According to Penn State Experts, oil companies are missing out on recoverable oil in unconventional reservoirs because of misused calculations.

Currently, companies develop unconventional reservoirs by drilling horizontal wells and creating hydraulic fractures to allow oil to flow. Primary recovery currently ranges between 3 and 10 percent of the original oil mass. Software forecasts the recovery amounts based on Darcy’s law — where flow is based on pressure differences. However, that may not be the appropriate application for shale reservoirs, according to research.

Researchers believe diffusion — not pressure differences — is the principle factor aiding oil recovery. Aside from affecting forecasts, this idea directly affects recoverable reserves after primary recovery. The existing industry practice is to use a conventional gas injection technique known as “huff ‘n’ puff” to improve oil mobility and increase recovery.

The “huff” period of the technique consists of wells being filled with high-pressure gas, followed by a short soaking period where the well is shut. During the “puff,” the well is opened to allow oil to be produced. Taking into consideration diffusion, rather than pressure differences, is responsible for aiding oil recovery, these “puff” periods could be increased by longer soaking times.

Learn more: Penn State > Understanding physics could lead to big gains in shale oil recovery