SECONDARY CEMENTING IN CASED WELLS IN ZHONGYUAN OILFIELD AND AUXILIARY TECHNOLOGIES

In Zhongyuan oilfield, casing damaged wells account for 20% of the total production wells, with casing damage happens in a long interval span from 400 m to pay zone, and this severely impacts the conduction of stimulations and improving of production/injection well pattern. As the conventional casing patching and replacing technology is insufficient enough for the long damaged interval, secondary cementing technology using small size casing is then presented, i.e., run Ф101.6mm casing in the damaged or thinned Ф139.7mm casing thoroughly or hang casing at certain locations. To assist the secondary cementing, high pressure time delay cement slurry, series Ф101.6mm casing were developed, time-delay cementing, small casing perforation, injection production and workover technologies were applied.