Continuous porosity characterization: Metric-scale intervals in heterogeneous sedimentary rocks using medical CT-scanner

• Published in: Marine and petroleum geology 2019-11, Vol.109, p.361-380
• Main Authors: Larmagnat, Stéphanie, Des Roches, Mathieu, Daigle, Louis-Fréderic, Francus, Pierre, Lavoie, Denis, Raymond, Jasmin, Malo, Michel, Aubiès-Trouilh, Alexandre
• Format: Article
• Language: English
• Subjects: 3D porosity; Carbonate; Core-flooding; CT scan
• ISSN: 0264-8172; 1873-4073
• DOI: 10.1016/j.marpetgeo.2019.04.039

Although computed tomography (CT-Scanning) has been regularly applied to core analyses in petroleum geology, there is still a need to improve our ways to document porosity and porosity distribution in the entire pore scale spectrum, from the tens of nanometer to the meter-scale. Porosity imaging is particularly crucial for complex and heterogeneous rocks such as hydrothermally altered and fractured carbonates. The present work proposes an improved method using medical-CT to reliably estimate reservoir porosity. An in-house core-flooding setup allowed to analyse several individual core samples, scanned simultaneously (dry and saturated), as well as continuous core sections up to 1.5 m long. Without any prior knowledge of samples, three-dimensional alignment and subtraction of the two data sets (dry and saturated states) results in the generation of 3D porosity matrices. The methodology tested on a large set of reference core material shows a strong correlation between conventional gas porosimetry techniques and porosity from CT-scan. The added value of the porosity measurements by CT-scan is, first of all, the generation of 3D images of pore network, allowing to assess spatial attributes of macropores, their distribution and connectivity. Secondly, the CT-scan method also provides continuous porosity profile at the millimetric scale. Both developments are crucial for the understanding of reservoir rock properties. •Combined core-flooding setup and medical-CT give porosity for heterogeneous material.•Reference core material were tested and included 8 different lithologies.•The new CT methodology developed strongly correlates with conventional gas porosimetry.•3D porosity matrices and continuous porosity profiles at submillimetric scale are produced.