Presented are results the of an experimental study of formation permeability damage caused by invasion of the inert and extraneous solids simulated by barite particles. The use of barite facilitated X-ray computer assisted tomography (CAT) analysis of solids in the rock (determination of penetration distance) is employed because of the method's high resolution to barium.
Laboratory flow tests were performed using two types of sandstone cores: outcrop-clay free, and low clay content cores from oil bearing formations. The cores were analyzed using SEM, XRD, and pore size distribution. Particle size distribution of barite suspended in the influent NaCl brine and effluent was measured by particle size (laser PSA) analysis.
The prevailing mechanism of particle capture and subsequent permeability reduction under the test conditions was found to be cake forming (particle straining) mechanism.
The depth of invading barite solids penetration was detected and quantified by consecutive CAT scanning of core samples during rock damage tests. The preliminary experimental data presented show that CAT scanning technique could be used in more detailed studies of formation damage phenomena employing barite particles.