| Bukowski-Bienski Unit O-3-21384 | Union Pacific Resources Company only | Giddings (Austin Chalk-3) | Brazos | 1 | 57.5K | 262K | by Jan 1993 – Jun 2000 |
| Scott-Ruesink Unit O-3-21182 | Union Pacific Resources Company only | Kurten (Buda) | Brazos | 1 | 56.6K | 57.7K | by Jan 1993 – Aug 1997 |
| Parker, J. E. "Z" O-10-34274 | Union Oil Company of California only | Andrews (Pennsylvanian) | Andrews | 2 | 56.5K | 43.3K | Sep 1994 – Sep 1995 |
| Lineberry -D- O-10-14034 | Escondido Bay Corporation only | Union | Andrews | 3 | 55.2K | 270 | by Jan 1993 – Aug 2026 |
| Gilbert, H. C. 43 O-5-3706 | Union Oil Company of California only | Van (Pecan Gap) | Van Zandt | 7 | 54.2K | 64K | Oct 2000 – Jul 2008 |
| University-Union "17" O-9-9900 | Last Dollar LLC only | Farmer (San Andres) | Reagan | 8 | 54K | 76.9K | by Jan 1993 – Aug 2026 |
| Parker, J. E. -G- O-10-34687 | Union Oil Company of California only | Andrews (Wolfcamp-Penn.) | Andrews | 2 | 53.6K | 63.5K | Oct 1995 – Nov 1997 |
| Hobbs Unit O-6-13489 | Union Pacific Resources Company only | Brookeland (Austin Chalk, 8800) | Newton | 1 | 53.5K | 366K | Nov 1995 – Jan 1997 |
| Oliver F. Goen Unit O-3-21675 | Union Pacific Resources Company only | Giddings (Austin Chalk-3) | Brazos | 1 | 53.3K | 359K | by Jan 1993 – Jul 1998 |
| Union Ranch-Lopez G-4-226329 | Mountain V Texas, LLC only | Tiffany (Wilcox Carrizo) | Webb | 1 | 52.4K | 3.21M | Feb 2007 – Aug 2026 |
| Parker, J. E. -P- O-10-31582 | Union Oil Company of California only | Parker (Pennsylvanian) | Andrews | 2 | 52.3K | 53.5K | by Jan 1993 – Aug 1994 |
| State Tract 563-L G-2-114520 | Reunion Energy Company only | Matagorda Block 563-L (6517) | Matgrda IS-LB | 1 | 52.3K | 127K | by Jan 1993 – Apr 1994 |
| Logsdon, C. W. -A- O-10-13651 | Unitex Oil & Gas, L.L.C. only | Union | Andrews | 2 | 52.1K | 264K | by Jan 1993 – Aug 2026 |
| Logsdon, C. W. O-10-13039 | Lime Rock Resources II-a, L.P. only | Union | Andrews | 3 | 51.5K | 144K | by Jan 1993 – Aug 2013 |
| Wardner O-4-11428 | Union Pacific Resources Company only | Stratton (F-39-11) | Nueces | 4 | 51K | 255K | by Jan 1993 – Oct 1996 |
| Brock, J. D. -A- O-4-3493 | Southern Tejas Asset Group LLC only | La Union (Brock Sand) | Starr | 3 | 50.9K | 128 | by Jan 1993 – Jun 2026 |
| RK-Union O-10-26328 | Diamondback E&P LLC only | Spraberry (Trend Area) | Martin | 1 | 50.3K | 63K | by Jan 1993 – Jul 2021 |
| Vandenberge & Hill O-2-7757 | Tri-Union Development Corp. only | Placedo, East (5730) | Victoria | 3 | 49.7K | 54.5K | by Jan 1993 – Mar 1999 |
| Dees-OL Unit O-3-22265 | Union Pacific Resources Company only | Giddings (Austin Chalk-3) | Lee | 1 | 48.8K | 57.3K | Jul 1993 – Oct 1998 |
| Union "A" O-11-66170 | Active Iron Energy, LLC only | Old Colony (L. Clearfork) | Andrews | 1 | 48.1K | 119K | by Jan 1993 – May 2026 |
| State Tract 563 O-2-7970 | Tri-Union Development Corp. only | Matagorda Block 563-L (6517) | Matgrda IS-LB | 1 | 47.7K | 45.3K | May 1994 – Sep 1999 |
| Burton-Wells Unit O-3-23513 | Union Pacific Resources Company only | Giddings (Buda) | Milam | 1 | 47.3K | 21.2K | Feb 1998 – Dec 1998 |
| Swain, O. L. 11 O-5-1891 | Union Oil Company of California only | Van (Austin Chalk) | Van Zandt | 2 | 47K | 67.2K | by Jan 1993 – Jun 2015 |
| BP Burrill A-5 O-3-24970 | Union Gas Operating Company only | Snark (Wilcox "C") | Hardin | 1 | 44.7K | 188K | Jul 2006 – Dec 2018 |
| Sadberry-Foyt Unit O-3-23508 | Union Pacific Resources Company only | Giddings (Buda) | Robertson | 1 | 43.5K | 24.2K | Feb 1998 – Dec 1998 |
| Horned Frog O-3-20900 | Union Pacific Resources Company only | Kurten (Buda) | Brazos | 2 | 43.5K | 95.9K | by Jan 1993 – Apr 1996 |
| Arco-Vastar Unit A-172A O-6-13211 | Union Pacific Resources Company only | Brookeland (Austin Chalk, 8800) | Newton | 1 | 43K | 218K | Aug 1993 – Feb 1995 |
| Woodyard-Cargill Unit O-3-22284 | Union Pacific Resources Company only | Giddings (Austin Chalk-3) | Brazos | 1 | 43K | 104K | Oct 1993 – Dec 1995 |
| White 502 O-5-3246 | Union Oil Company of California only | Van (Austin Chalk) | Van Zandt | 2 | 42.8K | 112K | by Jan 1993 – Jan 2004 |
| Union O-11-65494 | Active Iron Energy, LLC only | Old Colony (L. Clearfork) | Gaines | 1 | 42.5K | 102K | by Jan 1993 – Aug 2026 |
| Deford Unit O-10-11321 | Union Oil Company of California only | Andrews (Wolfcamp) | Andrews | 4 | 42.5K | 69.1K | by Jan 1993 – Sep 1995 |
| Jones-Jones Unit O-3-21524 | Union Pacific Resources Company only | Giddings (Austin Chalk-3) | Brazos | 1 | 42.4K | 259K | by Jan 1993 – Feb 1998 |
| Brock, J. D. -A- O-4-3494 | Southern Tejas Asset Group LLC only | La Union (Ross Sand) | Starr | 2 | 42.3K | 128 | by Jan 1993 – Jun 2026 |
| Arco Fee A-249 O-6-13377 | Union Pacific Resources Company only | Brookeland (Austin Chalk, 8800) | Jasper | 1 | 41.1K | 560K | Sep 1994 – Sep 1996 |
| Crim, J. F. 16 O-5-3611 | Union Oil Company of California only | Van (Rodessa) | Van Zandt | 1 | 41.1K | 161K | Feb 1998 – Jun 2009 |
| Parker, J. E. -D- O-10-284 | Union Oil Company of California only | Andrews (Wolfcamp) | Andrews | 2 | 40.8K | 31.7K | by Jan 1993 – Sep 1995 |
| Weedon-Weedon "B" Unit O-3-21918 | Union Pacific Resources Company only | Giddings (Austin Chalk-3) | Brazos | 1 | 40.2K | 160K | by Jan 1993 – Dec 1996 |
| Parker, J. E. -E- O-10-267 | Union Oil Company of California only | Andrews (Wolfcamp) | Andrews | 4 | 39.8K | 29.3K | by Jan 1993 – Sep 1995 |
| McCrary Unit G-3-156476 | Union Pacific Resources Company only | Giddings (Austin Chalk, Gas) | Grimes | 1 | 39.1K | 356K | Oct 1995 – Aug 1999 |
| Parker, Bessie O. O-10-33925 | Union Oil Company of California only | Parker (Wolfcamp) | Andrews | 1 | 38.8K | 39.3K | Aug 1993 – Aug 1994 |
| Parker, J. E. O-10-34688 | Union Oil Company of California only | Andrews (Wolfcamp-Penn.) | Andrews | 2 | 38.7K | 47.8K | Oct 1995 – Nov 1997 |
| Arco-Vastar Unit A-172 O-6-13031 | Union Pacific Resources Company only | Brookeland (Austin Chalk, 8800) | Newton | 1 | 38.7K | 262K | by Jan 1993 – Jun 1997 |
| Linebery, Evelyn, Etal -15- O-10-11711 | Texland Petroleum, L.P. only | Union | Andrews | 3 | 38.2K | 9.55K | by Jan 1993 – Jun 1996 |
| Samelson-Dunze Unit O-3-21687 | Union Pacific Resources Company only | Giddings (Austin Chalk-3) | Fayette | 1 | 38K | 50.8K | by Jan 1993 – Jan 1998 |
| Temple Industries O-6-13088 | Union Pacific Resources Company only | Brookeland (Austin Chalk, 8800) | Jasper | 1 | 37.9K | 149K | by Jan 1993 – Apr 1995 |
| Svruc Unit G-5-218074 | Union Oil Company of California only | Van (Rodessa) | Van Zandt | 1 | 37.7K | 372K | Apr 2006 – Jan 2020 |
| Sengelmann-Teinert O-3-21351 | Union Pacific Resources Company only | Giddings (Austin Chalk-3) | Fayette | 1 | 37.2K | 74.5K | by Jan 1993 – Feb 1998 |
| Yelderman-Bredthauer Unit G-3-142127 | Union Pacific Resources Company only | Giddings (Austin Chalk, Gas) | Washington | 1 | 36.7K | 707K | by Jan 1993 – Sep 2000 |
| Montrose O-11-67455 | Union Oil Company of California only | Blackwatch (San Andres) | Gaines | 2 | 36.2K | 20.6K | Oct 1995 – Sep 1997 |
| Warrenton Amarado Unit G-3-147182 | Union Pacific Resources Company only | Giddings (Austin Chalk, Gas) | Fayette | 1 | 36.2K | 1.04M | Oct 1993 – Oct 1996 |