Most chains break where you expect them to. A missing probate, a name that changed spelling between 1948 and 1953, a deed recorded in the wrong county. You find the gap, you go close it, you move on.
Depth severances are a different kind of trouble. Nothing breaks. The chain keeps reading clean, instrument after instrument, and yet the tract you thought you were tracing has quietly become two or three tracts stacked on top of each other. The surface to 13,808 feet belongs to one group. Below that, someone else. And a thin band between two depths might belong to a third party who bought it in 1983 and has never been heard from since.
We spent a good part of last week inside one of these on a New Mexico lease that has been held by production since 1952. Sixty-some recorded transfers. By the end, the working interest had been split at 13,808 feet, then split again between 13,499 and 13,808, then rolled through four family entities, two name changes, and a merger into an operator you'd recognize. Every link cited. Not one of them wrong. And still easy to misread if you weren't watching for the cut.
What a severance actually does
A depth severance is an assignment that conveys the working interest only within a stated depth range. The rest of the interest stays with the assignor. From that moment forward, the lease has more than one chain. Anything recorded later has to be read against the depth it affects, and a lot of later instruments don't bother to say.
That's the part that bites. A 2006 blanket assignment might say "all of assignor's interest in the lease." Which interest? The one above 13,808 feet, because that's all the assignor ever owned. The instrument won't tell you. Only the chain will.
How to spot the cut
The severing instrument usually announces itself. Look for language like "insofar as it covers depths from the surface to" a stated footing, or "limited to depths below the base of" a named formation. Formation names are the sneaky version. "Below the base of the Wolfcamp" is a depth severance even though no number appears, and you'll need the formation top from a well log or the lease file to know where the line falls.
After the cut, the tells are subtler. Two assignments of "100% working interest" in the same lease a few years apart, from different assignors, is not a mistake. It's two chains. The same operator appearing as both assignor and assignee in one filing is often a consolidation of depths, not a typo.
What it does to your runsheet
A flat runsheet handles this badly. You end up with one long list and a comments column doing all the real work. Our answer has been to treat each depth range as its own lane from the severance forward, so the chain above the cut and the chain below it can be read separately, and any instrument that spans both gets placed in both. On the ownership report, the same thing happens as rows: surface to 13,808 feet, then 13,499 to 13,808, then 13,808 and below, each with its own owners and decimals.
It looks like more work. It's actually less, because you stop re-reading the whole chain every time a reviewer asks which depth an override burdens.
Questions to ask before you rely on it
- Is the severance stated as a footing or a formation? If it's a formation, whose top are you using, and from which well?
- Do later blanket assignments cite the severing instrument? If they don't, has anyone confirmed which depths the assignor actually held?
- Where do the overrides sit? An ORRI carved out before the severance burdens everything. One carved out after only burdens the depths the assignor owned that day.
- Does the current operator's own affidavit of ownership match your depth lanes? On the lease we worked, it did. Nice when that happens. Don't assume it.
One more thing, and it's the honest one. We found interests in that chain supported by conveyances that were never filed in the county. The overrides referencing the tract made sense of them, so we carried them forward and flagged them for confirmation. That flag lives in the report, on the timeline, and in the flowchart. If a reviewer can't see the doubt, the doubt didn't make it into the work.
Depth severances aren't rare and they aren't exotic. They just reward the person who slows down at the right instrument. Slow down there.
Common questions
What is a depth severance?
An assignment that conveys working interest only within a stated depth range, from the surface down to a footing, below a formation, or between two depths. Everything outside that range stays with the assignor, and the lease has more than one chain from then on.
Why are depth severances easy to miss?
Because the chain keeps reading cleanly. Later instruments often say all of assignor’s interest without naming the depth, so you only know which depths moved by tracing what the assignor owned at the time.
How should a runsheet handle a depth severance?
Treat each depth range as its own chain from the severing instrument forward, and show ownership by depth as separate rows on the report. Instruments that cover more than one range get placed in each one they affect.
Want to see one of these laid out by depth?
Bring a lease with a severance in it. Thirty minutes, your records, no pitch.
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