Abstract:It is difficult to meet the needs of drilling engineering by simply changing the type and proportion of copolymer functional groups, for artificially synthesized polymers to be used as filtrate reducers for water-based drilling fluids, increasing the usage of energetic monomers will undoubtedly increase its cost, especially under ultra-high temperature and high salinity conditions, This study prepared a dual cross-linked fluid loss reducer by adding salt resistant monomer 2-acrylamide-2-methylpropanesulfonic acid (AMPS) and temperature resistant monomer N-vinylpyrrolidone (NVP) to the main monomer acrylamide (AM), and using organic and metal crosslinkers. Using the high-temperature filtration reduction effect of polymers as the evaluation index, single factor experiments were used to optimize the synthesis conditions: stirring speed of 300 rpm, monomer mass ratio AM/AMPS/NVP of 18/1/1, crosslinking agent dosage of 2.0wt%, organic crosslinking agent/metal crosslinking agent mass ratio (OC/MC) of 1/3, oil-water mass ratio of 3/2, and initiator dosage of 1.0 wt%. And the particle size distribution, surface morphology, element distribution, microstructure, and heat resistance of the copolymer were characterized using laser particle size analyzer, Fourier transform infrared spectroscopy (FT-IR), scanning electron microscope (SEM-EDS), and thermogravimetric analyzer (TGA). The high temperature and high pressure filtration loss (FLHTHP) and API filtration loss (FLAPI) of the system containing 1.0wt/vol% polymer decreased from 77.6mL and 18.8mL respectively to 31.2ml and 6.6ml after 16 hours of hot rolling at 210 ℃. The results indicate that the addition of a dual cross-linked structure filtrate reducer can significantly improve the high-temperature resistance of the base slurry. This article elaborates on the high-temperature and salt resistance mechanism of a dual cross-linked structure fluid loss reducer. The hydrolyzed polymer molecular chain undergoes secondary cross-linking with the metal cross-linking agent, which protects the hydrolyzed polymer molecular chain from rapid degradation and forms a more dense and complex three-dimensional network structure, resulting in excellent temperature resistance and fluid loss performance of the polymer fluid loss reducer.