calculation of bg gas formation volume f
Post on 10-Apr-2015
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Calculation of Gas Recovery
Gas Recovery
( )gi
w
BRFSAheryGas −
=1560,43covRe φ
A = drainage area in acreh = thickness in ftφ = Porosity (fraction)Sw = Water saturation (fraction)Bgi = Initial gas formation volume factor (ft3/SCF)RF = Recovery factor (fraction)
Gas Volume Calculation
( )∑=
−=NB
mwmmm ShAvolumeGas
11560,43 φ
Gas volume = volume of gas in reservoir ft3
NB = number of blocksAm = drainage area for block “m” (acre)h = thickness for block “m” (ft)φ= Porosity for block “m” (fraction)Sw = Water saturation (fraction)
Bg Calculation
)/..(*0283.0
1*)46060(***)7.14(
SCFftcuresp
ZTFp
ZTZTpZTpB
res
resres
res
resres
scscres
resresscg
=
+=
=
Zres Calculation
How to calculate Zres ??
Step 1:
Tres is known (available from logs/well test data)
Pres is known (available from logs/well test data)
Gas Composition is known
Step 2:
Calculate the apparent molecular weight:
Calculate the gas gravity:∑=
=NC
iiia MxMW
1
964.28a
gMW
=γ
Step 3:Obtain the pseudo critical pressure(Ppc) and pseudo critical temperature(Tpc) of the gas from Figure A-2 using gas gravity.
Correction for CO2, N2 and H2S if necessary.
Step 4:Calculate the reduced temperature(Tr) and reduced pressure(Pr)Tr = Tres/Tpc ; Pr = Pres/Ppc
Zres Calculation
Zres Calculation
Get Zres from Standing – Katz chart
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