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Emission Estimation Methods for Oil and Gas Operations

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Emission Estimation Methods for Oil and Gas Operations Powered By Docstoc
					EPA Region 6 National Multimedia
 Inspection/Enforcement Workshop
   Oil and Gas Emissions
        May16, 2012
      Brian Boyer
    COMM Engineering
        Oil and Gas Process
Ø Wellhead - Christmas tree and line heater
Ø Separation - 2 and 3 phase separation
Ø Gas to Compressor then to gas
  sweetening then to dehydration unit then
  to sales pipeline
Ø Oil to heater treater and then to storage
  tanks prior to sales by tanktruck or pipeline
Ø Produced water to storage prior to
  disposal in well
May 7, 2008       COMM Engineering   2
Oil and Gas Production Process
Typical Flash Destination
Dehydration Process
    ØAbsorption of water by glycol in
     contactor to remove water from natural
    ØDistillation of glycol in reboiler to
     remove water from glycol

 May 7, 2008         COMM Engineering   5
Dehydrator Process Flow
    O&G Production Process
Process and Emission Controls
Online tool
Global Methane Initiative
Pumping Unit on Well
Line Heater
Vertical Separators
Horizontal Separator
Compressor Rod Packing
Centrifugal Comp. Wet Seal
Centrifugal Comp. Dry Seal
Compressor and Engine
Generator Engine
Fuel Gas Scrubber
Pneumatic Devices
Glycol Reboiler/Still Column
Glycol Contact Tower
Glycol Dehydrator
Dehydrator Kimray Pump
Glycol Dehydrator Condenser
Heater Treaters
Heater/Reboiler Nameplate
Storage Tanks
Storage Tank Vent Piping
Storage Tank Vent Piping
Cold Vent
   Oil & Gas Emission Sources
Ø Combustion of fossil fuels (natural gas,
  diesel fuel) - primarily natural gas for oil and
  gas production operations
Ø Venting of natural gas and crude oil vapors
Oil & Gas Combustion Sources
Ø Sources that Burn Natural Gas or Diesel
   ØInternal combustion engines -
    reciprocating and turbines that drive
    compressors, generators, pumps, cranes
   ØHeaters, reboilers and boilers
      Fuel Combustion Pollutants
Ø Oxides of Nitrogen - NOx
Ø Carbon Monoxide - CO
Ø Volatile Organic Compounds (VOCs) -
  nonmethane/nonethane hydrocarbons
Ø Sulfur Dioxide - SO2
Ø Hydrogen Sulfide - H2S
Ø Particulate Matter
Ø Formaldehyde - hazardous air pollutant
       Venting O&G Sources
Ø Storage Tanks – oil, produced water
Ø Emergency/Process Vents - Cold Vents
Ø Glycol Dehydrators Still Column & Flash Tank
Ø Reciprocating and centrifugal compressor seal leaks
Ø Gas Actuated Pumps - Wilden/Aro/Texsteam/Kimray
Ø Pressure/Level Controllers
Ø Loading/Unloading Facilities
Ø Amine Gas Sweetening Units
Ø Fugitive Emissions – valves, flanges, seals, etc.
Ø Well unloading
Ø Well testing venting and flaring
Venting Pollutants of Concern
ØPollutants from venting of natural gas
 and hydrocarbon vapors:
  ØH2S other reduced sulfur compounds
 Venting Pollutants of Concern
ØVOC HAPs from Venting:
 Øxylenes          BTEX
 Ø2,2,4-trimethylpentane (iso-octane)
          General Helpful Hints
Ø Review data from and
Ø Walk down from wellhead to sales points
Ø Operator knowledge - contract or company
  operator; how long at the facility
Ø Review process/safety flow diagrams
Ø Determine all venting sources/locations –
  routine and nonroutine venting
Ø Determine all combustion sources
Ø Destination of flash gas
  O&G Facilities - General
u Listen and look for signs of leaking gas
u Housekeeping
u Morning reports – oil & gas production
  rates – reported daily, engine
  downtime/runtime, blowdown of natural
u Emission Inventory data on venting
u Upsets and start-up emissions
      Compressor Helpful Hints
Ø Emission controls installed and operating?
  Catalyst material in converter?
Ø Check most recent stack test results
Ø Air fuel ratio controller for nonselective
  catalytic reduction
Ø Compressor runtime log vs gas vented and
  reported in emission inventory – estimate or
Ø How often is compressor blowdown per
  month and volume blowdown? Gas
     Compressor Helpful Hints
Ø Gas destination if compressor down–
  burning flare or to atmosphere?
Ø Use portable analyzer and IR temp gun to
  check stack test results
Ø Compressor seals fugitive leaks
       Dehydrators - Helpful Hints
Ø Ensure all emission controls operating – trace
  control piping
Ø Will controls installed condense liquids? No steam
Ø Glycol circ. rate – use pump curve to convert from
  strokes/minute to gpm - (Kimray pumps see
Ø Is pump able to pump at rate used in GLYCalc
Ø Destination of gas from flash tank (aka gas-
  condensate-glycol separator)
Ø Can reboiler or flare burn all of gas from
  condenser and/or flash tank?
Dehydrators - Helpful Hints
Ø Check GLYCalc inputs vs actual operations
Ø Important GLYCalc inputs:
  ØGas analysis sample upstream of contactor –
   (C1-C10+ and BTEX and n-hexane)
  ØGas contactor temperature
  ØGas contactor pressure
  ØPresence/absence of flash tank
  ØExit temperature of condenser
  ØStripping gas used? (Stripping gas reduces
   efficiency of the condenser)
  GLYCalc order from
  Storage Tanks - Helpful Hints
Ø Determine if emission controls installed and
  operating – vapor recovery unit (VRU), flares
Ø Is VRU adequately sized?
Ø Is VRU connected and operation?
Ø Runtime meter on VRU?
Ø Tank hatches sealed?
Ø Any holes or other leaks?
Ø Motive force to send tank gas to flare
Ø Trace piping from tank to controls
Ø Permit for flash, standing/working losses
  Helpful Hints - Storage Tanks
Ø Check gas analysis used to speciate tank
  vapors – VOC content accuracy
Ø Check method used to estimate flash
  calculations for changes from permitted
  operating conditions
Ø Lower separator pressure upstream of tank
  to reduce emissions
Ø How oil sent to sales? Pipeline? Tank truck?
Helpful Hints - Flash VOC Losses
Ø Sources: separators, heater treaters, storage
  tanks, dehydrator flash tanks
Ø Check destination of flash gas - atmosphere,
  VRU, compressor suction – trace piping
Ø Check flash calculations for changes from
  permitted operating conditions
Ø Higher the pressure drop, the greater the
  expected flash scf per barrel of oil
   Direct Measurement Aug 2001
Ø 700 bbls condensate/day
Ø Pressure drop 80 psig to 0 psig between
  separator and storage tank
Ø API Gravity = 62
Ø 140.3 SCFM measured (90 to 160 SCFM)
Ø 202,000 standard cubic feet per day gas vented
Ø 1850 BTU/SCF (374 MMBTU/day)
Ø Methane Recovery: 678 tons/yr (CO2
  equivalent = 14,238 tons/yr)
 Helpful Hints – Flares (burning)
Ø Trace piping to determine what routed to flare
Ø Ensure that all sources routed to flare have
  enough motive force to get gas to flare tip
Ø Ensure that flare pilot lit or flare equipped with
  continuous sparking device
Ø Use IR temp. gun to check if pilot and flare
  burning – flame may not be visible
Ø Observe smoking condition
Ø Determine how gas volume measured or
  estimated; recordkeeping method used
COMM Engineering
P.O. Box 53463
Lafayette, LA
(337) 237-4373

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