EPA Office of Air and Radiation

epa.gov/gasstar

Overview of Reduced Emissions 

Completions (RECs)

Cost-effective practice to recover 

natural gas and condensate 

produced during flowback 

following hydraulic fracture of 

natural gas wells.
U.S. Oil & Natural Gas System Emissions

2

Oil and Gas 

Production, 

397 Bcf

64%

Transmission and 

Storage, 110 Bcf

18%

Distribution, 

72 Bcf

11%

Processing,

44 Bcf

7% 

Oil Downstream,

2 Bcf

<1% 

Bcf = billion cubic feet

EPA. Inventory of U.S. Greenhouse Gas Emissions and Sinks 1990 – 2009. April, 2011. Available on the web at: 

epa.gov/climatechange/emissions/usinventoryreport.html.

2009 U.S. Oil and Gas Industry Methane Emissions 

(624 Bcf / 252 million tonnes CO2E)
2009 Oil and Natural Gas Production 

Emissions Sources

3

2009 Production Sector Methane Emissions (397 Bcf / 160 million tonnes CO2e)

Source: EPA. Inventory of U.S. Greenhouse Gas Emissions and Sinks 1990 – 2009. April, 2011. Available on 

the web at: epa.gov/climatechange/emissions/usinventoryreport.html.

Storage Tank Bcf = billion cubic feet

Venting

14 Bcf

Other Sources 

13 Bcf

Pneumatic Devices

67 Bcf

Well Venting and 

Flaring 

217 Bcf

Offshore Operations

37 Bcf

Dehydrators 

and Pumps

19 Bcf

Meters and

Pipeline Leaks

12 Bcf

Compressor Fugitives, 

Venting, and Engine

Exhaust

18 Bcf
Overview of Hydraulic Fracturing

Gas wells in tight formations, coal beds, and shale may require 

hydraulic fracture to produce gas

For new wells or re-fracturing to stimulate production of existing wells 

(workovers)

During completion of the well, flowback of fracturing liquids 

and proppant (often sand) is necessary to clean out the well 

bore and formation prior to production

High volume of liquid and solids are produced at high pressure to 

expel sand, cuttings, and hydraulic fracture fluids prior to production

Hydraulic fracturing video: www.northernoil.com/drilling.php

Video is for oil production but well drilling and hydraulic fracture 

process similar for gas

4
Natural Gas Losses during Gas Well 

Completions and Workovers

One standard practice is for operators to produce 

flowback to an open pit or tank to collect sand, 

cuttings, and fluids for disposal

Vent or flare the natural gas 

Typical composition of pollutants in flowback 

emissions:

Primarily methane (CH4)

Substantial amount of VOCs

Trace amounts of HAPs

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Source: Newfield
Reduced Emission Completions (RECs)

Practice to recover natural gas and condensate produced during 

flowback following hydraulic fracture

Portable equipment brought to well site 

Separates sand and water

Processes gas and condensate for sales

Route recovered gas through dehydrator and meter to sales line, 

reducing venting and flaring while increasing gas sales

Portable REC Equipment Source: Weatherford 6
RECs: Equipment

Skid or trailer mounted portable equipment to capture 

produced gas during cleanup

Sand trap

Three-phase separator

Use portable dehydrator

to remove water 

from the produced gas 

before it enter sales line

Source: Williams

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RECs: Diagram

8

Temporary, Mobile Surface Facilities, Adapted from BP

(for produced 

fluid, mainly 

water)
RECs: Preconditions

Permanent equipment required on site before cleanup

Nearby gathering system / sales line

Piping from wellhead to sales line

Lease meter

Gas quality meets gathering system specification

Stock tanks for wells producing significant amounts of 

condensate

Dehydrator (if needed to process gas to pipeline 

specifications)

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RECs: Benefits

Reduced methane and other air emissions during 

completions and workovers

Increase sales revenue from recovered gas and condensate

Partners report recovering 500 to 2,000 Mcf/day/well 

Partners also report recovering zero to several hundred bbl/day/well 

of condensate (which can result in significant additional revenue)

Typical well flowback time is 3 to 10 days

Improved relations with government agencies, public, and 

neighbors

Reduced environmental impact

Reduced disposal costs

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Partner Experience Economics

Noble in Ellis County, Oklahoma

RECs on 10 wells using energized fracturing

Total cost of $325,000

Estimated net profits: $340,000, or $34,000 per well on average

BP in Green River Basin, Rocky Mountain region

RECs on 106 total wells, high and low pressure

Capital investment of ~$500,000 per skid (including portable 

three-phase separators, sand traps, and tanks)

Conservative net value of gas saved: $20,000 per well

A Partner Company (Fort Worth Basin, Texas)

RECs on 30 wells

Incremental cost of $8,700 per well

Conservative net value of gas saved: about $50,000 per well

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Related Regulations

Oil and Gas Systems Greenhouse Gas Reporting Rule, Subpart W 

Reporting of emissions from the oil and gas sector

For hydraulically fractured well completions and workovers, will collect total number of 

completions and workovers and emissions from these sources as well as the number of 

wells using Reduced Emission Completion techniques and total gas recovered for sales

Clean Air Act (CAA) New Source Performance Standards (NSPS) and National Emissions 

Standards for Hazardous Air Pollutants (NESHAP) Review

EPA is currently reviewing CAA NSPS and NESHAP for the oil and gas sector 

Proposed rule projected for release July 2011

EPA has identified completion of fractured gas wells to be a significant source of 

emissions and is considering coverage under the NSPS

State Regulations

Wyoming requires “flareless completions” for wells in Jonah-Pinedale and 

concentrated development areas

Colorado requires sand traps, surge vessels, separators, and tanks as soon as practicable 

during flowback and cleanout of certain wells

EPA is also addressing potential water or other impacts under relevant statutes including 

Safe Drinking Water Act, Clean Water Act, Resource Conservation and Recovery Act 12
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References

Natural Gas STAR Program: http://www.epa.gov/gasstar/

Natural Gas STAR Technical Documents:

http://www.epa.gov/gasstar/tools/recommended.html

2011 U.S. Greenhouse Gas Inventory Report:

http://epa.gov/climatechange/emissions/usinventoryreport.html