Performance and mechanism of new silicone polymer as filtrate reducer with inhibitory effect for water-based drilling fluid

An organic silicon filtrate reducer (AATN) with inhibitory effect, which can resist temperature up to 180 degrees C, was synthesized by using acrylamide (AM), vinyl trimethoxysilane (A-171), allyltrimethylammonium chloride (TM) and N-vinyl pyrrolidone (NVP) as monomers. AATN can effectively reduce the filtration loss of drilling fluid and inhibit the hydration expansion and hydration dispersion of the clay, which was beneficial to wellbore stability. Experimental results showed that the API filtration loss (FLAPI) of the drilling fluid containing 2 wt% AATN was only 7.8 ml. The siloxane groups of AATN were hydrolyzed in aqueous solution to generate Si-OH bonds, which can react with Si-OH bonds on hydrated clay surface to form a strong chemical adsorption. It was conducive to maintaining the dispersion of clay particles in the drilling fluid. The stable grid structure was formed by AATN and clay particles to reduce mud cake permeability, which can reduce the damage of drilling fluid filtrates to borehole stability. In addition, AATN can adsorb on the surface of sodium bentonite, thus forming a hydrophobic adsorption film on its surface, which effectively enveloped bentonite and inhibited the hydration expansion of bentonite.