SPE Reservoir Evaluation & Engineering
Volume 14, Number 4, August 2011, pp. 457-472

Summary

This paper presents a new spherical-flow cubic-analysis procedure for estimating horizontal and vertical permeabilities solely from pressure-transient data acquired at an observation probe of a dual-packer-probe wireline formation tester (WFT). The procedure applies for all inclination angles of the wellbore in a single-layer, 3D anisotropic porous medium. It does not require one to know the formation thickness or to obtain radial flow. It is shown that the procedure provides unique estimates of horizontal and vertical permeabilities from observation-probe pressure data obtained along both vertical and horizontal wellbores. However, for slanted-well cases, the analysis procedure yields two possible solutions for the horizontal and vertical permeabilities. Therefore, one must use a priori information on permeabilities, from sources such as core data or pretests, to help identify the appropriate solution for the slantedwell cases. For the more general case of a 3D anisotropic medium, except for the vertical wellbores, an estimate of the anisotropy ratio and the azimuth angle of the well are also required as inputs for determining the values of horizontal and vertical permeability with our analysis procedure. We illustrate the applicability of the proposed analysis procedure by considering two synthetic and two field packer-probe data sets from vertical and slanted wellbores.

© 2011. Society of Petroleum Engineers

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History

• Original manuscript received: 25 December 2009
• Meeting paper published: 8 December 2009
• Revised manuscript received: 25 February 2011
• Manuscript approved: 9 March 2011
• Published online: 25 July 2011
• Version of record: 15 August 2011