Abstract: In view of issues such as casing deformation and frequent failure of packers in high-temperature reservoir water injection wells,a chemical packer material suitable for horizontal well annuli in high-temperature reservoirs was developed.Its thixotropic properties,annular filling performance,and strength were tested,and the system sealing efficiency was evaluated.The results indicate that the optimal formulation of the high-temperature ACP(annular chemical packer)material is 4.000% acrylamide monomer+2.500% LAP thixotropic agent+0.007% ammonium persulfate initiator+(0.005% to 0.007%)MBAm crosslinker.The system structural recovery rate is 0.726,meeting industry standards.After intense shearing for 60 seconds and then standing for 60 seconds,the network structure of the system recovers and its cohesive strength increases,indicating good thixotropic performance.At 90 ℃,the system can achieve instantaneous annular filling with no gravitational collapse,and it migrates axially in a piston-like manner to both sides,maintaining the integrity of annular filling.The sealing efficiency is 99.68%,and the breakthrough pressure gradient is 7.5 MPa/m,indicating excellent sealing capacity.After 60 days,the system axial slip pressure and radial breakdown pressure remain above 0.5 MPa,indicating that excessive pressure does not cause the gel to slide in the annulus between the screen and the wellbore or cause the gel damage.Thus,this material can be directly used for water shutoff in high-temperature horizontal wells.This study provides theoretical guidance for horizontal well water injection development.

Key words: horizontal well, annular chemical packer, high temperature resistance, ACP, thixotropy