Difference between revisions of "Oil Material Balance"
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:<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 | ||
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:<math>G_{gi}</math> = gas injection volume, scf | :<math>G_{gi}</math> = gas injection volume, scf | ||
| − | :<math> m = \frac{HCPVgascap}{HCPVoil}</math> | + | :<math> m = \frac{HCPVgascap}{HCPVoil}</math> - initial gas cap oil leg ratio, dimensionless |
:<math> N </math> = stock tank oil initially in place, stb | :<math> N </math> = stock tank oil initially in place, stb | ||
:<math> N_p</math> = oil cumulative production volume, stb | :<math> N_p</math> = oil cumulative production volume, stb | ||
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:<math> P_i</math> = initial reservoir pressure, psia | :<math> P_i</math> = initial reservoir pressure, psia | ||
:<math> R_{si} </math> = solution oil-gas ratio, scf/bbl | :<math> R_{si} </math> = solution oil-gas ratio, scf/bbl | ||
| − | :<math> R_p = \frac{Gp}{Np}</math> | + | :<math> R_p = \frac{Gp}{Np}</math> - cumulative GOR, scf/stb |
:<math> </math> | :<math> </math> | ||
:<math> </math> | :<math> </math> | ||
Revision as of 13:08, 28 March 2018
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)
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
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
= initial oil formation volume factor, bbl/stb
= oil formation volume factor at Pres, bbl/stb
= water formation volume factor at Pres, bbl/stb
= formation compressibility at initial pressure and temperature, 1/psia
= water compressibility at Pres, 1/psia
= gas injection volume, scf
- initial gas cap oil leg ratio, dimensionless
= stock tank oil initially in place, stb
= oil cumulative production volume, stb
= average reservoir pressure, psia
= initial reservoir pressure, psia
= solution oil-gas ratio, scf/bbl
- cumulative GOR, scf/stb
R_s R_s S_{wc} Swc W_e W_i W_p
= gas formation volume factor, ft3/scf
= initial gas formation volume factor, ft3/scf
= gas initially in place, scf
= cumulative gas produced, scf
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.
