The largest oil and gas operators active in California — 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 daily from CalGEM well-header records. Data current as of 2026-09-06.
Quick answer: By wells operated, Chevron is the largest oil and gas operator in California with 59,410 wells on record, followed by Aera Energy (57,836) and California Resources Production (15,278). Ranked from California Geologic Energy Management Division (CalGEM) well-header records (as of 2026-09-06). This is an operated-well-count ranking, not a revenue or market-cap ranking.
As of 2026-09-06, the most active operator in California is Chevron with 59,410 wells on record and 2,403 recent permits, across the top 100 ranked operators, per California Geologic Energy Management Division (CalGEM) records.
| # | Operator | Wells | Permits 24mo | DUCs | Producing | Top Formation | Top County |
|---|---|---|---|---|---|---|---|
| 1 | Chevron | 59,410 | 2,403 | 7,340 | 36,624 | San Joaquin Basin | Kern |
| 2 | Aera Energy | 57,836 | 2,267 | 7,401 | 39,151 | Monterey-Temblor | Kern |
| 3 | California Resources Production | 15,278 | 764 | 1,327 | 8,937 | San Joaquin Basin | Kern |
| 4 | Sentinel Peak Resources Ca | 10,943 | 749 | 1,292 | 7,768 | Monterey-Temblor | Kern |
| 5 | Berry Petroleum Company | 8,439 | 756 | 793 | 6,331 | Monterey-Temblor | Kern |
| 6 | California Resources Elk Hills LLC | 7,577 | 894 | 352 | 6,777 | Monterey-Temblor | Kern |
| 7 | Tidelands Oil Production Company | 4,172 | 74 | 286 | 1,653 | Monterey | Los Angeles |
| 8 | E & B Natural Resources Management | 4,071 | 171 | 467 | 2,711 | San Joaquin Basin | Kern |
| 9 | Union Oil Company Of California | 2,561 | 0 | 143 | 761 | Monterey | Santa Barbara |
| 10 | Shell Oil Company | 2,503 | 4 | 295 | 315 | Monterey | Kern |
| 11 | Crimson Resource Management | 2,273 | 120 | 368 | 1,503 | Monterey-Temblor | Kern |
| 12 | Calnrg Operating LLC | 2,223 | 89 | 136 | 1,634 | Monterey | Ventura |
| 13 | Thums Long Beach Company | 2,124 | 99 | 144 | 1,607 | Monterey | Los Angeles Offshore |
| 14 | Mobil Oil | 1,926 | 0 | 272 | 199 | Monterey | Los Angeles |
| 15 | Exxon Mobil | 1,728 | 0 | 343 | 631 | Monterey | Los Angeles |
| 16 | Holmes Western Oil | 1,420 | 70 | 86 | 979 | Monterey-Temblor | Kern |
| 17 | Macpherson Oil Company | 1,244 | 91 | 125 | 873 | San Joaquin Basin | Kern |
| 18 | Midwaysunset Investors | 1,041 | 1 | 0 | 29 | Monterey-Temblor | Og |
| 19 | Union Pacific Resources Company | 966 | 0 | 13 | 262 | Monterey | Los Angeles |
| 20 | Cat Canyon Resources LLC | 887 | 0 | 9 | 692 | Monterey | Santa Barbara |
| 21 | Bridge Energy LLC | 814 | 15 | 21 | 533 | Monterey | Orange |
| 22 | Signal Hill Petroleum | 740 | 10 | 14 | 592 | Monterey | Los Angeles |
| 23 | Phillips Petroleum Company | 740 | 0 | 201 | 47 | Monterey | Kern |
| 24 | Lost Hills | 734 | 0 | 0 | 0 | — | Og |
| 25 | Arco Western Energy | 700 | 0 | 107 | 73 | San Joaquin Basin | Kern |
| 26 | Bridgeland Resources LLC | 678 | 53 | 28 | 533 | Monterey | Los Angeles |
| 27 | Carbon California Operating Company LLC | 667 | 9 | 80 | 553 | Ventura Basin | Ventura |
| 28 | Pacific Coast Energy Company | 666 | 36 | 42 | 457 | Monterey | Santa Barbara |
| 29 | Southern Community | 631 | 41 | 40 | 374 | Monterey | Los Angeles |
| 30 | Dcor | 626 | 33 | 200 | 400 | Monterey | Santa Cruz Area |
| 31 | San Joaquin Facilities Management | 587 | 9 | 8 | 445 | San Joaquin Basin | Kern |
| 32 | Atlantic Oil Company | 568 | 0 | 260 | 111 | Sacramento Basin | Yolo |
| 33 | Bellaire Oil Company | 536 | 9 | 1 | 474 | San Joaquin Basin | Kern |
| 34 | Shadow Wolf Energy LLC | 535 | 9 | 49 | 424 | Los Angeles Basin | Los Angeles |
| 35 | City Of Whittier | 525 | 0 | 3 | 211 | Monterey | Los Angeles |
| 36 | Hunter Edison Oil Development LTD | 525 | 4 | 10 | 509 | San Joaquin Basin | Kern |
| 37 | Newbridge Resources | 518 | 8 | 8 | 458 | Monterey | Santa Barbara |
| 38 | Kern River | 516 | 0 | 0 | 0 | — | Sc |
| 39 | Warren E & P | 504 | 9 | 65 | 361 | Monterey | Los Angeles |
| 40 | West Energy Operating LLC | 493 | 24 | 35 | 372 | Monterey | Los Angeles |
| 41 | Hathaway | 465 | 6 | 11 | 340 | San Joaquin Basin | Kern |
| 42 | Oxy | 464 | 3 | 146 | 36 | Monterey-Temblor | Kern |
| 43 | Freeport-Mcmoran Oil & Gas | 464 | 0 | 91 | 86 | Monterey | Ventura |
| 44 | Naftex Operating Company | 440 | 32 | 14 | 334 | San Joaquin Basin | Kern |
| 45 | Arco Oil & Gas Company | 419 | 0 | 27 | 23 | Monterey | Santa Barbara |
| 46 | Oryx Energy Company | 413 | 0 | 90 | 43 | San Joaquin Basin | Kern |
| 47 | Kern River Holdings Ii LLC | 410 | 12 | 38 | 322 | San Joaquin Basin | Kern |
| 48 | Amerada Hess | 408 | 0 | 279 | 45 | Sacramento Basin | Solano |
| 49 | Atlantic Richfield Company | 407 | 0 | 43 | 41 | Monterey | Los Angeles |
| 50 | Cymric | 388 | 0 | 0 | 0 | — | Og |
| 51 | West Newport Oil Company | 364 | 0 | 0 | 286 | Monterey | Orange |
| 52 | Brea Canon Oil Company | 355 | 16 | 19 | 166 | Monterey | Los Angeles |
| 53 | The Termo Company | 349 | 17 | 52 | 233 | Sacramento Basin | Los Angeles |
| 54 | Venoco | 330 | 0 | 129 | 92 | Sacramento Basin | Santa Cruz Area |
| 55 | Trc Operating Company INC | 308 | 18 | 1 | 294 | San Joaquin Basin | Kern |
| 56 | Petrolud | 291 | 20 | 74 | 207 | San Joaquin Basin | Kern |
| 57 | Texaco Producing | 288 | 0 | 0 | 2 | San Joaquin Basin | Kern |
| 58 | Hvi Cat Canyon INC | 282 | 5 | 15 | 208 | Monterey | Santa Barbara |
| 59 | Sequoia Exploration | 274 | 16 | 2 | 231 | San Joaquin Basin | Kern |
| 60 | Conocophillips Company | 262 | 0 | 77 | 15 | Monterey | Los Angeles |
| 61 | Vintage Petroleum | 231 | 0 | 5 | 8 | Monterey-Temblor | Kern |
| 62 | Capitol Oil | 221 | 0 | 115 | 101 | Sacramento Basin | Solano |
| 63 | Torrance Petroleum | 216 | 0 | 0 | 120 | Monterey | Los Angeles |
| 64 | Matrix Oil | 214 | 2 | 10 | 194 | Monterey | Los Angeles |
| 65 | Wilmington | 210 | 0 | 0 | 0 | — | Og |
| 66 | Dominguez Energy | 208 | 0 | 2 | 95 | Monterey | Los Angeles |
| 67 | Nahama & Weagant Energy Company | 208 | 0 | 116 | 61 | Sacramento Basin | Yolo |
| 68 | Seneca Resources | 203 | 0 | 1 | 1 | Monterey-Temblor | Kern |
| 69 | Cmo | 193 | 8 | 39 | 130 | San Joaquin Basin | Kern |
| 70 | Sycamore Development Partners LLC | 192 | 134 | 7 | 134 | Monterey | Orange |
| 71 | Vaquero Energy | 189 | 0 | 2 | 10 | San Joaquin Basin | Kern |
| 72 | Sunset Oil Company | 189 | 0 | 1 | 0 | Santa Maria Basin | Santa Barbara Offshore |
| 73 | Pacific Gas & Electric Company | 187 | 21 | 61 | 117 | Sacramento Basin | San Joaquin |
| 74 | Pyramid Oil Company | 186 | 0 | 1 | 33 | Monterey | Kern |
| 75 | Huntington Beach Company | 180 | 0 | 0 | 56 | Monterey | Orange |
| 76 | Saba Petroleum | 179 | 0 | 0 | 46 | Monterey | Santa Barbara |
| 77 | J P Oil Company | 173 | 7 | 1 | 85 | Monterey-Temblor | Kern |
| 78 | State Lands Commission | 172 | 2 | 46 | 96 | Monterey | Ventura Offshore |
| 79 | Tesoro Petroleum | 171 | 0 | 25 | 0 | San Joaquin Basin | Kern |
| 80 | Santa Fe Energy Resources | 169 | 0 | 38 | 7 | San Joaquin Basin | Kern |
| 81 | Trico Industries | 168 | 0 | 65 | 0 | San Joaquin Basin | Kern |
| 82 | Marathon Oil Company | 167 | 0 | 33 | 6 | Monterey-Temblor | Kern |
| 83 | Drilling & Production Company | 161 | 2 | 10 | 70 | Monterey-Temblor | Kern |
| 84 | Angel Petroleum LLC | 160 | 0 | 12 | 84 | Monterey | Santa Barbara |
| 85 | Royale Energy | 159 | 1 | 42 | 96 | Sacramento Basin | Colusa |
| 86 | Oro Negro INC | 158 | 0 | 10 | 106 | San Joaquin Basin | Kern |
| 87 | Rosetta Resources Operating | 157 | 0 | 54 | 91 | Sacramento Basin | Yolo |
| 88 | Towne Exploration Company | 153 | 0 | 59 | 78 | Sacramento Basin | Sacramento |
| 89 | Standard Oil Company | 151 | 0 | 1 | 43 | San Joaquin Basin | Kern |
| 90 | Petrolewis | 150 | 0 | 2 | 8 | Monterey | Los Angeles |
| 91 | Inglewood | 145 | 0 | 0 | 0 | — | Og |
| 92 | Beta Operating Company | 145 | 0 | 40 | 105 | Southern California Borderlands Province | Santa Catalina Area |
| 93 | Txo Production | 144 | 0 | 92 | 43 | Sacramento Basin | Solano |
| 94 | Synergy Oil & Gas | 144 | 25 | 14 | 87 | Monterey | Los Angeles |
| 95 | Kenneth H Hunterjr Trustee Of The Hunter Livin | 143 | 0 | 1 | 52 | San Joaquin Basin | Kern |
| 96 | Trivalley Oil & Gas Company | 142 | 5 | 48 | 31 | Sacramento Basin | Kern |
| 97 | Trc Operating Company Incorporated | 141 | 0 | 8 | 109 | San Joaquin Basin | Kern |
| 98 | Aba Energy | 139 | 7 | 52 | 82 | Sacramento Basin | Solano |
| 99 | Triton Oil & Gas | 138 | 0 | 38 | 71 | Monterey | Los Angeles |
| 100 | Poso Creek | 131 | 0 | 0 | 0 | — | Og |
Source: California Geologic Energy Management Division 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 California — and who's drilling the most NOW — helps mineral owners understand who they're dealing with at the lease level.
Refresh cadence: Daily. Data current as of 2026-09-06.
Cite this dataset
Permanently archived and citable via a DOI on Zenodo (CERN), under a CC BY 4.0 license. DOI: 10.5281/zenodo.21442884 · View on Zenodo
License & attribution: This data is licensed CC BY 4.0. You are free to share and adapt it, including commercially, provided you credit “Buckhead Energy” and link back to this page or the DOI above.
By wells operated, Chevron is the largest oil and gas operator in California, with 59,410 wells on record per California Geologic Energy Management Division (CalGEM) data. Note that "biggest" by revenue or market capitalization can rank differently — this measures operated well count.
The top 10 operators by operated well count are: Chevron, Aera Energy, California Resources Production, Sentinel Peak Resources Ca, Berry Petroleum Company, California Resources Elk Hills LLC, Tidelands Oil Production Company, E & B Natural Resources Management, Union Oil Company Of California, Shell Oil Company. The full top-100 ranking with permits, DUC inventory, and producing-well counts is in the leaderboard below.
Chevron operates the most wells in California at 59,410, with 2,403 permits filed in the last 24 months, per CalGEM well-header records.
This leaderboard ranks the top 100 operators active in California by total well count. Many more file with the regulator; these are the largest by operated wells.
By wells operated — the count of wells under each company's current operator-of-record designation in California Geologic Energy Management Division (CalGEM) records. It is not a revenue, production-volume, or market-capitalization ranking.
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State: California
Operators ranked: 100
Total wells: 215,193
Permits (24mo): 9,180
Last refresh: 2026-09-06
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