Sealing of the annular space between the casing and riser of a certain well of CNOOC

详细说明

After the completion of the drilling of a certain offshore well by CNOOC, conventional cement cementing was carried out. The cement return height between the riser and the casing was generally around 150m, and the pressure test required 500Psi. Due to the continuous failure of the pressure test, four conventional cementing operations were carried out, and the cement return height increased from 150m to 0.4m. The pressure test all met the design requirements, and secondary drilling could not be carried out. In December 2021, based on the analysis of the special situation of the well, 100kg of low density casing plugging material with full well temperature and shallow layer was used, and low-temperature additives were compounded. After mixing evenly on site, it was poured into the annulus and allowed to set for 48 hours. After a pressure test of 500Psi, the pressure was stabilized for 15 minutes without decreasing, and the pressure test was qualified. The second drilling was successfully carried out, ensuring the smooth progress of the drilling project.