Quantification of sub-resolution porosity in carbonate rocks by applying high-salinity contrast brine using X-ray microtomography differential imaging. (October 2016)

• Record Type: Journal Article
• Authors: Lin, Qingyang; Al-Khulaifi, Yousef; Blunt, Martin J.; Bijeljic, Branko
• Is Part Of: Advances in water resources. Volume 96(2016)
• Page Start: 306
• Page End: 322
• Publication Date: 2016-10
• Subjects: Carbonate -- X-ray microtomography -- Sub-resolution porosity -- Micro-porosity -- Differential imaging; Hydrology -- Periodicals; Hydrodynamics -- Periodicals; Hydraulic engineering -- Periodicals; 551.48
• DOI: 10.1016/j.advwatres.2016.08.002
• Languages: English
• ISSNs: 0309-1708

Abstract

Highlights: A new flow-based method quantifies sub-resolution porosity in carbonates. Good agreement between porosity from image analysis and Helium measurement. Connectivity is provided and distribution of sub-resolution porosity is evaluated. Abstract: Characterisation of the pore space in carbonate reservoirs and aquifers is of utmost importance in a number of applications such as enhanced oil recovery, geological carbon storage and contaminant transport. We present a new experimental methodology that uses high-salinity contrast brine and differential imaging acquired by X-ray tomography to non-invasively obtain three-dimensional spatially resolved information on porosity and connectivity of two rock samples, Portland and Estaillades limestones, including sub-resolution micro-porosity. We demonstrate that by injecting 30 wt% KI brine solution, a sufficiently high phase contrast can be achieved allowing accurate three-phase segmentation based on differential imaging. This results in spatially resolved maps of the solid grain phase, sub-resolution micro-pores within the grains, and macro-pores. The total porosity values from the three-phase segmentation for two carbonate rock samples are shown to be in good agreement with Helium porosity measurements. Furthermore, our flow-based method allows for an accurate estimate of pore connectivity and a distribution of porosity within the sub-resolution pores.