Cement slurry calculation (volume, density, yield) are quite simple and the basic behind is mass balance calculation. Cement calculation for common liquid and/or solid additive is pretty easy to understand. However, complex cement slurry as foam cement is almost not possible to do it by hand due to its complexity and for this case, you might need service company cement program to solve the problem. In this blog, I will write articles showing the cement calculation of common liquid and/or solid additive which you almost see every cement job on the rig.
Common terms that you need to know are listed below:
• By definition, one sack of cement is equal to 94 lb.
• Liquid additive in almost all cases is in US gal/sack.
• Density of fresh water is 8.33 ppg.
• Density of salt water varies from place to place. Personnel must check the figure for each specific area.
• Solid additives are mostly expressed in a percentage by weight of cement. For example, 35% silica sand means 35% silica sand by weight of cement.
• Salt cement is expressed in a different way. It is expressed in a percentage of salt by weight of water.
• Density of cement is commonly around 3.16 SG (26.32 ppg).
Common conversion factors used for cement calculation that you should know are as follows:
1 SG = 8.33 PPG
1 cu ft = 7.48 gal
1 Metric ton (1000 kg) = 2204.6 bl
1 kg = 2.2046 lb
1 bbl = 42 us gallon
Absolute Volume is an actual volume which is occupied by solid particles not voids between particles. For example, density of dry cement is 26.32 lb/gal therefore each lb of cement has cement volume of 1/26.32 gal = 0.038 gal/lb. This is very important concept that you should understand because cement calculations are based on the absolute volume.
Cement Yield is total volume of cement slurry per sack of dry cement.