (Kirkman 2013), and the modified Jacob and Lohman method (Huntley 2000). Determining the validity of oil transmissivity values is important (e.g., when used in extraction system design and operation) and not straightforward as these methods are based on different assumptions and boundary conditions and introduce different simplifying assumptions to allow for estimating oil drawdown. Data from 289 bail‐down tests performed during an oil remediation project were used in this evaluation. Analysis of these tests produced realistic transmissivity values and good correlation between these three methods, giving the authors confidence in the oil transmissivity values as this correlation is reflected across a significant number of data sets. Secondly, the nature of oil and water recharge to the wells interpreted from Kirkman's J‐ratio values largely validates the Huntley (2000) simplifying assumption that the potentiometric surface will be relatively constant during the test, allowing the use of the modified Bouwer and Rice method. Finally, the impact of oil extraction on measured oil thickness and estimated oil transmissivity was also assessed. The study showed a clear general decrease in both measured oil thicknesses and estimated oil transmissivity during the oil recovery project. However, measured oil thickness and estimated oil transmissivity are not clearly correlated, and, as a consequence, the range of decrease in one parameter does not allow any prediction of the range of decrease in the second parameter.

Evaluation of LNAPL distribution and mobility in heterogeneous porous media under water table fluctuations

“…It also comprises the coupled effects produced by the variable water 470 table as well as the potential migration and natural losses occurring within the NAPL 471 body. For instance, in this research the decrease in T n,BD due to natural conditions 472 without remediation operations was similar to that presented in the literature after 18 473 months of LNAPL recovery (Palmier et al, 2016). Consequently, the understanding 474 of these effects is essential in order to select the most adequate remediation 475 technology, for instance in cases where mass recovery techniques should be replaced 476 by monitored natural attenuation strategies; 477 (iii) the effect of the water table fluctuations is linked to the geological setting 478 and the NAPL distribution.…”

“…Thus, the 318 low intrinsic permeability at area C is a key factor for the lower T n values, besides of 319 the differences in LNAPL distribution. This lack of correlation between T n and b n was 320 unexpected since it has been also documented in the literature (Palmier et al, 2016). 322 However, a positive relationship between these two parameters was found at specific 323 tested wells under unconfined LNAPL conditions , consistent with the multiphase 324 theory (Lenhard et al, 2017), although the coefficients of determination were just 325 between 0.35 and 0.76.…”

“…7 indicated that the assessment of the performance of a 402 remediation system through T n could be misleading. For instance, other authors 403 acknowledged the effectiveness of a LNAPL recovery system after observing a T n 404 decrease of 47% in 18 months of recovery (Palmier et al, 2016). However, Fig.…”

“…The data was analysed by using 275 the modified Bouwer and Rice equation : 276 It should be noted that some of the theoretical assumptions in the Bouwer and 285 Rice approach are not necessarily met for multiphase 286 systems and T n analysis (Batu, 2012). However, several authors have defended this 287 methodology claiming that is robust enough under both field and laboratory 288 conditions (Charbeneau et al, 2013;Palmier et al, 2017), with different analytical 289 solutions presenting a good correlation at field scale under unconfined conditions 290 (Palmier et al, 2016). 291…”

Unifying NAPL Drawdown and Transmissivity Testing in Unconfined, Confined, Perched, and Fractured Settings using the Z‐Factor and MH Principles

“…The C coefficient is used because the well is typically screened over the entire mobile LNAPL interval. The accuracy of using a pseudosteady‐state methodology has been demonstrated to provide reasonable consistency with unsteady state methods in unconsolidated porous media (Palmier et al, ).…”