Enhancing Rock Mechanical Properties Estimation for Thin Beds Using Microresistivity Borehole Imaging Tool

Abstract

Abstract The knowledge of rock mechanical properties of the Zubair Formation is required to assure the success of future exploration and development of this reserves. Hence, high consistency and quality of these parameters could expressively increase the economic revenues derivable from the reservoir. The main objective of the current work is to generate a high-resolution continuous profile of the rock mechanical properties using microresistivity image log across the thin-bed intervals along with rock mechanical properties laboratory tests. Retrieved core samples from the Zubair sandstone formation were run through extensive laboratory testing. The rock strength parameters were determined using consolidated drained (CD) multistage triaxial tests, while static elastic parameters were measured using consolidated drained (CD) triaxial tests. A petrophysical log enhancement technique was applied to achieve enhanced resolution neutron porosity log (with a vertical resolution of 0.2 in.). The critical components of this process were achieved high-resolution neutron porosity log from microresistivity image log. This log was directly utilized to calculate high-resolution rock mechanical property logs through porosity empirical correlations. The resulting downscaled rock mechanical logs exhibited a reasonable degree of positive agreement between the estimated rock mechanical property logs (i.e., unconfined compressive strength (UCS), internal friction angle (φ), Young's modulus (E), Poisson's ratio (v), bulk modulus (K), and shear modulus (G)) and those acquired from the lab measurements, with 1.42%, 2.21%, 2.44%, 1.86%, 2.33%, and 1.92% absolute relative average difference (ARAD), respectively.