Stored formation/play groups ranked by recorded well count, with recorded operators and primary counties. Coverage is limited to the groups included below.
Buckhead Energy analysis of public oil and gas data. Daily refresh scheduled. Stored source refresh: 2026-10-02.
Stored source refresh: 2026-10-02. Formation/play groups require at least 25 recorded wells and a known operator; the directory shows at most 50 groups ranked by well count. Operator counts reflect distinct recorded operator names, not verified current operations. Permit counts use the preceding 24 months at summary refresh. Grouping can represent a formation, play or basin; it is not an inventory of every geological formation. Figures are Buckhead Energy analysis of public oil and gas data; counts under 3 wells are withheld.
Buckhead Energy analysis of public oil and gas data. Scheduled refreshes do not guarantee that new regulator filings are available; the state regulator remains the record of any specific well.
Quick answer: The highest well-count groups listed for California are the Monterey-Temblor, San Joaquin Basin, Monterey, Sacramento Basin and Coastal Basins, led by the Monterey-Temblor with 96,601 wells on record. Ranked by well count across 16 tracked formations from Buckhead Energy analysis of public oil and gas data. Stored source refresh: 2026-10-02. These are limited stored records; reporting windows are evaluated at source refresh.
The highest well-count groups listed for California are the Monterey-Temblor, San Joaquin Basin, Monterey, Sacramento Basin and Coastal Basins, led by the Monterey-Temblor with 96,601 wells on record. Ranked by well count across 16 tracked formations from Buckhead Energy analysis of public oil and gas data. Stored source refresh: 2026-10-02. These are limited stored records; reporting windows are evaluated at source refresh.
Top Operators:
Aera Energy (44,660), Chevron (16,193), California Resources Elk Hills LLC (7,374), Berry Petroleum Company (7,207), Sentinel Peak Resources Ca (5,640), California Resources Production (5,278), Crimson Resource Management (1,760), Holmes Western Oil (1,012), Shell Oil Company (604), Mobil Oil (420)
Primary counties: Kern, Kings, Fresno, Tulare
Top Operators:
Chevron (34,513), Aera Energy (8,892), California Resources Production (5,602), E & B Natural Resources Management (3,032), Sentinel Peak Resources Ca (2,824), Macpherson Oil Company (1,236), Berry Petroleum Company (1,175), Shell Oil Company (537), Bellaire Oil Company (535), Hunter Edison Oil Development LTD (525)
Primary counties: Kern, Fresno, Tulare, San Benito, Madera
Top Operators:
Chevron (4,968), Tidelands Oil Production Company (3,825), Aera Energy (2,634), California Resources Production (2,209), Union Oil Company Of California (1,931), Calnrg Operating LLC (1,919), Thums Long Beach Company (1,893), Sentinel Peak Resources Ca (1,657), Exxon Mobil (1,310), Union Pacific Resources Company (898)
Primary counties: Los Angeles, Orange, Ventura, Santa Barbara, Los Angeles Offshore
Top Operators:
California Resources Production (1,863), Chevron (755), Atlantic Oil Company (316), Amerada Hess (260), Capitol Oil (217), Shell Oil Company (174), Phillips Petroleum Company (166), Exxon Mobil (164), Pacific Gas & Electric Company (162), Rosetta Resources Operating (157)
Primary counties: Solano, Yolo, Colusa, Glenn, San Joaquin
Top Operators:
Chevron (1,810), Aera Energy (1,532), Sentinel Peak Resources Ca (526), Shell Oil Company (193), Phillips Petroleum Company (70), E & B Natural Resources Management (65), Calnrg Operating LLC (59), Exxon Mobil (57), Grace Petroleum (53), Arco Oil & Gas Company (51)
Primary counties: Monterey, San Luis Obispo, Kern, San Benito, Santa Barbara
Top Operators:
Shadow Wolf Energy LLC (535), Chevron (356), Sentinel Peak Resources Ca (283), Southern Community (258), West Energy Operating LLC (119), Warren E & P (116), Caltico Oil (94), Thums Long Beach Company (88), The Termo Company (67), Crimson Resource Management (63)
Primary counties: Los Angeles, Orange, Los Angeles Offshore, San Bernardino, Ventura
Top Operators:
Carbon California Operating Company LLC (606), Chevron (245), Calnrg Operating LLC (229), Shell Oil Company (102), Union Oil Company Of California (74), The Termo Company (53), Argo Petroleum (49), Arco Oil & Gas Company (48), American Oil (46), Adolfo Camarillo (46)
Primary counties: Ventura, Los Angeles, Ventura Offshore, Santa Barbara
Top Operators:
E & B Natural Resources Management (376), Sunset Oil Company (187), Arco Oil & Gas Company (108), Chevron (102), Seaside Oil Company (86), Saba Petroleum (69), Oryx Energy Company (55), Atlantic Richfield Company (34), Southern Community (34), Phillips Petroleum Company (31)
Primary counties: Santa Barbara, Santa Barbara Offshore, San Luis Obispo, Santa Rosa Island, Santa Cruz Area
Top Operators:
Tidelands Oil Production Company (285), California Resources Production (230), Beta Operating Company (138), Thums Long Beach Company (133), Dcor (37), Chevron (16), City Of Newport Beach (16), Union Pacific Resources Company (10), Exxon Mobil (9), Mobil Oil (7)
Primary counties: Los Angeles, Orange, Santa Catalina Area, Los Angeles Offshore, Orange Offshore
Top Operators:
Cardox CORP (125), Prado Petroleum (14), Chevron (8), The Hampton Oil (6), California Time Petroleum (5), J B Nelson (4), Pacific-Imperial Dri-Ice INC (4), Lynnhart Company INC (4), 104 Oil & Drilling Company (3), H H & W Exploration Company (3)
Primary counties: Imperial, Riverside, San Bernardino
Top Operators:
Chevron (35), Patriot Resources (21), Sargent Oil Company (20), H W Covert (14), E & B Natural Resources Management (12), Petaluma Oil & Gas Development Company (11), Hershey Oil (9), Mobil Oil (8), Shell Oil Company (7), E C Brown Operator (7)
Primary counties: Santa Clara, Alameda, Sonoma, Napa, Mendocino
Top Operators:
Neaves Petro Developments (40), Chevron (26), Union Oil Company Of California (22), Costa Loma (22), The Eric And Susan Dunn Living Trust Dated July 27 2006 (11), Botto & Miller Trustees (7), Peninsula Open Space Trust (6), Exxon Mobil (6), Ziaverde (5), Shell Oil Company (5)
Primary counties: San Mateo, Santa Cruz, Marin, Monterey
Top Operators:
Dcor (39), Exxon Mobil (16), Union Oil Company Of California (16), Venoco (16), Fred E Cole (15), Calnrg Operating LLC (12), Arco Oil & Gas Company (11), Transoceanic Oil (10), Atlantic Richfield Company (7), T G Ross (6)
Primary counties: Santa Barbara, Santa Cruz Area, Santa Barbara Offshore, Ventura, Ventura Offshore
Top Operators:
Optima Conservation Resources Exploration (16), Stone Cabin Resources (13), Padre Oil Company (11), Polaris Production (9), Chevron (6), Casex Company (6), The Major Oil (4), Chino Hills Oil Company (4), Charles C Carrillo & Chris B Pedersen (4), Mobil Oil (4)
Primary counties: San Bernardino, Riverside
Top Operators:
California Resources Production (44), Pacific Gas & Electric Company (23), Chevron (16), Harvest Petroleum (13), Zephyr Oil Company (11), Arco Western Energy (8), Jas E Babcock (6), Natural Gas CORP Of Calif (4), Argo Petroleum (3), North Companyunties Oil Company (3)
Primary counties: Humboldt, Del Norte
Top Operators:
Community Oil Well (4), Borderland Exploration (3), V O D Oil (3), Charles F Holmes (—), The Macgregor (—), Grober And Assoc (—), Mission Bay Oil Company (—), L Overbaugh & Rufus Choate (—), John F Sheran (—), Palm City Oil Company (—)
Primary counties: San Diego
Source: Buckhead Energy analysis of public oil and gas data, aggregated by primary play / interpreted formation / basin.
Threshold: Groups require at least 25 recorded wells and a known operator. The directory shows up to 50 groups by well count; omitted groups are not evidence of no activity.
Owner context: These formation summaries describe reported activity. They do not establish ownership, payment entitlement or a value for an individual tract.
Refresh cadence: Daily refresh scheduled. Stored source refresh: 2026-10-02.
The highest well-count formation/play groups listed for California are the Monterey-Temblor, San Joaquin Basin, Monterey, Sacramento Basin and Coastal Basins, among others. This directory tracks 16 recorded formation/play groups ranked by well count, per Buckhead Energy analysis of public oil and gas data. Stored source refresh: 2026-10-02. These are limited stored records; reporting windows are evaluated at source refresh.
The Monterey-Temblor has the most wells among the listed California groups — 96,601 wells, worked by 946 recorded operators, per Buckhead Energy analysis of public oil and gas data. This is a well-count ranking, not a reserves or value ranking. Stored source refresh: 2026-10-02. These are limited stored records; reporting windows are evaluated at source refresh.
The operators with the most wells on record in the Monterey-Temblor are Aera Energy, Chevron, California Resources Elk Hills LLC, Berry Petroleum Company, Sentinel Peak Resources Ca. Each formation card below lists its top operators by well count. Stored source refresh: 2026-10-02. These are limited stored records; reporting windows are evaluated at source refresh.
About 9,437 drilling permits were filed across the tracked California formations in the 24-month window at source refresh, per Buckhead Energy analysis of public oil and gas data — a rough measure of where new activity is concentrated. Stored source refresh: 2026-10-02. These are limited stored records; reporting windows are evaluated at source refresh.
Your deed and county records determine which formations your mineral rights cover; a tract can own multiple stacked formations. This directory is informational only, not a valuation. Stored source refresh: 2026-10-02. These are limited stored records; reporting windows are evaluated at source refresh.
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State: California
Active formations: 16
Total wells: 246,550
Recent permits: 9,437
Last refresh: 2026-10-02
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