Journal of Canadian Petroleum Technology
Volume 49, Number 7, July 2010, pp. 42-46

SPE-139430-PA

Discussion of Permeability Anisotropy Effect in Transformation

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DOI  More information 10.2118/139430-PA http://dx.doi.org/10.2118/139430-PA

Citation

  • Sheng, J.J. 2010. Discussion of Permeability Anisotropy Effect in Transformation. J Can Pet Technol  49 (7): 42-46. SPE-139430-PA. doi: 10.2118/139430-PA.

Discipline Categories

  • 6.8 Fundamental Research in Reservoir Description and Dynamics
  • 6.6.3 Pressure Transient Testing

Keywords

  • anisotropy, well testing, coordinate transformation, equivalent permeability, equivalent isotropic model

Summary

To solve an anisotropic flow problem, the problem is transformed into an equivalent isotropic problem. It is expected that an anisotropic solution can be readily obtained from the equivalent isotropic solution. However, sometimes that is not the case. Using the drawdown equation of a fully penetrated vertical well test and the drawdown and buildup equations for a probe test, this paper discusses when it is both possible and impossible to directly obtain an anisotropic solution from an isotropic solution. Because of the fact that transformation causes the changes in flow geometry and the shape of the wellbore or probe, the equivalent isotropic solution must be modified to obtain the anisotropic solution. Finally, a case of how horizontal well productivity was incorrectly derived in a published paper --caused by the misuse of the concept of anisotropy--is presented.

© 2010. Society of Petroleum Engineers

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History

  • Original manuscript received: 9 April 2008
  • Revised manuscript received: 3 May 2010
  • Manuscript approved: 6 May 2010
  • Published online: 1 July 2010
  • Version of record: 1 July 2010