Influence of the purification of bentonite clay from new deposits in the state of Paraíba-Brazil for use in water-based drilling fluids

Abstract

Bentonite clay is used all around the world as an additive in drilling fluids. However, impurities present in this material can compromise the compatibility of the clay-fluid system. The present study aimed to analyze the effects of the purification of bentonite samples from new deposits in the state of Paraíba, Brazil, in order to make them usable in water-based drilling fluids. The samples were first purified by centrifugation, and their characteristics were determined using the following techniques: laser granulometry, X-ray diffraction, chemical analysis, cation exchange capacity, thermogravimetric analysis, and differential thermal analysis. After these determinations, the polycationic clay samples were made sodic through the addition of sodium carbonate (Na2CO3) in the proportion of 125 meq/100 g of dry clay. The rheological and filtration properties (apparent viscosity, plastic viscosity, and filtrate volume) were then tested. The results showed that the purification process was efficient for removing accessory minerals such as quartz, iron, and carbonates. With regard to rheological and filtration properties, the results following centrifugation showed that the material can be suitable for use in water-based drilling fluids.

Influence of the additivation process on cation exchange capacity and viscosity of bentonitic clay dispersions

“…With such physicochemical versatility, bentonite clays have played an increasingly important role in many types of industrial applications, moving hundreds of millions of dollars into the global economy each year. Among these applications, this study highlights their use in aqueous drilling fluids [12][13][14].…”

“…Drilling fluids are primary suspensions of water and bentonite that play important roles in drilling wells [12,15,16]. Bentonite clays have been used for many years as a viscosifying agent in the composition of such suspensions and have various functions throughout the process.…”

“…Bentonite clays have been used for many years as a viscosifying agent in the composition of such suspensions and have various functions throughout the process. The success of drilling a well depends, among other factors, on the physical and chemical characteristics of the fluid used in the operation [12,17,18]. Their compositions are chosen to meet these characteristics, such as proper viscosity, consistency, filtrate control, lubrication coefficient, among others.…”

“…Their compositions are chosen to meet these characteristics, such as proper viscosity, consistency, filtrate control, lubrication coefficient, among others. To be used as a component of the drilling fluids, the bentonite must be sodic, so that the necessary swelling for the application is achieved [12], since the set of viscosimetric and filtration parameters (apparent viscosity -AV, plastic viscosity -PV, and filtrate volume -FV) has great influence of the polycations in the liquid phase of dispersions [19]. For use as components of drilling fluids in water-based petroleum wells, the presence of sodium as the predominant cation is required.…”

“…In Boa Vista, Paraíba, Brazil, due to the disorderly extraction, the clays of the best mineralogical compositions are exhausted. The varieties commercialized today are predominantly polycationic, containing other clay minerals, such as illite and kaolinite, as well as considerable amounts of non-clay components such as quartz and feldspar, which in turn compromise their technological applications [3,[9][10][11][12]. The polycationic bentonite clays can be changed to sodic form by a reversible double-exchange chemical reaction using sodium carbonate (Na 2 CO 3 ), since the interlamellar distance in the bentonites is higher when the lamellae have their charge compensated by the sodium ion, of lower valence, allowing the penetration of a greater amount of water in the space between the lamellae [1,16,17].…”