It is a water-soluble organic treatment agent made from natural lignite as the core raw material, through alkalization, sulfonation, condensation modification, and compounding with a small amount of additives. It is an anionic agent and is a classic medium- and high-temperature filtration loss reducer and shale inhibitor in water-based drilling fluid systems. It also has a slight anti-collapse and viscosity reduction effect. Its core characteristics are good temperature resistance, low cost, suitability for medium and deep well conditions, and excellent compatibility with various treatment agents. It is a basic additive in drilling fluid systems that balances performance and cost and is widely used in oil and gas wells and geological wells.