Royal Dutch Shell is testing a new device that uses lasers to help identify shale gas reservoirs, Wyoming-based oilfield service company WellDog announced Tuesday.

The device, which weights more than 100 pounds, is dropped into a wellbore where it shoots lasers and measures the frequency at which that light is reflected. That information helps production companies identify what type of hydrocarbons are located underground and where they are.

“The advantage of this is the sensor is down hole,” said WellDog CEO John Pope. “It’s a direct analyst of the exact oil or gas you’re trying to produce.”

The device is still in the testing phases. WellDog has been collaborating with Shell on the technology for about two years, Pope said. The hope is develop a system that gives producers a more accurate sense of where to drill, ultimately making drilling and fracking more efficient.

The effort comes at a time when operators are in a constant battle to reduce the costs of shale operations as they try to increase their profit margins.

The technology relies on something called the “Raman Effect,” which occurs when light scatters away from a molecule with slightly different characteristics after a molecule’s chemical bonds become excited. Every chemical gives off unique frequencies, similar to a fingerprint, which software can analyze. By measuring the change in that light frequency, WellDog can learn more about what substance the laser light initially struck.

Pope touted the device as superior to infrared systems, since Raman spectroscopy is not as sensitive to water. He also said it provides more accurate and reliable information about reservoirs than mud samples or seismic scans. The data is provided data in real-time, which Pope said is especially helpful to operators.

It only takes 5 or 10 seconds to get a reading, Pope said, and the device can also help measure the quantity of hydrocarbons in a reservoir. He said he believes his company is the only one with a Raman spectrometer for shale. He said the device has been used at a depth of 6,000 feet deep and can likely go even deeper.

Pope’s company originally developed the technology to identify the locations of coalbed methane, a form of natural gas extracted from coal formations. WellDog used the technology extensively in Wyoming’s Powder River Basin as well as Australia and other international locations, but now they’re adapting it to shale gas applications.

The company has been testing the shale version of the device with Shell in the laboratory for nearly two years, and last year, it successfully tested it in a Shell well in the Marcellus Shale, Pope said. Going forward, it will work with Shell to test the device in shale plays across the country.

A spokeswoman for Shell declined to discuss its use of WellDog’s technology, other than to say trials are ongoing.

Adapting the technology from its original use with coalbed methane has required careful work. “Shale reservoirs… are more complex geochemically,” Pope said. “They’re higher pressure and hotter. From a hardware standpoint, it’s a more challenging environment.”