The gas that emerges from wells in U.S. shale plays differs widely in its characteristics and quality. In the aptly named “dry” Marcellus in northeastern Pennsylvania, the gas is almost all methane, with only minute volumes of NGLs and contaminants, and requires minimal treatment before it’s fed into transmission pipelines. At the other end of the spectrum, the associated gas from a subset of crude-oil-focused wells in the Permian has high levels of hydrogen sulfide (a potentially deadly chemical) and carbon dioxide (a potent greenhouse gas), as well as a lot of NGLs. If the H2S level in the gas is relatively low, it can be removed from the gas stream onsite with a chemical “scavenger,” but higher levels of H2S quickly make that method prohibitively expensive. Another alternative, an onsite amine treatment facility, is more economical for removing higher levels of H2S — and it removes CO2 as well — but air permits typically limit how much can be flared off, requiring the costly and time-consuming development of acid-gas injection wells. Yet another, more centralized approach to dealing with H2S and CO2 — one that permanently stores large volumes of both deep underground — is being implemented over the next few weeks in southeastern New Mexico, as we discuss in today’s blog.
Dark Horse – ‘Sweetening’ Sour Natural Gas and Sequestering CO2 in the Permian
