| 1 | L & J Oil Co. | Borger, TX 79007 | Oil & Gas Operator | Apr 1999 |
| 2 | L & N Co. | | Oil Operator | Jul 1991 |
| 3 | L & S Service Corp. | | Oil Operator | Jul 1989 |
| 4 | L And L Production Company | Skellytown, TX 79080 | Oil & Gas Operator | Sep 1996 |
| 5 | L'Oil Operating And MGMT. Co. | | Oil & Gas Operator | Dec 2008 |
| 6 | L. C. Geer & Associates | | Oil & Gas Operator | Jan 1987 |
| 7 | L. R. Fitzgerald | | Oil & Gas Operator | Feb 2015 |
| 8 | La. Land & Expl. Co. | | Oil & Gas Operator | Dec 2010 |
| 9 | La.-TX. Operating, Inc. | | Oil & Gas Operator | May 1998 |
| 10 | Lacour & Nix | | Oil & Gas Operator | May 1986 |
| 11 | Lamar Matlock | | Oil Operator | Jan 2025 |
| 12 | Lance Gas & Oil Productions | | Oil & Gas Operator | Jan 2025 |
| 13 | Landmark Venture Group No. 1, Inc. | | Oil & Gas Operator | Jan 2025 |
| 14 | Landmark Venture Group, Inc. | | Oil Operator | Dec 2008 |
| 15 | Lanford Drilling Co., Inc. | | Oil Operator | Jun 1996 |
| 16 | Lanmarc Resources | | Oil Operator | Dec 2003 |
| 17 | Largo Oil Company | Longview, TX 75606 | Oil & Gas Operator | Feb 2026 |
| 18 | Lark Production, Inc. | | Oil & Gas Operator | Mar 2023 |
| 19 | Las Services, Inc. | | Oil & Gas Operator | Oct 1997 |
| 20 | Latex Petroleum Corp. | Houston, TX 77090 | Oil & Gas Operator | Aug 2012 |
| 21 | Latexo Oil & Gas Co. | | Oil Operator | Sep 1986 |
| 22 | Latham & Bonner | | Oil Operator | Aug 1987 |
| 23 | Latham Exploration Company Inc | | Oil & Gas Operator | Aug 1992 |
| 24 | Latham Production & Service Co | | Oil Operator | Jul 1989 |
| 25 | Lax, Inc. | | Oil & Gas Operator | Nov 1987 |
| 26 | Legacy Resources Co., L.P. | | Oil & Gas Operator | Apr 2019 |
| 27 | Legend Fund, LLC | | Oil & Gas Operator | Jan 2025 |
| 28 | Leshen Energy USA LLC | | Oil Operator | Jan 2025 |
| 29 | Lewis & Manziel | | Oil Operator | Apr 1989 |
| 30 | Li'L Sugar Oil Company | | Oil Operator | Nov 2019 |
| 31 | Liberty Oil & Gas Corp | Olney, IL 62450-2489 | Oil & Gas Operator | Dec 2021 |
| 32 | Limited Resources | Perryton, TX 79070 | Oil & Gas Operator | Aug 2003 |
| 33 | LL&N Oil & Gas Co., Inc. | | Oil Operator | Sep 1982 |
| 34 | Lloyd E. Hargrove | | Oil & Gas Operator | Aug 1998 |
| 35 | Lloyd M McKenzie | | Oil Operator | Mar 2001 |
| 36 | Long Bros. Oil Co. | | Oil Operator | Jul 2015 |
| 37 | Long Oil & Natural Gas Corp. | | Oil & Gas Operator | Feb 1996 |
| 38 | Louis J. Roussel | | Oil & Gas Operator | Sep 1991 |
| 39 | Louisiana Energy Consultants, Inc. | | Oil & Gas Operator | Dec 2024 |
| 40 | Louisiana Energy Investors, L.L.C. | | Oil & Gas Operator | Jun 2016 |
| 41 | Louisiana Operating Co., Inc. | | Oil & Gas Operator | Aug 1994 |
| 42 | Louisiana-Caddo Invest, Inc. | | Oil & Gas Operator | Jun 2008 |
| 43 | Loutex Production Company | Kilgore, TX 75663 | Oil & Gas Operator | Feb 2026 |
| 44 | Lucky Strike Production LLC | | Oil Operator | Dec 2024 |
| 45 | Luray Oil Co., L.L.C. | | Oil Operator | Jan 2025 |
| 46 | Luther W. Davis | | Oil & Gas Operator | Jun 1996 |
| 47 | Lwood Energy, Inc. | | Oil Operator | Dec 2002 |
| 48 | Lyons Petroleum, Inc. | | Oil & Gas Operator | Oct 1988 |
| 49 | Lyons, Hilliard & Watson, Inc. | | Oil & Gas Operator | Jan 1989 |