Depth Severance
A split of mineral rights by formation or depth, so production from one zone doesn't hold the rights to deeper or shallower zones.
A depth severance splits mineral rights by depth or geologic formation. It can come from a deed that conveys, say, only the rights below a certain depth, or from a vertical Pugh clause in a lease that releases undeveloped zones. The result is that one owner or one lease controls some intervals while others are open.
This matters in stacked plays. In the Permian, a well in one zone may not hold the deeper or shallower benches; with a depth severance or a Pugh clause, those untapped zones can be leased separately. Without one, a single well can keep every depth held by production.
Depth language is technical and easy to misread. Confirm it through a careful title search and have an attorney interpret the conveyance before you rely on it.