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Gas Industry Hydrocarbons, Measurements and Conversion Factors

Copyright © 2018 by International Human Resources Development Corporation. All rights reserved.

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Learning Objectives• Understand the chemical characteristics and physical properties of natural gas

and gas liquids

• Review the natural gas supply and distribution chain

ExxonMobil Commercial Skills

• Application of Business and Technical Knowledge – Flowing Gas, Transportation, and LNG

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Crude Oils Come in Many Varieties

Courtesy: Schlumberger

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Some Hydrocarbon Molecule Structures• Natural gas, as produced, is a complex mixture of many different hydrocarbon

molecules, inert gases and other components. It is then separated, or converted, into different marketable products as shown below.

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Some Hydrocarbon Molecule Structures

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Some Hydrocarbon Molecule Structures

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Natural Gas and Natural Gas Liquids• Natural Gas is the common description used for Methane (CH4) which is used

for heat, cooking, power generation • Gas Processing (Gas Plant) is used to separate Natural Gas (Methane) from

Natural Gas Liquids• Natural Gas Liquids (NGLs) contain heavier

components:– Ethane (C2H6)– Propane (C3H8)– Butane (C4H10)

• Iso Butane• Normal Butane

– And some heavier molecules C5 + (May be referred to as Field Natural Gasoline or FNG)

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Natural Gas Liquids• Fractionation can be used to further separate Natural Gas Liquids into

individual components

• Components may be steam cracked into products that may be further processed to produce higher value chemical products

• Butane, FNG may have higher value as a refinery gasoline blendstocks

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Liquefied Natural Gas• Natural Gas is most economically

shipped by pipeline

• LNG is Liquefied Natural Gas– Methane converted to a Liquid

• Typically by cooling to -162 ºC (-260 ºF) in a plant called LNG Train

– Benefit is reduction in volume by a ratio of 625:1

– LNG can then be commercially shipped by vessel when pipeline is not available/economic

Rasgas LNG Trains

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The Natural Gas Supply and Distribution Chain

Source: IHRDC

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Natural Gas Volumetric Units

UNITS TO BE USED IN THIS WORKSHOP

Natural Gas Volumetric Units

Units Quantity Symbol ft3 Symbol m3 Application

One 1 SCF m3 Standard unit

Thousand 1,000 KCF Km3 Basic unit of sale

Million 1,000,000 MCF Mm3 Daily well production

Billion 1,000,000,000 GCF Gm3 Annual field production

Trillion 1,000,000,000,000 TCF Tm3 Field reserves

3 units in pipeline(1000 psia, 60 °F)

1 unit in reservoir(4000 psia, 160 °F)

0.4 units as LNG(14.696 psia, -259 °F)

238 units at surface conditions(14.696 psia, 60 °F)

We normally measure gas in volumetric units…

.. but sell it in thermal units. Why?

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Thermal Energy of Natural Gas: BTU and Teapot Economics

• 1 SCF of methane has 1,010 BTUsHow many tea kettles will it heat?(6+ tea kettles)

• 1 British Thermal Unit = Energy required to raise 1 lb of water by 1°F

• Tea kettle must be heated from 60 °F to 212 °F to boil.

• How many BTU’s are needed? (152 BTUs)

• If 1 KCF of methane (10 ft x 10 ft x10 ft) costs $3.00/KCFHow many BTUs in 1 KCF? (~ 1 million BTUs)

• How much does it cost to heat a tea kettle? ($0.00045)

• And how many tea kettles will it heat? (6,644 tea kettles)

Tea kettle with 1 lb of water

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Gas Volume Meter Gas Calorimeter

Natural Gas Thermal Energy RelationshipsCombustion of Methane

CH4+2O2 CO2+2H2O101BTUs

Heat909 BTUs

EnergyBritish Thermal Units (BTU)

1 Million BTU = 1,055 MJ1,000 kcal = 3,968 BTU1 kWh = 3,412 BTU1 MWh = 3.412 million BTU

Therms (thm)1 thm =100,000 BTU1 thm = 25,200 kcal1 thm = 29.3071 kWh1 Dekatherm =10 thm1 Dekatherm = 1 Million BTU

Methane Energy Equivalents1 Cubic meter (m3) = 6.2898 boe6 thousand SCF (KCF) = 1 boeLNG1 mt LNG = 48.735 x 103 SCF NG

Gas and Liquids Thermal Energy Heating Values

Thermal EnergyHeating Value

RatioGrossBTU/scf

NetBTU/scf

Methane 1,010.0 909.4 0.9004

Ethane 1,769.6 1,618.7 0.9147

Propane 2,516.1 2,314.9 0.9200

i-Butane 3,251.9 3,000.4 0.9227

n-Butane 3,262.3 3,010.8 0.9229

i-Pentane 4,000.9 3,699.0 0.9245n-Pentane 4,008.9 3,706.9 0.9247

Note: 1 KCF = ~ 1 Million BTU

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Equivalent Hydrocarbon Volumes, Densities and Heating Values

Crude Oil

1 bbl of crude oil ≈ 6.0 million BTUs$60/bbl ≈ $10/million BTU

Natural Gas1,000 SCF = 1 KCF ≈1 million BTUs 1 KCF = $3.00- 18.00/million BTU6 KCF = 1 bbl equivalent (boe)LNG1 mt LNG = 2.21 m3 LNG = 1,380 m3 NG

= 48.7 KCFCoal1 tonne of coal = 24 million BTUs1 tonne of coal ≈ 4 bbl of crude oil equivalent1 tonne of coal ≈ $35-90/tonnes ($1.45 – $3.75/million BTU)

42 Gallons300 lbs.

(7.2–7.35 bbl/metric tonne)

1,000 SCF=1 KCF1 KCF = 1.0 MBTUNG : LNG Volume

625: 11,000 ft3

Barrels of Oil Equivalent (BOE)

1

4

0.167

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Thermal Energy of Various Fuels

Conversion Factors

Ethanol 77,000 BTU/gallon Gasoline 125,000 BTU/gallonPropane 91,500 BTU/gallon Kerosene 135,000 BTU/gallonButane 103,000 BTU/gallon Natural Gas 1,000 BTU/cu.ft.Electricity 3,413 BTU/kWh #2 Oil 138,500 BTU/gallonFirewood 20,960,000 BTU/cord (128 cu. Ft) #6 Oil 150,000 BTU/gallonCoal 12 -14,000 BTU/lb

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Physical Constants

COMPOUND FORMULA MOLECULAR MASS BOILING POINT FREEZING POINT VAPOR PRESSURE°F °C °F °C @100 °F, psia @40 °C, KPA

Methane CH4 16.043 -258.72 -161.51 -296.45 -182.47 (5,000) (35,000)Ethane C2H6 30.07 -127.46 -88.59 -297.04 -182.80 (800) (6,000)Propane C3H8 44.097 -43.73 -42.07 -305.73 -187.63 188.68 1,369.8Isobutane C4H10 58.123 10.78 -11.79 -255.30 -159.61 72.598 530.89n-Butane C4H10 58.123 31.08 -0.51 -217.05 -138.36 51.719 379.61Ethene (Ethylene) C2H4 28.054 -154.71 -103.73 -272.50 -169.17 (1,400) (9,700)Propene (Propylene) C3H6 42.081 -53.83 -47.68 -301.47 -185.26 232.8 16911-Butene (Butylene) C4H8 56.108 20.79 -6.23 -301.65 -185.36 62.55 459.0Methyl alcohol CH4O 32.042 148.41 64.67 -143.79 -97.66 4.631 35.44Ethyl alcohol C2H6O 46.069 172.87 78.26 -173.29 -114.05 2.313 17.903Carbon dioxide CO2 44.01 -109.24 -78.46 -337.04 -205.02 - -Hydrogen sulfide H2S 34.082 -76.49 -60.27 -121.81 -85.45 394.67 2,859.7Sulfur dioxide SO2 64.065 14.11 -9.94 -103.81 -75.45 85.46 630.2Ammonia NH3 17.0305 -27.98 -33.32 -107.77 -77.65 211.9 1,555Nitrogen N2 28.0134 -320.44 -195.80 -346.00 -210.00 - -Helium He 4.0026 -452.11 -268.95 -455.75 -270.97 - -

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Physical Constants

COMPOUND

DENSITY OF LIQUID14.696 psia, 60 °F

DENSITY OF LIQUID

101.3250 KPA (ABS), 15 °C

DENSITY OF LIQUID

DENSITY OF IDEAL GAS14.696 psia, 60 °F

DENSITY OF IDEAL GAS

101.3250 KPA (ABS), 150 °C

DENSITY OF IDEAL GAS

lb/gal(wt in vacuum) gal/lb mol kg/m3

(wt in vacuum) m3/kmol cu ft gas/lb

cu ft gas/galliquid m3 gas/kg Volume ratio

gas to liquid

Methane (2.5) (6.4172) (300) (.05) 23.654 (59.135) 1.4738 (442.15)Ethane 2.9696 10.126 357.76 0.084051 12.62 37.476 0.78635 281.32Propane 4.2268 10.433 507.3 0.086925 8.6059 36.375 0.53619 272.01Isobutane 4.6927 12.386 562.98 0.10324 6.5291 30.639 0.4068 229.02n-Butane 4.8691 11.937 584.06 0.099515 6.5291 31.791 0.4068 237.6Ethene (Ethylene) - - - - 13.527 - 0.84282 -Propene (Propylene) 4.3435 9.6883 521.36 0.080714 9.0179 39.169 0.56189 292.951-Butene (Butylene) 5.0052 11.21 600.41 0.093449 6.7636 33.853 0.42143 253.03Methyl alcohol 6.6381 4.827 795.94 0.040257 11.843 78.618 0.73795 587.37Ethyl alcohol 6.6193 6.9598 793.65 0.058047 8.2372 54.525 0.51324 407.33Carbon dioxide 6.8199 6.4532 821.94 0.053544 8.6229 58.807 0.53726 441.59Hydrogen sulfide 6.6817 5.1005 801.9 0.042499 11.1351 74.401 0.69382 556.37Sulfur dioxide 11.650 5.4991 1396.0 0.045892 5.9235 69.008 0.36907 515.22Ammonia 5.155 3.3037 617.7 0.027571 22.283 114.87 1.3884 857.61Nitrogen 6.7481 4.1513 808.6 0.034644 13.546 91.413 0.84402 682.48Helium 1.0430 3.8376 124.98 0.032026 94.814 98.891 5.9074 738.3

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The Gas Industry Acronyms and Definitions • NG: Natural Gas, mostly methane, after it has been treated to remove acid gases (H2S,

CO2), water vapor and, if present, stripped of the heavier hydrocarbons through gas processing. NG is of pipeline quality acceptable for delivery into a pipeline or can be cooled to form a liquid (LNG) at –258 °F (-163 °C).

• Condensates – the hydrocarbons that are separated as liquids in field separators.• NGL: Natural Gas Liquids - the mixture of hydrocarbons that are separated out as

liquids during gas processing.• LPG: Liquid Petroleum Gas - propane, butane, iso-butane as separate components

formed by fractionation and sold as separate products or, in some countries, as mixtures of propane and butane.

• LNG: Liquefied Natural Gas - natural gas (NG) that has been converted to a liquid by cooling to –258 °F (-163 °C).

• GTL: Gas-to-Liquids means the conversion of natural gas to liquid petroleum products such as clean diesel, gasoline and high purity lubricants.

• CNG: Compressed Natural Gas (NG) typically referring to the compression of natural gas into a tank for use as vehicle fuel.