{
  "name": "Illinois Oil & Gas Formations and Plays, Ranked by Well Count",
  "publisher": "Buckhead Energy",
  "url": "https://www.buckheadenergy.com/formations-illinois",
  "license": "https://creativecommons.org/licenses/by/4.0/",
  "doi": "https://doi.org/10.5281/zenodo.21442884",
  "dataAsOf": "2026-08-02",
  "count": 5,
  "formations": [
    {
      "state": "IL",
      "formationSlug": "illinois-basin",
      "formationName": "Illinois Basin",
      "wellCount": 199282,
      "activeOperators": 13020,
      "totalLateralFt": "469988",
      "recentPermits24Mo": 493,
      "primaryCounties": "CRAWFORD, WHITE, LAWRENCE, WAYNE, PEORIA",
      "topOperators": [
        {
          "name": "THE OHIO OIL",
          "slug": "the-ohio-oil",
          "wells": 10768
        },
        {
          "name": "MARATHON OIL COMPANY",
          "slug": "marathon-oil-company",
          "wells": 4511
        },
        {
          "name": "THE TEXAS COMPANY",
          "slug": "the-texas-company",
          "wells": 4094
        },
        {
          "name": "PURE OIL COMPANY",
          "slug": "pure-oil-company",
          "wells": 3187
        },
        {
          "name": "TEXACO",
          "slug": "texaco",
          "wells": 2426
        },
        {
          "name": "OHIO OIL COMPANY",
          "slug": "ohio-oil-company",
          "wells": 2179
        },
        {
          "name": "THE PURE OIL COMPANY",
          "slug": "the-pure-oil-company",
          "wells": 1943
        },
        {
          "name": "THE CARTER OIL",
          "slug": "the-carter-oil",
          "wells": 1811
        },
        {
          "name": "FOREST OIL",
          "slug": "forest-oil",
          "wells": 1671
        },
        {
          "name": "MAGNOLIA PETROLEUM COMPANY",
          "slug": "magnolia-petroleum-company",
          "wells": 1602
        }
      ],
      "dataAsOf": "2026-08-02"
    },
    {
      "state": "IL",
      "formationSlug": "wisconsin-arch",
      "formationName": "Wisconsin Arch",
      "wellCount": 3692,
      "activeOperators": 336,
      "totalLateralFt": "155",
      "recentPermits24Mo": 15,
      "primaryCounties": "WILL, MC HENRY, KANE, WINNEBAGO, DU PAGE",
      "topOperators": [
        {
          "name": "IL STATE GEOLOGICAL SURVEY",
          "slug": "il-state-geological-survey",
          "wells": 421
        },
        {
          "name": "NATURAL GAS PIPELINE CO OF AMERICA",
          "slug": "natural-gas-pipeline-co-of-america",
          "wells": 411
        },
        {
          "name": "VICKERY DRILLING",
          "slug": "vickery-drilling",
          "wells": 404
        },
        {
          "name": "NORTHERN ILLINOIS GAS COMPANY",
          "slug": "northern-illinois-gas-company",
          "wells": 314
        },
        {
          "name": "NATURAL GAS STORAGE COMPANY OF IL",
          "slug": "natural-gas-storage-company-of-il",
          "wells": 176
        },
        {
          "name": "WANG ENGINEERING",
          "slug": "wang-engineering",
          "wells": 145
        },
        {
          "name": "CENTRAL IL ELECTRIC",
          "slug": "central-il-electric",
          "wells": 135
        },
        {
          "name": "ALCO OIL & GAS",
          "slug": "alco-oil-gas",
          "wells": 112
        },
        {
          "name": "BAYS CARL A ETAL",
          "slug": "bays-carl-a-etal",
          "wells": 87
        },
        {
          "name": "PEOPLES GAS & COMPANYKE COMPANY",
          "slug": "peoples-gas-companyke-company",
          "wells": 81
        }
      ],
      "dataAsOf": "2026-08-02"
    },
    {
      "state": "IL",
      "formationSlug": "michigan-basin",
      "formationName": "Michigan Basin",
      "wellCount": 621,
      "activeOperators": 98,
      "totalLateralFt": "1175",
      "recentPermits24Mo": 0,
      "primaryCounties": "LAKE, COOK, MC HENRY, DU PAGE, WILL",
      "topOperators": [
        {
          "name": "IL STATE GEOLOGICAL SURVEY",
          "slug": "il-state-geological-survey",
          "wells": 193
        },
        {
          "name": "ILLINOIS STATE GEOLOGICAL SURVEY",
          "slug": "illinois-state-geological-survey",
          "wells": 74
        },
        {
          "name": "MILLER J P ART WELL",
          "slug": "miller-j-p-art-well",
          "wells": 28
        },
        {
          "name": "ISGS",
          "slug": "isgs",
          "wells": 26
        },
        {
          "name": "KEIFERASSOCIATES",
          "slug": "keiferassociates",
          "wells": 25
        },
        {
          "name": "NORTHERN ILLINOIS GAS COMPANY",
          "slug": "northern-illinois-gas-company",
          "wells": 24
        },
        {
          "name": "ALCO OIL & GAS",
          "slug": "alco-oil-gas",
          "wells": 16
        },
        {
          "name": "GEIGER S B COMPANY",
          "slug": null,
          "wells": 13
        },
        {
          "name": "SNELTON BROTHERS",
          "slug": null,
          "wells": 10
        },
        {
          "name": "PERRY EDWARD",
          "slug": null,
          "wells": 10
        }
      ],
      "dataAsOf": "2026-08-02"
    },
    {
      "state": "IL",
      "formationSlug": "new-albany",
      "formationName": "New Albany",
      "wellCount": 477,
      "activeOperators": 264,
      "totalLateralFt": "893",
      "recentPermits24Mo": 0,
      "primaryCounties": "JERSEY, CLARK, LAWRENCE, EDGAR, CRAWFORD",
      "topOperators": [
        {
          "name": "DAYTON WARD W",
          "slug": "dayton-ward-w",
          "wells": 31
        },
        {
          "name": "NATIONAL ASSOCIATED PETROLEUM COMPANY",
          "slug": "national-associated-petroleum-company",
          "wells": 23
        },
        {
          "name": "MARATHON OIL COMPANY",
          "slug": "marathon-oil-company",
          "wells": 18
        },
        {
          "name": "THE OHIO OIL",
          "slug": "the-ohio-oil",
          "wells": 14
        },
        {
          "name": "ZINK EARNEST",
          "slug": "zink-earnest",
          "wells": 11
        },
        {
          "name": "KELLEY CONRAD & KAYE",
          "slug": "kelley-conrad-kaye",
          "wells": 7
        },
        {
          "name": "FOREST OIL",
          "slug": "forest-oil",
          "wells": 7
        },
        {
          "name": "MIDWESTERN GAS TRANSMISSION COMPANY",
          "slug": "midwestern-gas-transmission-company",
          "wells": 7
        },
        {
          "name": "PENNTEX RESOURCES ILLINOIS",
          "slug": "penntex-resources-illinois",
          "wells": 7
        },
        {
          "name": "HF Sinclair Corporation",
          "slug": "hf-sinclair-corporation",
          "wells": 6
        }
      ],
      "dataAsOf": "2026-08-02"
    },
    {
      "state": "IL",
      "formationSlug": "lake-michigan",
      "formationName": "Lake Michigan",
      "wellCount": 61,
      "activeOperators": 5,
      "totalLateralFt": "0",
      "recentPermits24Mo": 0,
      "primaryCounties": "LAKE, COOK",
      "topOperators": [
        {
          "name": "ILLINOIS STATE GEOLOGICAL SURVEY",
          "slug": "illinois-state-geological-survey",
          "wells": 36
        },
        {
          "name": "IL STATE GEOLOGICAL SURVEY",
          "slug": "il-state-geological-survey",
          "wells": 11
        },
        {
          "name": "HESTER N C",
          "slug": null,
          "wells": 9
        },
        {
          "name": "MATTHEUS SPITZER AND PEARCE",
          "slug": null,
          "wells": 4
        },
        {
          "name": "U S GEOLOGICAL SURVEY",
          "slug": "u-s-geological-survey",
          "wells": 1
        }
      ],
      "dataAsOf": "2026-08-02"
    }
  ]
}