The "number" given by the operator to help identify the well; this is used exactly as it is reported for the well.
No formatting rules are imposed and the format varies from operator to operator, sometimes from well to well drilled by the same operator.
Some Well Numbers contain numerals, while others include text. In some instances, the Well Number is given as "Name 1-Comm." for a communitized well (a well that pools or combines acreage from several leases), where a nearby well drilled by the same operator places the "Comm." with the lease name and lists the number as "1."
An operator might have an "A" lease and "B" lease from the same landowner, and name his wells 1-A or 1A, and 1-B or 1B. B1 or A1 is also used.
On some occasions, a new operator may start operations long after an earlier group of wells has been drilled, and the new wells are indicated by starting a lettered sequence: A-1, A-2. Other possibilities abound; new operators have been known to assign entirely new well numbers to existing wells.