What To Do With Old Wells

_ The US Environmental Protection Agency has estimated the US is home to approximately 3.4 million old, unused wells. That’s an estimate. Many of these old wells are undocumented or otherwise unknown. Of the 3.4 million estimated by the EPA, only 117,672 are in the US Geological Survey’s data set of documented unplugged orphaned oil and gas wells. The problem becomes even more muddled by shifting definitions of “idle,” “abandoned,” and “orphan” wells. Different jurisdictions use different definitions, but the core meanings are the same. Idle wells are those that are not producing hydrocarbons but have not been plugged. In some definitions, these wells may have been shut in and may be able to return to production. Nonetheless, the owner is documented and remains responsible for the well. Abandoned wells are those that have been taken out of service. Typically, this involves plugging, and an operator usually maintains responsibility. Orphaned wells do not have a responsible party of record. For these wells that have outlived their usefulness, the National Academies of Sciences, Engineering, and Medicine says plugging is the best course of action. The Problem With Orphans Of the categories of old, unused wells, orphaned wells are the most problematic. These are wells that have not been plugged and are not associated with any responsible party. “That term ‘orphan’ … is essentially a well that doesn’t have a responsible operator,” said Nathan Meehan, professor of petroleum engineering at Texas A&M University and 2015 SPE President. The most insidious aspect of orphaned wells is that many of them are unknown, with no documentation that they ever existed. “My first experience with an orphaned well was when I first did a waterflood in Northwest Oklahoma in 1976 or ’77,” Meehan recalled. “We started injecting in our injection wells, hoping for increased oil production. All of a sudden, the farmer calls us furiously as salt water was bubbling up out of his field someplace. We had located an orphan well. The hard way.”