**Abstract**

The goal of rock fabric characterization is to describe the spatial and geometric distribution of pore attributes as they impact petrophysical parameter variations such as porosity, permeability, and water saturation. Pore attributes such as pore size and pore volumes are critical petrophysical properties as they change and vary over a short distance or side-by-side, and determine the exploitable capacity of sedimentary reservoir rocks. A proposed new insight is in the systematic characterization of fabrics by the combination of both digital petrographic scanning and conservative petrographic description, as we show that multiple fabrics occur in a single lithofacie in the form of a fabric domain. Characterization shows that these domain types determine the spatial and geometric distribution of the variable pore sizes and volume (porosity) within a certain lithofacie fabric. Based on this, we also infer that these fabric domain types are responsible for the multiple occurrences of hydraulic fluid units (HFU's) and anomalous porosity-permeability relationships in siliciclastic sandstone sedimentary rocks since no long-range process aligns the microscopic internal fabric or microfabric architecture among grain aggregates in sedimentary rock.

**Keywords:** sedimentary rock, rock fabric, fabric domain, reservoir characterization, pore size, petrographic description
