Physical- and geomechanical properties of a drill core sample from 1.6 km depth at the Heletz site in Israel: Some implications for reservoir rock and CO2 storage

We have measured physical- and geomechanical properties of a core sample that was collected from 1.6 km depth at the Heletz site in Israel, within reservoir rock, layer A. The core sample is composed of poorly consolidated sandstone, with several layers of coarser grain sizes. Average bulk density and porosity are 1.93 +/- 0.11 g/cm(3) and 36 +/- 5%, respectively. Both nondestructive and destructive tests have been made on the core sample and its subsamples, including CT-scanning, oedometer tests, drained direct shear tests, as well as measurements of index properties, X-ray fluorescence and X-ray diffraction. These tests provide an initial evaluation of the properties of the reservoir rock, but are far from capturing epistemic variability of the reservoir rock. The results support the macroscopic observation, that the sample is poorly consolidated compared to its depth of deposition. The effective pre-consolidation pressure is less than 0.2 MPa and the maximum peak shear strength obtained is less than 1 MPa (normal stress = 1 MPa). In comparison, effective vertical stress from weight of the overlying rocks is estimated to 14 MPa using the average bulk density of the core. All measurements suggest that our reservoir rock sample is extremely weak with respect to its depth of deposition. (C) 2016 Elsevier Ltd. All rights reserved.