Bentonite/Polymers composites development to application in drilling fluids

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.