Research and development of ultra-high temperature delayed crosslinking acid system

The average burial depth of carbonate reservoirs in Shunbei area exceeds 7300 meters, and the bottom hole temperature is as high as 160°C. The commonly used cross-linked acid system cannot meet the needs of acid fracturing. Therefore, this article uses AM, AMPS, acrylamide (AM) modified monomers, acrylic acid (AA) modified monomers to synthesize thickener SBCH-1, the organic zirconium crosslinking agent SBJL1 was synthesized with zirconium oxychloride, isopropanol, citric acid and diethanolamine. And other auxiliary agents are selected, and the final formula is determined as: 220% HCl+0.8% SBCH-1 thickener +0.8% SBJL-lcrosslinking agent +0.8% SBYC-1 crosslinking retarder +2% SBHS-1A high temperature corrosion inhibitor +2% SBHS-1B high temperature corrosion inhibitor +1% SBTW-4 iron ion stabilizer +1% SBZP-2 drainage aid +1% SBPR-1 demulsifier. The viscosity of the system stabilized above 200mPa⋅s after continuous shearing at 160°C, 170s-1 for 30min.