| 401 | Nomeco Oil & Gas Co. | Jackson, MI 49204 | Oil & Gas Operator | Dec 1994 |
| 402 | North Central Oil Corp | Houston, TX 77252 | Oil & Gas Operator | Dec 2005 |
| 403 | North Lake Resources LLC | Oklahoma City, OK 73132 | Oil & Gas Operator | May 2025 |
| 404 | Nueces Oil Company | George West, TX 78022 | Oil & Gas Operator | Mar 2008 |
| 405 | Ocean Energy, Inc. | Houston, TX 77002 | Oil & Gas Operator | Aug 2003 |
| 406 | Okla. Magic Circle Energy Corp. | Shawnee, OK 74801 | Oil & Gas Operator | Jul 2004 |
| 407 | Olipdp II, LLC | Lafayette, LA 70503 | Oil & Gas Operator | May 2025 |
| 408 | Omega Energy Corp. | Graham, TX 76450 | Oil & Gas Operator | May 2025 |
| 409 | Omega Energy, LLC | Corpus Chrsti, TX 78418 | Oil & Gas Operator | May 2025 |
| 410 | Origin Production Company, Inc. | New Braunfels, TX 78132 | Oil & Gas Operator | May 2025 |
| 411 | Origin Production Group LLC | Luling, TX 78648 | Oil Operator | May 2025 |
| 412 | Osborn Heirs Co | San Antonio, TX 78217 | Oil & Gas Operator | Mar 2025 |
| 413 | Osyka Oil & Gas, Inc. | Metairie, LA 70004 | Oil & Gas Operator | May 2025 |
| 414 | Outline Oil Corp. | San Antonio, TX 78217 | Oil & Gas Operator | May 2025 |
| 415 | Oxy USA Inc | Houston, TX 77046 | Oil & Gas Operator | May 2025 |
| 416 | P-R-O Management, Inc. | Dallas, TX 75240 | Oil & Gas Operator | May 2025 |
| 417 | Paleo Oil Company LLC | Corpus Chrsti, TX 78411 | Oil & Gas Operator | May 2025 |
| 418 | Paloma Operating, LLC | Corpus Chrsti, TX 78401 | Oil & Gas Operator | May 2025 |
| 419 | Paloma Resources, LLC | Houston, TX 77002 | Oil & Gas Operator | Jun 2018 |
| 420 | Par Producing Company | Snyder, TX 79550 | Oil & Gas Operator | Jun 2017 |
| 421 | Parker & Parsley Development Co. | Midland, TX 79702 | Oil & Gas Operator | May 1995 |
| 422 | Parker & Parsley Development L.P | Midland, TX 79702 | Oil & Gas Operator | Oct 2007 |
| 423 | Parker & Parsley Producing LP | Midland, TX 79702 | Oil & Gas Operator | Oct 1997 |
| 424 | Patrick Pet. Corp. Of Michigan | Houston, TX 77227 | Oil & Gas Operator | Aug 1995 |
| 425 | Patterson Energy Corporation | Dallas, TX 75205 | Oil & Gas Operator | May 2025 |
| 426 | Patterson Petroleum LLC | Snyder, TX 79550 | Oil & Gas Operator | Oct 2007 |
| 427 | Patterson Petroleum LP | Snyder, TX 79550 | Oil & Gas Operator | Mar 2008 |
| 428 | Patton Oil Corp. | Corpus Chrsti, TX 78466 | Oil & Gas Operator | Aug 2003 |
| 429 | Payne Producing Co. | Fredericksbrg, TX 78624 | Oil & Gas Operator | Jun 2008 |
| 430 | Payne, B.R. Oil & Gas, Inc. | Corpus Chrsti, TX 78411 | Oil & Gas Operator | Feb 2006 |
| 431 | Peach Creek Operating Co, LLC | Houston, TX 77007 | Oil & Gas Operator | May 2025 |
| 432 | Pearl, Bill H. Productions, Inc. | Corpus Chrsti, TX 78460 | Oil & Gas Operator | May 2025 |
| 433 | Pedco Resources Company | Tulsa, OK 74170 | Oil & Gas Operator | Mar 2008 |
| 434 | Penn VIrginia Oil & Gas Corp | Houston, TX 77024 | Oil & Gas Operator | Dec 2023 |
| 435 | Penn VIrginia Oil & Gas, L.P. | Houston, TX 77084 | Oil & Gas Operator | Nov 2022 |
| 436 | Penroc Oil Corp. | Hobbs, NM 88241 | Oil & Gas Operator | Feb 2025 |
| 437 | Petro-Chem Operating Company, Inc. | Shreveport, LA 71101 | Oil & Gas Operator | May 2025 |
| 438 | Petrocorp Incorporated,A TX.Corp | Tulsa, OK 74170 | Oil & Gas Operator | Apr 2005 |
| 439 | Petrohawk Operating Company | Houston, TX 77056 | Oil & Gas Operator | Oct 2021 |
| 440 | Petrolero Corp. | San Antonio, TX 78205 | Oil & Gas Operator | Feb 1998 |
| 441 | Petroleum Management, Inc. | Corpus Chrsti, TX 78471 | Oil & Gas Operator | May 2025 |
| 442 | Phillips Petroleum Company | Houston, TX 77251 | Oil & Gas Operator | Mar 2013 |
| 443 | Pi Energy, Inc. | Wichita Falls, TX 76301 | Oil & Gas Operator | May 2025 |
| 444 | Pickett, D. W. | Corpus Chrsti, TX 78403 | Oil & Gas Operator | Sep 2004 |
| 445 | Pintex Operating Inc. | Corpus Chrsti, TX 78478 | Oil & Gas Operator | Feb 2005 |
| 446 | Pioneer Natural Res. USA, Inc. | Irving, TX 75038 | Oil & Gas Operator | May 2025 |
| 447 | Pioneer Resources Producing, L.P | Irving, TX 75039 | Oil & Gas Operator | Feb 2001 |
| 448 | Pipeline Management, Inc. | Lubbock, TX 79401 | Oil & Gas Operator | Dec 2002 |
| 449 | Plains Exploration & Prod. Co. | Houston, TX 77002 | Oil & Gas Operator | Jul 2013 |
| 450 | Plains Resources Inc. | Houston, TX 77002 | Oil & Gas Operator | Jul 2008 |
| 451 | Pmi Energy Co. | Corpus Chrsti, TX 78471 | Oil & Gas Operator | Aug 2002 |
| 452 | Pogo Producing Company | Houston, TX 77002 | Oil & Gas Operator | Jan 2008 |
| 453 | Pogo Producing Company LLC | Houston, TX 77002 | Oil & Gas Operator | Mar 2025 |
| 454 | Prevail Energy, Inc | Corpus Chrsti, TX 78469 | Oil & Gas Operator | May 2025 |
| 455 | Pride Energy Company | Tulsa, OK 74170 | Oil & Gas Operator | May 2025 |
| 456 | Prize Operating Company | Grapevine, TX 76051 | Oil & Gas Operator | Aug 2016 |
| 457 | Professional Management GRP,Inc. | Boerne, TX 78006 | Oil & Gas Operator | Aug 1999 |
| 458 | Progas Properties, Inc. | New Braunfels, TX 78132 | Oil & Gas Operator | May 2025 |
| 459 | Proline Energy Resources Inc | Sugar Land, TX 77479 | Oil & Gas Operator | May 2025 |
| 460 | QNK Energy,Inc. | Alice, TX 78333 | Oil & Gas Operator | Aug 2016 |
| 461 | Quantum Resources Management LLC | Houston, TX 77010 | Oil & Gas Operator | Feb 2025 |
| 462 | Quintana Pet. Corp. | Refugio, TX 78377 | Oil & Gas Operator | Dec 2000 |
| 463 | Quorum Energy Company | Dallas, TX 75201 | Oil & Gas Operator | May 2025 |
| 464 | R & B Oil Company, LLC | Willis, TX 77318 | Oil & Gas Operator | May 2025 |
| 465 | Ram Operating Inc. | Browns, IL 62818 | Oil & Gas Operator | Aug 2008 |
| 466 | Ramsower Minerals Corporation | Beeville, TX 78104 | Oil & Gas Operator | Sep 2013 |
| 467 | Reavis, Tommy | San Antonio, TX 78227 | Gas Operator | May 2025 |
| 468 | Redding, Bobby L. | Three Rivers, TX 78071 | Oil & Gas Operator | Mar 2004 |
| 469 | Redstone Oil & Gas Company | Dallas, TX 75225 | Oil & Gas Operator | Jan 2020 |
| 470 | Reef Exploration, L.P. | Richardson, TX 75080 | Oil & Gas Operator | May 2025 |
| 471 | Rego Development Company, Inc. | Corpus Chrsti, TX 78401 | Oil & Gas Operator | Apr 2002 |
| 472 | Reh Energy, Inc. | Corpus Chrsti, TX 78413 | Oil & Gas Operator | May 2025 |
| 473 | Remora Operating LLC | Houston, TX 77056 | Oil & Gas Operator | May 2025 |
| 474 | Repsol Oil & Gas USA, LLC | The Woodlands, TX 77381 | Oil & Gas Operator | May 2025 |
| 475 | Republic Resources, LLC. | San Antonio, TX 78212 | Oil & Gas Operator | May 2025 |
| 476 | Richard C. Bellows Family Trust | George West, TX 78022 | Oil Operator | May 2025 |
| 477 | Richman Petroleum Corp. | Grapevine, TX 76051 | Oil & Gas Operator | Jul 2006 |
| 478 | Richter Operating Company | San Antonio, TX 78217 | Oil & Gas Operator | Dec 2007 |
| 479 | Riddle Engineering Corp. | Corpus Chrsti, TX 78401 | Oil & Gas Operator | Jul 2011 |
| 480 | Riley Exploration, LLC | Blanchard, OK 73010 | Oil & Gas Operator | May 2025 |
| 481 | Rincon Petroleum Corporation | Corpus Chrsti, TX 78427 | Oil & Gas Operator | May 2025 |
| 482 | Rio Bravo Royalty Co. | Bandera, TX 78003 | Oil & Gas Operator | Aug 2003 |
| 483 | Rio Exploration Company | San Antonio, TX 78209 | Gas Operator | Dec 2005 |
| 484 | Rio-Tex, Inc. | San Antonio, TX 78217 | Oil & Gas Operator | May 2025 |
| 485 | Rocanville Corporation | Dallas, TX 75225 | Oil & Gas Operator | Dec 2016 |
| 486 | Rodessa Operating Company | Corpus Chrsti, TX 78426 | Oil & Gas Operator | May 2025 |
| 487 | Roma Oil And Gas, Inc. | San Antonio, TX 78209 | Oil & Gas Operator | May 2025 |
| 488 | Rosetta Resources Operating LP | San Antonio, TX 78216 | Oil & Gas Operator | May 2025 |
| 489 | Rosewood Resources, Inc. | Dallas, TX 75201 | Oil & Gas Operator | May 2025 |
| 490 | Royal Production Company, Inc. | Corpus Chrsti, TX 78401 | Oil & Gas Operator | May 2025 |
| 491 | Royko Oil Company | Horseshoe Bay, TX 78657 | Oil & Gas Operator | May 2025 |
| 492 | RR Ventures Limited Partnership | San Antonio, TX 78239 | Oil & Gas Operator | May 2025 |
| 493 | Rse, Inc. | Houston, TX 77077 | Oil & Gas Operator | Sep 2000 |
| 494 | Rutherford Oil Corporation | Houston, TX 77046 | Oil & Gas Operator | Jun 2019 |
| 495 | Sage Energy Company | San Antonio, TX 78215 | Oil & Gas Operator | May 2025 |
| 496 | Sagebrush Operating LLC | Denver, CO 80203 | Oil & Gas Operator | Dec 2024 |
| 497 | Salt Creek Production, Inc. | Big Spring, TX 79721 | Oil & Gas Operator | May 2025 |
| 498 | Samson Hydrocarbons Company | Tulsa, OK 74103 | Oil & Gas Operator | Nov 2016 |
| 499 | Samson Lone Star LP | Tulsa, OK 74103 | Oil & Gas Operator | Jun 2007 |
| 500 | Samson Lone Star, LLC | Tulsa, OK 74103 | Oil & Gas Operator | May 2025 |