Preparation and properties of composite nano film-forming sealing agent for water-based drilling fluid
A organic/inorganic composite nano film-forming sealing agent was synthesized using modified nano SiO2 as rigid particles,acrylamide,2-acrylamido-2-methylpropane sulfonic acid,styrene,and vinyl acetate as polymerization monomers,nonylphenol polyoxyethylene ether(10)and sodium dodecyl sulfonate as emulsifying agents,and ammonium persulfate and sodium bisulfite as initiators,and then characterized by FTIR,SEM,dynamic light scattering(DLS)and TGA.The effects of mass fraction of composite nano film-forming sealing agent on rheological properties,filtration properties,and sealing performance of water-based drilling fluids were studied.The results indicated that the composite nano film-forming sealing agent was spherical in morphology and maintained a nanoscale distribution with a median particle size of 325 nm,while showed a mass loss rate of 14%at 340℃and increment in apparent viscosity and plastic viscosity after aging at 120℃for 16 h.When the mass fraction of composite nano film-forming sealing agent was 3%,the static filtration loss of water-based drilling fluid was 10 mL;When that was≥2%,the filtration loss of the sand bed was 0,when that increased from 0 to 4%,the high-temperature and high-pressure filtration loss was reduced from 104 mL to 29 mL,the permeability was 1.56×10-2 mD,and the sealing rate was 90.7%.
water-based drilling fluidsfilm-forming sealing agentsnanostable wellboreoil field chemicals