Monitoring short-term corrosion rates in some oilwell cements

The causes of oilwell external casing corrosion and the corrosion inhibiting properties of Portland cement are discussed. Two types of cement, API Class G and ASTM Type I, were used in a laboratory experiment in order to assess their short-term corrosion inhibiting properties. Synthetic carbonate formation brine and distilled water were used as the corrodants. The results showed that Type I cement is more effective than the more commonly used Class G oilwell cement in the short-term inhibition of corrosion. It is suggested that short-term corrosion inhibition can lead to better long-term protection.