From the site: "A cells polygon feature class was created by the U. S. Geological Survey (USGS) to illustrate the degree of exploration, type of production, and distribution of production in the State of Indiana. Each cell represents a quarter-mile square of the land surface, and the cells are coded to represent whether the wells included within the cell are predominantly oil-producing, gas-producing, both oil and gas-producing, or the type of production of the wells located within the cell is unknown or dry. The well information was acquired from the Indiana Geological Survey, Petroleum Database Management System (PDMS). Using the table viewer at http://igs.indiana.edu/pdms/getdata.cfm, oil and gas well events and locations tables were downloaded for the entire state of Indiana. Cells were developed as a graphic solution to overcome the problem of displaying proprietary well data. No proprietary data are displayed or included in the cell maps. The data are current as of 2006."
- HTMLhttp://catalog.data.gov/dataset/oil-and-gas-exploration-and-production-in-the-state-of-indiana-shown-as-quarter-mile-cells