The IGS ID Number is a unique identification number assigned by the Indiana Geological Survey (IGS) that serves to uniquely identify each well in the state and its corresponding Well Record in the Petroleum Database Management System (PDMS).
The IGS ID corresponds to a unique well location (a unique spot on the ground), except in cases where a well is permitted at the same location as an earlier unused permit; if the later-permitted well is unrelated to the earlier one, a new IGS ID may be assigned.
Caution: Division of Oil and Gas (DOG) sometimes uses the IGS ID Number in the Permit Number field in the DOG Online Well Records Database. This informal substitution is made when DOG scans a well's documents and no Permit Number for that record is available. In many cases, the PDMS would carry the corresponding IGS ID Number in the IGS ID Number data field, and a zero in the Permit Number field for the Well Event. The PDMS never uses the IGS ID Number in the Permit Number field.
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The API Well Number is another well-known identity number for wells used in the U.S. petroleum industry. For a number of reasons, they are not used by the IGS, nor by DOG. For an in depth discussion, see API Well Numbers in Indiana.