Cementing technology for a deep windowed and sidetracked well WEN13-STH305

Well WEN13-STH305 is a dual-target side-tracked directional well, and the target zone is the middle stratum at the depth of 3700 m in the east of WEN13 block. Windowing was made inside the ?139.7 mm casing, and the ?101.6 mm liner was run, after which it is cemented, The side clearance at overlapping section is only 9.88 mm, and the density of drilling fluid is up to 1.78 g/cm3, so the circulation loss and kick coexist in the section, with the great difficulty in cementing. It is currently the deepest sidetracked well with ?139.7 mm casing in China. By conditioning mud property, testing of drilling tools friction and pressure bearing, optimizing liner hanger before running casing, and using the AMPS polymer filtrate reducer and intermediate temperature retarder, the free water and water loss have been controlled in high temperature slurry, and the problem of upper strength developing slow has been overcome. By the matching cementing technology, the cementing operation was made smoothly, and the CBL was with high quality. The successful cementing in this well provides a technical support for developing matured fields with sidetracked deep directional wells in ZPEB.