▎ 摘　　要

NOVELTY - Externally-flexible internal rigid oil-based drilling fluid nano-plugging agent comprises nano-rigid material, benzene ring monomer, olefin containing carbon-carbon double bond and sodium methallyl sulfonate, and is prepared by (a) adding graphene oxide to deionized water in round bottom three-necked flask, performing ultrasonic dispersion treatment on obtained mixture, dripping 3-(isobutenyl) propyl trimethoxysilane and aqueous ammonia to dispersion, uniformly stirring, centrifuging obtained mixture, washing with ethanol and deionized water for removing impurities, and vacuum drying, and (b) introducing deionized water to round bottom three-neck flask, adding modified graphite oxide, performing ultrasonic dispersion process, adding olefin containing benzene ring monomer, carbon-carbon double bond-containing olefin, crosslinking agent, sodium dodecyl sulfate and polyethylene glycol octylphenyl ether, and uniformly stirring, adding potassium persulfate, grinding and dispersing. USE - The externally-flexible internal rigid oil-based drilling fluid nano-plugging agent used in oil-based drilling fluid. ADVANTAGE - The nano-plugging agent adopts easily available synthetic raw materials, is prepared by simple and reliable process, effectively plugs the nano-sized pores and fractures in mud shale well wall, has excellent compatibility, which effectively prevents the drilling fluid from penetrating to formation, stabilizes the well wall, prevents collapse, and has excellent plugging and fluid loss reduction effect. DETAILED DESCRIPTION - Externally-flexible internal rigid oil-based drilling fluid nano-plugging agent comprises nano-rigid material, benzene ring monomer, olefin containing carbon-carbon double bond and sodium methallyl sulfonate are prepared from the outer-soft rigid oil-based drilling fluid nano-plugging agent, and is prepared by (a) adding 5 g graphene oxide to 100-150 ml deionized water in 250 ml round bottom three-necked flask, performing ultrasonic dispersion treatment on obtained mixture for 30-40 minutes, dripping 10-15 ml 3-(isobutenyl) propyl trimethoxysilane and 3-5 drops aqueous ammonia to dispersion, uniformly stirring the mixture at a stirring speed of 400 rpm at room temperature for 30-40 minutes, soaking the flask in 60 degrees C water bath, uniformly stirring at a same stirring speed for 2-3 hours, centrifuging obtained mixture, washing with ethanol and deionized water for removing impurities, and vacuum drying at 60 degrees C for 24 hours, performing grinding and dispersion process to obtain modified graphene oxide, and (b) introducing 125-150 ml deionized water to 250 ml round bottom three-neck flask, adding 2-3 g modified graphite oxide, performing ultrasonic dispersion process for 30-40 minutes, adding 15-20 g olefin containing benzene ring monomer, 15-20 g carbon-carbon double bond-containing olefin, 15-20 g crosslinking agent, 0.5-1 g sodium dodecyl sulfate and 0.2-0.5 g polyethylene glycol octylphenyl ether, and uniformly stirring at a stirring speed of 350 rpm for 1-1.5 hours at room temperature to obtain pre-emulsion, maintaining pre-emulsion in water bath at 60-70 degrees C, uniformly stirring at 350 rpm, adding 0.2-0.3 g potassium persulfate to pre-emulsion, adding 0.2-0.3 g potassium persulfate in water bath of 60-70 degrees C, centrifuging product with ethanol and deionized water for 3 times for removing impurities, performing vacuum drying at 60 degrees C for 24 hours, and grinding and dispersing to obtain externally-flexible rigid oil-based drilling fluid nano-plugging agent. An INDEPENDENT CLAIM is included for an oil-based drilling fluid comprising 70-90 pts. wt. white oil, 0.5-1 pt. wt. main emulsifier, 1-3 pts. wt. secondary emulsifier, 5-10 pts. wt. filtrate reducer, 2-5 pts. wt. organic soil, 0.5-5 pts. wt. quicklime, 10-30 pts. wt. calcium chloride (20-25%), 0.5-2 pts. wt. wetting agent, 10-30 pts. wt. barite and 1-10 pts. wt. outer soft-rigid oil-based drilling fluid nano-plugging agent.