In the last decade, majority of works in oil and gas upstream industry relate clay is always associated with its application in drilling fluid. Clay is added into drilling fluids for viscosity control and to aid the transport of cuttings from the bottom of the well to the surface. Clay also helps create filtration control to minimize formation damage. Clay has the capability to create a stable network to keep drill cutting in suspension whenever circulation is halted. Based on this unique characteristic, Badrul has formulated super low density completion fluid (less than 5.0 ppg) with the use of clay as stabilizing agent and glass bubble as density reducing agent. Field trial using similar fluid based on formulation in the lab has shown remarkable increase of oil production. This paper presents a series of investigation with the use of XRD, SEM and particle size analyzer in an effort to understand the bonding mechanism and role of clay in the formulation. Clay was grind close to nano scale to increase fluid stability. Experimental results show that final fluid stability is strongly clay dependent. However, reduction of clay particle size close to nano size seems to break the network in the clay. Thus, it reduces the agglomeration power of the clay and prevents it from binding the glass bubble. It is concluded that reducing the clay particle size seems to impair stability of the super light completion fluids.