Effects of nanoparticles on the performance of drilling fluids

Bal, Berk
In this master thesis, effects of nanoparticles on the filtration and rheological properties of water-based drilling fluids are experimentally investigated. Four different silica nanoparticles are added into the lignosulfonate and bentonite based drilling fluids. By using data obtained at the end of this research, filtration and rheological properties of nanofluids are analyzed and compared with the base fluids at different temperatures. Two groups of experiments are conducted in this research. In the first group, four water-based drilling fluids are formed by using bentonite, chrome free lignosulfonate (CFL) and carboxymethyl cellulose (CMC) in different concentrations. These fluids are selected as base fluids, and 0.5 lb/bbl of four different silica nanoparticles are added them to obtain nanofluids. The rheological properties, fluid loss amounts and mud cake thicknesses of samples with nanoparticles are investigated at 77 ºF and 120 ºF, and compared with base fluids. Results reveal that, all of the nanoparticles increase fluid loss of bentonite muds. On the other hand, reduction in fluid loss is observed for some lignosulfonate muds containing nanoparticle. Moreover, no significant change in mud cake thickness and rheological properties is seen for both drilling fluids. In the second part, experiments are conducted to see more clearly the effects of nanoparticles in bentonite mud. Because of this reason, only bentonite is used as additive to eliminate other parameters. Since rheological enhancement were not observed at the first part, these experiments have higher concentrations of bentonite and nanoparticles than previous tests, with 7% by weight of bentonite and 0.5% and 1.5% by weight of nanoparticles. It is seen that the amount of fluid loss increases with the addition of nanoparticles in all concentrations and all sizes. The rheological analyses show that, only 15-20 nm porous nanoparticles affects the rheology negatively at 0.5 w/w %. In addition to these experiments, permeability of mud cakes are also compared using Darcy’s Law. It is concluded that nanofluids form permeable mud cakes compared to base fluid.