| Definition: | Oldest producing well in a 40 acre cell classified by 10 year intervals. |
| Gray - (non producing) | |
| Black - (no data) | |
| Pink - (Pre 1900) | |
| Red - (1900's) | |
| Light Green - (1910's) | |
| Green - (1920's) | |
| Light Blue - (1930's) | |
| Dark Blue - (1940's) | |
| Light Sky Blue - (1950's) | |
| Sky Blue - (1960's) | |
| Light Purple - (1970's) | |
| Purple - (1980's) | |
| Yellow - (1990's) |