通过室内岩心驱替实验、接触角测量、红外光谱分析研究了不同pH值清洗条件下聚氧乙烯脂肪胺乳状液对硅酸盐岩润湿性、渗透性的影响规律及聚氧乙烯脂肪胺在硅酸盐岩表面的吸附行为,提出了关于可逆逆乳化钻井液储集层损害特性和机理的新认识,以及可改进完井、固井效果的井眼清洗方法。研究表明:pH值为4~8的清洗条件下,聚氧乙烯脂肪胺在硅酸盐岩表面发生吸附,使岩石表面由水润湿状态转变为油润湿状态,严重损害储集层渗透性;pH值为10的清洗条件下,聚氧乙烯脂肪胺发生脱附,使储集层岩石表面恢复为水润湿状态,有利于减轻钻井液对储集层渗透性的损害。建议采用“先酸后碱”的井眼清洗方法,或者在酸清洗液中加入润湿反转剂。图2表2参21
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.