耐温抗盐软弹体颗粒堵剂的研制OA

To address the dehydration-induced shrinkage and loss of elasticity of conventional plugging agents under the high-temperature and high-salinity conditions of deep fractured-vuggy carbonate reservoirs,a soft elastic particle plugging agent was developed using polyvinyl alcohol(PVA)as the gelling agent and terephthalaldehyde as the crosslinking agent with synergistic modification by nano-silica and sulfonated tannin.The effects of the component content on the gelation time,storage modulus,dehydration rate,and adhesion performance were investigated,and the mechanisms responsible for the temperature and salt resistance of the plugging agent were elucidated by means of rheological tests,mechanical characterization,EDS,and SEM.The results show that the soft elastic particle plugging agent prepared with 10%(w)PVA,0.2%(w)terephthalaldehyde,0.2%(w)dichloroacetic acid,5%(w)nano-silica,and 2%(w)sulfonated tannin exhibits the higher storage modulus.After thermal aging at 130℃for 60 d in brine with a salinity of 2.2×105 mg/L,its dehydration rate remains below 40%,and the particles withstand 10 repeated compression cycles without damage,demonstrating good elasticity.The mechanistic analysis shows that sulfonated tannin acts as a"molecular bridge"between nano-silica and the PVA molecular chains,constructing a physical crosslinking network stabilized by multiple hydrogen bonds.This network,together with the covalent crosslinking network,forms a dual-network structure,thereby enhancing the strength and temperature-and salt-resistant stability of the material.This plugging agent provides a novel elastic sealing material for profile control and water shutoff in high-temperature and high-salinity fractured-vuggy reservoirs.