The comments with the map are not entirely correct. Effect of gravity- Gaseous (methane), light and liquid hydrocarbon compounds will tend to rise in a formation, thus "uphill." Does the map show only drilling for fracking, or are some actually oil wells?
The 1000 feet limitation is ridiculous, as mentioned. Depends on porosity of the sediments, type of contaminant, etc. Gaseous and light compounds can go a long distance if there is no natural barrier such as lack of porosity.