Compaction localization in porous rock

Experimental work on shear localization in porous sandstone led to the observation of nonuniform compaction. By analogy with shear localization, the process is referred to as compaction localization. To gain insight into the process of compaction localization, acoustic emission locations were used to define and track the thicknesses of localized zones of compaction during axisymmetric compression experiments. Zones of acoustic emission, demarcating the boundaries between the uncompacted and compacted regions, developed and moved parallel to the sample axis at velocities an order of magnitude higher than the imposed specimen shortening rate. Thus tabular zones of compaction were found to grow (thicken) in the direction of maximum compressive stress. These structures may form due to tectonic stresses or as a result of local stresses induced during production of fluids from wells, resulting in barriers to fluid (oil, gas, water) movement in sandstone reservoirs.