Here are Ohio's Top 10 companies for oil production in 2013, based on data from the Ohio Department of Natural Resources:
1. Chesapeake Energy/Chesapeake Exploration, 2,078,570 barrels.
2. Gulfport Energy, 675,097 barrels.
3. Antero Resources, 215,627 barrels.
4. PDC Energy, 204,524 barrels.
5. R.E. Gas Development, 180,308 barrels.
6. Atlas Noble, 46,030 barrels.
7. Chevron AQppalachia, 45,582 barrels.
8. EQT Production, 40,956 barrels.
9. Anadarko, 38,902 barrels.
10. EnerVest, 31,835 barrels.
Twelve other companies reported oil production in 2013, the ODNR said.
With thanks to co-worker Rick Armon.
Chesapeake Energy Corp,the Oklahoma-based firm is the No. 1 driller in Ohio.
Rig Count Interactive Map by Baker Hughes, an energy services company.
Shale Sheet Fracking, a Youngstown Vindicator blog.
The Ohio Environmental Council, a statewide eco-group based in Columbus.
Earthjustice, a national eco-group.
People's Oil and Gas Collaborative-Ohio, a grass-roots group in Northeast Ohio.
Concerned Citizens of Medina County, a grass-roots group.
No Frack Ohio, a Columbus-based grass-roots group.
Fracking: Gas Drilling's Environmental Threat by ProPublica, an online journalism site.
Pipeline, blog from Pittsburgh Post-Gazette on Marcellus shale drilling.
Allegheny Front, environmental public radio for Western Pennsylvania.