BS&W (basic sediment and water) is the combined volume fraction of water and sediment entrained in a crude oil, expressed as a percentage. It is measured by the centrifuge method (API MPMS Chapter 10.3 / ASTM D4007) and deducted from the gross standard volume to give the net oil volume in custody transfer.

How is net oil calculated from BS&W?

Free water (separately gauged) is removed first, then BS&W is applied as a percentage of the remaining volume: Net Oil = (Gross Volume − Free Water) × (1 − BS&W/100).

What BS&W is acceptable for pipeline crude?

Pipeline crude custody specifications typically require BS&W of 1% or less; many pipelines specify 0.5%. Higher BS&W reduces the net oil credited and may be rejected.

BS&W / Net Oil Calculator | API MPMS Ch. 10.3

Volume

Gross (Standard) Volume

bbl

Free Water (gauged)

bbl

BS&W

Entry Mode

BS&W

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BS&W by centrifuge, free water, and the net oil deduction in custody transfer

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Formula

Net Oil = (Gross − FW) × (1 − BS&W/100)

FW = free water (gauged separately)

BS&W = basic sediment & water (%)

W&S = (Gross−FW)·BS&W/100 + FW

Standards & References

API MPMS Ch. 10.3 / ASTM D4007
Water & Sediment in Crude Oil by Centrifuge
API MPMS Ch. 12
Calculation of Petroleum Quantities (net oil)

Engineering Notes

Free water first: deducted before applying the BS&W percentage.
Custody spec: pipeline crude BS&W typically ≤ 1%.
High water/emulsions (>30%) need Ch. 10.1 distillation, not centrifuge.

Frequently Asked Questions

What is BS&W?

Basic sediment & water — the combined volume fraction of water and sediment in crude, measured by centrifuge (API MPMS 10.3 / ASTM D4007) and deducted to give net oil.

How is net oil calculated?

Net Oil = (Gross − Free Water) × (1 − BS&W/100).

What BS&W is acceptable?

Pipeline crude custody specs typically require ≤ 1% (often 0.5%).

Basic Sediment & Water (BS&W) / Net Oil Calculator

Volume

BS&W

📚 Learn the Theory

Results

Formula

Standards & References

Engineering Notes

Frequently Asked Questions

Basic Sediment & Water (BS&W) / Net Oil Calculator

Volume

BS&W

📚 Learn the Theory

Results

Formula

Standards & References

Engineering Notes

Frequently Asked Questions

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