Primary cementing is the process of placing cement between the casing and borehole in a well. The main objectives of primary cementing are to seal the annulus and to obtain zonal isolation. For zonal isolation to be achieved, all drill cuttings and drilling fluid must be removed from the annulus and replaced by cement slurry. Cement slurry must then undergo hydration, changing from the liquid to the solid phase and developing properties to prevent flow of formation fluids and to support the casing. The cement sheath should also be able to withstand different operations such as stimulation, perforation, production, and intervention during the life of the well. Adequate thickening times are required for a good cement job. Study was made with 36 thickening time test results carried out for a 5 inch high temperature liner cementing jobs done in the past at temperature range of 230oF to 284oF for different retarder concentrations. Thickening time plots for the retarded cement slurry was obtained for the temperature range investigated. Model which predicts thickening time at the specified retarder concentrations and temperatures was developed. The model equation at the different temperatures and retarder concentrations is given by: Y = 32.53882954 – 0.15380761X1 + 12.10530547X2 + 29.80930457X3. Thickening times predicted showed good agreement with experimental values with less than 10% deviation. The model equation developed will help predict the thickening time at the various retarder concentrations and temperatures and thereby help in saving time and cost associated with the rigour in actual laboratory experimental recipe design and testing.
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