Characteristics of ethoxylated fatty amine emulsion: Effects on the wettability and permeability of silicate formation under various pH conditions

Abstract

The effects of ethoxylated fatty amine emulsion on the wettability and permeability of silicate rock under various pH conditions, as well as the adsorption behavior of ethoxylated fatty amine on the silicate rock surface, were investigated using core displacement test, contact angle test and infrared spectroscopy. A new knowledge about the characteristic and mechanism of formation damage from reversible invert emulsion drilling fluids and a new method for the completion and cementing of a well drilled by reversible invert emulsion drilling fluids were proposed. Under pH of 4 to 8, exthoxylated fatty amine can adsorb on the rock surface to various degrees, resulting in the strong oil-wet condition of rock which does a serious harm to the permeability of the formation. Under pH of 10, no exthoxylated fatty amine adsorbs in the rock, resulting in the water-wet condition of the rock surface which is benefit to mitigating the damage of mud to the permeability of the formation. It is suggested removing the reversible invert emulsion drilling fluid using acidic fluids followed by basic fluids or using acidic fluids combined with wettability alteration agents. Key words: reversible invert emulsion drilling fluid, ethoxylated fatty amine, wettability, permeability, wettability reversal, formation damage