| Rank | County | Production Period | Oil Production |
|---|---|---|---|
| #1 | Kern County, CA | Dec 2017 | 9.9M BBLs |
| #2 | Los Angeles County, CA | Dec 2017 | 894.9k BBLs |
| #3 | Orange County, CA | Dec 2017 | 163.4k BBLs |
| #4 | Monterey County, CA | Dec 2017 | 613.6k BBLs |
| #5 | Ventura County, CA | Dec 2017 | 331.1k BBLs |
| #6 | Fresno County, CA | Dec 2017 | 515.8k BBLs |
| #7 | Santa Barbara County, CA | Dec 2017 | 294.2k BBLs |
| #8 | San Luis Obispo County, CA | Dec 2017 | 54.7k BBLs |
| #9 | Kings County, CA | Dec 2017 | 6.8k BBLs |
| #10 | Sacramento County, CA | Dec 2017 | 871 BBLs |
| #11 | San Benito County, CA | Dec 2017 | 1.4k BBLs |
| #12 | Santa Clara County, CA | Dec 2017 | 1.5k BBLs |
| Rank | County | Production Period | Gas Production |
|---|---|---|---|
| #7 | Sutter County, CA | Dec 2017 | 322.8k MCF |
| #8 | Madera County, CA | Dec 2017 | 956.4k MCF |
| #9 | Santa Barbara County, CA | Dec 2017 | 1.3M MCF |
| #10 | Contra Costa County, CA | Dec 2017 | 256.2k MCF |
| #11 | Sacramento County, CA | Dec 2017 | 286.6k MCF |
| #12 | Glenn County, CA | Dec 2017 | 268.1k MCF |
| #13 | Ventura County, CA | Dec 2017 | 377k MCF |
| #14 | Orange County, CA | Dec 2017 | 102.9k MCF |
| #15 | Tehama County, CA | Dec 2017 | 64.9k MCF |
| #16 | Monterey County, CA | Dec 2017 | 78.8k MCF |
| #17 | San Luis Obispo County, CA | Dec 2017 | 45.8k MCF |
| #18 | Humboldt County, CA | Dec 2017 | 34.4k MCF |