一种新型温控变黏酸体系的研究

根据地层温度随深度升高而升高的特点，以聚合物与表面活性剂Biggs三阶段模型为理论基础，由BCG-5稠化剂、HB-2缓蚀剂、NC-1活性剂构成了一种变黏酸体系，该体系低温低黏度，随温度升高表观黏度增大。对比了不同稠化剂浓度的增黏能力，测试了活性剂含量对体系温控变黏性能的影响，优选了缓蚀剂的型号与含量。结果表明，室温下该体系的表观黏度为29 mPa×s，在90℃下加热20 min后表观黏度逐步上升到250 mPa×s，100℃下仍具有变黏能力，缓蚀率可达到90.1%，与岩屑反应后表观黏度下降至5 mPa×s，表面张力为20 mN/m，有利于提高施工的供液能力、降低摩阻、深部酸化及酸压。 

Study on a New Temperature-controlled Variable Viscosity Acid

A variable viscosity acid was formulated with a viscosifier BCG-5, a corrosion inhibitor HB-2 and an active agent NC-1. This acid, formulated on the theoretical basis of the Biggs’ three-stage model describing the reaction between polymer and surfactant, shows low apparent viscosity at low temperature, and shows high apparent viscosity at high temperature. Since formation temperature increases with depth, this acid, when injected into the formation, will show low viscosity in shallow depth and high viscosity in deep depth. Laboratory experiments have been conducted to compare the viscosifying capacity of different thickening agents, test the effects of the content of the active agent on the viscosifying of the acid under the control of temperature, and optimize the type and concentration of the corrosion inhibitor. It was found that the apparent viscosity of the acid was 29 mPa·s at room temperature, and gradually increased to 250 mPa·s after being heated at 90 ℃ for 20 min. At 100 ℃, the acid still had ability to change its viscosity. The corrosion rate of this acid was retarded by 90.1%. The apparent viscosity of the acid was reduced to 5 mPa·s after reaction with rocks, and the surface tension of the acid became 20 mN/m, which is helpful to increasing the flow conductivity, reducing friction and drag and performing in-depth acidizing and acid-fracturing.