Luciana Viana Amorim

Bentonites from Boa Vista, Brazil: physical, mineralogical and rheological properties

The aim of this work is to characterize physically and mineralogically six samples of natural and industrialized bentonites from Paraiba, Brazil, and to study its rheological properties to be used as a components of water based drilling fluids. Also it is intended to compare the evolution of the mineralogical composition and rheology of these clays after 40 years of exploitation. The natural bentonite clays were transformed into sodium bentonite by addition of concentrated Na2CO3 solution. The suspensions were prepared with 4.86% w/w to measure their rheological properties (apparent and plastic viscosities and water loss). The results showed that: i) the samples present typical mineralogical compositions of bentonites, but after four decades of exploitation, presents inferior quality and ii) among the clays samples, only one presented satisfactory rheological properties be used as a components of water based drilling fluids.

Fluidos de perfuração à base de água. Parte I: efeitos de aditivações poliméricas nas propriedades reológicas

Foram estudados os efeitos da incorporacao de quatro diferentes aditivos polimericos nas propriedades reologicas e de filtracao de fluidos de perfuracao a base de agua e argilas bentoniticas de Boa Vista, PB. Os resultados mostraram que estas propriedades sao fortemente influenciadas pela presenca dos polimeros e que o tamanho da cadeia polimerica e um fator determinante.

Desenvolvimento de compósitos bentonita/polímeros para aplicação em fluidos de perfuração

The polymeric addictivation of fluids used in oil wells drilling is a common practice and among the addictives more used, is the carboximethyl cellullose (CMC) and the partially-hydrolyzed polyacrylamide (PHPA), and depending of their characteristics, carry out different functions and they are added individually. The objective of this work is study binary compositions of cellullosics and non-cellullosic polymers to development of bentonite/polymers compositions to use in water based drilling fluids. Was studied one sodic bentonite clay sample from Paraiba and three polimerics additives (low viscosity and high viscosity CMC and PHPA). The polymer mixtures was elaborated to explore the basic compositions (100%-0%; 50%-50% and 0%-100%) as initial step. The polymeric compositions in three different concentrations was mixed with dry clay and after the drilling fluids was prepared. Following 24 h fluid resting, the apparent and plastic viscosities and water loss were established according to Petrobras standards. The results evidenced that the cellullosic and non-cellullosic polymers mixture showed to be more efficient improving the rheologic and filtration properties of water based drilling fluids. This way, is able the combination of raw materials of different attributes to obtain polymeric compositions to be added on bentonitics intending the development of bentonite/polymer composite to wells drilling uses.

Estudo da reologia e espessura do reboco de fluidos de perfuração: influência de dispersantes e umectante aniônicos

The aim of this work is to evaluate the influence of dispersants additives and anionic surfactants in the apparent viscosity (AV), plastic viscosity (PV), water loss (WL) and filter-cake thickness (FT) of the water based drilling fluids with bentonite clay. The fluids were prepared with 4.86 wt % of bentonite clay and the additives studied in the concentrations of 0.025 g to 0.300 g/24.3 g of dry clay for the dispersants and 0.005 g to 0.300 g/24.3 g of dry clay for the anionic surfactant. The results had shown the filter-cake thickness was significantly reduced by the presence of the anionic surfactant, without, however, to modify the taxes of filtration of studied fluids. As it was waited, it was observed the reduction in the values of AV and PV after treating the fluids with dispersants addictives. Also, the abrupt change in the values of AV, PV and FT of fluids treated with the anionic surfactant in the concentration of 0.100 g/24.3 g of dry clay evidenced that this is very probably the critical concentration micelar of this additive.

Bentonite/polymer compound development to application in drilling fluids: Part 2

The most important bentonite clays sources are placed at Paraíba state, Brazil. These clays are largely used as viscosity agent in drilling fluids. Unfortunately for some kinds of available clay their parameters are far from PETROBRAS standard. Treatments based on polymeric addition consist on method to improve such parameters. In order to improve these parameters, this work proposes a methodology to develop bentonite/polymers compound for use in water based drilling fluids. Besides the raw clay others samples have been evaluated: i) one sample of a commercial bentonite; ii) two samples of carboximethyl cellullose (CMC) and iii) one sample of partially-hydrolyzed polyacrylamide (PAM). Based on experimental planning, ten compositions of polymeric compound (mix of two and three polymers) have been evaluated. For each composition of polymeric compound three different concentrations was added to clay. All experimental fluids have been evaluated accordingly with PETROBRAS standard to determine apparent and plastic viscosity, yield stress, and water loss. The results of the analysis show that by polymeric treatment of bentonite clay with compound polymeric allow to obtain a mixture with improved rheologic properties. Finally, this procedure allows to use low quality bentonite clays for drilling fluids application.

Compostos poliméricos como aditivos de argilas bentoníticas

The aim of this work is to evaluate the effect of polymeric compound on the treatment of bentonite clays for using in water and clay based drilling fluids for the improvement of the filtration and the rheological properties. One industrialized sodic bentonite clay sample and three polymeric additive samples, being two samples of carboximethylcellulose and one of partially-hydrolyzed polyacrylamide, were studied. The compositions of the polymeric compound were obtained through the methodology of mixture design, being defined ten different compositions. The polymeric compound with dry clay was mixed in different concentrations and the drilling fluids were prepared according to the Petrobras standards; the apparent and plastic viscosities, the yield stress and the water loss were determined. The results show that the use of additives in bentonite clays with polymeric compound improves their properties, according to the Petrobras specifications for their use in water based drilling fluids.

Utilização do planejamento experimental no estudo do efeito da composição de misturas de bentonitas na reologia de fluidos de perfuração. Parte II: composições ternárias

The purpose of this work was to study of composition effect of ternary bentonite mixtures on the rheology of drilling fluids. Through the experimental design were defined the components proportions in the ternary clays mixtures and then adjusted regression models relating apparent and plastic viscosities and water loss, with the proportion of each clay. The application of mixture experimental design, include ternary composition, response surface methodology, graphic and mathematical optimization allowed to delimit a strip of compositions that favors the improvement of the rheological properties of the drilling fluids.

Degradação térmica de fluidos de perfuração argilosos aditivados com polímeros e lubrificante

The behavior of drilling fluids at high temperatures, particularly those which are water based drilling fluids, is unpredictable and, , has not been totally understood. In this way, optimizing the composition of the fluids becomes one of the main factors for the control of their properties. This is so because the rheological properties of the drilling fluids can present great differences at ambient temperature and in the interior of the well. This work aimed to evaluate the behavior of clay drilling fluids with polymer and lubricant additives at high temperature. Therefore studies were performed on the rheological properties, filtration and pH. The results evidenced that the fluids studied presented low values for the rheological properties and high values for the filtration properties. In addition to that, thermal aging caused a degradation process of the additives used, mainly the xanthan gum, resulting in pH reduction and in the caramelization of the fluids.

Bentonite Clays from Paraíba State, Brazil: Effects of Na and Mg Compounds in the Rheology of the Dispersions

The aim of this work is to study the effect of Na and Mg compounds (sodium carbonate and magnesium hydroxide) in the rheology of the bentonite clay dispersions from Paraíba State. Three samples of polycationics bentonites clays called Bofe, Chocolate and Verde-lodo from Paraiba deposits were studied. The results showed that the sequence of compound addition can modify the rheological behavior of the clay dispersions.

Avaliação de emulsificante baseado na borra de óleo de soja para fluidos de perfuração sintéticos.

Este trabalho visa avaliar o desempenho de um emulsificante baseado na borra de oleo de soja (EBO) para fluido de perfuracao sintetico a base de n-parafina. O estudo do emulsificante foi realizado em tres etapas distintas: na primeira, a caracterizacao do emulsificante por meio dos ensaios de ATG, DTA e FTIR; na segunda, a avaliacao do emulsificante de acordo com a norma EP-1EP-00028-A da Petrobras e, a terceira e ultima etapa, dedicada a avaliacao do emulsificante em formulacoes da industria, por meio das propriedades reologicas (viscosidade aparente (VA), viscosidade plastica (VP), limite de escoamento (LE) e forca gel (FG)), a estabilidade eletrica (EE) e o volume de filtrado HPHT (VF). A partir dos resultados obtidos pode-se concluir que: o emulsificante obtido a partir da borra do oleo de soja (EBO) e formado a partir de acidos graxos com ligacoes dos tipos C-H, C-O, C=O e C=C, com picos de intensidades e posicoes semelhantes ao oleo de soja puro, apresentando tres etapas de decomposicao termica: a primeira referente a perda de material volatil, a segunda a materia carbonosa e a terceira a decomposicao termica do EBO; a borra de oleo de soja pode ser utilizada como emulsificante primario para fluidos de perfuracao sintetico e, por fim, que o emulsificante EBO apresentou maior eficiencia nas propriedades reologicas (VA, VP, LE e FG) e de filtracao (VF) para fluidos sinteticos com razao oleo agua 60/40. No entanto, quando se trata da EE os melhores resultados foram obtidos para fluidos com razao oleo agua 70/30.