No More Lost Light Gases

Adapting failed automotive capture technology for the oil and gas industry

IN August 2018, engineers at metal organic framework (MOF) specialist framergy confirmed what they had long suspected: that their chemical materials would unlock the huge potential for MOFs to be commercialised for capturing and separating associated gas at oil and gas wellheads – reducing the need for wasteful venting and flaring at stranded gas fields.

For several years now, US-based framergy has been working with oil and gas companies under funding from the National Science Foundation (NSF) to verify lab results which suggested that methane, and other associated gases and liquids, could be stored at low pressures and managed selectively with MOFs. We believe that this breakthrough has the chance to radically alter how oil and gas processing, from the well to consumer use of plastics, is managed.

framergy has been working with oil and gas companies to verify lab results which suggested that methane, and other associated gases and liquids, could be stored at low pressures and managed selectively with MOFs

The technology first saw light as an adsorbed natural gas (ANG) project to develop low-pressure natural gas vehicles. In that (auto) project, novel MOF AYRSORB F250 showed comparable energy density to compressed natural gas (CNG) at 85% less pressure. Unfortunately, the concept of an ANG car didn’t materialise, and partners such as General Motors and Research Triangle International failed to commercialise the material. We repositioned that technology for the oil field.

MOFs & light hydrocarbons

Founded in 2011, framergy was the first company in the world to focus solely on MOFs. Our product line, AYRSORB, is made up of adsorbents based on MOFs and similar chemistry. The designs were inspired by innovations from the labs of Hong-Cai “Joe” Zhou at Texas A&M University and Christian Serre at ESPCI in Paris, France. A MOF is porous medium, but with incredible tunability and recyclability. A sample the size of a sugar cube can be spread out across an entire football field. Zhou, framergy’s co-founder, says: “MOFs are a material perfectly positioned to change the way modern industries use energy, (and) the NSF project MOFs provide a significant step towards deploying MOFs in a variety of applications, including in natural gas containment.”

While reviewing the original project in 2015, we saw an opportunity to reposition this technology for the oil and gas sector. At the time, according to a report from Ceres, companies in the maturing Bakken Formation in North Dakota were venting and flaring off US$100m worth of natural gas a month.¹ So the obvious question for us was, could MOFs be used to capture valuable natural gas that companies would desperately need to meet the bottom line as oil prices began to fall? We thought so, but some literature suggested otherwise.

The obvious question for us was, could MOFs be used to capture valuable natural gas that companies would desperately need to meet the bottom line as oil prices began to fall?

After a competitive project was stopped due to performance issues, its group published a paper which suggested that heavier hydrocarbons would lower adsorption of methane.² But our lead scientist disputed this computational finding, and began a rigorous set of tests to determine if in fact low-pressure ANG techniques from the original auto project could be used at the wellhead. Ray Ozdemir had researched CNG systems from 50 years previously, where heavier hydrocarbons were used to lower pressure levels.^3,4 Ozdemir sought to reduce compression and/or refrigeration for natural gas storage, by doping the methane vessel with heavier hydrocarbons. Or inversely, this strategy could be used to increase the energy density of the vessel by volume at a given pressure point.

This time we filled the vessel with AYRSORB F250 and heavier hydrocarbons, then injected it with pressurised methane. The results were astonishing, and suggested that in fact ANG in the presence of other heavier hydrocarbons actually increases the uptake of methane and in some cases, quite significantly.⁵ Measured on a volumetric basis, low-pressure ANGs with our MOFs deliver the equivalent driving distance as CNGs. But when we added a small amount of decane, the energy density of the same containment vessel increased by 20%.