Análise do efeito da concentração e da temperatura em fluidos com características reológicas similares as lamas de perfuração

Abstract

The drilling phase of an oil well in ultra-deep water depths (such as the pre-salt) is one of the most critical operations for oil and gas extraction. Thus, for the success of the drilling operation, there is a need to control various process parameters, such as drill bit cooling, maintenance of ideal operating pressure, and carrying of cuttings to the surface. These functions are usually performed by drilling fluids. Such drilling fluids have rheological properties (such as pseudoplasticity and thixotropy) whose complete phenomenological understanding has not yet been fully established. In this context, the main objective of this study was to evaluate the effect of temperature on the rheological properties of fluids with characteristics similar to drilling muds. Such a fluid was prepared based on xanthan gum, a polymer commonly used as a viscosifier in drilling muds used in offshore operations. In this study, the behavior of rheological properties was studied for three different volume concentration rates: 0.2%, 0.3%, and 0.4%. Furthermore, the behavior of the same mixture with a 0.3% concentration of xanthan gum was studied under temperature variation, which was 24°C, 34°C, and 44°C. The test was performed using a Brookfield DV-II+Pro digital viscometer, and temperature variation was obtained using the Brookfield TC-550 thermal bath. For each of the tests, ascending deformation rates were imposed on the fluid with the collection of viscosity-related information every 30 seconds. The results showed that as the polymer concentration in the solution increased, the apparent viscosity and pseudoplasticity of the fluid also increased. However, under conditions of high deformation rates, the influence of concentration was shown to be a variable with less influence on the fluid's rheology. Additionally, it was observed that the increase in temperature of the solutions reduced the apparent viscosity and degree of pseudoplasticity of the fluid.