Every well has a floor. It's the day the oil revenue stops covering lease operating expense — the pumper's time, the electricity on the rod pump, the chemical, the saltwater disposal. Below that line, a well is losing money every month it stays on. Above it, even a 6-barrel-a-day stripper can be worth keeping.
The question an operator actually asks isn't "which wells are old?" It's "which wells are about to go sub-economic, and how long do I have before I'm making a plugging decision?" The record can answer that with two things it already holds: current producing rate and the decline that's driving it.
What the economic limit actually is
The economic limit is the rate where monthly net revenue equals monthly operating cost. You set the cost side from your own field data — call it $6,000 to $10,000 a month for a pumping oil well, more if you're hauling a lot of water. At $70 oil and, say, a $6,000 monthly LOE, the break-even is roughly 3 bopd net. Add water handling and workover reserve and that number climbs fast.
Wellsite doesn't know your LOE — that's your number to bring. What the data lake holds is the other half of the equation: where each well is producing today, how steeply it's declining, and therefore when it will cross whatever threshold you set. That's the part that's tedious to do by hand across a few hundred wellbores and trivial to ask for in plain language.
Screen the book by current rate first
Start with the simplest cut. Ask for every well in the book producing under 10 bopd on its most recent months. That's the classic stripper definition, and it's usually a surprising share of a mature operator's well count — the long, flat tail that produces a small fraction of the volume but carries a large fraction of the headcount and the disposal bill.
That list alone reorganizes how you think about the asset. The 15 wells doing 200 bopd get the attention; the 140 wells doing 4 bopd quietly set your operating cost. Ranking the low-rate wells by current volume tells you which ones are already flirting with the line.
Project the crossing with each well's own decline
Current rate is a snapshot. The decision is about direction. A well at 8 bopd that's holding flat on a shallow terminal decline might produce for another decade. A well at 8 bopd fading at 20% a year hits 3 bopd inside three years.
So the second pass fits each well's recent decline and projects it forward to your economic-limit rate. Ask the question directly: given this well's trend, when does it fall below 3 barrels a day? The answer sorts the stripper list into three buckets — wells already below the line, wells crossing within 12 months, and wells with real runway left. The first bucket is a P&A and idle-well conversation today. The second is a watch list. The third you leave alone.
Separate the truly dying from the merely neglected
Before anyone signs a plugging AFE, check that a low rate is decline and not downtime. A well sitting at 2 bopd because it's been half-shut-in for six months on a bad pump is a workover candidate, not a plugging candidate. The production history usually shows the difference — a genuine economic-limit well steps down gradually along its decline, while a choked or mechanically-limited well drops abruptly and holds flat at an unnaturally low level.
The same check runs the other way. A well that looks fine on cumulative can still be quietly rolling over. Benchmarking each low-rate well against its own trend and its offsets flags the ones where the reservoir, not the equipment, is the problem.
Turn the crossing into a standing alert
The economic limit isn't a one-time report. Prices move, and so does the line — a run from $70 to $85 oil pulls your break-even down and pardons wells you'd have plugged; a slide the other way pushes marginal wells under water. Setting an alert on the wells clustered just above your threshold means you find out when one crosses on its own decline, or when a bad month tips it over, instead of discovering it in next quarter's LOE variance.
Why it matters
The wells near the economic limit are where operating margin quietly leaks and where plug-and-abandon liability accrues. Knowing which ones are about to cross — and how much runway the rest have — turns a vague sense that "we've got a lot of old wells" into a ranked, dated list you can act on: plug these, watch those, leave the rest. The record has the rates and the declines. You bring the cost line, and the crossing dates fall out.