Sodium 3-chloro-2-hydroxypropanesulfonate can be etherified with starch in alkaline environment to prepare starch derivatives containing sulfonic acid groups. This kind of starch derivatives containing sulfonic acid group is a kind of drilling fluid loss reduction material with excellent performance, and has good temperature resistance, salt resistance, calcium and magnesium resistance. After sulfoalkylation modification of natural starch, sulfonic acid group and hydroxyl group are introduced into the starch molecule, which enhances the hydrophilicity, forms soft and dense filter cake on the well wall, and endows the starch with the ability of reducing filtration.

Preparation of 2-hydroxy-3-sulfonic propyl starch ether

Add 16.2g of starch, 1.12ml of 40% sodium hydroxide solution and a certain amount of anhydrous ethanol in a four port flask equipped with thermometer, stirring rod and condensing tube, stir and react at 35 ℃ for 30min. Raise the temperature, then add the etherifying agent sodium 3-chloro-2-hydroxypropanesulfonate, drop a certain amount of 40% sodium hydroxide solution, and continue stirring. Heat preservation for a period of time, cool the product, adjust the pH value to about 7-8 with dilute hydrochloric acid, filter by suction, wash the filter cake with appropriate concentration of ethanol, dry it in a vacuum drying oven and grind it into powder to obtain 2-hydroxy-3-sulfonylpropyl starch ether (HSPs).