Material balance calculator
Field units
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Original oil in place for an undersaturated reservoir, and original gas in place from p/z. Every equation and assumption is listed under the answer.
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Undersaturated oil
| Effective compressibility c_e | 21.33 ×10⁻⁶ /psi | |
| Original oil in place N | 14.761 MMSTB | |
| Recovery factor so far | 1.69 % |
- Undersaturated oil, no gas cap, no water influx: N = Np Bo / (Boi c_e Δp), c_e = (c_o S_o + c_w S_wc + c_f)/(1 − S_wc).
- Valid only above the bubble point. Water drive or a gas cap makes this an overestimate.
Dry gas p/z
| Original gas in place G | 55.784 Bcf | |
| Recovery factor so far | 21.51 % | |
| p/z now | 3,488 psia |
- Volumetric dry gas: p/z = (pi/zi)(1 − Gp/G). One point gives G; plot several points to check for water drive (upward bend).