This paper aims to study the effect of compositions of bentonite organoclays for drilling fluids containing organic base. The compositions were studied using the mixture design of experiment methodology and their performance evaluated by rheological behavior (flow curves, the initial gel, final gel apparent viscosity, plastic, and flow limit) and the tests recommended by API (specific gravity, electrical stability and filtrate volume). Results were compared to those obtained with standard fluid used by Petrobrás. The results showed that among the developed compositions, two compositions showed promising potential for use in organic drilling fluids, achieving most of the limits of the normalization. Compositions containing high amount of low quality clays (Bofe and verde-lodo) and a minimum of high quality clay (Chocolate) of the mines of Boa Vista PB were developed for using in drilling fluids operation.
drilling fluids; rheology; non-ionic additive
