# Williston Basin wells, USGS picks (Gelman & Johnson 2023) wells in table: 16200 wells with a Deadwood (Cambrian) pick: 152 wells with a basement pick: 31 adjacent picks out of depth order, all wells: 698, the largest by 16 ft (pinch-out rounding) ## Wells reaching the Deadwood, by systems picked 101 9 systems picked: Cretaceous, Jurassic, Triassic, Pennsylvanian, Mississippian, Devonian, Silurian, Ordovician, Cambrian 23 8 systems picked: Cretaceous, Jurassic, Triassic, Mississippian, Devonian, Silurian, Ordovician, Cambrian 6 2 systems picked: Ordovician, Cambrian 5 6 systems picked: Cretaceous, Mississippian, Devonian, Silurian, Ordovician, Cambrian 3 8 systems picked: Cretaceous, Jurassic, Triassic, Pennsylvanian, Mississippian, Devonian, Ordovician, Cambrian 3 7 systems picked: Cretaceous, Jurassic, Triassic, Mississippian, Devonian, Ordovician, Cambrian 2 5 systems picked: Mississippian, Devonian, Silurian, Ordovician, Cambrian 2 6 systems picked: Cretaceous, Pennsylvanian, Mississippian, Devonian, Ordovician, Cambrian 2 8 systems picked: Jurassic, Triassic, Pennsylvanian, Mississippian, Devonian, Silurian, Ordovician, Cambrian 1 7 systems picked: Cretaceous, Pennsylvanian, Mississippian, Devonian, Silurian, Ordovician, Cambrian 1 8 systems picked: Cretaceous, Jurassic, Pennsylvanian, Mississippian, Devonian, Silurian, Ordovician, Cambrian 1 7 systems picked: Cretaceous, Jurassic, Mississippian, Devonian, Silurian, Ordovician, Cambrian 1 4 systems picked: Devonian, Silurian, Ordovician, Cambrian 1 7 systems picked: Cretaceous, Triassic, Mississippian, Devonian, Silurian, Ordovician, Cambrian ## The 101 wells with picks in all nine picked systems Spearfish top to Tyler top (lower Spearfish, Permian Opeche and Broom Creek, Pennsylvanian Amsden): min 134 ft, median 892 ft, max 1331 ft highest Cretaceous pick to Deadwood top: min 5134 ft, median 8018 ft, max 12165 ft Otter top to Deadwood top (Tippecanoe and Kaskaskia, without the Deadwood) in 101 wells: min 2744 ft, median 5393 ft (1644 m), max 7070 ft at the median, 40 days means at least 41 m of rock per day, 1.7 m per hour Deadwood thickness where the basement is picked (26 wells): median 521 ft, max 820 ft surface bedrock above the 101 wells (Macrostrat medium-scale map): 50 Sentinel Butte Formation (56-57.0667 Ma on the map) 24 Bullion Creek Formation (56.8-58.4 Ma on the map) 6 Tongue River Member of Fort Union Formation (56.8-59.2 Ma on the map) 6 Tongue River Member of Fort Union Formation (58.4-59.2 Ma on the map) 3 Gravel (0-1.806 Ma on the map) 3 Golden Valley Formation (53.95-56 Ma on the map) 1 Tullock Member of Fort Union Formation (62.7-66 Ma on the map) 1 Gravel (2.588-11.62 Ma on the map) 1 Bearpaw Formation (71.0833-74.0167 Ma on the map) 1 Lebo Member of Fort Union Formation (59.2-62.7 Ma on the map) 1 Alluvium (0-1.806 Ma on the map) 1 Cannonball Formation (59.2-66 Ma on the map) 1 White River Group (26.8325-32.45 Ma on the map) 1 Sentinel Butte Formation (56-56.8 Ma on the map) 1 Hell Creek Formation (66-67.037 Ma on the map) wells whose surface unit is Paleogene or Neogene (Tertiary): 95 of 101; Quaternary gravel or alluvium (bedrock beneath not shown): 4; Cretaceous: 2 ## Full wells: WELL_ID, lat, long, surface unit 142 47.7449 -105.3599 Tongue River Member of Fort Union Formation 181 47.0662 -104.4078 Tongue River Member of Fort Union Formation 884 47.6034 -104.2422 Gravel 896 47.6007 -104.2284 Gravel 933 47.7485 -104.6599 Tongue River Member of Fort Union Formation 1065 47.7053 -104.2415 Gravel 1415 48.3874 -104.3324 Tongue River Member of Fort Union Formation 1496 48.5035 -105.2831 Tullock Member of Fort Union Formation 1552 48.4947 -105.1653 Gravel 1742 48.2400 -105.1229 Bearpaw Formation 1782 48.8328 -104.7960 Lebo Member of Fort Union Formation 1829 48.5829 -104.4300 Tongue River Member of Fort Union Formation 1906 48.6173 -104.1408 Tongue River Member of Fort Union Formation 1934 48.5155 -104.4126 Tongue River Member of Fort Union Formation 1935 48.5024 -104.4236 Tongue River Member of Fort Union Formation 1942 48.5323 -104.2725 Tongue River Member of Fort Union Formation 2350 46.7085 -104.0832 Tongue River Member of Fort Union Formation 2353 46.6732 -104.0779 Tongue River Member of Fort Union Formation 2363 46.9336 -104.1386 Tongue River Member of Fort Union Formation 2369 47.2426 -104.2742 Alluvium 2493 47.1731 -103.3848 Sentinel Butte Formation 2739 47.1054 -103.3258 Sentinel Butte Formation 2771 47.1714 -103.3441 Sentinel Butte Formation 2982 46.8702 -103.5118 Bullion Creek Formation 4420 48.8460 -102.8882 Sentinel Butte Formation 4735 48.8566 -103.1382 Bullion Creek Formation 4738 48.9395 -103.0617 Bullion Creek Formation 4745 48.6679 -103.2624 Sentinel Butte Formation 4779 48.9649 -103.3963 Bullion Creek Formation 4782 48.9830 -103.4128 Bullion Creek Formation 5061 48.8394 -103.7740 Cannonball Formation 5360 47.3086 -102.2162 Sentinel Butte Formation 5412 47.2721 -102.5019 Sentinel Butte Formation 5430 47.2434 -102.3893 Sentinel Butte Formation 5459 47.4841 -103.0960 Sentinel Butte Formation 5495 47.1242 -102.4585 Sentinel Butte Formation 5496 47.0155 -102.4758 Sentinel Butte Formation 5509 47.2874 -102.2671 Sentinel Butte Formation 5523 47.1299 -102.9755 Sentinel Butte Formation 5543 47.0916 -102.4058 Sentinel Butte Formation 6159 47.0879 -102.3902 Sentinel Butte Formation 6629 47.9727 -102.8684 Sentinel Butte Formation 6642 48.1062 -102.9415 Bullion Creek Formation 6878 46.8593 -103.9260 Bullion Creek Formation 6881 46.8949 -103.8215 Bullion Creek Formation 6944 47.0723 -104.0181 Bullion Creek Formation 6947 47.0466 -103.9904 Bullion Creek Formation 6963 47.0502 -104.0279 Bullion Creek Formation 7012 47.8900 -100.8885 Bullion Creek Formation 7256 47.6429 -103.6786 Sentinel Butte Formation 7820 47.6156 -103.7436 Sentinel Butte Formation 8139 48.0429 -102.8206 Sentinel Butte Formation 8160 48.0187 -102.7764 Sentinel Butte Formation 8174 48.0279 -102.7895 Sentinel Butte Formation 8181 47.8435 -102.8840 Golden Valley Formation 8279 47.8495 -102.9988 Sentinel Butte Formation 8316 47.9455 -102.8682 Sentinel Butte Formation 8325 48.0177 -102.8832 Sentinel Butte Formation 8416 47.8600 -102.9456 Sentinel Butte Formation 9058 48.4249 -102.9205 Sentinel Butte Formation 10837 47.6551 -102.0649 Sentinel Butte Formation 10845 47.6904 -100.8773 Bullion Creek Formation 10914 47.1519 -102.1381 Golden Valley Formation 10915 47.3443 -102.1809 Golden Valley Formation 10920 47.1707 -102.0197 Sentinel Butte Formation 11053 47.8856 -102.0024 Sentinel Butte Formation 11055 48.0716 -101.9893 Sentinel Butte Formation 11103 48.3649 -102.4584 Sentinel Butte Formation 13034 46.4951 -102.9390 Sentinel Butte Formation 13147 46.8714 -102.9548 Sentinel Butte Formation 13161 47.0083 -102.4696 Sentinel Butte Formation 13165 46.7597 -102.2985 Sentinel Butte Formation 13166 46.9017 -102.6190 Sentinel Butte Formation 13169 46.7083 -102.2984 Sentinel Butte Formation 13170 46.6750 -102.6931 Sentinel Butte Formation 13172 46.8419 -102.3614 Sentinel Butte Formation 13174 46.7427 -102.1623 Sentinel Butte Formation 13176 46.8530 -102.3768 Sentinel Butte Formation 13177 46.8379 -102.3408 Sentinel Butte Formation 13178 46.8196 -102.8136 Sentinel Butte Formation 13180 46.8224 -102.3332 Sentinel Butte Formation 13186 46.7294 -102.9067 White River Group 13202 46.6433 -102.2358 Sentinel Butte Formation 13206 46.7930 -102.7317 Sentinel Butte Formation 13919 48.3308 -102.9087 Bullion Creek Formation 13920 48.2506 -103.0070 Bullion Creek Formation 13926 48.2946 -103.0052 Bullion Creek Formation 13928 48.3311 -102.9308 Bullion Creek Formation 14029 48.3409 -103.9635 Sentinel Butte Formation 14099 48.2718 -103.5803 Bullion Creek Formation 14301 48.4793 -103.1974 Sentinel Butte Formation 14474 48.5295 -102.8999 Sentinel Butte Formation 14508 48.3184 -102.9335 Bullion Creek Formation 14513 48.2777 -102.9821 Bullion Creek Formation 14522 48.3074 -102.9900 Bullion Creek Formation 14525 48.2085 -103.0189 Bullion Creek Formation 14605 48.3673 -103.1158 Sentinel Butte Formation 14628 48.3997 -103.1408 Sentinel Butte Formation 14652 48.2519 -103.0057 Bullion Creek Formation 14655 48.2562 -102.9734 Bullion Creek Formation 16114 45.7634 -103.4400 Hell Creek Formation Limits: a missing pick is not a missing unit; the Permian and the Paleogene are not picked; pick order is by construction, so the order check tests the table, not the rocks.