Difference between revisions of "Oil Material Balance"
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Np = (N * (Bo - Boi) + N * (Rsi - Rs) * Bg + m * N * Boi * (Bg / Bgi - 1) + N * (1 + m) * Boi * (Pi - Pres) * (cw * Swc + cf) / (1 - Swc) - (Wp * Bw - Wi * Bw - Gging * Bgi - We * Bw)) / (Bo + (Rp - Rs) * Bg) | Np = (N * (Bo - Boi) + N * (Rsi - Rs) * Bg + m * N * Boi * (Bg / Bgi - 1) + N * (1 + m) * Boi * (Pi - Pres) * (cw * Swc + cf) / (1 - Swc) - (Wp * Bw - Wi * Bw - Gging * Bgi - We * Bw)) / (Bo + (Rp - Rs) * Bg) | ||
| + | |||
| + | === Above the bubble point === | ||
| + | |||
| + | |||
| + | :<math>N_p B_o = N B_{oi} (P_i - P_{res}) c_e - (W_p B_w - W_i B_w - W_e B_w) </math> | ||
| + | where | ||
| + | :<math>c_e = \frac{c_o S_o + c_w S_{wc} + c_f}{1 - S_{wc}}</math> | ||
| + | |||
| + | |||
| + | :<math>S_o = 1 - S_{wc}</math> | ||
| + | |||
| + | |||
| + | :<math>c_o = \frac{1}{B_{oi}} \frac{B_o-B_{oi}}{Pi - Pres}</math> | ||
== Discussion == | == Discussion == | ||
| Line 34: | Line 47: | ||
:<math> B_{oi}</math> = initial oil formation volume factor, bbl/stb | :<math> B_{oi}</math> = initial oil formation volume factor, bbl/stb | ||
:<math>B_w</math> = water formation volume factor at Pres, bbl/stb | :<math>B_w</math> = water formation volume factor at Pres, bbl/stb | ||
| + | :<math>c_e</math> = effective system compressibility at Pres, 1/psia | ||
:<math>c_f</math> = formation compressibility at initial pressure and temperature, 1/psia | :<math>c_f</math> = formation compressibility at initial pressure and temperature, 1/psia | ||
:<math>c_w</math> = water compressibility at Pres, 1/psia | :<math>c_w</math> = water compressibility at Pres, 1/psia | ||
Latest revision as of 11:36, 20 April 2024
Contents
Brief
The general form of the Oil Material Balance equation was first published by Schilthuis in 1941[1].
Math & Physics
Equating all underground withdrawals to the sum of the volume changes[1]:
For use in the code to find Pres:
Pres = Pi - (Np * Bo + Np * (Rp - Rs) * Bg + (Wp * Bw - Wi * Bw - Ggi * Bginj - We * Bw) - (N * (Bo - Boi) + N * (Rsi - Rs) * Bg + m * N * Boi * (Bg / Bgi - 1))) * (1 - Swc) / (N * (1 + m) * Boi * (cw * Swc + cf))
For use in the code to find Np:
Np = (N * (Bo - Boi) + N * (Rsi - Rs) * Bg + m * N * Boi * (Bg / Bgi - 1) + N * (1 + m) * Boi * (Pi - Pres) * (cw * Swc + cf) / (1 - Swc) - (Wp * Bw - Wi * Bw - Gging * Bgi - We * Bw)) / (Bo + (Rp - Rs) * Bg)
Above the bubble point
where
Discussion
... most powerful tool for investigating reservoirs and understanding their performance ...— L.P. Dake [2]
... the safest technique in the business since it's minimum assumption route through the subject of reservoir engineering ...— L.P. Dake [2]
See also
Gas Material Balance
Gas Flowing Material Balance
Oil Flowing Material Balance
Nomenclature
= gas formation volume factor at Pres, bbl/scf
= initial gas formation volume factor, bbl/scf
= injection gas formation volume factor at Pres, bbl/scf
= oil formation volume factor at Pres, bbl/stb
= initial oil formation volume factor, bbl/stb
= water formation volume factor at Pres, bbl/stb
= effective system compressibility at Pres, 1/psia
= formation compressibility at initial pressure and temperature, 1/psia
= water compressibility at Pres, 1/psia
= gas injection volume, scf
= gas cumulative production volume, scf
= initial gas cap hydrocarbon pore volume, bbl
= initial oil hydrocarbon pore volume, bbl
, initial gas cap oil leg ratio, dimensionless
= stock tank oil initially in place, stb
= oil cumulative production volume, stb
= initial reservoir pressure, psia
= average reservoir pressure, psia
, cumulative GOR, scf/stb
= solution oil-gas ratio, scf/bbl
= initial solution oil-gas ratio, scf/bbl
= initial gas saturation, fraction
= initial oil saturation, fraction
= connate water saturation, fraction
= water influx volume, stb
= water injection volume, stb
= water production volume, stb
References
- ↑ 1.0 1.1 Dake, L.P. (1978). Fundamentals of Reservoir Engineering. Amsterdam, Hetherlands: Elsevier Science. ISBN 0-444-41830-X.
- ↑ 2.0 2.1 Dake, L.P. (1994). The Practice of Reservoir Engineering. Amsterdam, Hetherlands: Elsevier Science. ISBN 0-444-88538-2.
