Material balance calculator
0D tank match in your browser — oil Havlena–Odeh, Campbell, energy split; dry-gas p/Z and Cole. PVT is the same Vasquez–Beggs / DAK pack as the flash calculator. Sliders are Free; this is not an autofit of N or G.
Scenario
Pick a demo or paste history. Move N / we_mult — charts update live (Free: no autofit).
Eng-Man case 1 water-drive morphology. FieldFlow uses Vasquez–Beggs + DAK (tutorial used Glaso/Beal) — curve shapes, not bit-identical N.
Reservoir
Stocks & gas cap
OOIP — slope of Havlena–Odeh when We = 0
m = G·Bgi / (N·Boi); 0 = no free gas cap
Aquifer
Pot aquifer: We = we_mult · (pi − p). Size × compressibility (ce·Wi). 0 = off. Slider grows with the value (water-drive demos are ≫ 1000).
PVT
Optional; leave blank to derive from Rsi
History (rates)
Rates, not cumulatives. Uncheck Use to drop a survey from H–O / residual / RMSE (production still integrates). Click a row to inspect. Edit via paste.
11 / 11 used in match · drag the bar below to resize
| Use | t (d) | qo (STB/d) | qg (Mscf/d) | qw (STB/d) | p (psia) |
|---|---|---|---|---|---|
| 0 | 0 | 0 | 0 | 2754.6959 | |
| 366 | 21530.0546 | 16362.8415 | 0 | 2514.6959 | |
| 731 | 28876.7123 | 26235.8904 | 0 | 2304.6959 | |
| 1096 | 29397.2603 | 30830.411 | 0 | 2123.6959 | |
| 1461 | 31616.4384 | 35218.6301 | 0 | 1963.6959 | |
| 1827 | 25819.6721 | 32023.7705 | 0 | 1832.6959 | |
| 2192 | 22684.9315 | 29654.2466 | 0 | 1716.6959 | |
| 2557 | 19095.8904 | 25711.7808 | 0 | 1622.6959 | |
| 2922 | 14657.5342 | 20895.0685 | 0 | 1549.6959 | |
| 3288 | 10382.5137 | 16719.9454 | 0 | 1494.6959 | |
| 3653 | 7917.8082 | 12247.9452 | 0 | 1454.6959 |
Theory: Havlena–Odeh
F vs Etot · F−We when aquifer on · line y = N·x through origin
Equation at point
Click a Havlena–Odeh point — or a history row — to see voidage F and expansion E_tot with the same numbers the solver used.
Residual r(t)
Pressure p(t)
Cumulatives Np, Gp, Wp
Aquifer influx We(t)
Accumulated Rp = Gp/Np
Instantaneous GOR
qg/qo from rates · gap when qo = 0