Quantifying Contact and Grain Stresses Driving Pressure Solution Creep

Pressure solution creep (PSC) is a major deformation mechanism in the Earth’s upper crust that constrains geophysical processes and the performance of hydrogen and CO2 storage reservoirs. PSC occurs in fluid-saturated granular media (e.g., halite, calcite, or quartz grains) through dissolution of minerals at particle contacts, transport of minerals through fluid-filled pores, and deposition of minerals onto grain surfaces. Despite extensive study, many uncertainties persist regarding the appropriate relationships between local stresses, local dissolution/precipitation rates and global creep rates. The purpose of the proposed work is to provide the first simultaneous measurements of contact-scale stresses driving dissolution, grain-scale shape changes resulting from precipitation, and sample-scale creep rates during the PSC process in small packings of halite grains by using x-ray tomography (XRT), 3D x-ray diffraction (3DXRD) and scanning 3DXRD (s3DXRD).