No abstract

The search for new formulations of lubricating additives in drilling fluids is constant, due to the need of the oil and gas industry to improve products and processes and preserve the ecosystem, contributing to the sustainable development. The use of microemulsions in the upstream phase is increasing, mainly in the area of advanced oil recovery, but innovative in the area of oil well drilling. The objective of this study was to develop and characterize biodegradable microemulsions and of low production costs for application as a lubricant additive for water-based drilling fluids. For this purpose, the following were carried out: a) stability test on microemulsions and additive drilling fluids; b) particle size testing in the microemulsions; c) turbidity point test, in order to evaluate the microemulsion behavior regarding temperature; and d) lubricity test of microemulsions, proposed lubricant and additive drilling fluids. The lubricity results found were satisfactory, showing that the microemulsified systems evaluated can be applied as biodegradable lubricant additives in water-based drilling fluids for oil well drilling, causing less environmental impact.

RESUMOOs fluidos de perfuração são definidos como fluidos de circulação utilizados para auxiliar a operação de perfuração de poços. Especialmente, os fluidos base água apresentam uma série de características ambientalmente mais favoráveis, visto que seus descartes são aceitáveis pelos órgãos ambientais. Porém, a contaminação do fluido com sal originado das formações é um fator crítico para o uso do fluido base água, pois durante o processo de perfuração, o fluido pode sofrer a contaminação salina provocando um aumento repentino na taxa de penetração, na floculação e na viscosidade do fluido. Com isso, este trabalho teve o objetivo estudar a influência da concentração do sal (NaCl) na reologia de fluidos de perfuração base água. Com isso, foram formulados dois fluidos: FP1, com concentrações de NaCl de 2, 61, 2,87,3,12,3,37,3,62, 4,0 % em massa e FP2, com suspensão de bentonita previamente hidratada e 4% em massa de NaCl. Verificou--se que, o aumento da concentração de NaCl provocou um aumento em quase todos os parâmetros reológicos do FP1 (viscosidade aparente, forças géis iniciais e finais), causando a sedimentação das partículas sólidas do fluido na concentração de 4,0 % de NaCl, devido à sensibilidade da argila bentonita aos íons de sódio inibindo sua hidratação. Para o FP2, o uso da argila hidratada promoveu uma redução dos parâmetros reológicos, quando comparado ao FP1 com 4% de NaCl, evitando a sedimentação das partículas sólidas e garantindo, assim, sua estabilidade e seu uso em aplicações petrolíferas.PALAVRAS--CHAVE: fluidos de perfuração, reologia, Cloreto de sódio (NaCl). RHEOLOGICAL BEHAVIOR STUDY OF DRILLING WATER BASED FLUIDS: EFFECT OF CONCENTRATION NaCl ABSTRACTDrilling fluids are defined as circulation fluids used to aid the drilling of wells. Especially, water--based fluids have a number of more environmentally friendly characteristics, as their discards are acceptable to environmental agencies. However, the contamination of the salt fluid from the formations is a critical factor for the use of the water--based fluid, because during the drilling process the fluid can suffer saline contamination causing a sudden increase in the rate of penetration, flocculation and viscosity of the fluid. This study aimed to develop and study the influence of salt concentration (NaCl) on the rheology of water--based drilling fluids. Thus, two fluids were formulated: FP1, with NaCl concentrations of 2. 61, 2.87, 3.12, 3.37, 3.62, 4.0 mass% and FP2, with suspension of bentonite previously hydrated and 4% by mass of NaCl. It was verified that the increase of the NaCl concentration caused an increase in almost all rheological parameters of FP1 (apparent viscosity, initial and final gels), causing sedimentation of the solid particles of the fluid in the concentration of 4.0% NaCl, due to the sensitivity of the bentonite clay to the sodium ions inhibiting its hydration. For FP2, the use of the hydrated clay promoted a reduction of the rheological parameters when compared to FP1 with 4% of NaCl, avoiding the sediment...

This work has developed and evaluated a microemulsion-based drilling fluid formulation with characteristics to be applied in oil wells. The microemulsion was formulated with a solution of water/glycerol, pine oil, and Tween 80, a nonionic and biodegradable surfactant. The physical and chemical properties of the drilling fluid obtained in this work were investigated through rheology and filtration analysis, solids content, aging, lubricity, toxicity, and thermal degradation. A non-toxic microemulsion-based drilling fluid oil-in-water (O/W) with high lubricity (0.07638) and thermal stability was obtained with suitable viscosity, gel strength and low fluid loss (4.0 mL), low solids content (6%), stability in a wide range of salinity conditions, and the possibility of high water content (above 85% in mass fraction). The fluid presented a pseudoplastic behavior, and statistically significant Herschel–Bulkley parameters were obtained.

This study aimed to develop microemulsion through of ternary system composed of brine (aqueous phase), vegetable oil (oil phase), and non-ionic polyethoxylated surfactants, T20 and T80. From the ternary diagrams obtained, two systems were chosen in the regions of microemulsion (Winsor IV) and, subsequently, were conducted rheological study, at different temperatures, and cloud point studies of these systems. The results showed that the microemulsion of T20/brine/vegetable oil presented thermal stability up to 53° C and microemulsions of T80/brine/vegetable oil up to 72 o C, that could be due a change in micelle morphology and cloud point of each microemulsion system. The rheological results indicated non-Newtonian behavior, adjusted by Herschel -Bulkley model.