Cement volume calculation is based on annular capacity multiplied by length of cement as per cement program.
This topic will demonstrate you how to determine cement volume as per specification and displace volume. After reading and understanding the concept, you will be able to apply to your cement job.
The knowledge required: annular capacityy and inner capacity of cylindical object
Well information:
Well is drilled with 8.5 inch bit to 9,015 MD/8,505 TVD with
oil based mud (9.5 ppg). Estimated hole sized based on an open hole log is 8.6 inch.
Previous casing size is 9-5/8” and its shoe is at 6,500 MD/5000’TVD.
Plan to run 7” casing and planned shoe depth at 9,000’MD/8,500’TVD.
There is one float collar at 8960’MD/8470’ TVD.
Top of cement is 2000 ft above 9-5/8” casing.
Spacer volume is from top of cement to surface.
Casing information
7” casing ID = 6.185”
9-5/8” casing ID = 8.85”
Use hole size measured from the open hole log to determine cement volume.
The well schematic should look like this.
Determine the following items:
• Cement volume
• Spacer volume
• Displace volume
As per the cement program, the final schematic will look like this.
Determine cement volume
Total cement volume = cement in the annulus between open hole and 7” casing + cement in annulus between 9-5/8” casing and 7” casing + cement in shoe track
There are three parts that you need to calculate in order to get total cement volume as listed below:
1. cement in the annulus between open hole and 7” casing
2. cement in annulus between 9-5/8” casing and 7” casing
3. cement in shoe track
The cement volume is based on annular capacity multiplied by cement length of each section.
Cement in the annulus between open hole and 7” casing
Annular capacity between open hole and 7” casing = (8.6
^{2}-7
^{2}) ÷ 1029.4 = 0.02425 bbl/ft
Length from 7” casing shoe to 9-5/8” casing shoe = 9000 – 6500 = 2500 ft
Cement in the annulus between open hole and 7” casing = 0.02425x2500 = 60.6 bbl
Cement in annulus between 9-5/8” casing and 7” casing
Annular capacity between 9-5/8” casing and 7” casing = (8.85
^{2}-7
^{2}) ÷ 1029.4 = 0.02849 bbl/ft
Length of cement inside 7” casing = 2000 ft
Cement in annulus between 9-5/8” casing and 7” casing = 0.02849 x 2000 = 57 bbl
Cement in shoe track
Capacity of 7” casing = 6.185
^{2} ÷ 1029.4 = 0.03716 bbl/ft
Shoe track length = 40 ft
Cement in shoe track = 40 x 0.03716 = 1.5 bbl
Total Cement Volume
Total cement = 60.6 + 57 + 1.5 = 119.1 bbl
Determine space volume
As per the cement program, spacer will be at surface.
Spacer volume = Annular capacity between 9-5/8” casing and 7” casing x length of spacer
Annular capacity between 9-5/8” casing and 7” casing = (8.85
^{2}-7
^{2}) ÷ 1029.4 = 0.02849 bbl/ft
Length of spacer = volume annulus to TOC
TOC 2000 ft inside casing shoe = 6,500 – 2,000 = 4,500 ft
Spacer volume = 0.02849 x 4,500 = 128.2 bbl
Determine displace volume
The displacement volume is from surface to the float collar where the top plug will sit on.
Displacement volume = Capacity of 7” casing x Length to the float collar
Capacity of 7” casing = 6.185
^{2} ÷ 1029.4 = 0.03716 bbl/ft
Length to the float collar = 8,960 ft
Displacement volume = 0.03716 x 8960 = 333 bbl
Conclusion for this cement calculation
• Cement volume = 119.1 bbl
• Spacer volume = 128.2 bbl
• Displace volume = 333 bbl
With this example, I wish you would understand more about how to determine cement volume. Please remember that any cement volume calculation is based on this concept.
Ref: The topic of
Calculate Cement (Oil Well Cement) Volume Required at the
drilling formulas blog.
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