Fluidos inibidos para perfuração de folhelhos.

Abstract

To study geological formations susceptible to hydration is a challenge because it is a phenomenon responsible for about 90% of problems associated to the drilling of oil well, in addition it is a topic that deal with mechanisms little known governing this event and also due to the scarcity of the studies focused on the analysis of different products that avoid the occurrence of the hydration problems (inhibitors). In this way, the aim of this work was study the efficiency of the based water inhibited drilling fluids free of chlorine in the control of hydration of shale formation from various regions of the country. For this, it was studied thirteen samples of brazilian shales and two samples of bentonite clays. Firstly, it was done the characterization of the samples with the purpose of identifying the more susceptible to hydration. Then, it was studied the best concentration of the inhibitor to hinder the expansion of reactive clays and from these results it was established the best concentration of inhibitor (20g/350mL of water). After, it was developed drilling fluids with four different inhibitors of expansive clay (potassium phosphate, potassium acetate, potassium citrate and potassium chloride) and estimated the pH, density, rheological and filtration properties of these fluids. It is also estimated the dispersibility of the developed fluids. From the results, it was concluded that the fluids was developed with success and presented satisfactory rheological, filtration and inhibits properties. Excellent results with regard to the rates of dispersibility were also obtained. In general, the results indicated that the inhibitor potassium citrate presented the best control of reactivity of the formation and it constitutes an alternative to substitute the commercial inhibitors used by petroleum industry.