[CCoE Notice] Thesis Defense: Developing a Standard Protocol for Permeability from Thin Section Image Analysis

[Grayson, Audrey A]

Master’s Thesis Defense
Dutt Tripathi

Developing a Standard Protocol for Permeability from Thin Section Image Analysis

Date: May 3, 2018
Location: Energy Research Park, Building 9, Room 123
Time: 2 pm – 4 pm

      Committee Chair: Dr. Lori Hathon, Dr. Michael T. Myers, Dr. Matthew Andrew

Estimation of the petrophysical properties of subsurface samples using imaging techniques and image analysis has received a lot of attention in recent years.  Most of this has been focused on 3D imaging and subsequent modeling of formation properties, termed Digital Rock Physics, or DRP.  This work typically requires that an intact sample of material is available.  For cases in which sample type or quality are not sufficient for 3D imaging, or where cost is prohibitive, modeling of petrophysical properties using standard thin section images and image analysis is a viable alternative.  We apply   a Carmen-Kozeny type model to thin section images of samples for which laboratory measurements of porosity and brine permeability were made.  This has allowed us to model absolute permeability to within a factor of two for two sandstone samples having laboratory-measured permeability 600 mD, and 8 D respectively.  A key input parameter to this model is an estimate of specific surface area.  The 2D estimate of specific surface area is the ratio of the intergranular porosity perimeter to the total area analyzed.  As image magnification changes, and as down-sampling or filtering of the image are applied during analysis, the measure of specific surface area also changes. Fractal analysis for sandstones in thin section is performed, which allows us to account for the impact of magnification and processing when modeling permeability from 2D image data.  In addition to the 2D image analysis, application of the Lattice Boltzman model to high-resolution Micro-CT scans of the same samples provides additional flow estimates as well as permeability measurement.  The 3D images of the samples are analyzed with commercially available software.  In general the 2D model performs as well as, or better than, the 3D modeling for estimating absolute permeability.  In addition, total porosity from 2D image segmentation agrees to within +/- 2% of laboratory measured porosity, over a range of porosities from 15% - 35%.  The advantages of thin section imaging for estimating petrophysical properties,  include the ability to identify framework grain types for provenance and reservoir quality modeling studies, to differentiate between detrital and authigenic phases (e.g. detrital quartz framework grains versus quartz overgrowths), and to establish paragenesis.
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