Integrated Techniques for Continuous Rocks Elastic Properties Profile and Geomechanical Characterization

Abstract

The knowledge of rocks elastic properties (REP) is crucial to geomechanical modeling throughout an asset life cycle. Reliable geomechanical models requires calibration of well log REP with core measurements. However, sample availability, representativeness, time, and cost are problems associated with core measurements. In this paper, we integrated REP derived from two laboratory techniques performed on several core covering over 800 ft interval samples from Paleozoic tight sands and shale reservoirs to obtain a continuous REP profile for better- upscaling of reservoir model parameters. For lithology delineation, intact core samples were scanned utilizing MicroXRF. While, REP was measured using Autoscan and AutoLab systems. The Autoscan employs non- destructive technique to characterize the variability of REP. The AutoLab uses the standard triaxial testing method to provide REP at reservoir conditions. The results were tabulated and statistically treated to establish significant empirical relationships. REP derived from triaxial tests on selected samples include, the P and S wave velocities (Vp and Vs), static moduli (Young’s modulus (Es) and Poisson’s ratio (vs)), as well as dynamic moduli (Young’s modulus (Ed) and Poisson’s ratio (vd)). While the reduced Young’s modulus (E*) was obtained from non- destructive method. Lithofacies were established from elemental data. The E* reveals details of several geomechanical heterogeneity and anisotropy which are not possible with traditional triaxial method. There is a significant correlation between E* and Es, Ed, Vs, and Vp. A continuous REP profile was developed using E* with geochemical data. Based on the characterized profile, fracture height growth barriers identified were toughness/modulus and interface barriers. These can significantly affect hydraulic fracture vertical growth within the studied Paleozoic tight sands and shale reservoirs units. The approach, which uniquely considered scales of rock geochemical and mechanical properties and data analytics, demostrate the possibility of generating a continuous REP profile using laboratory aquired dataset. Thus, the difficulty associated with geomechanical characterization and model calibration of highly laminated unconventional reservoirs using actual laboratory data is resolved. This has a directly implication to both conventional and unconventional geomechanical modeling, where the determination of upscaled-reservoir model parameters matters.