Pengenalan CBM

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

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13 V. PENGENALAN SIMULASI RESERVOIR CBM1. Latar Belakang2. Metodologi3. Pemodelan Reservoir4. Hasil5. Kesimpulan


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.


Structure of Coal & Gas FlowPhysics

Primary Porosity: CoalMatrix

Secondary Porosity:Cleats (Fractures)


CO2CH4

N2

Flow Regimes in Coal

Primary CBMrecovery

CO2 enhancedrecovery (CO2-ECBM) N2 enhancedrecovery (N2-ECBM) Flue gas enhancedrecovery


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


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


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


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


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


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


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


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


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


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


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


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


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


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


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 -


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.

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