▎ 摘　　要

NOVELTY - Preparing graphene oxide nano hydrogel plugging agent involves putting an appropriate amount of graphite, sodium nitrate, and concentrated sulfuric acid with a mass concentration of 98 wt.% in a three-necked flask, slowly adding an appropriate amount of potassium permanganate, and stirring for 5-10 hours at a temperature of 35℃, adding the second portion of potassium permanganate, and stirring the reaction for 8-12 hours. The hydrogen peroxide solution used to remove remaining potassium permanganate. The product is repeatedly washed with centrifugation and distilled water in turn, and obtained the graphene oxide dispersion by ultrasonic treatment, then vacuum-dried graphene oxide dispersion at 65℃ to obtain the graphene oxide powder. The graphene oxide is dispersed in deionized water and ultrasonically stirred for 30 minutes to obtain a uniform graphene oxide dispersion, which is then transferred to a three-necked flask. USE - Method for preparing graphene oxide nano hydrogel plugging agent for aqueous drilling fluid (claimed). ADVANTAGE - The method uses graphene oxide nano hydrogel as a blocking agent, the particle size of the graphene oxide nano hydrogel is approximately distributed between 30 nanometer and 1700 nanometer, and the nano pore gaps in the shale stratum can be effectively blocked, so that the well wall can be effectively stabilized, and collapse can be prevented, the plugging agent has small influence on the performance of the drilling fluid, is beneficial to reducing the filtration loss of the drilling fluid, and the aqueous drilling fluid has good performances in rheological property, water loss wall-building property, plugging property and the like under the condition of shale formation. DETAILED DESCRIPTION - Preparing graphene oxide nano hydrogel plugging agent involves putting an appropriate amount of graphite, sodium nitrate, and concentrated sulfuric acid with a mass concentration of 98 wt.% in a three-necked flask, slowly adding an appropriate amount of potassium permanganate, and stirring for 5-10 hours at a temperature of 35℃, adding the second portion of potassium permanganate, and stirring the reaction for 8-12 hours. The hydrogen peroxide solution used to remove remaining potassium permanganate. The product is repeatedly washed with centrifugation and distilled water in turn, and obtained the graphene oxide dispersion by ultrasonic treatment, then vacuum-dried graphene oxide dispersion at 65℃ to obtain the graphene oxide powder. The graphene oxide is dispersed in deionized water and ultrasonically stirred for 30 minutes to obtain a uniform graphene oxide dispersion, which is then transferred to a three-necked flask. An appropriate amount of amide compound, amide sulfonic acid compound, and N,N-methylene-bis-acrylamide are added, then after 30 minutes added an appropriate amount of initiator ammonium persulfate aqueous solution. The pH to be adjusted within the range of 7-8, and stirred the reaction for 3-6 hours under nitrogen atmosphere and 80℃ until a viscous solution is produced. The reaction mixture is cooled to room temperature, washed with acetone, and dried under vacuum at 65℃ to obtain graphene oxide nanohydrogels. The mass ratio of graphite and sodium nitrate is 2:1-3:1. The ratio of the graphite to the concentrated sulfuric acid is 1g:50-60 ml, the mass ratio of the graphite to the potassium permanganate is 1:2-1:4. The ratio of graphite to hydrogen peroxide solution is 1g: 100-200 ml, and the mass concentration of hydrogen peroxide is 25-30 wt.%. The added amount of the graphene oxide is 1-1.5 g. The ratio of the graphene oxide to the deionized water is 1 g: 80-100 ml, the added amount of the amide compound is 8-12 g, and the mass ratio of the amide compound to the amide sulfonic acid compound is 4:1.