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PENGENALAN SIMULASI RESERVOIR CBMKULIAH MINGGU XIII PEMODELAN & SIMULASI RESERVOIR
Joko PamungkasReservoir Simulation Specialist
Minggu XIiIBab V Pengenalan Siimulasi Reservoir CBM 2
PENGENALAN SIMULASI RESERVOIR CBM
Pertemuanke-
Pokok bahasan atausubpokok bahasan
13 V. PENGENALAN SIMULASI RESERVOIR CBM1. Latar Belakang2. Metodologi3. Pemodelan Reservoir4. Hasil5. Kesimpulan
Minggu XIiIBab V Pengenalan Siimulasi Reservoir CBM 3
1. LATAR BELAKANG Reservoir gas konvensianal cadangannyasemakin menipis dan kebutuhan semakinmeningkat
CBM merupakan alternatif cadangan gas yangperlu dikembangkan saat ini
Perlunya diketahui kinerja masing-masingreservoir yaitu : gas konvensional dan CBM
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2. MetodologiPerbandingan kinerja, meliputi : Perhitungan cadangan Laju produksi gas Penurunan tekanan reservoir Metode perhitungan dengan simulasi reservoir Nama simulator : CMG (computer ModellingGroup)
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Classification of Unconventional gas
Natural gas from Coal NGC : Natural Gas from Coal CBM: Coal Bed Methane CSG: Coal Seam Gas
Shale Gas Tight Gas Gas hydrates or Methane hydrates.
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Structure of Coal & Gas FlowPhysics
Primary Porosity: CoalMatrix
Secondary Porosity:Cleats (Fractures)
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CO2CH4
N2
Flow Regimes in Coal
Primary CBMrecovery
CO2 enhancedrecovery (CO2-ECBM) N2 enhancedrecovery (N2-ECBM) Flue gas enhancedrecovery
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CH4
CH4CH4 CH4
CH4Coal Matrix
CH4H2O
Coal Cleats/fractures
Primary CBM Recovery Mechanisms Reduce cleat pressure by producing water Methane desorbs from matrix, diffuses to cleats/fractures Methane and water flow to wellbore
Darcy Flow through fractures Face and Butt Cleats Vertical connection of Face & Butt cleats
Darcy or Pipe Flow in large fractures Large Cleats Induced Fracture(s)
Pipe Flow in production tubing/wellbore Cleat permeability affected by matrix responses
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Enhanced Coalbed Methane (ECBM) Recovery Green House Gas (GHG) Sequestration
ECBM Mechanisms
CO2Deep Coalbed CH4 CH4CH4
CH4 toSales
N2
Coal
Flue Gas CO2 N2
Injection
Green PowerPlant
Separation
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Properties of Coal: Multiple porositysystem Primary porosity system (coal matrix) Microporosity (< 2 nm) Mesoporosity (2 50 nm)+ Very low flow capacity: perms in microDarcy range Only Diffusive flow
Secondary porosity system (coal cleats) Macroporosity (> 50 nm) Natural fractures Much greater flow capacity: perms in milliDarcy range Darcy Flow
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Volume Gas Storage (CBM)G = 1359.7 .A .h .B. Gc
A = Drainage Area, Acreh = Ketebalan, ftB = average Coal Bulk Density, g/ccGc = Average Gas Constant, scf/ton
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Calculating Gas In Place (gas convensional)
G = (43560 .Vb. . (1-Sw))/BgG = Gas in Place, SCFVb = Bulk Volum, Acre-ft= PorositySw = Water saturationBg = Gas volume factor, cu ft/scf
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3. Pemodelan reservoir gas konvensionaldan CBM
Uraian Reservoir gas konvensional Reservoir CBMJenis Grid Orthogonal OrthogonalJumlah Grid 36x32 x 4 = 4608 buah 36x32 x 4 = 4608 buahGrid Aktif 4608 buah 4608 buahUkuran 1 grid 50x 50 x 10 ft 50x 50 x 10 ftSistim Porositas Dual porositas Dual porositasJumlah Sektor 1 buah 1 buahBatas Gas Minyak (GOC) 1640 ft -Tekanan Awal 600 Psi 600 PsiSumur Produksi 5 Sumur 5 SumurPorositas fracture 0.10 (fraksi) 0.10 (fraksi)Permeabilitas fracture 10 mD 10 mD
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Uraian Reservoir gas konvensional Reservoir CBMPorositas matriks 0.02 0.02Permeabilitas matriks 2 mD 2 mDFracture Spacing 0.2 0.2Coal desorbtion time (Ch4) day - 50Coal desorbtion time (CO2) day - 50Global Composition (CH4) - 0.8Global Composition (CO2) - 0.2Langmuir Adsorbtion Constant (CH4) - 3E-4 1/psiMaximum Adsorbed Mass (CH4) gmol/lb - 0.357Maximum Adsorbed Mass (CO2) gmol/lb 0.538Water Saturation 0.3 0.9
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Parameter Satuan CBM Gas KonvensionalOriginal Gas in Place, OGIP STD FT3 1.14E+09 1.32E+09Original Water in Place, OWIP STD BBL 6.00E+06 3.34E+05
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SkenarioModel Gas Konvensional CBM
Base Case (1) K = 10 mD K = 10 mD2 K = 15 mD K = 15 mD3 K = 5 mD K = 5 mD4 1 Sumur Produksi, q = 0.3 MMCF/day 1 Sumur produksi, q max5 1 Sumur Produksi, q = 1.5 MMCF/day -
Catatan : Semua skenario menggunakan Tekanan alirdasar sumur (Pwf) = 50 psi
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CBMDefault-Field-PRO
Time (Date)
Gas
Rat
e SC
(MM
SCF/
day)
2011-1 2011-7 2012-1 2012-7 2013-1 2013-7 2014-1 2014-7 2015-10.00
0.10
0.20
0.30
0.40
0.50
Base CaseK = 15 mDK = 5 mDsingle well qmaxPerbandingan Laju Produksi
gas Skenario Base case, 2 ,3dan 4
Conventional Gas Reservoir performance
Time (Date)
Gas
Rat
e SC
(MM
SCF/
day)
2011 2012 2013 2014 2015 2016 2017 20180.00
0.50
1.00
1.50
2.00
Base CaseK = 5 mDK = 15 mDSingle Well, Q = 0.3 MMSCF/DSingle Well, Q = 1.5 MMSCF/D
4. Hasil
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Perbandingan ProduksiKumulatif Gas Skenario Basecase, 2 ,3 dan 4
Default-Field-PRO CBM_2b.irf
Time (Date)
Cum
ulat
ive
Gas
SC
(MM
SCF)
2011-1 2011-7 2012-1 2012-7 2013-1 2013-7 2014-1 2014-7 2015-10
200
400
600
800
CBM_2b.irfCBM_2b1.irfCBM_2b2.irfCBM_2b3b.irf
Conventional Gas Reservoir performance
Time (Date)
Cum
ulat
ive
Gas
SC
(MM
SCF)
2011 2012 2013 2014 2015 2016 2017 20180
200
400
600
800
1,000
1,200
1,400
Base CaseK = 5 mDK = 15 mDSingle Well, Q = 0.3 MMSCF/DSingle Well, Q =1.5 MMSCF/D
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Perbandingan Tekananrata-rata LapanganSkenario Base case, 2 ,3dan 4
CBM
FIELD
Time (Date)
Ever
age
Pres
sure
(psi
)
2011-1 2011-7 2012-1 2012-7 2013-1 2013-7 2014-1 2014-7 2015-1100
200
300
400
500
600
Base CaseK = 15 mDK = 5 mDSingle Well qmax
Conventional Gas Reservoir performance
Time (Date)
Res
ervo
ir pr
essu
re (p
si)
2011 2012 2013 2014 2015 2016 2017 20180
100
200
300
400
500
600
Base CaseK = 5 mDK = 15 mDSingle Well and Q = 0.3 MMSCF/DSingle Well and Q = 1.5 MMSCF/D
Minggu XIiIBab V Pengenalan Siimulasi Reservoir CBM 22
Recovery Factor Diawal Tahun 2015Skenario Model Kumulatif Produksi gas Kumulatif Porduksi gas Recovery Factor Recovery Factor
Gas Konvensional (MMSCF) CBM (MMSCF) Gas Konvensional (%) CBM (%)Base Case (1) 1188.95 405.35 89.74 35.48
2 1209.23 525.36 91.27 45.993 1128.24 195.97 85.16 17.164 493.50 72.23 37.25 6.325 959.73 - 72.44 -
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5. Kesimpulan1. Dengan nilai permeabilitas yang sama, ternyata laju
produksi Gas reservoir CBM lebih rendah dari reservoir gaskonvensional.
2. Tingkat pengurasan reservoir lebih jauh reservoir gaskonvensional bila dibandingkan dengan reservoir CBM,sehingga reservoir CBM perlu sumur yang lebih banyak.
3. Pengaturan laju produksi di reservoir gas konvensional lebihmudah bila dibandingkan dengan reservoir CBM.
4. Recovery factor yang didapat dalam kurun waktu yang sama,reservoir CBM lebih rendah bila dibandingkan denganreservoir gas konvensional.