| Duncan "A" G-3-180840 | Hilcorp Energy Company only | Bonus, SW. (Wilcox) | Wharton | 1 | 426K | 7.35M | Jan 2001 – Apr 2026 |
| Duncan, F. B. G-3-233223 | Sandel Operating Company only | Cypress Eagle (Wilcox) | Wharton | 1 | 209K | 9.92M | Oct 2007 – Mar 2016 |
| Duncan "A" G-3-183527 | Hilcorp Energy Company only | Bonus, SW. (Wilcox) | Wharton | 1 | 185K | 2.42M | Feb 2001 – Apr 2026 |
| Gardner Duncan G-3-257155 | Sandel Operating Company only | Cypress Raven (Wilcox) | Wharton | 1 | 184K | 8.62M | Apr 2010 – Mar 2024 |
| Vastar-Duncan "A" G-3-163144 | Magnum Producing, LP only | Egypt (Cook MTN) | Wharton | 1 | 159K | 9.03M | May 1997 – Sep 2004 |
| Duncan, F. B. G-3-239837 | Sandel Operating Company only | Cypress Eagle (Wilcox) | Wharton | 1 | 154K | 9.08M | Jun 2008 – Jan 2026 |
| Duncan, F. B. G-3-236221 | Sandel Operating Company only | Cypress Eagle (Wilcox) | Wharton | 1 | 129K | 6.19M | Apr 2008 – Nov 2015 |
| Duncan G-3-167982 | Faulconer, Vernon E., Inc. only | Egypt, N. (Cook MTN RA) | Wharton | 1 | 125K | 6.61M | Mar 1998 – May 2013 |
| Vastar-Duncan "D" G-3-172021 | Faulconer, Vernon E., Inc. only | Egypt (Cook MTN) | Wharton | 1 | 118K | 10.4M | Jan 1999 – Apr 2016 |
| Duncan G-3-164835 | Faulconer, Vernon E., Inc. only | Egypt, N. (Cook Mtn.) | Wharton | 1 | 107K | 6.97M | Mar 1997 – Jul 2008 |
| Duncan, G. C. G-3-160307 | Magnum Producing, LP only | Egypt (First Wilcox) | Wharton | 1 | 63.4K | 1.94M | Sep 1996 – Oct 2018 |
| Duncan G-3-171657 | Sandel Operating Company only | Bernard, W. (7850) | Wharton | 1 | 50.8K | 7.45M | Dec 1998 – Jun 2023 |
| Santos-Lewis GU G-3-188995 | Atlas Operating LLC only | Duncan Slough (Frio Cons.) | Matagorda | 1 | 49K | 2.3M | Sep 2001 – Mar 2026 |
| Duncan, F. B. G-3-5248 | Proline Energy Resources Inc only | Bernard, W. (Clodine) | Wharton | 1 | 40.8K | 4.2M | Jan 1993 – Mar 2021 |
| Lewis, J. C. G-3-160251 | Atlas Operating LLC only | Duncan Slough (Frio Cons.) | Matagorda | 1 | 37.8K | 859K | Sep 1996 – Mar 2026 |
| Williams G-2-203882 | C & E Operating, Inc. only | George Duncan (Melbourne J-1, A) | Calhoun | 1 | 31.5K | 500K | Sep 2002 – Nov 2005 |
| Duncan G-3-183975 | XTO Energy Inc. only | Bonus, SW. (Wilcox) | Wharton | 1 | 31.3K | 511K | May 2001 – Nov 2005 |
| Henderson G-3-255474 | Duncan Oil, Inc. only | Echo (Hackberry) | Orange | 1 | 30K | 623K | Mar 2010 – Jun 2012 |
| Duncan Ranch "B" G-3-258907 | Milagro Exploration, LLC only | Hollywood, South (Frio 7900) | Matagorda | 1 | 29.8K | 1.54M | Nov 2010 – Feb 2013 |
| Runnells Gas Unit G-3-201102 | IV Standard, LLC only | Duncan Slough (Frio Cons.) | Matagorda | 1 | 29.7K | 4.72M | Nov 2003 – Apr 2026 |
| Pierce Est. Oil & Gas Ints. G-3-48189 | IV Standard, LLC only | Duncan Slough, S. (Frio, Lo.) | Matagorda | 1 | 26.8K | 1.92M | Sep 1993 – Apr 2026 |
| Lewis, J. C. "C" G-3-217099 | Atlas Operating LLC only | Duncan Slough (Frio Cons.) | Matagorda | 1 | 26.5K | 773K | Mar 2006 – Mar 2026 |
| Waddell "A" G-3-148472 | M & S Exploration only | Duncan, S. (Yegua 6500) | Wharton | 1 | 25.2K | 98.2K | Feb 1994 – Jun 2012 |
| Duncan G-3-168092 | Faulconer, Vernon E., Inc. only | Egypt, N. (Cook MTN RA) | Wharton | 1 | 24.6K | 1.27M | Dec 1997 – Nov 2011 |
| Allegro-Buckeye G-3-202774 | Gaither Petroleum Corporation only | Duncan Slough (Frio Cons.) | Matagorda | 1 | 22.4K | 1.1M | Feb 2004 – Nov 2014 |
| Lewis, J. C., -C- G-3-6039 | Expro Engineering, Inc. only | Duncan Slough (Frio-2) | Matagorda | 1 | 21.6K | 471K | Jan 1993 – Feb 2006 |
| Duncan "A" G-3-187053 | Hilcorp Energy Company only | Bonus, SW. (Wilcox) | Wharton | 1 | 21.6K | 638K | Sep 2001 – May 2013 |
| Duncan G-3-182405 | Dynamic Production, Inc. only | Dynamic (Wilcox 12,500) | Wharton | 1 | 20.5K | 993K | Feb 2001 – Apr 2026 |
| Vastar-Duncan "E" G-3-171201 | Walter Oil & Gas Corporation only | Egypt (7950) | Wharton | 1 | 19.7K | 2.58M | Oct 1998 – Apr 2001 |
| Duncan G-14-145131 | Makar Production Company only | MO-Tex (Meisner) | Wheeler | 1 | 19.4K | 2.45M | Mar 1993 – Apr 2026 |
| Duncan G-3-179138 | Dynamic Production, Inc. only | Dynamic (Yegua 7250) | Wharton | 1 | 17.4K | 390K | Nov 1999 – Aug 2002 |
| Buckeye Ranch Unit G-3-271146 | Tri-C Resources Partners I, LLC only | Duncan Slough (Frio Cons.) | Matagorda | 1 | 17.2K | 312K | Oct 2013 – Apr 2024 |
| Duncan, Ann G-3-145062 | Texana Operating Company only | Witter (Wilcox 9750) | Colorado | 1 | 16.8K | 1.7M | Mar 1993 – Apr 1999 |
| Duncan Ranch "A" G-3-244604 | Milagro Exploration, LLC only | Hollywood, South (Frio 7900) | Matagorda | 1 | 16.7K | 1.09M | Dec 2008 – Oct 2012 |
| Duncan G-14-165148 | Makar Production Company only | MO-Tex (Meisner) | Wheeler | 1 | 15.4K | 4.84M | Sep 1997 – Apr 2026 |
| Lewis, J. C. G-3-153266 | Expro Engineering, Inc. only | Duncan Slough (Frio-8) | Matagorda | 1 | 13.7K | 689K | Feb 1995 – Jul 2000 |
| Fisher-Duncan GU G-6-138228 | Craton Operating LLC only | Willow Springs (Cotton Valley) | Gregg | 1 | 12.9K | 1.01M | Jan 1993 – Apr 2026 |
| Steele, L. M. Trust G-3-130044 | Amrwr, LLC only | Duncan Slough, SW (Frio 7) | Matagorda | 1 | 12.7K | 3.08M | Jan 1993 – May 2011 |
| Bse - Duncan "A" G-3-187023 | Newfield Exploration Company only | Dynamic (Wilcox 15,150) | Wharton | 1 | 12K | 589K | Jan 2002 – Nov 2013 |
| Duncan G-14-161951 | Makar Production Company only | MO-Tex (Meisner) | Wheeler | 1 | 11.2K | 1.79M | Dec 1996 – Dec 2023 |
| Duncan, Donald B. G-3-197080 | Beard Oil Company, LLC only | Spanish Camp (Yegua 6800) | Wharton | 1 | 10.7K | 1.18M | Sep 2003 – Apr 2026 |
| Duncan, Jim et Al G-6-32049 | Samson Lone Star LP only | Pone (Pettit, Lo. -G-) | Rusk | 1 | 10.4K | 570K | Jan 1993 – May 2006 |
| Henke G-2-196832 | C & E Operating, Inc. only | George Duncan (Melbourne K-1) | Calhoun | 1 | 10.3K | 853K | May 2003 – Feb 2008 |
| Pierce Estates G-3-51155 | Bushmaster Production Comp, LLC only | Duncan Slough, SE. (Frio Lo.) | Matagorda | 1 | 10K | 696K | Jan 1993 – Mar 2026 |
| Santos-Lewis GU G-3-188108 | Gaither Petroleum Corporation only | Duncan Slough (Frio Cons.) | Matagorda | 1 | 9.83K | 249K | Feb 2002 – Sep 2005 |
| Wells G-3-168656 | Crimson Exploration Oper., Inc. only | Duncan (Wilcox) | Wharton | 1 | 7.98K | 1.32M | May 1998 – Sep 2004 |
| Duncan Gas Unit No. 1 G-5-205562 | Hilcorp Energy Company only | Bald Prairie (CV Consolidated) | Robertson | 1 | 7.97K | 1.68M | Oct 2004 – Apr 2026 |
| Lewis, J. C. G-3-214657 | Atlas Operating LLC only | Duncan Slough (Frio Cons.) | Matagorda | 1 | 7.19K | 166K | Nov 2005 – Mar 2026 |
| Duncan, Donald G-3-139926 | Bse Production Co. only | Spanish Camp (Yegua 6800) | Wharton | 1 | 6.81K | 1.02M | Jan 1993 – Dec 2018 |
| Fisher-Duncan GU G-6-140509 | Craton Operating LLC only | Willow Springs (Cotton Valley) | Gregg | 1 | 6.68K | 920K | Jan 1993 – Apr 2026 |