Effects of chitosan treatment on strength and thickening properties of oil well cement

The research objectives were to investigate the influence of chitosan on strength and thickening properties of oil well cement under the downhole temperature condition. The results showed that the chitosan has the ability to increase the thickening time, but due to chelating Ca2+ ion, it may cause consistency wave at initial stage, and shorten thickening time at higher dosage and higher temperature. Chelating pretreatment will weaken the retarding effect of chitosan. Effects of LMW chitosan on strength and thickening properties are more acute than that of HMW chitosan. Because of increasing induction period, the pre-chelating LMW chitosan extends thickening time.