Multi interval cement volume worksheet with worked answers
PetroCalcHub · Original synthetic teaching exercise · 2026-10-24

Use this worksheet to build a multi-interval volume ledger, assign excess by interval, convert to sacks and calculate water from the prepared batch.

Annulus A: 8.5/5 in × 1,000 ft; B: 7.75/5 in × 1,000 ft. Shoe-track ID 4.276 in. No excess is added in this geometry-only ledger.

1. What is the fastest dimensional check before dividing slurry volume by yield?

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2. Reproduce the baseline Track volume (bbl) without rounding intermediate values.

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3. Compare the first and last recorded scenarios. Which input changes?

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4. What would be needed to apply this example to a different physical system?

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5. Convert 55.08 bbl slurry to ft³ and theoretical sacks at 1.32 ft³/sk.

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6. How much mixing water does that 235-sack batch need at 6.3 US gal/sk?

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ANSWER KEY

1. The volume numerator and the volume part of yield must match, such as ft³ divided by ft³/sk, leaving sacks.
2. VA = 45.9; VB = 34.0607143; track = π/4 × 4.276² × 40/808.5 bbl; add the three nonoverlapping entries. Track volume (bbl) = 0.710469177. The internal track requires ID, while each annulus uses outer-boundary ID and inner-string OD.
3. Shoe-track length (ft) changes from 0 to 100. Other controls remain as stated in the premise. Track volume (bbl) changes from 0 to 1.77617294.
4. Replace the synthetic controls with compatible documented inputs and check the relation's assumptions. Annular entries use the library's rounded 0.7854 coefficient; the internal track uses π/4. All lengths are measured feet. The internal track requires ID, while each annulus uses outer-boundary ID and inner-string OD.
5. 55.08 × 42 × 231/1728 = 309.25125 ft³; /1.32 = 234.28125 sk, rounded upward to 235 for one batch.
6. 235 × 6.3 = 1,480.5 US gal. The water uses whole prepared sacks.

Method: Original synthetic teaching calculation. Equations and fixed controls are stated here; these are not field measurements.
Sources:
SLB: slurry yield: https://glossary.slb.com/en/terms/s/slurry_yield
NIST SP 811: pressure, temperature and volume conversions: https://www.nist.gov/pml/special-publication-811/nist-guide-si-appendix-b-conversion-factors/nist-guide-si-appendix-b9
SLB: annulus geometry: https://glossary.slb.com/en/terms/a/annulus