Slurry Volume
The slurry volume = cement volume, gal+ water volume, gal+ additive volume, gal
Yield of Cement
Y = yield of slurry = (slurry volume gal /7.48) ft3/sack
Cement Slurry Requirements
Number of sacks of cement = slurry volume, cu.ft / yield of cement, cu.ft/sack
Mix Water Requirement
- Mix water requirement = mix water per sack x number of sacks
- Number of sacks of additive = number of sacks x percentage of additive
- Weight of additive = number of sacks of additive x 94 lbs
Slurry Density
Slurry density = (weight of cement, lb+ weight of water, lb+ weight of additive, lb)/ (volume of cement, gal+ volume of water, gal+ volume of additive, gal)
Hydrostatic Pressure Reduction
Hydrostatic pressure reduction due to spacer = 0.292 (density of mud, ppg – density of spacer, ppg)x annular capacity, ft3/ft x spacer volume, bbl
Contact Time
An estimation of the volume of cement needed for removal of mud cake by turbulent flow is :
- Volume of fluid (in turbulent flow), ft3 /bbl= 5.616 x contact times, minutes x displacement rate, bbl/min
Gas Migration Potential
Gas migration potential = 1.67 x (length of the pipe column exposed to the cement from the reservoir zone, ft /( diameter of the hole, in – outside diameter of the casing pipe, in)/Formation pressure, psi
Ranges:
- 0 – 3 Low
- 3 – 8 Moderate
- > 8 High
Cement Plug
- Number of sacks of cement = length of plug, ft x capacity of the hole, ft3/ft/ yield of cement
- Spacer volume ahead of slurry = volume of spacer behind slurry x annular capcity/ pipe volume, ft3
- Length of Plug = number of sacks x yield/ ( anular volume of pipe + annular volume)