Federal and State regulatory rules require oil and gas (O&G) operators to reduce natural gas venting and leaks from their operations. NSPS OOOO has standards for VOC emissions from storage tanks, compressor seals, pneumatic controllers and fugitive leaks (primarily natural gas processing). NSPS OOOOa has standards for VOC emissions from storage tanks, compressor seals, pneumatic controllers, pneumatic pumps and fugitive leaks. Several State environmental regulatory agencies have their own State specific regulations for venting and leaks.

Besides these rules, there is a general duty to operate O&G facilities with minimal leaks ­– especially from storage tanks, emission control piping (closed vent systems) and fugitive components (e.g., valves, flanges, connections, etc.). Venting and leaks of natural gas can also be health (worker exposure) and safety (flammable gases) issues.

Using a system to manage and control venting and leaking of natural gas reduces emissions and improves safety. It can also be a part of a company’s voluntary effort to reduce methane from their operations that is facilitated by the ONE Future Coalition, The Environmental Partnership and EPA Methane Challenge/Natural Gas STAR Program.


IQR Emission Survey System

As a part of a company’s vent gas management system, Cimarron uses its IQR services to Identify, Quantify and Rectify venting and leaking of natural gas from oil and gas production facilities, gathering stations and gas processing plants.

IQR stands for Identify, Quantify and Rectify.


The identify part of IQR gathers data on emission sources that could vent or leak natural gas. This can be a facility-wide or equipment specific inventory. This can serve multiple needs to meet emission control/standard requirements, facility permitting and GHG, criteria pollutant and hazardous air pollutant emission inventories.

This could include a partial or complete inventory including emission sources such as:

  • Storage tanks – crude oil, condensate, produced water
  • Piping for closed vent systems serving emission controls (e.g., VRU, flares, enclosed combustors)
  • Compressor seals
  • Pneumatic devices using natural gas (controllers, pumps)
  • Glycol dehydration units
  • Production equipment (separators, heater treaters, line heaters, engines, etc.)
  • Fugitive components

Methods used to Identify emission sources can include:

  • Site visit to facility to gather data for targeted emission sources
  • Operator supplied information
  • Piping and Instrumentation diagrams (P&IDs) and process flow diagram review

Typical data gathered can include:

  • Process flow with attention for sources venting to the atmosphere and recovered and controlled
  • Process conditions (pressure, temperature)
  • Production/throughput rates of oil, natural gas and produced water
  • Emission controls operating
  • Sales gas analyses
  • Flash gas analyses


Methods used to quantify venting can include direct measurement, sample collection/chemical analysis and process simulators.

Direct measurement methods typically measure natural gas venting for a duration of 6 to 24 hours giving data on the cyclical flow (minimum, maximum, average) of gas. A chemical analysis representative of the gas vented is used to obtain the mass amounts of VOCs and methane. This can be used for storage tank, pressure vessels (e.g., heater treaters) and glycol dehydration unit still column vents.

Direct measurements used for storage tank venting include:

  • Turbine meters
  • Thermal mass flow meter

Process simulators can also be used if have an available representative wellstream or pressurized oil/gas chemical analysis, accurate process flow and process operating conditions (e.g, pressure, temperature). Pressurized oil samples that are “flashed” in the laboratory can be used to obtain a flash factor gas to oil ratio (GOR) that estimates flash gas. The GOR units are standard cubic feet (SCF) per barrel of oil throughput. Using oil throughput, the facility can estimate daily and annual venting volumes and masses (e.g., tons per year).

Fugitive leak monitoring focus on detecting leaks from oil and gas equipment. Method typically used to find fugitive leaks include:

  • IR Cameras to detect the presence or absence of a leak
  • Hi-Flow Samplers – quantifies the leaking component mass amount of gas
  • Volatile Organic analyzer (EPA Method 21) to detect presence or absence of a leak with a concentration (ppmv) leak standard
  • Acoustic meters for through valve leak detection



Rectifying emissions seeks to eliminate or reduce the venting or leaking of VOCs and methane to the atmosphere.

Where feasible, recovery of natural gas is most beneficial. This can maximize the amount of natural produced at the wellhead that is sent to the sales pipeline. This increases facility profits, lowers worker exposure to chemicals and reduces emissions.

Rectifying emissions can include methods to:

  • Recover vent gas and put it back into the system
  • Combust vent gas
  • Leak prevention
  • Find, identify and repair leaking components

The following are typically used to rectify vent gas and fugitive emissions:

  • Vapor Recovery Units (VRU)
  • Vapor Recovery Towers (VRT) (in conjunction with a VRU or VCU)
  • Vapor Combustor Unit (VCU)
  • Flares – open-tipped pipe flares
  • Periodic Optical Gas Imaging (OGI) or EPA Method 21 Organic Volatile Analyzer surveys
  • Routine service and maintenance of control equipment by qualified personnel for VRUs, VRTs and VCUs.

Cimarron IQR Services

Let Cimarron help your company Identify, Quantify and Rectify (IQR) your facility emissions.  Using our IQR services your company can stay in compliance with NSPS OOOO and state air permits and make your company money. Our IQR team can also assist with gathering data for your air permitting and emission inventory needs.

A part of our IQR service for NSPS OOOOa compliance includes first attempt to repair the source of fugitive emissions which gives the operator more time to finalize repairs if needed.

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