Pay Zones are Geologic Units specifically used for oil and gas operations. They differ from Completion Formations which include borehole intervals used for saltwater disposal, waste disposal, non-potable water supply, and other non-petroleum (non-pay) purposes.
Zones used for water injection (waterflood) and other types of enhanced recovery are considered Pay Zones.
Unlike the Completion Formation, Pay Zones do not occupy space in the PDMS data tables. Instead, they are derived programmatically from values for Completion Formations and Well Events for a given well.
Pay Zones are used in the PDMS Map Viewer to show the distribution of wells producing from specific intervals. Due to correlation difficulties and numerous cases of insufficient information about completed wells, Pay Zones are grouped into even broader units than Completion Formations. As an example, a well completed in either the Yankeetown, Renault, or Aux Vases Completion Formations is assigned to the single Paoli Pay Zone.
Pay Zones identified as "Pennsylvanian Coal CBM" and "Pennsylvanian Coal MV" are neither formal nor informal units. What’s more, they denote gas production, which has nothing to do with being a stratigraphic unit. Nevertheless, they are exceptionally called Pay Zones in the PDMS so that they can be manipulated as Completion Formations in computer-generated, color-coded Pay Maps (maps showing productive Geologic Units) prepared by the Indiana Geological Survey. “Pennsylvanian Coal CBM” refers to any coal interval in Pennsylvanian rocks that produces methane gas, and “Pennsylvanian Coal MV” indicates gas production from mine voids resulting from underground coal mining. A search for "Pennsylvanian" as a Completion Formation in the Search Menu will return all wells completed in the Pennsylvanian, including those identified as "Pennsylvanian Coal CBM" and "Pennsylvanian Coal MV." A separate search option can be used to find only coalbed gas wells (both "Penn. Coal MV" and "Penn. Coal CBM").
Placing a check mark alongside one of the zones in the Pay Zone Layer and left-clicking Refresh Map causes a colored symbol to be placed over any well on the Map if it is classified as a Pay Zone.
The symbols indicate whether a well, at anytime in its past, was used for oil and gas production, enhanced recovery, or other It generally does not pay to select multiple zones to view on the map because the same symbols would be used to show the production for all of the selected zones.
Notice that if a formation in a well has produced both oil and gas from the same formation, the symbols are designed to overlap in such a way that the oil half moon is visible as a green half moon on the lower half, while the gas zone is a red half moon in the upper half. Obviously, some combinations do not work together, for example "enhanced recovery" and "gas."
For additional discussion of pay zones, completion intervals, and stratigraphic units, see Chart Showing Stratigraphic Terminology