Effect of Silica Nanoparticles on Thermal Stability in Bentonite Free Water-Based Drilling Fluids to Improve its Rheological and Filtration Properties After Aging Process

In the Oil & Gas industry, preserve filtration properties of the drilling fluids based on the rheological behavior under prolonged exposure time, and temperature (aging process) are the most important challenges due to the implications that lead to the formation damage. The polymers as xanthan gum (XG) suffer degradation due to the drilling processes losing their viscosifying capacity, solid suspension, and subsequent the filtration control since the effective build-up of the mudcake is not possible. In this way, this study aims to evaluate the effect of SiO2 nanoparticles on thermal stability under thermal rolling process in the filtration properties through of the rheological behavior in bentonite-free water-based mud (BFWBM). Two kinds of SiO2 nanoparticles were evaluated: (1) synthesized through the sol-gel method and (2) fumed silica nanoparticles. SiO2 nanoparticles were characterized by dynamic light scattering (DLS), Fourier transform infrared spectroscopy (FTIR), and zeta potential (ZP). The SiO2 -XG interactions were evaluated through polymer adsorption onto nanoparticles using a batch-mode, rheological studies, and evaluation of thermal stability. Additionally, the effect of SiO2 nanoparticles on basic (pH, density, solid content, rheological, and filtration) properties in BFWBM were studied according to American Petroleum Institute (API) standard after aging through hot roller oven at 77°C for 16 hours. Results of adsorption experiments showed that adsorption isotherms of XG polymer onto silica followed a Type I behavior and these were modeled using solid-liquid equilibrium (SLE) model, showing an uptake adsorbed higher for the SiC nanoparticle than other materials. The rheological conduct of XG polymer - SiO2 nanoparticles system showed a pseudoplastic behavior with a high performance of SiC nanoparticles with an increase of 15% of the viscosity and inhibition of the degradation of the 32.2% compared with the polymer sample without nanoparticles. Also, the experimental results showed that the addition of SiO2 nanoparticles did not alter the basic properties such as pH, density, and solid content. Meanwhile, SiC increased the plastic viscosity (PV), yield point (YP), yield stress (YS), and gel strength of the drilling fluid and reduced the filtration volume and the mudcake thickness of the drilling fluid after the thermal rolling process. Also, these nanoparticles showed the highest increase of the VP, YP, and YS by 12, 19, and 100%, respectively. Additionally, SiC nanoparticles reduced the spurt loss and total filtration volume by 67 and 49%, respectively. Nanoparticles strengthened the hydrogen bonds with polymer preventing the hydrolysis.