GAS QUALITY: HOW IT IMPACTS QUESTAR GAS

Docket 04-057-09October 13, 2004

NATURAL GAS

AIR

HEAT + H20 + CO2 + CO + Other Stuff

Try to keep as high as possibleTry to keep as low as possible

Orifice size adjusted for specificinstallation conditions:- Altitude- Gas Composition

COMBUSTION THEORY 101

• Efficient and safe combustion requiresthe correct ratio of oxygen and fuel

• The ability of an appliance to properly combusta fuel different than what it was adjusted fordepends on the heating value and specificgravity of the fuel

Specific Gravity

Heating ValueWobbe Number =

1060 Btu/CF & .61 S.G.(Wobbe # 1357)

AIR

Appliance Properly Adjusted for Altitude and 1088 Btu/CF & .62 Specific Gravity (Wobbe # 1382)

IMPACT OF GAS QUALITY CHANGE ON APPLIANCE PERFORMANCE

Case 1: Ideal Conditions

• Proper flame characteristics• Appliance will perform as rated• Low carbon monoxide emissions

NATURAL GAS

985 Btu/CF & .575 S.G.(Wobbe # 1299)

AIR

Appliance Properly Adjusted for Altitude and 1088 Btu/CF & .62 Specific Gravity Gas (Wobbe # 1382)

IMPACT OF GAS QUALITY CHANGE ON APPLIANCE PERFORMANCE

Case 2: Introduction of Coal Seam Gas

•Flame instability (liftoff and possible blow-off)•Appliance will produce less heat than rated•Increase in carbon monoxide emissions

NATURAL GAS

985 Btu/CF & .575 S.G.(Wobbe #1329)

AIR

Appliance Properly Adjusted for Altitude and 1003 Btu/CF & .56 Specific Gravity Gas (Wobbe #1340)

IMPACT OF GAS QUALITY CHANGE ON APPLIANCE PERFORMANCE

Case 3: Re-Orifice Appliance Southern System Set-Point

•Proper flame characteristics•Appliance will perform as rated•Low carbon monoxide emissions

NATURAL GAS

Change orifice out with larger diameter orifice

Approximate Interchangeability Ranges

960 980 1000 1020 1040 1060 1080 1100

BTU

UINTA

PICEANCE

SAN J UAN

POWDER RIVER

Denver

GREEN RIVER

FERRON

1975 Salt Lake City

- Legend -

Other Pipelines in the Interstate Grid

Producing Basins

Questar Pipeline System

Northwest

CIG

El Paso

Transwestern

UINTA

PICEANCE

SAN J UAN

POWDER RIVER

Denver

GREEN RIVER

1998 Salt Lake City

FERRON

- Legend -

Other Pipelines in the Interstate Grid

Producing Basins

Questar Pipeline System

Northwest

CIG

El Paso

Transwestern

UINTA

PICEANCE

SAN J UAN

POWDER RIVER

Denver

GREEN RIVER

FERRON

Main Line 104 (2001)

Current

Kern River Loop (2003)

Salt Lake City

- Legend -

Other Pipelines in the Interstate Grid

Producing Basins

Questar Pipeline System

New Pipelines after 1998

Northwest

CIG

El Paso

Transwestern

PIPELINE BTU SPECIFICATIONS(September, 2004)

PIPELINE COMPANY MINIMUM BTU MAXIMUM BTU

ANR 967 1200

CIG 968 1235

Columbia Gulf 978 None

El Paso Natural Gas 967 None

Florida Gas Transmission 1000 None

NGPL 950 None

Northern Border 967 None

Northwest Pipeline 985 None

Panhandle Energy 950 1200

Sonat 950 None

Kern River 970 None

Tennessee 967 1100

Texas Eastern 967 None

Trailblazer 950 None

Transco 980 1100

TransWestern 970 None

Trunkline 950 1200

Questar 950 1150

Questar Pipeline – Downstream Btu Delivery Specs.

KRGT (Goshen)

Min. – 970 Btu/CFMax.– No Limit Btu/CF

QGC (Payson)

Min. - 950 Btu/CfMax. – 1150 Btu/CF

KRGT (Roberson Creek)Min. - 970 Btu/CF

Max.– No Limit Btu/CF

TransColoradoMin.- 967 Btu/Cf

Max.- No Limit Btu/CF

Southern StarBtu Delivery Requirements

Min.– 970Max.– No Limit

NPC (XO-16)

Min. - 985 Btu/CFMax. – No Limit

QGC (Northern Wasatch Front)

Min. - 950 Btu/CFMax.– 1150 Btu/CF

NPC (Clay Basin)

Min. - 985 Btu/CFMax. – No Limit

Kanda

FidlarPrice

ML 40/41

ML 104

ML 40

ML 68

ML’s 1/13/15

ML

80M

L58/

101

ML 22

Greasewood

Legend:

OakSpring

Eakin

Davis Plant - 3rd Party

JL 47

Overthrust Pipeline

Compressor Station

Delivery Point

CO2Plant

CIGMin.– 968 Btu/CF

Max.– 1235 Btu/CFWIC

Min.– 950 Btu/CFMax. –No Limit

Natural Gas Producers

Questar Pipeline Tariff Min.- 950 Btu/CF

Max.- 1150 Btu/CF

Basin Map

C

M

M TCGTFIDLAR

MCIG

NATURALBUTTES

CRMNG

RIFLE

REDWASH

M.L

.80

S

CLAYBASIN

CRAIG

C

DRIPPINGROCK

STATELINE

M SKULLCREEK

C

SIMON

M

HAYSTACK

WGPC

C NIGHTINGALE

M.L

.58

NPC

C

M

MM OT

MMUDDY CREEK

WHITNEYCANYON

OT

J.. L

36

KRGT

SLEROY EAKIN

M.L. 1,1

3,15

CIGWIC

M.L.40

C

OAK SPRING

M

M

M

M

M

MM INDIANOLAQGCNEPHI

CITY

PAYSON GATE

S CHALK CREEKS

COALVILLE

LITTLEMOUNTAIN

PORTERS LANE

SUNSET GATE

HYRUM GATE

QGC

QGC

QGC

QGC

QGC

KR

GT

IDAHO WYOMING

UTAH

COLORADO

NPC

NPC

SOUTH LAKE

MC

KANDA/COLEMAN

PRICE

M

M DRAGON TRAIL

NPC

XO-16

C

CO2 PLTCM

ELBERTA

M

Piceance Basin

Uinta Basin

Ferron

East Fields

Green River Basin

Overthrust

Questar Pipeline – Gas Quality Distribution

KRGT (Goshen)

Min. – 970 Btu/CFMax.– No Limit Btu/CF

QGC (Payson)

Min. - 950 Btu/CfMax. – 1150 Btu/CF

KRGT (Roberson Creek)

TransColorado

Southern Star

QGC (Northern Wasatch Front)

Min. - 950 Btu/CFMax.– 1150 Btu/CF

NPC (Clay Basin)

Kanda

FidlarPrice

ML 40/41

ML 104

ML 40 ML 68

ML’s 1/13/15

ML

80M

L58/

101

ML 22

Greasewood

OakSpring

Eakin

Davis Plant - 3rd Party

JL 47

Overthrust Pipeline

CO2Plant

CIGWIC

East Fields

Max. Btu-1150Min. Btu-950

Green River BasinMax. Btu-1176Min. Btu-1025

Overthrust

Max. Btu-1170Min. Btu-1000

FerronMax. Btu-1060Min. Btu-984

Uinta BasinMax. Btu-1150Min. Btu-1020

Piceance BasinMax. Btu-1200Min. Btu-1020

Historical Basin Heating Value

900

950

1,000

1,050

1,100

1,150

1,200

1,250

Jan-

97

May

-97

Sep-

97

Jan-

98

May

-98

Sep-

98

Jan-

99

May

-99

Sep-

99

Jan-

00

May

-00

Sep-

00

Jan-

01

May

-01

Sep-

01

Jan-

02

May

-02

Sep-

02

Jan-

03

May

-03

Sep-

03

Jan-

04

Date

Cal

orifi

c V

alue

, Btu

per

cub

ic fo

ot

Piceance

Uinta Basin

East Fields

Green River

Overthrust

Ferron

Updated on: May 5,2004

Historical Basin Daily Volume

-

50

100

150

200

250

300

Jan-

97

Apr-

97

Jul-9

7

Oct

-97

Jan-

98

Apr-

98

Jul-9

8

Oct

-98

Jan-

99

Apr-

99

Jul-9

9

Oct

-99

Jan-

00

Apr-

00

Jul-0

0

Oct

-00

Jan-

01

Apr-

01

Jul-0

1

Oct

-01

Jan-

02

Apr-

02

Jul-0

2

Oct

-02

Jan-

03

Apr-

03

Jul-0

3

Oct

-03

Jan-

04

Apr-

04

Date

Vol

ume

, MM

cfd

Piceance

Uinta Basin

East Fields

Green River

Overthrust

Ferron

Updated on: May 5,2004

PRICE AREA COAL BEDPRODUCTION HISTORY

0

50,000

100,000

150,000

200,000

250,000

300,000

Th

ousa

nd

Cu

bic

Fee

t p

er D

ay

1993

1995

1997

1999

2001

2003

YEAR

TYPES OF NATURAL GAS

Traditional Supplies 970 – 1250• Associated Gas • Dry Gas • Sour Gas

Current/Future Supplies• Coal Seam Gas 970 - 1030• LNG 1040 - 1200 Manufactured Gas 500 – 1000• Coal Gasification • Landfill/Biomass

Supply Source

Btu Range

WOBBE - INDEXIts Importance to Gas Interchangeability

• Wobbe Number – Relationship between the heating Value and Specific Gravity, defined as

• Wobbe Number is a good first-order predictor of appliance performance relative to a base or adjustment gas

• Wobbe Number is used throughout the world as the most common interchangeability metric

• Gas is generally considered interchangeable when the Wobbe number lies within a +/- 5% tolerance band around a set-point

Specific Gravity

Heating ValueWobbe Number =

Gas CompositionCoal Seam Gas

984

0.588

96.4%

0.27%

0.0543%

0.0139%

0.0018%

2.5%

-110.5°

0.18%

1283

Uinta Basin Gas1115

0.632

90.7%

5.06%

1.95%

0.863%

0.5923%

0.629%

70.4°

0.24%

1402

Representative BtuSpecific GravityPercent Methane(1010 Btu/Scf) Percent Ethane(1789 Btu/Scf)Percent Propane(2516 Btu/Scf)Percent Butane(3250 Btu/Scf)Percent C5+(5500+ Btu/Scf)Percent Inerts(CO2, etc.)Hydrocarbon DewpointPercent NitrogenWobbe (W = HV/G)

Northern Gates Gas1070

0.616

92.0%

4.35%

1.20%

0.491%

0.315%

0.629%

40.9°

0.48%

1363

Approximate Interchangeability Ranges

960 980 1000 1020 1040 1060 1080 1100

BTU

Btu Ranges for Area Production

900 1000 1100 1200

Piceance Fields

Uinta Basin

East Fields

Green River

Overthrust

Coal Seam Gas

Questar Gas Interchangeablity

10

20

Btu

10

60

Btu

Questar Gas Btu Delivery Ranges(1995 – Present)

900

920

940

960

980

1000

1020

1040

1060

1080

1100

8/3

0/1

995

12/3

0/1

99

5

4/3

0/1

996

8/3

0/1

996

12/3

0/1

99

6

4/3

0/1

997

8/3

0/1

997

12/3

0/1

99

7

4/3

0/1

998

8/3

0/1

998

12/3

0/1

99

8

4/3

0/1

999

8/3

0/1

999

12/3

0/1

99

9

4/3

0/2

000

8/3

0/2

000

12/3

0/2

00

0

4/3

0/2

001

8/3

0/2

001

12/3

0/2

00

1

4/3

0/2

002

8/3

0/2

002

12/3

0/2

00

2

4/3

0/2

003

8/3

0/2

003

12/3

0/2

00

3

4/3

0/2

004

8/3

0/2

004

Date

Btu

Hyrum Gate Station Btu

Little Mountain Gate Station Btu

Payson Gate Station Btu

Kern Gas Quality to QGC

1000

1010

1020

1030

1040

1050

1060

1070

Nov-9

9

Jan-

00

Mar

-00

May

-00

Jul-0

0

Sep-0

0

Nov-0

0

Jan-

01

Mar

-01

May

-01

Jul-0

1

Sep-0

1

Nov-0

1

Jan-

02

Mar

-02

May

-02

Jul-0

2

Sep-0

2

Nov-0

2

Jan-

03

Mar

-03

May

-03

Jul-0

3

Sep-0

3

Nov-0

3

Jan-

04

Mar

-04

May

-04

Jul-0

4

Sep-0

4

Date

BT

U

Kern BTU Southern Kern Northern Kern

ML #104

10

00

11

00

10

50

Btu/SCF

1003

QG

C S

OU

TH

PO

ST

-199

8

1088

Pre

-199

8 B

ase

Gas

1048

1006

1023

QG

C N

OR

TH

PO

ST

199

8

QGC BTU SET-POINTS RELATIVE TO BTU OF GAS DELIVERED TO 26 MAJOR URBAN AREAS1/

National LDC Btu Range

Encompasses 90% of Data

1/”Variability of Natural Gas Composition in Select Major Metropolitan Areas of the United States,” preparedby the American Gas Association Laboratories for Gas Research Institute, GRI-92/0123, March 1992

Questar Gas Position Points

1. An improperly adjusted appliance creates a safety hazard.

2. QGC and QPC constantly manage heat content and other gas quality criteria for safe, reliable use.

3. Post FERC regulations, Rocky Mountain pipelines have adopted national interstate grid gas quality specifications.

4. QGC’s gas sources (QPC & Kern River), as part of the interstate pipeline grid, supply volumes whose gas quality is aligned to the national market.

5. Markets, beyond the Rocky Mountains, have a major influence on

gas quality and the physical flows of Rocky Mountain production.