Digital rock analysis is a pore-scale imaging and numerical modelling technology to extract nanometre to centimetre scale geological and petrophysical information, as well as multi-phase fluid-flow data based on pore-scale displacement processes from digitised rock samples.

A prerequisite for calculating representative rock properties are high-quality 3D multi-scale images of a rock sample that capture the representative elementary volume (centimetre-millimetre) and at the same time resolve the finest structures, such as the smallest pores (micrometre-nanometre scale). Computed tomography is currently the best-suited technique to acquire 3D images of rock samples over several decades of length scales.

However, CT imaging with benchtop micro-CT machines below 1-micron voxel size are of lower quality and are extremely time consuming (>1 day/sample); imaging below 0.5 microns/voxel is not possible in a reasonable time and with acceptable quality.

The crux is that more than 60% of the reservoirs worldwide consist of rocks with very small pore systems, which require imaging at voxel sizes (far) below 1 micrometre with ideal scanning resolutions between 100 and 300 nanometres/voxel.

IRock scientists came to beamline ID19 to scan rock samples with varying sample diameters at resolutions ranging from micro- to nano-scale. They obtained quick and high-quality imaging at flexible voxel sizes and a range of sample sizes, which is not achievable with laboratory CT machines. The acquired images provide a profound base to build representative 3D digital rock models and extract rock properties at a high confidence level (Figure 145).


Fig. 145: Comparison of a carbonate rock imaged with conventional micro-CT (upper panel; 2 mm side length, 1 micro-metre voxel size) and synchrotron CT (lower panel; 0.5 mm side length, 280 nm voxel size). To the left are the 3D volumes, to the right are 2D slices. Black colour is pore space, light grey indicates solid grains and intermediate grey shades are unresolved voxels (partial volume effect).

In addition to the image quality, the higher sample throughput compared to laboratory devices helps iRock to plan and conduct projects for the oil and gas industry in a shorter time.