▎ 摘　　要

NOVELTY - Polysulfonic acid silane composite graphene oxide plugging agent comprises graphite, aminosilane compound, diene compound and aminosulfonic acid compound, prepared by (1) mixing graphite in concentrated sulfuric acid and phosphoric acid, adding potassium permanganate, stirring at 80 °C for 12-24 hours, adding hydrogen peroxide solution, stirring, and post-processing to obtain graphene oxide powder, (2) dispersing graphene oxide in absolute ethanol, stirring ultrasonically, adding ethanol solution of aminosilane compound, reacting, and post-processing to obtain amino-functionalized graphene oxide, (3) dispersing amino-functionalized graphene oxide in methanol solution, stirring ultrasonically, dropping diene compound, reacting, and post-processing to obtain product A, and (4) dispersing the product A in methanol, ultrasonically stirring, adding methanol solution of aminosulfonic acid compound, reacting under nitrogen atmosphere and ice-water bath condition, and post-processing. USE - The plugging agent is useful in oil-based drilling fluid (claimed). ADVANTAGE - The plugging agent: has particle size roughly distributed between 30 and 1600 nm, and thus blocks the micro-nano pores and fractures in the shale formation, stabilizes the well wall, and prevents collapse; and has little effect on the performance of the drilling fluid, which is beneficial to reduce the filtration loss of the drilling fluid. The oil-based drilling fluid has excellent performance in terms of rheological properties and plugging properties under shale formation conditions. DETAILED DESCRIPTION - Polysulfonic acid silane composite graphene oxide plugging agent comprises graphite, aminosilane compound and aminosulfonic acid compound. The plugging agent is prepared by (1) mixing graphite in concentrated sulfuric acid and phosphoric acid with a mass concentration of 98% and stirring for 10-30 minutes, then gradually adding potassium permanganate into the solution, stirring at 80 °C for 12-24 hours, adding hydrogen peroxide solution, and stirring for 1-2 hours to obtain bright yellow solution, then centrifuging the bright yellow solution, washing with deionized water, washing with absolute ethanol, vacuum drying at 65 °C, and grinding to obtain graphene oxide powder, (2) dispersing graphene oxide in absolute ethanol and stirring ultrasonically for 30 minutes, slowly adding ethanol solution of aminosilane compound, reacting by stirring at 35-55 °C for 8-12 hours, precipitating with n-hexane, centrifuging, washing with acetone, and drying to obtain amino-functionalized graphene oxide, (3) dispersing the amino-functionalized graphene oxide in methanol solution, placing it in three-necked flask and stirring ultrasonically for 30 minutes, slowly dropping diene compound under the conditions of nitrogen atmosphere and ice-water bath, and reacting at 65-85 °C for 6-8 hours, then washing with absolute ethanol, precipitating, and vacuum drying at 65 °C to obtain product A, and (4) dispersing the product A in methanol, ultrasonically stirring for 30 minutes, slowly adding methanol solution of aminosulfonic acid compound, reacting under nitrogen atmosphere and ice-water bath condition for 12-48 hours, then washing with absolute ethanol, centrifuging, and vacuum drying at 65 °C to obtain final product i.e. polysulfonic acid silane composite graphene oxide. In the step (1): the weight ratio of graphite to concentrated sulfuric acid is 1 g:100-150 ml; the weight ratio of graphite to phosphoric acid is 1 g:10-15 ml; the mass ratio of graphite to potassium permanganate is 1:3-5; the weight ratio of graphite to hydrogen peroxide solution is 1 g:100-200 ml; and the mass concentration of hydrogen peroxide is 25-30%. In the step (2): the weight ratio of graphene oxide to absolute ethanol is 1 g:150-200 ml; the weight ratio of graphene oxide to ethanol solution of aminosilane compound is 1 g:50-100 ml; and the volume ratio of the aminosilane compound to ethanol in the ethanol solution of the aminosilane compound is 1:10-15. In the step (3): the weight ratio of the amino-functionalized graphene oxide to methanol is 1 g:10-15 ml; the weight ratio of the amino-functional graphene oxide to the methanol solution of the diene compound is 1 g:10-15 ml; and the volume ratio of the diene compound to methanol is 1 g: 10-15 ml. is 1:2-3. In the step (4): the weight ratio of the amino-functionalized graphene oxide to the methanol solution of the aminosulfonic acid compound is 1 g:80-120 ml; and the volume ratio of the aminosulfonic acid compound to methanol is 1:6-10. An INDEPENDENT CLAIM is also included for oil-based drilling fluid comprising 70-90 pts. wt. white oil, 0.5-1 pt. wt. main emulsifier, 1-3 pts. wt. auxiliary emulsifier, 5-10 pts. wt. fluid loss control agent, 2-5 pts. wt. organic soil, 0.5-5 pts. wt. quicklime, 10-30 pts. wt. calcium chloride (concentration of 20-25%) brine, 0.5-2 pts. wt. wetting agent, 10-30 pts. wt. barite and 1-10 pts. wt. polysulfonic acid silane composite graphene oxide plugging agent.