Definitions and Notes

Class II wells are wells that have been drilled or converted for use in secondary or enhanced recovery operations. These "secondary recovery input" wells are generally water or inert gas (CO2) injection wells. Specifically, the definition and operation of Class II wells falls under the regulatory jurisdiction of the United States EPA Region 4 Office in Atlanta, GA.
Development wells are wells drilled to recover resources within a known producing area to a known producing zone. By rule of thumb, development wells may be drilled up to 0.5 miles away from existing producing areas.
Exploratory wells are wells drilled to find new producing zones or to extend an area of known production. Exploratory wells include New Pool or Field Wildcats, Deeper or Shallower Pool Tests, and Extension (or Outpost) wells. By rule of thumb, wildcat wells are drilled more than 1 mile from known producing areas and extension wells are from 0.5 to 1 mile from known producing areas.
Number reported in these columns represent the number of wells whose deepest penetration (the total depth) tested strata of the specified age (i.e., Pennsylvanian strata, etc.).
Wells reported as "O&G" have been completed as combined oil and gas producers according to the Well Log and Completion Report filed by the operator of the well.
In Kentucky, a permit to drill, re-open, or deepen an oil or gas well is in effect for one year after the date of issue. The permit may be cancelled at any time during that year prior to initiating drilling operations at the request of the operator. The permit may also be allowed to expire at the end of the year (again without initiating drilling operations).  Both of these actions result in the "termination" of the permit.