Synergistic effect of nanoparticles and viscoelastic surfactants to improve properties of drilling fluids

Abstract

The conservation of rheological and filtration properties of drilling fluids is essential during drillingoperations. However, high-pressure and high-temperature conditions may affect drilling fluid additives,leading to their degradation and reduced performance during operation. Hence, the main objective ofthis study is to formulate and evaluate a viscoelastic surfactant (VES) to design water-based drillingnanofluids (DNF). Silica nanomaterials are also incorporated into fluids to improve their main functionalcharacteristics under harsh conditions. The investigation included: i) synthesis and characterization ofVES through zeta potential, thermogravimetric analysis (TGA), Fourier transform infrared spectroscopy(FTIR), atomic force microscopy (AFM), and rheological behavior; ii) the effect of the presence of VEScombined with silica nanoparticles on the rheological, filtration, thermal, and structural properties bysteady and dynamic shear rheological, filter press, thermal aging assays, and SEM (SEM) assays,respectively; and iii) evaluation of filtration properties at the pore scale through a microfluidic approach.The rheological results showed that water-based muds (WBMs) in the presence of VES exhibited shearthinningand viscoelastic behavior slightly higher than that of WBMs with xanthan gum (XGD).Furthermore, the filtration and thermal properties of the drilling fluid improved in the presence of VESand silica nanoparticles at 0.1 wt%. Compared to the WBMs based on XGD, the 30-min filtrate volume forDNF was reduced by 75%. Moreover, the Herschel-Bulkley model was employed to represent the rheologicalbehavior of fluids with an R2 of approximately 0.99. According to SEM, laminar and sphericalmicrostructures were observed for the WBMs based on VES and XGD, respectively. A uniform distributionof the nanoparticles was observed in the WBMs. The results obtained from microfluidic experimentsindicated low dynamic filtration for fluids containing VES and silica nanoparticles. Specifically, thefiltrate volume of fluids containing VES and VES with silica nanoparticles at 281 min was 0.35 and0.04 mL, respectively. The differences in the rheological, filtration, thermal, and structural results weremainly associated with the morphological structure of VES or XGD and surface interactions with otherWBMs additives.