new - natural gas properties

8/12/2019 New - Natural Gas Properties

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CONSTANTS

R = 10.73 (psi*ft3)/(lb-mol*R

o)

Mair= 28.97 lb/lb-mol

Psc = 14.65 psia

Tsc = 60 oF 520 oR

Convert Gas Gravity in separator to Gas Gravity in reservoir (need to account for liquids):

FIRST METHOD IS VIA SEPARATOR EQUATIONS - SECOND IS VIA YIELD EQNS

1 stage separator 2 or 3 stages: dry gas sg at end of 1st, liq sg at end of last

API, cond = 50 a3 -0.0001785

y,o = 0.779614 a2 1.25


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M,o = 144.8385 a1 9.13875382

Vo [scf/stb] 717.5929 scf/stb Rs 11.4048379 scf/stb gas in sol af

ps1 55 psia

rho,g b4 sep= 0.108294 lbm/ft3 ts1 520 oR

Rg scf/stb = 3333.333 Vo [scf/stb 728.997688 scf/stb

yg,sp = 0.65

rho,l = 48.64793 lbm/ft3

y,g res = 1.417462 y,g res = 1.418556

EQUATION USING YIELD TO DETERMINE y,g res

YIELD = 300 STB/MMSCF

y,g res = 1.421

FOR COND WELLS WHERE THERE IS 2 PHASE IN RES:

above Dew Point - liq only - same as wet gas above

below dew point - dual phase

need to use two-phase z-factor:

when c7+ > 4%. Knowing sg of flowing gas

yc7+ = 11.14%

pr 1.81 ?

tr 1.55 ?

z,tp = 0.66847

Rt = 4062.331

Bt (total) = 43.93421 cf/stb


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T = 100 oF 560 oR

P = 1216 psi

yg,corr

for nonHC

MOLECULAR Pc Tc Vc

COMPOUND WEIGHT psiaoR ft

3/lb Zc yi

Methane C 1 H 4 16.04 667.8 343 0.0091 0.2884 0.786

Ethane C 2 H 6 30.07 707.8 549.8 0.0788 0.2843 0.07

Propane C 3 H 8 44.10 616.3 665.7 0.0737 0.2804 0.01

n-Butane C 4 H 10 58.12 550.7 765.3 0.0702 0.2736 0.002

iso-Butane C 4 H 10 58.12 529.1 734.7 0.0724 0.2824 0.006

n-Pentane C 5 H 12 72.15 488.6 845.4 0.0675 0.2623 0.003

iso-Pentane C 5 H 12 72.15 490.4 828.8 0.0679 0.2701 0.001

neo-Pentane C 5 H 12 72.15 464 781.11 0.0674 0.2537

n-Hexane C 6 H 14 86.18 436.9 913.4 0.0688 0.2643 0.001

n-Heptane C 7 H 16 100.20 396.8 972.5 0.0691 0.2633 0.001

n-Octane C 8 H 18 114.23 360.6 1023.9 0.069 0.2587

n-Nonane C 9 H 20 128.26 332 1070.3 0.0684 0.2536

n-Decane C 10 H 22 142.28 304 1111.8 0.0679 0.2462

Ethylene C 2 H 4 28.05 729.8 508.6 0.0737 0.2765

Propene C 3 H 6 42.08 669 656.9 0.0689 0.2752

Acetylene C2

H2

26.04 890.4 555.3 0.0695 0.2704

Carbon Dioxide C 1 O 2 44.01 1071 547.6 0.0342 0.2742 0.05

Hydrogen Sulfide H 2 S 1 34.08 1306 672.4 0.0459 0.2831 0.02

Sulfur Dioxide S 1 O 2 64.06 1145 775.5 0.0306 0.2697 0

Nitrogen N 2 28.13 493 227.3 0.0514 0.2916 0.05

Water H 2 O 1 18.02 3208 1165 0.05 0.235 0

1

yhc =

A =

B =

e =

FORMULA

PHYSICAL CONSTANTS FOR PURE COMPONENTS


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ter 1st stg


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yg Ppr Tpr Z (graph) rhog [lb/ft3] B mu,g [cp] mu,g [cp]

0.70 1.81 1.55 0.830 4.43 0.010815 0.013354 0.014715

0.63 112.4068 K 124.1448

5.464533 X 0.007225

0.70 1.307093 Y 1.367877

6.324058

0.07109

yiMWi yiPci yiTci added high

12.61 524.89 269.60

2.10 49.55 38.49

0.44 6.16 6.66

0.12 1.10 1.53

0.35 3.17 4.41

0.22 1.47 2.54

0.07 0.49 0.83

0.00 0.00 0.00

0.09 0.44 0.91

0.10 0.40 0.97

0.00 0.00 0.00

0.00 0.00 0.00

0.00 0.00 0.00

0.00 0.00 0.00

0.00 0.00 0.00

0.00 0.00 0.00

2.20 53.55 27.38

0.68 26.12 13.45

0.00 0.00 0.00

1.41 24.65 11.37

0.00 0.00 0.00

20.38 691.99 378.12

663.29 377.59 SUTTON: HIGH MW, RICH IN C7+, MINOR C02 AND N2, NO H2S. 0.57


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Rsw, scf/stb R,brine

9.967435084 7.689965

K 3.73583 50000 S, ppm

SIG 0.005420337

Y -2.43143E-07

X

rho,g

er MW particles

G


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Hall-Yarborough (1973) z-factor calculation

Hall, K.R. & Yarborough, L. (1973): A New Euation of State for Z-factor Calculations,

The Oil and Gas Journal, June 18, 82-92

Molecular weight oxygen, MO 15.9994 g/mole

Molecular weight sulfur, MS 32.07 g/mole

Molecular weight, carbon, MC 12.01 g/moleMolecular weight, hydrogen, MH 1.01 g/mole

Molecular weight air, MA 28.97 g/mole

Components Molecular weight Mole fraction Tci Tci Pci Pci

g/mole yi oR K psia Mpa

Methan, CH4 16.042 0.786 343 190 667.8 4.61

Ethan, C2H6 30.07 0.07 549.8 305 708 4.88

Propan, C3H8 44.10 0.01 665.7 370 616 4.25

i-Butane, C4H10 58.12 0.006 734.7 408 529 3.65

n-Butane, C4H10 58.12 0.002 765 425 551 3.80

i-Pentane C5H12 72.15 0.001 829 460 491 3.39

n-Pentane C5H12 72.15 0.003 845 469 489 3.37

Hexane C6H14 86.18 0.001 913 507 437 3.01

Heptane C7H16 100.21 0.001 972 540 397 2.74

Hydogen, H2 2.02 0 60 33 187 1.29

Nitrogen, N2 28.01 0.05 227.4 126 492 3.39

Oxygen, O2 32.00 0 277.8 154 731 5.04

Carbon dioxid, CO2 44.01 0.05 547.6 304 1071 7.38

Hydrogensulfid, H2S 34.08 0.02 672.4 373 1306 9.01

Dihydrogenoksid, H2O 18.02 0 1165 647 3199 22.06

Mole fraction1.0000

Total molecular weight gas 20.38 g/mole

Spesific gravity 0.70

Temperature 37.78oC 310.93 K

Pressure 8.384E+06 Pa

Method used (1, 2 or 3) 1

Compressebility factor, z 0.8298

Method 1 (Properties from composition, Key's rule)

Pseudo critical temperature

TPc (oil field units) 378.13 oR

TPc (SI units) 209.74 K

Pseudo critical pressure

PPc (oil field units) 691.90 psia

iiyPPPc

iiyTTPc


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PPc (SI units) 4.8E+6 Pa

Method 2 (Sutton's correlations)

Pseudo critical temperature

TPc (oil field units) 378.43 oRTPc (SI units) 209.90 K




Method 3 (Standing's correlation)

Pseudo critical temperature If we have a "

TPc (oil field units) 390.42 oR

TPc (SI units) 216.57 K




Pseudo reduced properties

TPR 1.482PPR 1.757

Hall-Yarborough

t 0.675

a 0.037

Reduced-density parameter, y0 0.01

Continue until f(y) < 1x10^(-5)

Iteration 1

f(y) -54.5E-3

Derivated of f(y), df(y) 0.945

Newton Rapson: Reduced- density parameter, y1 0.067670896


Iteration 2

dy

ydf

yf

prTt 1

pc

prp

pP

pc

pr

T

TT

75=PPc

169.TPc

168pcHCT

667pcHCp

y

pZ

pr

a


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f(y) -7.0E-3


Newton Rapson: Reduced-density parameter y2 0.077219952


Iteration 3

fy -95.9E-6


Newton Rapson: Reduced-desity parameter y3 0.077


Iteration 4

f(y) -16.3E-9




Iteration 5

f(y) -478.6E-18Derivated of f(y), df(y) 0.712



yfy

yy ii'

1


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Convertion

oC -> K 273.15

atm -> bar 1.01325

cp -> Pas 1.00E-03

bar -> Pa 1.00E+05

m m -> m 1.00E-03

oR -> K 0.56

psig -> bar 0.07

oF -> oR 460

Instructions

1. Insert mole fractions.

2. Insert temperature [C] and pressure [Pa].

3. Choose which pseudo method you will use.

4. Read your z-factor beneath.

(Insert values in cells where the font color is red)

Methods for finding pseudo critical pressure and

pseudo critical temperature

1. Properties from composition, Key's rule (Preferred choice).

Newton-Rapson iteration.

2. Sutton's correlations

3. Standing's correlations


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ry" gas, SG < 0,75 If we have a "wet" gas, SG 0,75

tttyttt

y

yyyy 2324

432

2,2427,9082,218,216,952,1952,291

4441

pr ytttytttyyyyy

ap 32232

3

432

4,422,2427,9058,476,976,1410

2

g3.6-131,0-6.8 g

2

gg 74,0-349.5+2

25,1225 gHCgHC

25,370,5 gHCgHC

25,71330187 gHCgHCpcHCT

21,117,51706 gHCgHCpcHCp

212,106125,0 tet


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tyt 82,218,134,2

t82,218,


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Drainage Area Ad = ac

Net Pay h = ft

Porosity

Initial W.Sat Swi =

Temp T = 123oF

Specific Gravity yg = 0.64Initial Press. pi = 1422 psia

Water Compress cw=

Date Pressure z p/z Gp Bg F/Eg

psia MMSCF cf/scf MMscfD

1 1661 0.8287 2004 166 0.008232 #DIV/0!

2 1406 0.8456 1663 293 0.009923 1719.085

3 1135 0.8687 1307 406 0.012628 1166.195

4 847 0.8841 958 490 0.017222 938.6614

5 0 0 #DIV/0! 0 #DIV/0! #DIV/0!

6 0 0 #DIV/0! 0 #DIV/0! #DIV/0!

7 0 0 #DIV/0! 0 #DIV/0! #DIV/0!

8 0 0 #DIV/0! 0 #DIV/0! #DIV/0!

9 0 0 #DIV/0! 0 #DIV/0! #DIV/0!

10 0 0 #DIV/0! 0 #DIV/0! #DIV/0!

11 0 0 #DIV/0! 0 #DIV/0! #DIV/0!

12 0 0 #DIV/0! 0 #DIV/0! #DIV/0!

13 0 0 #DIV/0! 0 #DIV/0! #DIV/0!

14 0 0 #DIV/0! 0 #DIV/0! #DIV/0!

15 0 0 #DIV/0! 0 #DIV/0! #DIV/0!16 0 0 #DIV/0! 0 #DIV/0! #DIV/0!

17 #DIV/0! #DIV/0! #DIV/0!

18 #DIV/0! #DIV/0! #DIV/0! Second plo

19 #DIV/0! #DIV/0! #DIV/0! First plot -

VOLUMETRIC: 0 MMSCF

P/Z PLOT: 13000 MMSCF

F/EG PLOT: 13000 MMSCF

GENERAL INPUT

PRODUCTION CALCULATED0

500

1000

1500

2000

2500

p/z,psia

2

4

6

8

10

12

14

16

18

20

F/Eg,

MMscf


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leads to less error for VOLUMETRIC DEPLETIONS

asks any forms of depletion, the F/Eg plot gives more insight

0 100 200 300 400 500 600 700 800 900 1000

Gp, MMscf

0

0

0

0

0

0

0

0

0

0

0

0 10000 20000 30000 40000 50000

Gp, MMscf


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Res. Press pr = 3500 psia Gas Viscosity

Res. Boundary re = 1589 ft

Gross hg = 24 ft Velocity Coeff

Net hn = 24 ft Non-D Coeff.

Permeability k = 0.13625 md

WB Radius rw = 0.34 ft

SGU gas yg = 0.7Skin S = 0 Linear flow ends

Res. Temp T = 190 oF 650 P.Radial Begins

Porosity phi = 0.11 PSS time start

Compressibilit ct = 0.00024 /psi DIM FRAC COND =

Water Sat. Sw = 0.35 Eff WB Radius

Fract Cond kf*w = 582 mD-ft

Half Length xf = 369 ft

25

P2 VALID UP TO 3000 PSI

pwf p2

psia qsc McfD

3500 0

3000 73

2000 185

1000 252

500 269

0 275


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ug = 0.020578 cp

z = 1.00

Beta = 2.5528E+11 1/ft

D 0.0003548

ug, avg= 0.01872 D/MSCF Find u at 1750 psi

agp = 44626.0538 2177120.07

bgp = 2.06440509 100.3209782tL,end = 10 days

t,pr beg= 257 days

tpss = 419 days in transient flow

cfd = 11.5760424

rw'/xf = 0.44 from figure 4.24 based on cfd

rw' = 162.36 ft

agt = 312110

p2-nonD m(p)

qsc McfD qsc McfD qsc McfD

0 7.82E+08 0 0 0

73 5.61E+08 102 101 709.5342

183 3.10E+08 217 215 1511.796

249 7.70E+07 324 319 2258.874

266 1.87E+07 351 345 2445.585

271 0.00E+00 359 353 2505.504

0

500

1000

1500

2000

2500

3000

3500

4000

0 100 200 300

pwf,psia

Flow Rate, MSCFD

P2 method


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A B C

1212678 1915.7 0.878

1212678 1915.7 0.878

5118.7 355.9 1.4871

5118.7 355.9 1.4871

111 0 1.9365

108.03 0 1.9635

400

p2 Darcy

p2 non-Darcy

m(p) Darcy

m(p) non-Darcy


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CALCULATING BHP FROM WHP GIVEN RATE: Dry Gas:

Single Phase water or Undersaturated oil: No Viscosity/Density changes with T,P

WHP = 2534 PSI Qg, MMcf/

Depth 8500 ft Depth

Visc of water uw = 1 cp BHP =

Water Rate qw 1680 bpd 1.17 bpm ID =

roughness e = 0.00005 ft 70 bph e =Angle (+90 up) theta = 90 degrees T =

Inside Diameter ID = 3.826 in SGU =

Density pg = 62.5 lbm/ft3 Theta =

1500

Superficial Velocity 8500 Assumptio

v = 1.37 ft/sec

Re = 40548.49 TURBULENT IF > 2100 TURBULENT P avg =

f = 0.022316 z (from INP

0.127134 psf/ft friction first term ug (from IN

neglect kinetic second term

62.5 psf/ft gravity third term Nre =

dp/dl= 0.434911 psi/ft TOTAL f =

3696.741 Delta P from 1 to 2 if (-) then WHP < BHP C2 =

BHP = 6231 psi 7.504422

3689.236 c1/c2 =

WHP =

IN SINGLE PHASE, BOTH FORCES ACT DOWNWARD WHEN PRODUCING AT

INCREASING RATES, SO VLP CURVE ALWAYS INCREASES.

0 784010000 7920

20000 8064

50000 9115

90000 11811

95000 122510

5000

10000

15000

0 20000 40000 60000 80000 100000


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HP from BHP while flowing:

d 10 Input Yellow boxes and Green assumption

5000 ft Find z and ug

2500 psi Use WHP at bottom as new assumption

2.91 inches Type in Green Box.

0.00005 ft Find new z and ug110 F repeat til convergence.

0.7

90

= 1500 psi WHP

2000

UT) = 0.754 Type Pavg, T, and SGU into I&R sheet

PUT) = 0.0174 Type Pavg, T, and SGU into I&R sheet

2765493.542

0.0142

3.05389E-05

843753.6892

2094

30 40 50 60 70

1500 0.29 0.72 1 1.32

8500 1.67 4.12 5.69 7.5

1.96 0 4.84 6.69 8.82


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BOTTOMHOLE PRESSURE FROM SURFACE

Pwh = 1050 psig p2

Depth = 9500 ft

yg = 0.72

T_bar = 100 oF

Theta = 90 degrees (going up) find p1 (BHP)

Assume

p1 (bhp) = 1383 psig Guess

pbar = 1216.5 psig

z = 0.83 Pick

C2 = 2.9E-05

p1 = 1384 Make this new guess, find new z, til convergence

1383.589 alternative equation

This is how gas lift injection at bottom is calculated

0.15 psi/ft


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BOTTOMHOLE PRESSURE FROM SURFACE

Pwh = 1050 psig p2

Depth = 9500 ft

yg = 0.72

T_bar = 100 oF

Theta = 90 degrees (going up) find p1 (BHP)

Assume

p1 (bhp) = 1383 psig Guess

pbar = 1216.5 psig

z = 0.83 Pick

C2 = 2.9E-05

p1 = 1384 Make this new guess, find new z, til convergence

1383.589 alternative equation

This is how gas lift injection at bottom is calculated

0.15 psi/ft


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GAS FLOWRATE THROUGH AN ORIFICE

yg = 0.72

Valve Size = 0.375 inch

P1, upstream, Pinj at depth = 950 psig

P2, downstream, Flowing Prod Press = 900 psig

T1, Inj gas temp at depth, TgD = 140 deg F

qgsc = 1311.23593 Equation for chart, need to correct for Temp

CgT = 1.13068277

qga = 1159.68507 Mscf/d

Rate for new choke size:

Orifice size = 0.5 inch

qgc = 2331.08609 Mscf/D


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Ground Elevation = 438 ft Patm= 14.43 psi

WH Flow Rate qsc = 2.5 MMscfD

Gas Specific Grav. yg = 0.72

Suct Pressure ps = 35 psig pabs = 49.4 psia

Suct Temp Ts = 100 oF Tabs = 560 oR

Z-factor zs = 0.72

Disch Pressure pd = 1100 psig pabs = 1114.4 psia

Z-factor zd = 0.72 zavg = 0.72

Specific Heat k = 1.25

Adiabatic Eff na = 1 (n-1)/(nk) = 0.267

Polytropic Eff np = 0.75

Mech Efficiency Em = 0.95

scan eo vs rp plot

scan type vs rate plot

THERMODYNAMIC PROPERTIES

EFFICIENCY

CALCULATED VALUESGENERAL INPUT

San Antonio, TX is 650 ft

Laredo, TX is 438 ft

GAS PROPERTIES

SUCTION SIDE

DISCHARGE SIDE


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THERMODYNAMIC COMPARISON

ISOTHERMAL

HEAD = 92,975 [(ft-lbf)/lb]

POWER REQ'D = 310 HP

ADIABATIC

HEAD = 129,025 [(ft-lbf)/lb]

POWER REQ'D = 431 HPPOLYTROPIC

HEAD = 144,941 [(ft-lbf)/lb]

POWER REQ'D = 645 HP

DESIGN PROCESS

1. NUMBER OF STAGES

Total Compression Ratio RT = 22.55

Discharge Temperature Td = 279 oF

Number of Compress Stages # STG = 3

Compression Ratio per Stage rp = 2.82

Factor F = 1.1

2. RATE

Actual cubic feet per minute ACFM = 400 cfm

Type based on rate/pressure From Figure

3. POWER - for general compressor

Quick eqution calculation BHP = 513 HP

Precise equation calculation BHP = 435 HP

SPECIAL CASE - RECIPROCATING COMPRESSOR

Engine Speed N = 1100 RPM

Stroke Length St = 3.5 in

Cylinder Diameter D = 4.3 in

Rod Diameter d = 1.25 in

Clearance C = 15 %

Overall Eff based on rp Eo = 0.84 From Figure

Piston Displacement

Single Acting Pd,s = 32 cfm

Double Acting Pd,d = 62 cfm

Select: double

Volumetric Efficiency EV = 70.9 %

Capacity Q = 44.0 cfm

Piston Speed Ps = 642 fpm Keep between 600-800

Tension Load Tl = 14098 lbf

Power Required BHP = 356 HP

-15%


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single

double


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Orifice Diameter d1 = 0.323 in.

Pipe ID d2 = 3 in.

Static Pressure pf = 200 psia

Differential hw = 100 in. of water

Specific Gravity yg = 0.6

Base Pressure p = 14.6 psiaBase Temperature T = 75

oF

z = 0.99

qsc = 1.54 MMSCFD

Fb = 341.7 TABLE

Ftb = 1.028846

Fpb = 1.008904

Fg = 1.290994

Ftf = 0.985882

b = 0.0332 TABLE Calculates Fr = 1.000235

Fpv = 1.005038

Beta = 0.107667 hw/pf = 0.5 Find Y = 1.003 TABLE

C ' = 455.2

GENERAL INPUT

CALCULATING FLOW RATE - ORIFICE METER

fwsc phCq '


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FT PSIA

0 14.70

328 14.50

500 14.40

656 14.301000 14.20

1312 14.00

1500 13.90

2000 13.70

2500 13.40

3000 13.20

3500 12.90

4000 12.70

4500 12.40

5000 12.20

5500 12.00

6000 11.80

6500 11.50

7000 11.30

7500 11.10

8000 10.90

8500 10.70

9000 10.50

10000 10.10


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y = -0.0005x + 14.665

13.60

13.80

14.00

14.20

14.40

14.60

14.80

0 500 1000 1500 2000 2500


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Series1

Linear (Series1)

new - natural gas properties

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