| 901 | Oil Mountain Energy Inc | Casper, WY 82609 | Oil Operator | Jul 2026 |
| 902 | Oildigger Resources Fund L LLLP | Billings, MT 59101 | Oil & Gas Operator | Jul 2026 |
| 903 | Oilfield Consultants | | Oil & Gas Operator | Dec 1987 |
| 904 | Oilfield Salvage & Service Company | Littleton, CO 80120 | Oil & Gas Operator | Jun 2026 |
| 905 | Okie Crude Company | Tulsa, OK 74103 | Oil & Gas Operator | May 2026 |
| 906 | Oklahoma Oil Company | Dallas, TX 75206 | Oil & Gas Operator | Aug 2013 |
| 907 | Okmar Oil Company | Marietta, OH 45750 | Oil & Gas Operator | Jun 2005 |
| 908 | Okt Petroleum Company Inc | Oklahoma City, OK 73118-7425 | Oil & Gas Operator | Oct 2013 |
| 909 | Olds Oil Company | Casper, WY 82604 | Oil Operator | Jun 1988 |
| 910 | Olympic Exploration Inc | Denver, CO 80202 | Oil & Gas Operator | Jul 2004 |
| 911 | Omimex Petroleum Inc (Co) | Newcastle, WY 82701 | Oil & Gas Operator | May 2001 |
| 912 | Omimex Petroleum Inc (De) | Fort Worth, TX 76120 | Oil & Gas Operator | Aug 2020 |
| 913 | Omni Operating Company | Osage, WY 82723 | Oil & Gas Operator | Sep 2001 |
| 914 | Oneida Energy Corporation | Tulsa, OK 74137 | Oil & Gas Operator | Jul 2003 |
| 915 | Open Range Energy LLC | Jones, OK 73049-8744 | Oil & Gas Operator | Dec 2024 |
| 916 | Opes Production Inc | Buffalo, WY 82834 | Gas Operator | Mar 2015 |
| 917 | Orion Energy Partners LP | Denver, CO 80202 | Oil & Gas Operator | Nov 2010 |
| 918 | Oryx Energy Company | Dallas, TX 75221 | Oil & Gas Operator | May 2002 |
| 919 | Osage Hot Oil Service | Newcastle, WY 82701 | Oil & Gas Operator | Jul 1997 |
| 920 | Osage Operating Company LLC | Seattle, WA 98133 | Oil Operator | May 2006 |
| 921 | Osage Partners LLC | | Oil & Gas Operator | Jul 2026 |
| 922 | Osborn Heirs Company LTD | San Antonio, TX 78217 | Oil & Gas Operator | Apr 2026 |
| 923 | Ott Inc | Casper, WY 82602 | Oil Operator | Oct 2025 |
| 924 | Overland Resources LLC | Greenwood VIllage, CO 80111 | Oil & Gas Operator | Feb 2019 |
| 925 | Ovintiv USA Inc. | Denver, CO 80202 | Oil & Gas Operator | Sep 2026 |
| 926 | Oxbow Properties Inc | Centennial, CO 80122-1422 | Oil & Gas Operator | Jan 2025 |
| 927 | Oxford Exploration Company | Denver, CO 80237 | Oil & Gas Operator | Aug 1995 |
| 928 | Oxtex Inc | | Oil & Gas Operator | Oct 1989 |
| 929 | Oxy Petroleum Inc | | Oil & Gas Operator | Jan 1986 |
| 930 | Oxy USA Inc | Houston, TX 77046 | Oil & Gas Operator | Sep 2026 |
| 931 | P & M Petroleum Management LLC | Denver, CO 80202 | Oil & Gas Operator | Oct 2021 |
| 932 | P & P Producing Inc | Midland, TX 79702 | Oil & Gas Operator | Feb 2015 |
| 933 | P.O.&G. Operating, LLC | Houston, TX 77057 | Oil & Gas Operator | Sep 2026 |
| 934 | Pacific Enterprises Oil Co USA | Dallas, TX 75201 | Oil & Gas Operator | Feb 2001 |
| 935 | Pacific Transmission Supply | | Oil & Gas Operator | Dec 1987 |
| 936 | Pajaro Energy LLC | Santa Fe, NM 87501 | Oil & Gas Operator | Dec 2023 |
| 937 | Pal LLC | Gillette, WY 82718 | Oil Operator | Dec 2019 |
| 938 | Paladin Energy Partner LLC | Denver, CO 80201 | Oil & Gas Operator | Aug 2006 |
| 939 | Palo Petroleum, Inc. | Dallas, TX 75360 | Oil & Gas Operator | Sep 2026 |
| 940 | Pancanadian Petroleum Company | | Oil & Gas Operator | Oct 1989 |
| 941 | Panther Energy Company III LLC | Tulsa, OK 74136 | Oil & Gas Operator | Jul 2020 |
| 942 | Paoli Investors LTD | | Oil & Gas Operator | Aug 1985 |
| 943 | Par Oil Company Inc | Denver, CO 80201 | Oil & Gas Operator | Jun 2003 |
| 944 | Park Oil Properties LLC | Plano, TX 75025 | Oil Operator | Oct 2019 |
| 945 | Park Robert E | | Oil Operator | May 1983 |
| 946 | Parker & Parsley Producing LP | Midland, TX 79702 | Oil & Gas Operator | Oct 1997 |
| 947 | Pathfinder Energy Inc | Casper, WY 82605 | Oil & Gas Operator | May 2024 |
| 948 | Patina Oil & Gas Corporation | Denver, CO 80202 | Oil & Gas Operator | May 2016 |
| 949 | Patrick Petroleum Co. | Jackson, MI 49201 | Oil & Gas Operator | Nov 1993 |
| 950 | Patriot Energy Resources LLC | Golden, CO 80401 | Gas Operator | Aug 2014 |
| 951 | Patriot Production LLC | Southlake, TX 76092 | Oil & Gas Operator | Apr 2023 |
| 952 | PDS Resources LLC | | Oil & Gas Operator | May 2026 |
| 953 | Peabody Natural Gas LLC | Gillette, WY 82718 | Oil & Gas Operator | Jul 2026 |
| 954 | Peak Powder River Resources LLC | Durango, CO 81301 | Oil & Gas Operator | Jun 2026 |
| 955 | Peakview Oil Company LLC | Denver, CO 80202 | Gas Operator | Jul 2026 |
| 956 | Pearce Leonard | Manderson, WY 82432 | Oil Operator | Dec 1999 |
| 957 | Pearce Mary | | Oil Operator | Dec 1999 |
| 958 | Pearce Oil Company | Manderson, WY 82432 | Oil Operator | Jun 1999 |
| 959 | Pease Oil & Gas Company | Grand Junction, CO 81506 | Oil & Gas Operator | May 2000 |
| 960 | Pecos Development Corporation | San Antonio, TX 78209 | Oil Operator | Aug 1988 |
| 961 | Pedco Resources Company | Tulsa, OK 74170 | Oil & Gas Operator | Mar 2008 |
| 962 | Pedry J J | | Oil Operator | Sep 1989 |
| 963 | Pelican Dome Exploration | Harahan, LA 70123 | Oil & Gas Operator | Jun 1997 |
| 964 | Pendragon Energy Partners Inc | Midland, TX 79701 | Oil & Gas Operator | Nov 2009 |
| 965 | Pennaco Energy Incorporated | Gillette, WY 82718 | Oil & Gas Operator | Feb 2021 |
| 966 | Penneco Exploration Company Of Wyo LLC | Delmont, PA 15626 | Oil Operator | Aug 2021 |
| 967 | Pennzoil Company | Midland, TX 79710-0090 | Oil & Gas Operator | Mar 2000 |
| 968 | Petcon Associates LTD | Denver, CO 80202 | Oil & Gas Operator | Sep 2018 |
| 969 | Peters Walter J | | Oil & Gas Operator | Jul 1991 |
| 970 | Peterson Energy Management Inc | | Oil Operator | Aug 2010 |
| 971 | Peterson Energy Operating Inc | Loveland, CO 80537 | Oil & Gas Operator | Jul 2026 |
| 972 | Petra Petroleum Inc | Littleton, CO 80160-0319 | Oil & Gas Operator | Jun 2005 |
| 973 | Petral Exploration Inc LLC | Denver, CO 80217 | Oil & Gas Operator | May 2007 |
| 974 | Petro Energy Inc | Farmington, NM 87499 | Oil & Gas Operator | Sep 2025 |
| 975 | Petro Search Exploration Corp | | Oil & Gas Operator | May 1993 |
| 976 | Petro-Canada Resources (USA) Inc | Denver, CO 80202-472 | Oil & Gas Operator | Feb 2010 |
| 977 | Petro-Hunt Corporation | Dallas, TX 75201 | Oil & Gas Operator | Jun 2003 |
| 978 | Petro-Hunt, L.L.C. | Dallas, TX 75201 | Oil & Gas Operator | Sep 2026 |
| 979 | Petro-Lewis Corp. | | Oil & Gas Operator | Feb 1994 |
| 980 | Petrocarbon Energy Corporation | | Oil Operator | Sep 1996 |
| 981 | Petrocarbon Energy Trust | | Oil Operator | Sep 1996 |
| 982 | Petrocorp Incorporated | Tulsa, OK 74170 | Oil & Gas Operator | Nov 2021 |
| 983 | Petrogulf Corporation | Denver, CO 80202 | Oil & Gas Operator | Sep 2026 |
| 984 | Petrohawk Operating Company | Houston, TX 77056 | Oil & Gas Operator | Oct 2021 |
| 985 | Petrolero Corp. | San Antonio, TX 78205 | Oil & Gas Operator | Feb 1998 |
| 986 | Petroleum Corp Of Delaware The | | Oil & Gas Operator | May 1991 |
| 987 | Petroleum Inc | Wichita, KS 67202 | Oil & Gas Operator | Oct 2021 |
| 988 | Petroleum Management LLC | Platteville, CO 80651 | Oil & Gas Operator | Mar 2011 |
| 989 | Petroleum Products Inc | | Oil Operator | Jun 1996 |
| 990 | Petroleum Resource Management Corp | Denver, CO 80203 | Oil & Gas Operator | Jun 2026 |
| 991 | Petrorep Inc | | Oil Operator | Oct 1998 |
| 992 | Petrox Resources Inc | Meeker, CO 81641 | Oil & Gas Operator | Jul 2026 |
| 993 | PGC LLC | Newcastle, WY 92701 | Oil Operator | Oct 2023 |
| 994 | Phillips Petroleum Company | Houston, TX 77251 | Oil & Gas Operator | Mar 2013 |
| 995 | Phoenix Operating LLC | Denver, CO 80237 | Oil & Gas Operator | Jun 2026 |
| 996 | Phoenix Production Company | Cody, WY 82414-3607 | Oil & Gas Operator | Oct 2023 |
| 997 | Phoenix Resources Co | | Oil & Gas Operator | Jun 1984 |
| 998 | Pine Haven Resources LLC | Boulder, CO 80305 | Oil Operator | Jul 2026 |
| 999 | Pinedale Energy Partners Operating LLC | Tulsa, OK 74105 | Oil & Gas Operator | Apr 2021 |
| 1000 | Pinedale Investment Inc | Pinedale, WY 82941 | Oil & Gas Operator | Jul 2026 |