Marathon Oil worksite

Emissions Methodology, Performance and Metrics

We report our air emissions resulting from fuel combustion and venting, using methodologies based on the emissions source and the regulatory requirements in the country of origin.

Our Methodology

Our emissions reporting methodology varies depending on the emissions source and the regulatory requirements in the country of origin. Air emissions from the oil and gas industry can be divided into two primary categories: combustion and venting. Emissions from fuel combustion result from operating equipment such as engines, heaters and generators. Fuel combustion results in emissions of nitrogen oxides (NOx), carbon monoxide (CO), sulfur dioxide (SO2), particulate matter (PM), volatile organic compounds (VOCs) and carbon dioxide (CO2). Venting primarily results in VOCs and methane (CH4), generally from storage tanks, well venting, gas dehydrators and equipment leaks. Flares and other control equipment eliminate most of the VOCs and methane. Control equipment is the preferred method to lower VOCs and methane emissions if there are no operational or safety restrictions on their use.

In this report, we include direct emissions (Scope 1) and indirect emissions (Scope 2) as defined by the IPIECA/API/IOGP Petroleum Industry Guidelines for Reporting Greenhouse Gas Emissions, on an operated basis. We include emissions from contractors’ equipment and activities (such as drilling and completions) and other temporary activities (such as well test flaring) when local regulations require it. Direct emissions are measured and/or estimated, recorded and reported in accordance with applicable regulatory requirements for the respective operations. Indirect emissions are estimated based on Company energy use.

For example, we use methodologies outlined in the Environmental Protection Agency’s (EPA) GHG Mandatory Reporting Rule (MRR) to calculate emissions from U.S. oil and gas operations. Approximately 99 percent of our U.S. operations report to the EPA through this program on a barrel of oil equivalent basis. We use the same methodology for U.S. assets that are not required to report to the EPA under this regulation and include those emissions in this report. When no regulatory requirements apply, we calculate GHG emissions using the API Compendium of Greenhouse Gas Emissions Methodologies for the Oil and Gas Industry. For indirect emissions, we track purchased electricity and calculate emissions using the API Compendium.


Air Emissions Performance

Marathon Oil evaluates our emissions performance on an absolute and rate basis. Our absolute emissions and rates of emissions are influenced by factors including activity levels and portfolio changes. We evaluate our performance using greenhouse gas (GHG) and methane emissions intensity, expressed as carbon dioxide equivalent (CO2e) emissions per equivalent barrel of all hydrocarbon produced.

In 2017, global GHG emissions and intensity increased by 18 percent and 15 percent, respectively. The increases were primarily due to higher activity in Oklahoma and the North Dakota Bakken, and our entry into the Permian Basin. We identified all emissions sources in the Permian Basin and are integrating the asset into our management system. Our methane emissions and methane intensity decreased in 2017, primarily due to removal of high bleed pneumatic controllers in Oklahoma and divestiture of non-core assets.

We also measure total methane emissions as a percentage of total natural gas produced, even though we have a liquids-dominated portfolio, particularly in the U.S. Our overall methane emissions ratio decreased by 7 percent in 2017, primarily due to increased gas production from the Alba compression project in Equatorial Guinea, and increased activity in Oklahoma and the Bakken, along with the aforementioned methane emissions reductions.

GHG emissions and GHG emissions intensity in Bakken increased 36 percent and 31 percent, respectively. While we have connected 96 percent of the production facilities to third-party gas pipelines, constrained gas pipeline capacity in the region increased our GHG emissions from flaring of associated gas. Our strategies to continue reducing the amount of gas flared include enabling third-party gas gatherers to build gas infrastructure by providing our drilling plans, assisting with landowner right-of-way acquisitions and prioritizing connections to the gas infrastructure.



Air Emissions Reduction Strategies

Marathon Oil takes action to find and develop oil and natural gas safely and responsibly, including by reducing greenhouse gas (GHG) and other air emissions from our operations. Our efforts reduce our exposure to potential changes in climate change regulations, which could increase the costs of emitting GHGs or reduce demand for oil and gas over time. We continuously evaluate and implement strategies and technologies, and annually review cost-effective methods to reduce air emissions from our operations throughout the drilling and production lifecycle.

In 2017, we assisted in establishing The Environmental Partnership as a founding member. This voluntary group of U.S. natural gas and oil companies has a mission to continuously improve the industry's environmental performance by taking action, building knowledge and fostering collaboration among stakeholders. To that end, Marathon Oil enrolled in the partnership's environmental performance programs aimed at reducing emissions of methane and volatile organic compounds (VOCs):

  • Phase-out of high-bleed pneumatic controllers
  • Monitoring manual liquids unloading operations to minimize emissions
  • Leak detection and repair

In early 2016, our Oklahoma asset set a goal to reduce methane intensity in the asset by at least 50 percent by 2020. We surpassed that goal by the end of 2017, reducing methane intensity by more than 54 percent from the total in 2015. This was achieved by replacing high-bleed pneumatic devices with low-bleed or non-bleeding mechanical controllers in all our Oklahoma facilities.

As part of our commitment to innovation, we implemented a project in 2017 that cut electricity costs and per-barrel production costs by reducing energy used by rod pumping units. This energy efficiency project uses solar technology to power the unit's motor. In six pilots in the Eagle Ford and Bakken, the technology offsets increases in electricity usage from higher activity. In addition, the system uses a solar panel to power the capacitor bank, which generates renewable energy for federal and Texas state tax credits on new installations. In 2017, Marathon Oil retrofitted approximately one-third of our existing pumping units with the technology, and we plan to install it on all new pumping units.

Our operations use infrared cameras to detect temperature differences that can indicate equipment leaks. Leaking equipment, if found, is repaired as soon as practicable. Some assets initiated a voluntary infrared camera program in 2014; however, all assets now regularly employ infrared camera inspections at operating facilities as required by state and federal requirements. Infrared camera monitoring, along with maintenance and operating practices, continue to minimize air emissions from company facilities.

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