Dr. Jerry Jensen, Ph.D.
Bureau of Economic Geology
The University of Texas at Austin
Engineers love permeability. After all, permeability is simple in concept, a major control on production and economics, and it is easy to measure. What’s not to love about permeability?
Alas, in truth, permeability is a difficult and mercurial rock property: 1) it is extremely variable, typically varying by four to six orders of magnitude in a reservoir; 2) permeability is scale-dependent, changing with sample size; and 3) permeability is direction dependent, changing by a factor of 10 or 100 when the flow direction changes. What a monster! Fortunately, there are a few ways to tame the beast, including 1) taking many samples, 2) measuring permeability in multiple ways; and 3) relating the permeability to the reservoir geological features.
This talk will demonstrate all these taming ways in a case study. We show that 1) integrating probe permeameter, core plug, and wireline tester measurements with the geology leads to a coherent picture of vertical permeability for the Ormskirk Sandstone; 2) without the geological information, we needed twice as many samples to obtain the same level of uncertainty of the estimated vertical permeability; and 3) permeability assessment within a geological framework reduces the upscaled vertical permeability variation from more than three orders of magnitude to less than one order of magnitude.