A new iteration of NETL's CO₂-SCREEN software application is enabling researchers to more accurately estimate carbon dioxide storage potential in previously overlooked locations, opening the door for carbon capture utilization and storage (CCUS) projects on a large scale, along with new enhanced oil recovery operations.

Originally developed to estimate prospective carbon dioxide (CO₂) storage potential in saline and shale formations, the latest version of the Lab's CO₂-SCREEN (Storage prospeCtive Resource Estimation Excel aNalysis) tool can be used for estimations in residual oil zones (ROZs), which can serve as valuable sites for CCUS projects.

ROZs are deposits of immobile oil typically found underneath conventional reservoirs. These reservoirs have essentially been "waterflooded” by nature — natural water movement through the reservoir, pushing the oil in the direction of production wells. The U.S. Department of Energy estimates ROZs could contain 100 billion barrels of recoverable oil, representing a substantial yet underutilized source of domestic energy.

Once overlooked due to past technological limitations and natural obstacles such as the presence of water, ROZs are gaining interest for their potential to boost economic activity via energy production while storing CO₂ emissions. Although they essentially possess the same potential for captured CO₂ storage as saline formations, ROZs have the advantage of containing valuable hydrocarbons that can be produced through enhanced oil recovery — injecting the CO₂ into the pore spaces of a rock to extract crude oil. This provides an investment incentive for producers while the captured gas used for extraction remains sequestered underground.

The accurate data and estimations provided by applying CO₂-SCREEN during CCUS projects can connect industrial sources of carbon dioxide to geologic formations, such as ROZs, where it can achieve maximum benefit.

"With the latest version of CO₂-SCREEN, we have an opportunity to harness captured gases, transforming them into a potent economic asset,” NETL's Angela Goodman, the principal investigator, said. "ROZs are becoming increasingly attractive as potential reservoirs for CO₂ storage. These places are enticing to oil and gas recovery operations because they contain immobile oil that can be produced using the right techniques, such as CO₂ enhanced oil recovery techniques or by reservoir depressurization.”

The CO₂-SCREEN tool allows users to quickly estimate potential CO₂ storage with increased reliability which minimizes costs in terms of time and money. This capability allows better accounting of a formation's geologic characteristics. Using this information with uncertainties removed, investors can move forward in confidence allowing for the widespread deployment of CCUS projects on a commercial scale.

Using CO₂-SCREEN may also allow CCUS projects to bypass unnecessary costs by avoiding a duplication of efforts. For example, to store CO₂ in depleted hydrocarbon-bearing shales, operators may be able to use existing surface pipeline rights-of-way, well infrastructure, and most importantly, the engineered hydraulic fracture networks created for hydrocarbon production — saving time and reducing expenses.

“If we're to realize the goal of widespread storage of captured CO₂, we need incentives for industry,” NETL's Sean Sanguinito, CO₂-SCREEN's developer, said. "These incentives can come in many forms but among the most important is the removal of uncertainties that make investment decisions difficult. With assets like CO₂-SCREEN, we've developed means of removing these uncertainties while providing the most informed path forward for potential investors and energy producers alike.”

DOE's National Energy Technology Laboratory develops and commercializes advanced technologies that provide reliable and affordable solutions to America's energy challenges. NETL's work supports DOE's mission to advance the national, economic, and energy security of the United States.