Estudo da influência dos polissacarídeos e sais orgânicos nas propriedades físico-químicas de fluidos de perfuração aquosos

Abstract

Due to the main environmental restrictions regarding the use of oil-based drilling fluids, there is an increasing interest in the use of biopolymers in the composition of water-based fluids, due to the properties they provide to the mud. However, the relation between the polysaccharide's chemical structure and the drilling fluids properties is not commonly studied. The following work intends to establish the polysaccharide's contributions into aqueous drilling fluids properties, seeking to set a correlation among the chemical structure of Xanthan Gum, Guar Gum and Hydroxypropyl Starch, and the properties observed on mud. Xanthan Gum and Guar Gum showed a significant performance as rheological modifiers. This occurs, among other factors, because their high molar mass and employed conformation by the chain in the solution. The Hydroxypropyl Starch did not stand out as a rheological modifier, but as a filtrate controller agent, forming a low permeability cake. Furthermore, it was studied the changes caused in rheological and filtration parameters altering the brine of NaCl to an organic salts brine, in this case, Sodium formate (HCOONa), Potassium formate (HCOOK), Sodium acetate (CH3COONa) and Potassium acetate (CH3COOK), because this would cause a high environmental gain, since the disposal of drilling fluids at on-shore probes often occurs indiscriminately. When the constituted brine is composed of NaCl, the Cl- ion leaches the soil and can pollute aquifers, making the water unsafe for usage. it was verified that the change from the NaCl brine to the organic salts brine did not present any detriment in the rheological and filtration parameters, thus showing the organic salts can provide technically feasible fluids with less environmental impact. Although, regarding the salt's cost, the use of organic salts presents the downside of being considerably more expensive.