Comparison and Analysis of Thickening Experiment Methods for Chemically Foamed Cement Slurry

Consistency tester is used to measure the thickening of cement slurry.For foamed cement slurries,air contained in the slurries often results in errors in consistencies measured.To minimize the effects of air on the consistency of cement slurry,three methods have been used to measure the consistencies of foamed cement slurries treated with different concentrations of foamers,and an optimized measuring method has been selected.Sources of the errors have been analyzed,and the consistency curves obtained from the optimized measuring method corrected through mechanical analyses and calculation.It was found that the residue foamers in cement slurry accelerated the thickening process,and the thickening time of the cement slurry containing residue foamer was 41% less than that of the cement slurry with no residue foamer,indicating that the effects of residue foamer should not be ignored.In two consistency tests with one cement slurry containing air and another one containing no air in it,the differences in thickening times were small (1 min and 11 min,respectively),while the shapes of the thickening curves were quite different;the thickening curve of the foamed cement slurry was more of right-angled.Cement slurry containing less air,or cement slurry with later consistency increasing faster,difference between the thickening times before and after correction was small;for chemically foamed cement slurries,this time difference was only 3 min when the consistencies before and after correction had both reached 100 Bc.For cement slurries with low density and high air content,or cement slurry with its later consistency increasing slowly,the consistency measured has to be corrected.