Experimental Study on Transport of Ultra-Dispersed Catalyst Particles in Porous Media

In situ upgrading of heavy oil by catalytic hydrogenation using submicrometer sized dispersed catalysts during thermal recovery is a promising new idea to achieve an environmentally sustainable method for unlocking heavy oil and bitumen resources. This requires placement of the ultradispersed catalyst particles deep into the formation where it can accelerate the high-temperature upgrading reactions. The objective of this work was to investigate the feasibility of transporting such ultradispersed catalyst particles through porous rock formations. This paper presents the results of experiments carried out to systematically examine the propagation of ultradispersed catalyst suspensions in sand packs. These experiments involved the injection of submicrometer-sized catalyst particles suspended in oil into a sand pack and analysis of the produced fluid samples and the sand bed. The results show that it is possible to propagate the ultradispersed catalyst suspension through sand beds. However, a fraction of the catalyst particles are retained by the sand (around 14 to 18%), and much higher retention occurs in the entrance region of the bed. Particles appear to be deposited on sand surfaces by an attachment mechanism deep inside the bed, but larger particles appear to be strained by mechanical trapping near the inlet face. The deposition of particles was found to be almost irreversible in the sense that the deposited particles could not be remobilized by reverse flow of the suspending medium.