Avaliação de argila modificada por tensoativo para aplicação em fluido de perfuração à base de óleo vegetal

Abstract

The oil based drilling fluids are used in situations which require special characteristics such as high pressures and high temperatures required in drilling Pre-salt. For the development of a new formulation based fluid oil microemulsion was chosen due to its greater stability in the emulsion traditionally used. The fluids were prepared using a composition of the microemulsion (Winsor IV) defined by the ternary phase diagram consisting of soybean oil, lauryl alcohol trietoxilado and brine. In this microemulsion system was added sodium bentonite modified hexadecyl trimethyl ammonium bromide and barytes. The clay modification step was performed using three different concentrations of cationic surfactant in order to make possible the clay dispersion in organic medium. To evaluate the surface modification of clays were carried out the surface tension analysis and wettability analysis soybean oil, with the advance angle determination. To assist in implementation and processing of the data used a factorial design 2³ with the center point triplicate to evaluate the influence of the concentration of hexadecyl trimethyl ammonium surfactant in organophilization clay, the viscosifying concentration in the drilling fluid composition and temperature by the variables obtained responses. Rheological analysis provided plastic viscosity results, apparent viscosity, thixotropy and yield strength. The modified clay was measured as a function of contact angle and the results showed that there was a decrease in the contact angle as larger amounts of quaternary ammonium cations were adsorbed on clay surface, suggesting increased affinity for oil soybeans. The study of the effect of independent variables showed that temperature is the most influential factor in therheological properties of the prepared fluid.