Researchers at the U.S. Department of Energy’s National Energy Technology Laboratory (NETL) are developing advanced methods to significantly increase oil and natural gas recovery from unconventional and tight reservoirs such as shale.

An opportunity to capture hydrocarbons that remain trapped after hydraulic fracturing is presented byPrimary recovery with fracturing (as shown above) typically extracts only a small percentage of hydrocarbons in place. Nuclear magnetic resonance is being advanced to increase recovery rates in these unconventional formations. Source: NETL nuclear magnetic resonance (NMR) spectroscopy. The technology can be deployed to quantify fluids in subsurface cores by determining the porosity and pore size distribution for pores as small as 1 nanometer. NMR can also identify the type of fluid in the core by differentiating fluids of different viscosities, such as water, hydrogen, heavy oil, light oil and natural gas, and characterize a core’s wetting properties to determine whether the rock will preferentially take up water, oil, natural gas and carbon dioxide to promote oil and gas recovery.

“We begin with saturating shale cores in hydrocarbon oil. Hydrogen atoms are abundant in the hydrocarbon-soaked cores. When the rock core is placed in the NMR unit’s magnetic field, the hydrogen nuclei align themselves with the field,” explained the researchers. After a radio frequency pulse is applied and turned off, the resulting nucleic relaxation time provides information about in-situ porosity, permeability and fluid saturation of the formation

The NMR technology will be used to conduct experiments in which the oil-saturated rock core is held at high pressure and injected with natural gas, water, surfactant or carbon dioxide to reveal how injected fluid moves oil and water throughout the rock pores, including fluid in nanopores.