Interstate Pipeline Gas Quality Primer

1
Interstate Pipeline Gas Quality Primer

• Business Practices Subcommittee
• June 15-16, 2004
• PIPELINE SEGMENT
• Wholesale Gas Quadrant
• North American Energy Standards Board

2
OVERVIEW

• Basis for Gas Quality Specifications
• Development
• Criteria
• Trade-offs
• Gas Quality Data
• Collection
• Availability
• Usage
• Gas Quality Specifications/Applicability
• Components
• Understanding
• Conclusions

3
Basis for Gas Quality Specifications

• Industry Development
• First pipelines (1920s 1930s) were regional
• Few pipe-to-pipe deliveries
• Specific supplies delivered to specific markets
• Little concern about variations in supply mix
• Each system developed criteria for specific
  safety and market requirements
• End-use equipment designed and installed based on
  specific supply availability
• Subsequent development of pipeline grid
  (1970s-1980s)
• Additional quality criteria applied to specific
  systems
• Additional pipe-to-pipe deliveries
• Minimum coordination of quality specifications at
  interconnects

4
Basis for Gas Quality Specifications

• Gas quality specifications have been developed
  based on
• Operational Safety
• Operational Efficiency
• Supply availability
• Market requirements
• Processing responsibilities
• Deliberate trade-offs between economics and
  requirements of production, transportation and
  end-use parameters

5
Basis for Gas Quality Specifications

• Operational Safety
• Limitations on harmful components
• H2S highly poisonous
• Sulfur by-products during combustion
• Specifications to control damaging properties
• Water/water vapor content corrosion
• Oxygen corrosion
• Carbon Dioxide - corrosion

6
Basis for Gas Quality Specifications

• Operational Efficiency
• Btu parameters
• Throughput capacity
• Specific Gravity
• Gas flow efficiency
• Hydrocarbon Liquefiables
• Capacity restrictions
• Inerts
• Btu impact
• Emissions concerns

7
Basis for Gas Quality Specifications

• Gas Quality Trade-offs
• After assuring safety, other quality criteria
  often established to optimize availability of
  supplies, market requirements and economics

8
Gas Quality Data

• Gas Quality Data Collection
• Electronic evaluation (Chromatograph and other
  instrumentation)
• Relatively expensive
• Often telemetered
• May not be operationally feasible (power/radio)
• Sampling physical evaluation
• Continuous sample
• Gas stream tested for a specified period
• Spot sample
• Gas stream tested at a point in time
• Other Sample
• Random sample/sample period
• Equipment in place is pertinent to pipeline and
  customer requirements
• Data requirements may be contract driven

9
Gas Quality Data

• Data availability
• Location
• Electronic measurement (EMS) vs. charts
• Size of meter
• Frequency of flow
• Support for installation (power, transmission)
• SCADA
• Operational data
• Not billing quality information
• Timing
• Measurement parameters
• Data availability
• Reporting frequency
• Adjustments
• Operational vs. Billing Quality
• Not all data is available and/or monitored daily

10
Gas Quality Data

• Quality Data Usage
• Real Time vs. Periodic Reporting
• Electronic reporting
• Sampling frequency
• Proprietary Issues
• Operator-to-operator specific performance issues
• Within Tariff tolerance is criteria for other
  performance
• Receipt-to-delivery relationships
• Blending
• Timing of quality readings (transients)
• Delivered quality
• Specific supply quality may not be an issue

11
Gas Quality Specifications/Applicability

• Typical Pipeline Gas Quality Components
• Btu Content (Minimum/Maximum limits)
• Hydrogen Sulfide (H2S)
• Total Sulfur (S)
• Nitrogen (N)
• Carbon Dioxide (CO2)
• Oxygen (O2)
• Water and/or Water Vapor
• Hydrocarbon Liquefiables
• Temperature
• Total Inerts
• Dust, Gum, Dirt
• Other
• Burnability (HHV, HV, Input Factor, Wobbe)
• Mercaptans
• Not all applicable to all pipelines

12
Gas Quality Specifications/Applicability

• Context of Gas Quality Data
• Transient information
• Upstream information may not be a predictor of
  delivery quality
• Level of data availability/presentation
• Pooling/Blending
• Reticulated systems (variable direction flows)
• Downstream blended data may be more indicative of
  gas quality performance

13
Conclusions

• Understanding the context of quality information
  is critical for its use
• Not all gas quality information is captured at
  all points
• Gas quality at any point is a mix of input
  qualities/quantities and existing line pack
• Real-time information is probably not feasible
  for posting
• Daily data (if electronic) may be best available
  information
• Blended information (24 hours)
• May not be reflective of future flows
• May not be available at all locations