Accuracy evaluation of an X-ray microtomography system

Area of Science:

• Geology
• Materials Science
• Petroleum Engineering

Background:

• Accurate microstructural parameter evaluation of reservoir rocks is crucial for petroleum production.
• X-ray computed microtomography (μ-CT) is a valuable non-destructive technique for assessing rock porosity, permeability, and pore size distribution.
• Existing calibration phantoms for μ-CT accuracy verification are often large and assessed at lower resolutions, posing limitations.

Purpose of the Study:

• To determine the accuracy of a specific X-ray computed microtomography system (Skyscan 1172).
• To validate the μ-CT method for precise microstructural parameter assessment in reservoir rocks.

Main Methods:

• Utilized a Skyscan 1172 X-ray microtomograph for analysis.
• Employed a nylon thread of known diameter within a glass tube as a calibration standard.
• Analyzed 401 cross-sectional images to evaluate porosity, size, and phase distribution.

Main Results:

• Porosity determined by μ-CT (31.0±0.3%) closely matched geometrically calculated values (33.4±3.4%).
• Excellent accuracy was achieved, with minimal variability (30.9% to 31.1%) across all analyzed cross-sections.
• Generated a 3-D volumetric rendering of the sample's porous structure from 2-D images.

Conclusions:

• The Skyscan 1172 X-ray microtomography system demonstrates high accuracy for reservoir rock microstructural analysis.
• μ-CT is a reliable and efficient method for obtaining precise porosity and pore size distribution data.
• The technique's non-destructive nature and minimal sample preparation requirements enhance its utility in petroleum geosciences.