The largest oil and gas operators active in Illinois — ranked by total well count, with recent drilling activity, DUC inventory, and producing-well counts for each. Click any operator to see their full profile and current permits.
Refreshed monthly from IDNR well-header records. Data current as of 2026-06-14.
As of 2026-06-14, the most active operator in Illinois is The Ohio Oil with 10,780 wells on record, across the top 100 ranked operators, per Illinois Department of Natural Resources, Office of Oil & Gas (IDNR) records.
| # | Operator | Wells | Permits 24mo | DUCs | Producing | Top Formation | Top County |
|---|---|---|---|---|---|---|---|
| 1 | The Ohio Oil | 10,780 | 0 | 0 | 0 | Illinois Basin | Crawford |
| 2 | Marathon Oil Company | 4,529 | 0 | 0 | 0 | Illinois Basin | Lawrence |
| 3 | The Texas Company | 4,094 | 0 | 0 | 0 | Illinois Basin | Marion |
| 4 | Pure Oil Company | 3,109 | 0 | 0 | 0 | Illinois Basin | Richland |
| 5 | Texaco | 2,427 | 0 | 0 | 0 | Illinois Basin | Marion |
| 6 | Ohio Oil Company | 2,180 | 0 | 0 | 0 | Illinois Basin | Crawford |
| 7 | The Pure Oil Company | 2,012 | 0 | 0 | 0 | Illinois Basin | Wayne |
| 8 | The Carter Oil | 1,812 | 0 | 0 | 0 | Illinois Basin | Fayette |
| 9 | Forest Oil | 1,678 | 0 | 0 | 0 | Illinois Basin | Cumberland |
| 10 | Magnolia Petroleum Company | 1,605 | 0 | 0 | 0 | Illinois Basin | Marion |
| 11 | Il State Geological Survey | 1,557 | 0 | 0 | 0 | Illinois Basin | Will |
| 12 | National Associated Petroleum Company | 1,556 | 0 | 0 | 0 | Illinois Basin | White |
| 13 | Shell Oil Company | 1,483 | 0 | 0 | 0 | Illinois Basin | Hamilton |
| 14 | Tide Water Associated Oil Company | 1,419 | 0 | 0 | 0 | Illinois Basin | Crawford |
| 15 | Exxon Mobil | 1,299 | 0 | 0 | 0 | Illinois Basin | Fayette |
| 16 | Superior Oil Company | 1,278 | 0 | 0 | 0 | Illinois Basin | White |
| 17 | Union Oil Company Of California | 1,223 | 0 | 0 | 0 | Illinois Basin | Clay |
| 18 | Carter Oil Company | 1,206 | 0 | 1 | 0 | Illinois Basin | Fayette |
| 19 | Brehm C E Drilling & Producing | 1,167 | 0 | 0 | 0 | Illinois Basin | White |
| 20 | Northern Illinois Gas Company | 1,115 | 5 | 1 | 0 | Illinois Basin | Livingston |
| 21 | Gulf Refining Company | 1,010 | 0 | 0 | 0 | Illinois Basin | Clinton |
| 22 | Sun Production CO Sun Oil | 987 | 0 | 0 | 0 | Illinois Basin | White |
| 23 | Phillips Petroleum Company | 964 | 0 | 0 | 0 | Illinois Basin | White |
| 24 | Associated Oil Production Company | 845 | 0 | 0 | 0 | Illinois Basin | Crawford |
| 25 | Campbell Energy | 800 | 38 | 3 | 0 | Illinois Basin | White |
| 26 | Mahutska Oil Company | 780 | 0 | 0 | 0 | Illinois Basin | Crawford |
| 27 | The Texas | 774 | 0 | 0 | 0 | Illinois Basin | Marion |
| 28 | Petco Petroleum | 764 | 0 | 0 | 0 | Illinois Basin | Fayette |
| 29 | Natural Gas Pipeline CO Of America | 737 | 11 | 2 | 0 | Wisconsin Arch | Kankakee |
| 30 | Mcbride W C | 719 | 0 | 0 | 0 | Illinois Basin | Lawrence |
| 31 | Zanetisjohn Mestate Of | 706 | 0 | 0 | 0 | Illinois Basin | Jasper |
| 32 | Alco Oil & Gas | 686 | 0 | 0 | 0 | Illinois Basin | Henderson |
| 33 | Calvert Drilling | 675 | 0 | 0 | 0 | Illinois Basin | Richland |
| 34 | Ashland Oil & Refining | 672 | 0 | 0 | 0 | Illinois Basin | Crawford |
| 35 | Citation Oil & Gas | 667 | 45 | 0 | 0 | Illinois Basin | Marion |
| 36 | Bipetro | 639 | 22 | 0 | 0 | Illinois Basin | Mc Donough |
| 37 | C E Brehm Drilling & Production | 619 | 0 | 0 | 0 | Illinois Basin | Hamilton |
| 38 | Southern Community | 586 | 0 | 0 | 0 | Illinois Basin | Wabash |
| 39 | Vickery Drilling | 579 | 0 | 0 | 0 | Wisconsin Arch | La Salle |
| 40 | Kingwood Oil Company | 578 | 0 | 0 | 0 | Illinois Basin | Hamilton |
| 41 | R K Petroleum | 565 | 0 | 0 | 0 | Illinois Basin | White |
| 42 | George & Wrather Oil | 547 | 0 | 0 | 0 | Illinois Basin | Wabash |
| 43 | Collins Brothers Oil Company | 545 | 0 | 0 | 0 | Illinois Basin | Hamilton |
| 44 | Duncan Walter | 542 | 0 | 0 | 0 | Illinois Basin | Coles |
| 45 | Granholm & Assoc | 540 | 0 | 0 | 0 | Illinois Basin | Montgomery |
| 46 | Illinois State Geological Survey | 533 | 0 | 0 | 0 | Illinois Basin | Cook |
| 47 | Christa Oil Company | 527 | 0 | 0 | 0 | Illinois Basin | Crawford |
| 48 | Oelze Elmer Jr | 519 | 0 | 0 | 0 | Illinois Basin | Washington |
| 49 | Shakespeare Oil | 516 | 0 | 1 | 0 | Illinois Basin | Wayne |
| 50 | Illinois Power Company | 511 | 0 | 0 | 0 | Illinois Basin | St Clair |
| 51 | Skiles Oil | 510 | 0 | 0 | 0 | Illinois Basin | Crawford |
| 52 | Crete Oil Investments | 506 | 0 | 0 | 0 | Illinois Basin | Crawford |
| 53 | Hydrocarbon Survey | 504 | 0 | 0 | 0 | Illinois Basin | Henry |
| 54 | Fulk Perry | 504 | 0 | 0 | 0 | Illinois Basin | Richland |
| 55 | Sohio Petroleum Company | 499 | 0 | 0 | 0 | Illinois Basin | Marion |
| 56 | Hf Sinclair Corporation | 477 | 0 | 0 | 0 | Illinois Basin | White |
| 57 | Elysium Energy | 477 | 0 | 0 | 0 | Illinois Basin | White |
| 58 | Gallagher Victor R | 436 | 0 | 0 | 0 | Illinois Basin | Franklin |
| 59 | Pioneer Oil | 428 | 14 | 0 | 0 | Illinois Basin | Crawford |
| 60 | Farrar Oil | 423 | 0 | 0 | 0 | Illinois Basin | Franklin |
| 61 | Gulf Oil | 422 | 0 | 0 | 0 | Illinois Basin | White |
| 62 | Coy Oil | 418 | 0 | 0 | 0 | Illinois Basin | White |
| 63 | The Nation Oil Company | 417 | 0 | 0 | 0 | Illinois Basin | Wayne |
| 64 | Red Bank Oil Company | 401 | 0 | 0 | 0 | Illinois Basin | Crawford |
| 65 | Jet Oil Company | 384 | 0 | 0 | 0 | Illinois Basin | Clinton |
| 66 | Plains Illinois | 380 | 0 | 0 | 0 | Illinois Basin | Lawrence |
| 67 | Republic Oil Company | 370 | 0 | 0 | 0 | Illinois Basin | Wayne |
| 68 | Dee Drilling | 365 | 11 | 0 | 0 | Illinois Basin | Gallatin |
| 69 | Peoples Gas Light & Companyke Company | 356 | 0 | 0 | 0 | Illinois Basin | Champaign |
| 70 | Richardson M H | 355 | 0 | 0 | 0 | Illinois Basin | Douglas |
| 71 | Western Oil & Gas Dev Company | 355 | 0 | 0 | 0 | Illinois Basin | Crawford |
| 72 | Van Fossan Oil | 343 | 0 | 0 | 0 | Illinois Basin | Wayne |
| 73 | Texas Company | 338 | 0 | 0 | 0 | Illinois Basin | Marion |
| 74 | Skiles C E | 336 | 0 | 0 | 0 | Illinois Basin | Wabash |
| 75 | Zink Earnest | 334 | 0 | 0 | 0 | Illinois Basin | Edgar |
| 76 | Owner | 333 | 0 | 0 | 0 | Illinois Basin | Fayette |
| 77 | Central Il Light Company | 333 | 0 | 0 | 0 | Illinois Basin | Peoria |
| 78 | Penntex Resources Illinois | 331 | 0 | 0 | 0 | Illinois Basin | Lawrence |
| 79 | Shulman Bros | 326 | 0 | 0 | 0 | Illinois Basin | Clay |
| 80 | Continental Oil Company | 320 | 0 | 0 | 0 | Illinois Basin | Wabash |
| 81 | Assoc Pet Production | 319 | 0 | 0 | 0 | Illinois Basin | Crawford |
| 82 | Illinois Midcontinent Company | 315 | 0 | 0 | 0 | Illinois Basin | Wayne |
| 83 | Black & Black Oil Company | 302 | 0 | 0 | 0 | Illinois Basin | Crawford |
| 84 | Constantin E Jr | 302 | 0 | 0 | 0 | Illinois Basin | Crawford |
| 85 | Podolsky Bernard | 301 | 0 | 0 | 0 | Illinois Basin | Wayne |
| 86 | Vickery Drlg | 300 | 0 | 0 | 0 | Illinois Basin | Mc Lean |
| 87 | Slagter Arthur J Jr | 292 | 0 | 0 | 0 | Illinois Basin | White |
| 88 | Indiana Farm Bureau Coop Assn | 290 | 0 | 0 | 0 | Illinois Basin | Crawford |
| 89 | Bradley Producing | 285 | 0 | 0 | 0 | Illinois Basin | Lawrence |
| 90 | Energy Resource Technology Gom | 283 | 0 | 0 | 0 | Illinois Basin | Crawford |
| 91 | Humble Oil And Refining Company | 280 | 0 | 0 | 0 | Illinois Basin | Fayette |
| 92 | Robinson & Puckett | 275 | 0 | 0 | 0 | Illinois Basin | Wayne |
| 93 | Snowden Bros & Company | 274 | 0 | 0 | 0 | Illinois Basin | Lawrence |
| 94 | Obering Earnest | 273 | 0 | 0 | 0 | Illinois Basin | Madison |
| 95 | Beeson Richard W | 269 | 0 | 0 | 0 | Illinois Basin | Saline |
| 96 | Carey John Oil | 268 | 0 | 0 | 0 | Illinois Basin | Sangamon |
| 97 | Equinox Oil Company | 266 | 0 | 0 | 0 | Illinois Basin | White |
| 98 | Ouabache Oil & Gas Company | 265 | 0 | 0 | 0 | Illinois Basin | Crawford |
| 99 | Peoples Gas & Companyke Company | 263 | 0 | 0 | 0 | Illinois Basin | Will |
| 100 | Parrish Oil Production | 259 | 0 | 0 | 0 | Illinois Basin | Jasper |
Source: Illinois Department of Natural Resources, Office of Oil & Gas well-header records.
Ranking: Operators ranked by total well count under their current operator-of-record. Recent permits cover the last 24 months; DUC count is wells spudded but not yet producing; producing-well count is wells with a first-production date on file.
Why it matters: Knowing who operates the most wells in Illinois — and who's drilling the most NOW — helps mineral owners understand who they're dealing with at the lease level.
Refresh cadence: Monthly. Data current as of 2026-06-14.
Whether your operator is on this list or not, your Illinois mineral interest may be more valuable than you think. Get a free, no-obligation written offer.
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State: Illinois
Operators ranked: 100
Total wells: 85,323
Permits (24mo): 146
Last refresh: 2026-06-14
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