Abstract: After changing pH value of water in Pucheng Oilfield, a lot of bottom sludge was produced during water treatment, which occupied large land and polluted environment seriously. Based on lab test, bottom sludge caused by water treatment was analyzed that main component of bottom sludge was calcium carbonate, which has good sealing characteristics. Through test and optimizing formula, bottom sludge was applied to profile control widely. Field tests in 45 wells showed bottom sludge can be applied to profile control, and it could not only reduce contamination to environment but also obtain good economic benefits.