explainer: what is pore space?

Geologic carbon sequestration, or storing carbon dioxide (CO₂) safely and permanently deep underground, is a promising technology in the effort to reach climate goals. And it relies on, well, a lot of nothing. Geologists call it pore space.

Similar to holes in a sponge, pore space is the empty space between particles of sand and sediment or the space within and between rocks. When we inject CO₂ into the ground, it fills in these spaces.

A component of carbon capture, utilization, and storage (CCUS), sequestration can help lower the carbon intensity of our operations and those of other industries, such as liquefied natural gas, refining, petrochemicals, power, steel and cement. While a number of considerations go into choosing a site for carbon storage, pore space is essential. Without it, we can’t store CO₂ underground.

Ideally, geologic formations that could permanently store CO₂ would be everywhere. But because there are limited possible reservoirs, transporting CO₂ from industrial areas to those reservoirs is critical to gaining ground on CCUS.

A project to inject CO₂ underground near businesses that have a high volume of emissions can be useful in developing CCUS hubs. These hubs allow each company to reduce their carbon intensity, noted Shalyce Holmes, who helps negotiate contracts for Chevron's right to use pore space. The potential storage site may be under land outside of major cities, in inactive oil and gas reservoirs, or offshore, deep under the seabed.

After we find a location with the appropriate pore space, we need to acquire it or the right to use it. And that is no small feat.

Pore space ownership in the United States varies from state to state and can be owned by the State, by the U.S. government or private individuals. In other countries, subsurface rights are controlled entirely by the government.

In the U.S., Chevron negotiates with the pore space owner, who in most current instances is the same person who owns the land surface. That contrasts with mineral rights that are necessary for oil and gas development, which are frequently owned by someone other than the surface owner.

A CO₂ reservoir can span multiple properties, requiring agreements with multiple landowners. A single reservoir can have hundreds of landowners.

As Chevron works to secure pore space agreements with landowners for a storage project, we work with the surface owners to compensate them for the pore space and, if applicable, surface area for things like injection wells, pipelines and facilities. Chevron aspires to be a partner of choice in working with landowners on the development of CCUS projects.

Chevron helped pioneer injecting CO₂ underground more than 40 years ago. We also have a team of experts in earth sciences who help us carefully choose a site and monitor it after injection.