Stand Tall and Speak Up: We Can Be a Key Player in the Solution to Global Warming
Authors: Sprunt Eve S. 
Published: February 2015

Whether or not you are convinced that climate change from rising levels of atmospheric CO2 is a serious problem, you must admit that it has become a real business issue. Like any change, concerns about global warming present both opportunities and threats for the petroleum industry. Let's focus on the opportunities.

Although many people dream of a society that is powered by renewable energy, most recognize that dream is still many years away. The question then is, how can fossil fuels, which are regarded as the major cause of increasing atmospheric CO2, be used in a climate-friendly way?

CO2 capture and storage has been identified as a promising alternative. The CO2 would be captured from large, stationary point sources such as electric power plants, combined heat and power plants, and district heating, and through industrial processes such as oil refining, natural gas processing, iron and steel smelting, and cement processing. Capturing CO2 from vehicles is not practical with current technology. Many of the emissions captured would be from coal, but reduction of global CO2 emissions would diminish concern about emissions from use of petroleum as a transportation fuel.

Once CO2 has been captured, there are several alternatives, including storing it in the ocean, converting it to another stable form through chemical processes, and storing it underground. Oceanic storage poses a host of environmental issues. Transforming CO2 into other materials is being evaluated for technical feasibility. Underground storage, also known as geologic sequestration, is considered by many groups, including the International Energy Agency (IEA), to be the most promising option.

When it comes to storing gas underground, the petroleum industry is the home of much of the expertise. We know how to locate appropriate rock formations, deter-mine the storage capacity of the rock, assess the ease with which gas can be injected and immobilized with time, and determine the maximum gas pressure that can be sustained without risk of fracturing or exceeding the sealing capacity of the cap rock. Injection into hydrocarbon-bearing formations, even depleted ones, includes the additional benefit of enhanced recovery. Theoretical modeling is now underway to see if repressurization with CO2 can also produce additional methane from depleted natural gas reservoirs. Thus, while the oil industry has been viewed as a major contributor to global warming, it can also be a key player in the solution.

Three different underground storage alternatives have been identified: storage in deep, saline water-bearing formations; storage in depleted oil and gas reservoirs; and storage in unmineable coal seams. Let's look at the status of each of these.

Statoil has played a major role in demonstrating the validity of geological sequestration by capturing and storing CO2 from the Sleipner West natural gas field, which is located in the Norwegian sector of the North Sea. Gas from the Sleipner West field has 9% CO2, which is above the 2.5% European export limit. CO2 is separated offshore and injected into an aquifer 800 m below the sea floor and 2500 m above the reservoir. Since 1996, Statoil has injected about 1 million tons of CO2 per year. Other commercial-scale projects entailing injection of CO2 stripped from natural gas include BP's In Salah project in central Algeria (2004), Statoil's Snohvit LNG project in the Barents Sea (2006), and Chevron's Gorgon LNG project at Barrow Island off Northwest Australia (2010).