Fluido de perfuração aquoso viscosificado com atapulgita - efeito da contaminação com hidróxido de cálcio e salmoura

Abstract

Drilling fluids are of great importance in the drilling of well, facilitating the separation of gravel on the surface, keeping solids in suspension when at rest, be inert and not damage the producing rocks. A contaminant is considered any material that causes undesirable changes in the properties of the drilling fluid. Contamination of aqueous fluid by calcium hydroxide (Ca(OH)2) present in the well cement paste composition can cause undesirable variations in the drilling fluid properties, increasing the filtrate volume and pH, slowing the drilling rate, altering the rhelogical properties. Brine contamination can be critical to aqueous drilling fluid increasing rheological parameters. This work aims to analyze the effect of contamination by calcium hydroxide (Ca(OH)2) and brine in two aqueous drilling fluids, one viscosified with polymer and the other viscosified with attapulgite, verifying how much this contamination alters the properties of the fluids. The results obtained from the contamination with (Ca(OH)2) for the polymeric fluid and viscosified with attapulgite, and the polymeric fluid contaminated with brine show that these can be used without many problems in regions that do not have exploratory interests, which does not prevent the increase in the concentrations of contamination makes these fluids unfeasible. The results showed that the viscosified fluid with atapulgite is more resistant to this contamination, due to the low values of the filtrate volume.