Development of high strength polyvinyl alcohol gel for water shutoff in carbonate reservoirs

To provide a high-strength, non-resin organic plugging agent for water shutoff in carbonate fracture and cave reservoirs, high-strength gel was prepared with polyvinyl alcohol 1788 as gelant p-phthalaldehyde crosslinker this study. By selecting latent acids rather than strong acid such hydrochloric sulfuric catalysts, by adding clay sulphonated phenolic resin stabilisers to the gelation, drawbacks of short gelation time high dehydration rate formed soaking brine were overcame. The evaluation results showed that gellant composed 7wt% alcohol, 4wt% clay, 0.3wt% aldehyde crosslinker, 0.25wt% acid, 1.5wt% sulfonated resin, hexamethylenetetramine had 2 h at 130 °C. storage modulus up 2000 Pa, after synthetic 30 days less 15%. Furthermore, breakthrough pressure gradient slim tube diameter 3mm reached 15 MPa / m, which indicated is temperature salinity resistant ability.