Experimental Study on the Effect of Nano-silica on Mud Density in Synthetic Based Mud

Drilling fluids play important roles in drilling operations to suspend cuttings, counter high formation pressure and to ensure wellbore stability. Amongst the different types
of drilling fluids, currently synthetic based muds are the choice drilling fluid due to its high performance in HPHT wells in terms of wellbore stability and high penetration rates. However, under HPHT conditions, the well will encounter thermal degradation of mud properties, which will affect the performance of the mud, such as fluid loss, unstable rheology and barite sag. Barite sag is an effect of high density and high solid content in muds, in which the heavy solids in the mud settle at the bottom of the wellbore causing pipe sticking and lost of circulation. The experiment was carried out at LPLT, starting of HPHT and extreme HPHT conditions with a varying nano-silica concentration of 0%(base case) to 40%. At different mud weights, the formulated drilling fluid will be tested for HPHT filtrate loss, stable rheology and static sag at a 45° tilt. Nano-silica has been proven in this project to be only effective for fluid loss and improve mud rheology due to the nature of nano-silica as a plugging agent. The nano-silica had no effect on barite sag as proven in this experiment. Nevertheless, the newly formulated mud is still effective for solving and preventing downhole problems.