Retarders are the chemicals that delay the setting time of the cement slurry. Use of retarders allow sufficient time for slurry placement in deep and hot wells, or those applications which require long working times
>> Low temperature retarders
– for BHCT below 200F
Application: Temperature: to 60°C [140°F] when used alone and 85°C [185°F] with a dispersant.
Description: Light brown, water soluble powder
Primary purpose: Temperature: to 60°C [140°F] when used alone and 85°C [185°F] with a dispersant. Concentration: 0.1–0.5% BWOC. Can be used in fresh water and seawater.
Guidelines for use: The product is a purified Calcium Lignosulphonate, derived from wood. It is a basic retarder for cement slurries that retards the thickening time of slurries at temperature ranging from 0-90 degC. It is compatible with all classes of API cement. As a basic retarder, it also acts as a mild dispersant and is effective in fresh and (saturated) salt water. It can be dry-blended with cement or prehydrated into the mixing water.
>> Mid temperature retarders
– for BHCT from 200F to 300F
Application: Retarder up to 140 degC
Description: Dark brown powder
Primary purpose: Retarder can be used to provide cement systems with optimum thickening times from 52 degC to 121 degC BHCT. This BHCT can be extended to 154 degC when used in conjunction with a retarder aid
Guidelines for use: The optimum BHCT range for this product is between 52 degC and 121 degC. Retarder response is consistent over this temperature range, and is almost independent of variations in cement quality. When used in conjunction with retarder aids, the temperature range is extended to 154 degC but with reduced retarder efficiency. The concentrations range from 0.25% – 0.60% BWOC for a BHCT from 52 degC to 93 degC. The retarder concentration must be increased to up to 2.5% BWOC as the BHCT approaches 121 degC.
>> High temperature retarder aids
– used together with retarders to improve effectiveness at high temperatures with BHCT above 300F
>> Retarders for wide temperature range
– for BHCT from 250F to 400F