A Weak Spot in Carbon Sequestration: Abandoned Oil and Gas Wells

Carbon Storage Projects and the Risk of Leaky Abandoned Wells

After more than a century of pulling carbon from underground, a rush is underway to pump it back down. Companies have applied for scores of permits across the country to inject carbon dioxide deep into the earth. Several projects have already been approved.

Introduction

With industry planning to inject tens of millions of tons annually, a looming question is whether the climate-warming gas will stay underground.

The Risk of Abandoned Wells

The most likely points of failure, experts say, could be some of the millions of abandoned oil and gas wells that perforate the nation, often in the same areas targeted for storing carbon dioxide underground. A new report underscores the risk those wells pose in Louisiana, home to more proposed carbon storage projects than any other state.

There are about 120,000 abandoned wells in Louisiana overlying geological zones that could store carbon dioxide, more than 13,000 of which were plugged before modern standards were adopted in 1953, according to a report published by the Center for Applied Environmental Science at the Environmental Integrity Project, a watchdog group. A separate count, by the Louisiana-based advocacy group Healthy Gulf, looked within a 5-mile radius of the proposed projects and found about 7,000 oil and gas wells.

“It’s not a question of whether they’re going to leak,” said Abel Russ, director of the Center for Applied Environmental Science, which published an accompanying map of the wells. “It’s a question of how much, how often, and whether it’s an acceptable level of leakage.”

The Role of Sustainable Development Goals (SDGs)

With support from the Biden administration and billions of dollars in new subsidies and tax incentives, energy companies and others are planning to capture millions of tons of industrial carbon dioxide emissions and then pipe the climate pollutant for underground storage, part of an effort to reduce the nation’s greenhouse gas pollution. Federal and state regulators are reviewing 69 projects or permits to store CO2 underground, with 24 of those in Louisiana. Nine projects have already been approved while one more, in California, is pending.

Concerns and Skepticism

Companies plan to inject carbon dioxide into porous rock formations that are usually filled with brine containing not only extremely high salt levels but often heavy metals, hydrocarbons, and radioactive elements. Brine leaks, therefore, can be even more worrying than the escape of CO2.

Many scientists who study underground carbon dioxide storage say the risk of large-scale leaks is low. While there will inevitably be some leaks, they say, they will likely be slow, detectable and relatively easy to fix.

“Alertness is reasonable, but great fear is not,” said Susan Hovorka, a senior research scientist at the Bureau of Economic Geology at the University of Texas, which is funded by government and energy companies involved in carbon storage.

Many environmental advocates remain skeptical, however, and they point to problems caused by the injection of oilfield wastewater under high pressure in West Texas and other regions, the best existing analogue for the planned industrial-scale storage of CO2.

The Challenge of Abandoned Wells

In recent years, toxic brine has seeped and spewed out of old oil and gas wells across West Texas near wastewater injection wells, spouting more than 100 feet in the air and creating an artificial saline lake. The wastewater injections have also caused earthquakes, as the pressurized fluid interacts with faults. Carbon dioxide would be injected as a “supercritical” fluid that has properties of both a gas and liquid.

While the regulations for carbon dioxide storage are more rigorous than those that cover injection of other substances, abandoned oil wells represent a weak spot in the rules, said Dominic DiGiulio, a former EPA geoscientist and co-author of the new report.

“Plugged wells do leak. These wells were plugged a long time ago, and now we’re going to store supercritical CO2 under very high pressure and hope that these things somehow last thousands of years,” DiGiulio said. “It’s a problem.”

Concerns in Louisiana

Environmental advocates are especially concerned about Louisiana, which recently became the third state, after North Dakota and Wyoming, to get EPA approval to regulate CO2 injection wells. Many advocacy groups worry the state is not equipped to handle oversight of this new and complex technical challenge, and they say state regulators have a history of deferring to the oil and gas industry. They point out that the new secretary of the Department of Energy and Natural Resources, which regulates the wells, previously led Louisiana’s chief oil and gas lobbying group.

Patrick Courreges, a department spokesman, said the secretary does not have control over regulators.

The Geological Features and Risks

Over millions of years, oil and gas accumulated in some of the porous layers, held in place by the frosting on top. Hovorka and others say the same geological features that held the hydrocarbons in place can now do the same for carbon dioxide.

The problem is that people, over the last 150 years or so, have poked some 3.9 million straws into the cake in the form of oil and gas wells, according to the EPA, puncturing the layers and opening up paths for fluids and gases to migrate up.

The Risk of Leaky Wells

Hundreds of thousands of these abandoned wells have no records, so no one knows exactly where they are. Others may have been plugged with wood or in some cases not at all. Most wells are lined with steel casings that are cemented to the surrounding earth, and are plugged with cement once they’re out of use. But even properly drilled and plugged wells can fail over time as the steel corrodes or the cement degrades. Fluids and gases can then leak up these straws into groundwater or to the surface. Carbon dioxide is buoyant and will move upward if given the chance.

It is these leaky, old wells that have caused the geysers and artificial lakes in West Texas. Elsewhere, including in Louisiana, sinkholes have opened up, sometimes forcing evacuations. More commonly, the wells leak smaller amounts of brine and gas. The EPA estimates abandoned wells release about 300,000 metric tons of methane every year.

The Challenge of Identifying and Plugging Wells

Many of the proposed carbon storage projects in Louisiana have at least a few and sometimes dozens of wells within a couple of miles. The regulations say companies must identify each of the wells within a certain radius of the project and make sure they are properly plugged or secured. For any that are not, companies must plug the well, which can cost hundreds of thousands of dollars per well.

That is

SDGs, Targets, and Indicators Analysis:

1. Which SDGs are addressed or connected to the issues highlighted in the article?

• SDG 13: Climate Action
• SDG 15: Life on Land

The article discusses the issue of carbon dioxide storage and the potential risks associated with leaking abandoned oil and gas wells. This relates to SDG 13, which focuses on taking urgent action to combat climate change and its impacts. The article also mentions the environmental risks posed by leaking wells, which connects to SDG 15, which aims to protect, restore, and promote sustainable use of terrestrial ecosystems.

2. What specific targets under those SDGs can be identified based on the article’s content?

• SDG 13.2: Integrate climate change measures into national policies, strategies, and planning
• SDG 15.1: By 2020, ensure the conservation, restoration, and sustainable use of terrestrial and inland freshwater ecosystems and their services

The article highlights the need for proper regulation and oversight of carbon dioxide storage projects to prevent leaks from abandoned wells. This aligns with SDG 13.2, which emphasizes the integration of climate change measures into policies and planning. Additionally, the article discusses the potential risks to terrestrial ecosystems and the need for proper conservation and restoration efforts, which relates to SDG 15.1.

3. Are there any indicators mentioned or implied in the article that can be used to measure progress towards the identified targets?

• Number of approved carbon storage projects with proper oversight and regulation
• Number of abandoned wells identified and properly plugged within the area of review for carbon storage projects
• Amount of leaked methane and carbon dioxide from abandoned wells

The article mentions the need for companies to identify and properly plug abandoned wells within the area of review for carbon storage projects. The number of approved projects with proper oversight and regulation can serve as an indicator of progress towards integrating climate change measures into policies and planning (SDG 13.2). Additionally, monitoring the amount of leaked methane and carbon dioxide from abandoned wells can provide insights into the conservation and restoration efforts of terrestrial ecosystems (SDG 15.1).

Table: SDGs, Targets, and Indicators

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Source: undark.org

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