Nuclear magnetic resonance (MR) (NMR) is commonly used for the determination of rock porosity, as well as pore size distribution (PSD) and tortuosity, required to handle hydrocarbon exploitation. Emerging technologies for NMR equipment now enable the visualization of porosity using magnetic resonance imaging (MRI). Currently, single‐point imaging is the most common MRI technique employed, but diffusion‐weighted imaging has been attracting the attention of geologists and geophysicists. In this study, a more advanced technique, diffusion tensor imaging (DTI), is proposed for the characterization of rock core samples. The main purpose of this paper is to demonstrate the usefulness of DTI in the petrophysical characterization of rocks and discuss its strengths. As an example, a carbonate core sample was examined using DTI. The diffusion tensor (DT) was obtained and DT parameters (mean diffusivity, MD; fractional anisotropy, FA; three eigenvalues; DT components; and proton density, PD) were visualized in 2D and 3D. Each parameter was described and its utility in terms of pore space characterization was analyzed. In addition, a new parameter, principal diffusion tracts, was introduced based on the DT tractography performed in the study. The analysis is summarized in a set of DT parameters and a resultant ellipsoid that delivers complementary information about the sample's pore network microgeometry, including referential measurements of anisotropic phantoms. The applications of DTI for the determination of pore size distribution, tortuosity and conductivity are also shown. The study ends with a consideration of the potential prospects and challenges for DTI‐based examination of rock core samples.

The development of a relatively small and isolated part of the Wuchiapingian, Zechstein Wielichowo Reef was possible owing to a progressive subsidence and frequent sea level fluctuations. Three biofacies were distinguished within the studied object: (1) a shallow-water and highly energetic Acanthocladia biofacies, dominated by bryozoans and crinoids, with poorly preserved porosity, reduced mainly by calcite cementation and compaction; (2) the Horridonia biofacies comprising numerous brachiopods, preferring a moderate depth of water, with comparably poor porosity; and (3) the Fenestella/Kingopora biofacies rich in fossils of the highest variability, related to the deepest and calmest waters, occurring on the top of the profile and showing a significant effective porosity, reaching almost 13%. Among many diagenetic processes altering the reef, several lines of evidence suggest that it was the meteoric diagenesis to enhance its porosity the most extensively. Since no stromatolites are present, the final sea level decrease is interpreted to be rapid, hence creating conditions favourable for the meteoric dissolution. Some intraparticle porosity, however, seems to be of a depositional origin.