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Environment - Air

Energen has worked for many years to reduce methane emissions. These efforts include voluntary implementation of emissions reduction activities and equipment as well as compliance with methane emission control, reduction, and reporting regulations. In addition, Energen’s strategic decision in 2009 to shift its focus from natural gas to oil has significantly reduced the company’s methane footprint.

The company’s transformation to a leader in the drilling and development of horizontal oil formations in the Midland and Delaware basins culminated in 2016 with the sale of Energen’s remaining assets in the San Juan Basin, one of the largest onshore natural gas producing regions in the United States. Energen also sold its gassier assets in the western portion of the Delaware Basin in 2016. Several years prior, Energen sold its gas assets in the Black Warrior Basin and the north Louisiana/east Texas area; and in 2014, Energen sold its legacy natural gas utility. Today, Energen’s only gas production is associated with its oil production.

The mix of the company’s production from continuing operations in 2016 was 80% oil and liquids and 20% natural gas. Underscoring the company’s strategic shift to oil producer and the resulting reduction of its methane footprint, Energen has cut its annual natural gas production in just five years by 67%, from 11,953 MBOE in 2011 to only 3,905 MBOE in 2016.

Since 2003, the company has participated in the United States Environmental Protection Agency (EPA) Natural Gas STAR Program. Gas STAR is a voluntary program that encourages oil and natural gas companies to employ technologies and practices to improve operational efficiency and reduce methane emissions. Since joining, the company has achieved Gas STAR-estimated cumulative methane emission reductions of more than 9.0 billion cubic feet (Bcf) through 2016. According to the EPA, this corresponds to more than 4.3 million metric tons of carbon dioxide-equivalent reductions, which also equates to carbon sequestration of more than 3 million acres of pine forest.

Energen achieved these reductions through actions that were voluntary at the time achieved and included:

  • Installation of electric motors on pumping units and compressors previously fueled by natural gas
  • Installation of vapor recovery units (VRUs) at some production tank batteries
  • Installation of pumping units on gas wells with plunger lift to reduce venting while removing fluids from gas well bores
  • Capture of casing head gas by VRU or compressor
  • Reduction of blanket gas on tank battery facility
  • Flaring instead of venting where gas could not be captured into a pipeline system

New Regulations for 2016

Prior to 2016, EPA regulations addressed emissions associated with natural gas wells. In 2016 the EPA enacted the New Source Performance Standard (NSPS) OOOO (a) that expanded emission reduction regulations to hydraulically fractured oil wells.

Energen’s primary focus continues to be on identified best practices as well as the utilization of proven technology innovations to manage and mitigate the effects of emissions in its operations.

Emission controls are employed on 57% of our existing battery facilities; the remaining facilities, for which such controls are not required by EPA or State regulations, are monitored daily for leaks and repaired as soon as possible. We expect all future battery facilities will be constructed with control technology to meet EPA and State requirements.

Some examples of ways in which Energen is reducing methane and volatile organic compounds (VOC) at our battery facilities are:

  • Vapor recovery units on storage tank facilities capture VOC emissions in the tank’s head space that are generated from producing oil into a storage tank. These VOCs contain merchantable components which are then routed to a natural gas sales line at the facility. Utilizing the latest thief hatch and pressure regulation technology on oil and water storage tanks also minimizes emissions from storage tanks.
  • A Leak Detection and Repair (LDAR) program is used at affected facilities to identify and eliminate fugitive emissions from tanks and other components. Twice a year, a certified thermographer is used to identify leaks and work with operations personnel to repair leaks as soon as possible. While approximately 5% of existing facilities are required to be covered by the LDAR program, all future facilities are expected to be covered.
  • Use of Lease Automatic Custody Transfer (LACT) units allows for oil sales directly into a pipeline, thereby avoiding truck-loading emissions. Additional benefits are reduced diesel emissions and nuisance dust emissions from truck traffic on our locations.
  • Electric instrument air compressors to supply air to control devices have been installed at some battery facilities in lieu of natural gas supplied controls.
  • Energen has installed “emergency flares” at locations that allow for flaring of gas instead of venting. Operational flaring occurs periodically at facilities during upset and maintenance activities or in certain emergency situations. Flaring in lieu of venting allows for safer operations and reduced overall emissions due to the combustion of the associated gas volume.

In addition, completion/operational practices that allow for the reduction or, in some cases, elimination of flared gas during completion activities have led to a reduction in flaring during completion activities from an average of 15 days in 2015 to just over 3.5 days. Reductions of this magnitude are largely accomplished by having operational infrastructure in place prior to completion activities which allows gas to be routed to a natural gas sales pipeline.


Each owner or operator of onshore petroleum and natural gas systems operating in a geologically defined hydrocarbon basin(s) that emits 25,000 metric tons or more of greenhouse gas (GHG) is required to report annual GHG emission data under subpart W of the Greenhouse Gas Reporting Program (GHGRP). The GHGRP requires reporting of carbon dioxide, methane, and nitrous oxide emissions from various source categories within the petroleum and natural gas system. Emission data is expressed in metric tons of Carbon Dioxide equivalent (mtons CO2e).

The data in the table below shows Energen’s reported GHG emissions from all our operated facilities in 2016 as adjusted by the EPA to reflect Global Warming Potential..

Subpart W Reported emissions (mtons CO2e) 
 Carbon Dioxide 409,518
Nitrous Oxide299

Energen’s top three GHG emission sources are combustion, flare stacks, and atmospheric tanks.

Reduction of emissions from oil and gas operations into the air continues to be an area of focus at Energen, and the company continues to work diligently with Federal and State agencies to comply with applicable regulations regarding daily operations.