Element Definition
Legacy wells are defined as wells that were previously drilled for groundwater, oil and gas exploration or production, natural gas storage, waste disposal, or other subsurface purposes and that penetrate one or more geologic units relevant to CO₂ storage or containment. For this element, legacy wells include wells documented in state well databases that intersect identified storage formations, confining units, or both. Wells currently active or properly plugged are included if they meet these criteria.
Mapped Feature Description
This element is displayed as point features representing the surface locations of documented legacy wells in Illinois. Each point corresponds to a well record in the source database and reflects the reported location accuracy of that record. The map does not depict well construction details, plugging quality, casing integrity, or subsurface well trajectories beyond the surface location.
Source: Illinois Oil and Gas Resources
Suitability Classifications
See how to use suitability classifications.
| Classification | Criteria (Density, Wells per Square Kilometer) |
|---|---|
| Less Suitable | >10 |
| Suitable | 5-10 |
| More Suitable | 2-5 |
| Most Suitable | 0-2 |
| More Information Needed | N/A |