Experimental investigation of the effects of silica nanoparticle on hole cleaning efficiency of water-based drilling mud

摘要

Effective cuttings transports and hole cleaning is crucial for obtaining an efficient drilling operation. Recently, the use of nanotechnology have been exploited to improve rheological and filtration properties of water-based mud. Herein, water-based mud (WBM) was formulated with nanosilica to enhance cuttings and solid particles transports from the wellbore to the surface. Different weight percent concentrations of nanosilica (0.001-1.5 wt %) at three different flow rates in litres/seconds (0.4, 0.6 and 1.0) and cuttings sizes (small, medium and large) were used to investigate the formulated water-based mud lifting capacity of the drilled cuttings. Experimental results show that addition of the nanosilica concentrations to the WBM enhances the viscosity, thereby increasing the muds carrying and circulating capacity. Moreover, nanosilica water-based mud (n-WBM) displays improved mud stability with high propensity to prevent intrusion of formation fluids. The effect of cuttings size on the wellbore cleaning is minimal. The large cuttings size shows a lower degree of cuttings transportation compared with the small and medium cutting size. Accordingly, the small cuttings size has higher cuttings recovery to the surface. Finally, though increase in flow rate leads to more cuttings recovery, there is every tendency that much fluid flow rate will cause an increase in frictional pressure losses and equivalent circulating density, high pump pressure requirement and potential hole erosion.