| Nietsche-Sylvester Unit O-3-21756 | Union Pacific Resources Company only | Giddings (Austin Chalk-3) | Fayette | 1 | 35.7K | 69.4K | by Jan 1993 – Jan 1999 |
| Cordova Union -A- O-9-897 | Helmerich & Payne, Inc. only | McCamey | Upton | 3 | 34.4K | 18 | by Jan 1993 – Jul 1999 |
| Gilbert, H. C. 43 O-5-3275 | Union Oil Company of California only | Van (Austin Chalk) | Van Zandt | 7 | 34.3K | 138K | by Jan 1993 – Jul 2008 |
| Heath G-5-139694 | Old Union Operating Company only | Winkler, S.(cotton Valley Lime) | Freestone | 1 | 34K | 4.51M | by Jan 1993 – Aug 2026 |
| Union Ranch G-4-186078 | Mountain V Texas, LLC only | Tiffany (Wilcox Carrizo) | Webb | 1 | 33.4K | 5.2M | Nov 2001 – Aug 2026 |
| Fowler, B. M. 303 O-5-3216 | Union Oil Company of California only | Van (Austin Chalk) | Van Zandt | 2 | 33.4K | 65.8K | by Jan 1993 – Nov 2009 |
| Lenz Unit O-3-21475 | Union Pacific Resources Company only | Giddings (Austin Chalk-3) | Brazos | 1 | 33.1K | 270K | by Jan 1993 – Aug 1999 |
| Gruene, O. A. O-4-10871 | Union Pacific Resources Company only | Stratton (G-15-5) | Nueces | 1 | 32.7K | 27.9K | by Jan 1993 – Oct 1996 |
| Leonard, J. H. 30 O-5-1885 | Union Oil Company of California only | Van (Austin Chalk) | Van Zandt | 2 | 32.3K | 102K | by Jan 1993 – Jan 2013 |
| Parker, J. E. -N- O-10-32364 | Union Oil Company of California only | Parker (Pennsylvanian) | Andrews | 1 | 32K | 37.2K | by Jan 1993 – Aug 1994 |
| Arco Fee Unit A-15 G-6-163658 | Union Pacific Resources Company only | Brookeland (Austin Chalk, 8800) | Jasper | 1 | 31.5K | 1.34M | Mar 1997 – Jul 1999 |
| Howell, R. A. 44 O-5-3294 | Union Oil Company of California only | Van (Austin Chalk) | Van Zandt | 4 | 31.4K | 152K | by Jan 1993 – Mar 2010 |
| BP Fee A-6 G-3-212203 | Union Gas Operating Company only | Buna, West (Wilcox) | Jasper | 1 | 31K | 405K | Jun 2005 – Nov 2009 |
| Zgabay, Edwin "C" O-3-15923 | Union Pacific Resources Company only | Giddings (Austin Chalk-3) | Burleson | 1 | 30.8K | 251K | by Jan 1993 – Aug 1998 |
| Parker, J. E. O-10-248 | Union Oil Company of California only | Andrews (Pennsylvanian) | Andrews | 2 | 30.2K | 47.3K | Nov 1994 – Sep 1995 |
| Cordova Union -E- O-10-1627 | Avra Oil Company only | Fromme | Pecos | 9 | 29.9K | 94.1K | by Jan 1993 – Feb 2025 |
| Freeman, L. V. 208 O-5-1167 | Union Oil Company of California only | Van | Van Zandt | 5 | 29.6K | 7.31K | by Jan 1993 – Oct 2013 |
| Runion O-9-14852 | Dallas Production, Inc. only | Runion (Strawn) | Tom Green | 1 | 29.5K | 38.6K | Jan 1999 – Jun 2001 |
| Union Cent. -B- O-4-12872 | Sarita Energy Resources, Ltd. only | Stratton (Consolidated) | Nueces | 1 | 29.1K | 6.9K | Nov 1999 – Aug 2026 |
| State Tract 563-L O-2-7335 | Tri-Union Development Corp. only | Matagorda Block 563-L (6820) | Matgrda IS-LB | 1 | 28.8K | 48.3K | by Jan 1993 – May 1999 |
| Craddock O-10-34402 | Union Oil Company of California only | Andrews (Pennsylvanian) | Andrews | 2 | 28.8K | 48.8K | Jan 1995 – Sep 1995 |
| Bush-Bush Unit O-3-21684 | Union Pacific Resources Company only | Giddings (Austin Chalk-3) | Burleson | 1 | 28.7K | 201K | by Jan 1993 – Mar 2000 |
| Williams, Henry Gas Unit G-5-141886 | Old Union Operating Company only | Teas (Cotton Valley) | Freestone | 1 | 28.6K | 1.3M | by Jan 1993 – Aug 2026 |
| Stetz-Rancho Grande Unit O-3-21986 | Union Pacific Resources Company only | Giddings (Austin Chalk-3) | Brazos | 1 | 28.3K | 187K | Mar 1993 – Nov 1999 |
| Powderhorn Co. O-2-2420 | Tri-Union Development Corp. only | Powderhorn (4 Sand) | Calhoun | 1 | 28.3K | 35K | by Jan 1993 – May 1999 |
| Cermorleb-Harbers Unit O-3-21670 | Union Pacific Resources Company only | Giddings (Austin Chalk-3) | Fayette | 1 | 28K | 205K | by Jan 1993 – Apr 1994 |
| Parker, J. E. -AA- O-10-30495 | Union Oil Company of California only | Andrews (Pennsylvanian) | Andrews | 1 | 27.9K | 38.8K | by Jan 1993 – Sep 1995 |
| Logsdon, Etal -D- O-10-13343 | Texland/JMC Joint Venture only | Union | Andrews | 5 | 27.4K | 33.4K | by Jan 1993 – May 1995 |
| Parker, J. E. -AB- O-10-31511 | Union Oil Company of California only | Parker (Wolfcamp) | Andrews | 3 | 26.9K | 47.6K | by Jan 1993 – Aug 1994 |
| State of Texas AG O-10-33954 | Union Oil Company of California only | Andrews (Pennsylvanian) | Andrews | 1 | 26.8K | 23.5K | Aug 1993 – Sep 1995 |
| Oliver, J. R., 207 O-5-1927 | Union Oil Company of California only | Van (Shallow) | Van Zandt | 2 | 25.9K | 15.1K | by Jan 1993 – May 2012 |
| W.R.B. O-11-67383 | Union Pacific Resources Company only | Pancho-Mag, SW. (Canyon Reef) | Borden | 1 | 25.8K | 5.64K | Mar 1995 – Dec 1996 |
| Cook 42 O-5-3245 | Union Oil Company of California only | Van (Austin Chalk) | Van Zandt | 4 | 25.3K | 54.5K | by Jan 1993 – May 2008 |
| Texaco "C" O-6-12999 | Union Pacific Resources Company only | Brookeland (Austin Chalk, 8800) | Newton | 2 | 25.2K | 316K | by Jan 1993 – Mar 1995 |
| Zgabay, Delbert O-3-13119 | Union Pacific Resources Company only | Giddings (Austin Chalk-3) | Burleson | 2 | 25.2K | 263K | by Jan 1993 – Feb 1996 |
| Swain, W. F. 9 O-5-3597 | Union Oil Company of California only | Van (Upper Carlile) | Van Zandt | 2 | 25.1K | 40.8K | Oct 1997 – Jan 2000 |
| Howell-Anderson G-5-141212 | Old Union Operating Company only | Winkler, S.(cotton Valley Lime) | Freestone | 1 | 24.9K | 2.21M | by Jan 1993 – Jun 2026 |
| Anderson Gas Unit G-5-46571 | Old Union Operating Company only | Reka (Cotton Valley Lime) | Navarro | 1 | 24.8K | 805K | by Jan 1993 – Jun 2026 |
| Carroll-Beiring Unit O-3-21156 | Union Pacific Resources Company only | Giddings (Austin Chalk-3) | Brazos | 1 | 24.5K | 114K | by Jan 1993 – Sep 1996 |
| Parker, J. E. -F- O-10-18670 | Union Oil Company of California only | Andrews (Pennsylvanian) | Andrews | 2 | 24.5K | 18.8K | Jul 1993 – Sep 1995 |
| Salpetro-Penicka Unit O-3-22421 | Union Pacific Resources Company only | Giddings (Buda) | Brazos | 1 | 24.4K | 37.8K | May 1994 – Apr 1996 |
| York, W. A. 13 O-5-3805 | Union Oil Company of California only | Van (Shallow) | Van Zandt | 2 | 24.3K | 18.1K | Apr 2005 – Sep 2015 |
| Brawner -10- O-5-3271 | Union Oil Company of California only | Van (Austin Chalk) | Van Zandt | 3 | 24.3K | 92.2K | by Jan 1993 – Sep 2013 |
| Union Pacific O-9-15342 | Scout Energy Management LLC only | Ozona (Clear Fork) | Crockett | 4 | 24.3K | 234K | Oct 2002 – Aug 2026 |
| Mills-McGee Trust Unit O-3-23514 | Union Pacific Resources Company only | Giddings (Buda) | Milam | 1 | 24.3K | 48.3K | Mar 1998 – Dec 1998 |
| Knox, J. et Al O-3-11828 | Union Pacific Resources Company only | Giddings (Austin Chalk-3) | Lee | 1 | 24.2K | 280K | by Jan 1993 – Oct 1996 |
| Camper, B. W. 110 O-5-3327 | Union Oil Company of California only | Van (Austin Chalk) | Van Zandt | 1 | 24.1K | 12.2K | by Jan 1993 – Dec 2007 |
| Union Ranch-Moreno GU G-4-192640 | Mountain V Texas, LLC only | Tiffany (Wilcox Carrizo) | Webb | 1 | 23.9K | 4.03M | Dec 2002 – Aug 2026 |
| Luedecke-Davros Unit O-3-22451 | Union Pacific Resources Company only | Giddings (Buda) | Brazos | 1 | 23.9K | 62.4K | Jan 1994 – Oct 1994 |
| Moss, Edward O-3-21800 | Union Pacific Resources Company only | Giddings (Austin Chalk-3) | Fayette | 1 | 23.7K | 49.5K | by Jan 1993 – Mar 1999 |