Nano-clays as additives for controlling filtration properties of water-bentonite suspensions

Formation damage is a process that impairs the permeability of a reservoir and consequently decreases the natural flow of fluids from the reservoir into the formation. This phenomenon may occur due to various mechanisms, which reduces the well production. One of the most important factors that cause formation damage is drilling fluid invasion. Hence, designing additives for drilling fluid to minimize filtration into the formation is essential. Prior to the mud cake development, the primary factor involved in nano particles movement through the formation matrix seems to be due to the extra small size of these particles. However, in the case of mud cake creation, the nano particles bridging provides a barrier by which the transport of these tiny materials would be decreased substantially. In this study, the effect of different nano-materials like nano titanium, nano copper oxide, nano alumina, and nano-clay on drilling fluid filtrate is examined. Viscosity, filtration, and rheological properties of the newly designed mud were measured to characterize the formation damage due to mud invasion. Nano clay shows the best performance in controlling filtration and at a concentration of 6% it was able to reduce the filtration rate by about 5% more than conventional additives.