Synthesis and Properties of High Temperature Resistant Environmental Protection Shear Strength Improving Agent

In order to improve the anti-viscosity and environmental performance of the extractant used for water-based drilling fluid, LVHY-1 was synthesized by using low viscosity anionic cellulose sodium salt (PAC-LV) and hexadecyl isocyanate as raw materials, and dibutyltin dilaurate (DBTDL) as catalyst. The optimum synthesis conditions were determined by orthogonal experiment: mass ratio of PAC-LV to cetyl isocyanate 4:1, reaction temperature 60 ℃, reaction time 12 h, DBTDL concentration 0.4%. The molecular structure was characterized by ¹H-NMR. Rheological property test results showed that the dynamic plastic ratio (RYP) increased with the increase of LVHY-1 after hot aging test at 120 ℃. After hot aging at 170 ℃ for 16 h, the RYP of 0.2% LVHY-1 drilling fluid still reached 0.5 Pa/mPa·s, and kept good effect after hot aging for 64 h, showing excellent temperature and weather resistance. Transmission electron microscopy (TEM) observation showed that LVHY-1 could form a three-dimensional network structure in solution, which was the reason for the effect of LVHY-1. The test structure of environmental performance showed that the semi-maximum effective concentration (EC₅₀) of LVHY-1 was 30 100 mg/L, and the biodegradability evaluation index (Y) was 18.25, which met the emission standard and was easy to be degraded by microorganisms.