Formulation Development of Drilling Fluids with DOE Mixture Model Design Technique.

Abstract

The aim of this thesis study is to investigate the effect of three components of a formulation of an oil-based drilling fluid, and how the variation of the percentage of each component affects the rheological behavior of the drilling fluid. By using statistic tools, the Mixture Design concept, and Design Expert software, a first design with 14 runs that vary the percentage of the components was created. After analyzing the results of this first design, data corrections and tests repetitions, more designs were developed. After the two first designs, a contaminant was introduced to the study as another component and its effect in three levels: low, medium and high. At this point the study turned to a Combined design, since we have a Mixture and Level design. To achieve the goal of the study, laboratory experiments and tests of various drilling fluid samples were conducted. These experiments were done at a constant temperature to study the following attributes: shear stress at different shear rates, the viscosity and the electrical stability. The experiments show that higher temperature has a more significant effect on the drilling fluid behavior, also the effect of the contaminant increases within the temperature. In addition, diagnostics plots of each component variation were studied to validate the model for each attribute. It was observed that the electrical stability does not have any relation with the components studied since no model fitted the data.