Estimating vertical permeability in the Ormskirk Sandstone, East Irish Sea Basin

Presenter

Dr. Jerry Jensen, Ph.D.
Research Engineer
Bureau of Economic Geology
The University of Texas at Austin

Description

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.