‘Supercharged’ Shale EOR: A Liquid-Hydrocarbon-Based Approach Enters the Fray
Authors: Jacobs Trent 
Published: October 2024

Around a decade of research and testing has passed by, and the unconventional sector has yet to show that natural gas huff-and-puff can scale effectively across tight-oil fields.

This doesn’t mean enhanced oil recovery (EOR) in shale is a lost cause. Though it does suggest that the industry needs alternatives to the first and most well-known method.

Proof of this can be found in North Dakota’s Bakken Shale where researchers, operators, and a firm called EOR ETC have tried to show that the water-alternating-gas method is a cheaper, less gas-intensive way of adding incremental barrels. EOR ETC has indicated on its website that ExxonMobil subsidiary XTO Energy is currently testing the technology.

Chevron has also recently shared how it has rethought shale EOR methods by designing a program for production-boosting surfactant injections and gas injections that can be done with artificial lift instead of giant compressors.

Another emerging shale EOR concept goes a step further, arguing that the unconventional sector should abandon natural gas injections altogether. Denver-based Shale Ingenuity proposes that liquid-hydrocarbon solvents should be used instead.

Shale Ingenuity has patented a process called SuperEOR, which it claims delivered a strong showing during its initial field test in the Eagle Ford Shale of south Texas.

After nearly a year of cyclic solvent injections, which began in early 2023, a horizontal well with a 4,400-ft lateral and 16 fracture stages produced 44% more oil than its previous total output. This resulted in a 30-fold boost in flow rate, from 13 to 391 B/D.

Building on its initial success, Shale Ingenuity informed JPT that two private producers in the Permian Basin and the Eagle Ford have selected its EOR technology for upcoming projects. Both will involve single four-well pads, with EOR operations expected to begin in 2026.

The solvents used in the pilot consisted mostly of natural gas liquids (NGL)—ethane, propane, butane, and pentane. Shale Ingenuity said formulations may include other hydrocarbon and nonhydrocarbon liquids.

While the bulk of these products flow straight out of thousands of wellheads in the US shale sector, Shale Ingenuity emphasizes that the key to unlocking their potential for EOR lies in its proprietary method of blending, or “tuning,” the solvents based on formation and crude oil properties.

This allows the injected solvents to quickly mix with and help mobilize the residual oil droplets that are trapped in tight-rock formations, according to the company.

Robert Downey, founder and CEO of Shale Ingenuity, explained the process. “The tuned solvents we are using have a minimum miscibility pressure (MMP) of 700 to 900 psi, which means it doesn’t take much pressure to drive them into solution. When pumped into the well, they instantly become miscible with oil, and as the formation heats up and the well is reopened, the solvents expand back into gas at 100 to 200 times their liquid volume.”

The effect of all this is what he describes as a “supercharging” of the solution gas drive mechanism that promotes the strong early well flow shale wells are known for. This is the energy released by dissolved gas in the oil as it expands during the pressure drop brought on by producing the well.