--> Exploration History and Petroleum Geology of the Central Utah Thrust Belt, by Douglas A. Sprinkel and Thomas C. Chidsey, Jr. #10103 (2006).

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Exploration History and Petroleum Geology of the Central Utah Thrust Belt*


Douglas A. Sprinkel1 and Thomas C. Chidsey, Jr.1


Search and Discovery Article #10103 (2006)

Posted May 13, 2006


*Modified from oral presentation at Rocky Mountain Section AAPG Annual Meeting, Jackson, Wyoming, September 24-26, 2005. Appreciation is expressed to Lyn George, Technical Program Chair, and Don French, for encouraging the authors to submit this presentation and, especially, to the authors for submitting the presentation and for their patience and perseverance.


Editor’s Note: The viewer may wish also to access two other articles pertaining to this area and topic: Structural Architecture, Petroleum Systems, and Geological Implications for the Covenant Field Discovery, Sevier County, Utah, by Doug Strickland et al., Search and Discovery Article #110014 (2005) and Central Utah, a New Oil and Gas Province, by Floyd C. Moulton and Michael L. Pinnell, Search and Discovery Article #50020 (2005).


Click to view presentation in PDF format.


1Utah Geological Survey, Salt Lake City, UT 84116 ([email protected]



Central Utah has seen cycles of petroleum exploration for the past 50 years because explorationists viewed the geology as a natural extension of successful plays elsewhere in Utah. Early efforts tested anticlines identified from surface mapping and seismic reflection data. During the late 1970s to early 1980s companies drilled thrust belt-style structures in the wake of the Pineview discovery in northern Utah. Although these efforts failed, companies confirmed the area was similar in structural style, reservoir types, and timing to the productive thrust belt to the north. The lack of a Cretaceous source seemingly was to blame for these failures; however, oil and gas shows were common in Mississippian, Permian, Triassic, and Jurassic rocks. The recent discovery of Covenant field by Wolverine Oil and Gas Company in the Jurassic Navajo Sandstone along the Sanpete-Sevier Valley antiform has rekindled thoughts of exploration in central Utah; however, this time exploration is based on local success.

Exploration in the central Utah thrust belt will focus on a thrust belt of Paleozoic-cored blind thrusts east of the exposed Charleston-Nebo and Pavant thrusts, which formed during the Cretaceous and early Tertiary Sevier orogeny. Likely targets include anticlines associated with thrust imbricates (or imbricate fans) and possible antiformal stacks of horses forming duplex structures in the Navajo and other reservoirs such as the Permian Park City-Kaibab Formations, Triassic Moenkopi Formation, and Jurassic Twin Creek Limestone. These features are obscured by complex surface geology, but may be closely related to regional antiforms in the Jurassic Arapien Shale.





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Figure 1. Placid Oil Company WXC-State 1 well. Southwest view of Penrod rig 20 on location in central Utah. The Canyon Mountains are in distance where Neoproterozoic strata are thrusted over Cambrian through Devonian strata. Photograph by Doug Sprinkel, winter 1978.

Figure 2. Oil and gas map of Utah. Oil and gas fields in Utah showing geologic provinces, sedimentary basins, and principal structural boundaries (modified from Chidsey et al., 2005).

Figure 3. Northern Utah thrust belt analog. Central thrust belt Utah play in the late 1970s was pursued based on the success in the northern Utah sector of the Sevier thrust belt.

Figure 4. Utah thrust belt and newly discovered Covenant field. Oil and gas map showing leading edge of Sevier thrust belt and location of the Covenant field.


Click to view in sequence Figures 2, 3, and 4 (oil and gas fields and Utah thrust belt).

Figure 5. Exploration history of central Utah (thrust fault locations modified from Willis, 1999). The map area represents about 276 square townships. The map area has had fewer than 120 wells drilled since 1918, which means one well has been drilled per every two townships or one well per about 72 square miles. The increase in drilling in the 1970s and early 1980s was due to significant increase in oil prices from the Arab oil embargo, the discovery of the Pineview field in northern Utah, and the Iranian revolution.

Figure 6. Key shows. Several wells had shows that may be key to future exploration. These wells highlight the potential targets in the Twin Creek Limestone, Navajo Sandstone, Sinbad Limestone (Moenkopi Formation), and Permian section. See Figures 78, 10, and 11.


Click to view in sequence Figures 5 and 6 (exploration history and key shows).

Figure 7. Placid WXC-State 1. The WXC-State 1 well penetrated a repeated Twin Creek and Arapien section with gas shows in the hanging wall (HW) section of Arapien and footwall section of Twin Creek and Navajo. Three cores were taken from the Navajo in which oil stain along fractures were noted. Swab test in the Navajo yielded a small flare of gas. The Twin Creek was not swabbed. The dipmeter analysis suggested this well was on the west flank of the structure. Data are from mud log and personal notes of Doug Sprinkel.

Figure 8. Placid WXC-Howard 1A. The WXC-Howard 1A well had no apparent thrusted sections, and had multiple gas and oil shows in the Twin Creek. No oil or gas shows were visible in the Navajo but trip gas was abundant and increased on subsequent trips. Swab tests through casing in multiple zones of the Twin Creek and Navajo yielded some gas. Data are from mud log and personal notes of Doug Sprinkel.

Figure 9. Reason to drill WXC-Howard 2. The WXC-Howard 2 well was drilled to evaluate shows tested and described in the WXC-Howard 1A well in an up-dip position. A similar argument led American Quasar to Pineview discovery in 1975.

Figure 10. Placid WXC-Howard 2. This well gained structural elevation and had shows in several of the key reservoirs of the Twin Creek Limestone and Navajo Sandstone. The Navajo was tested with a gas flare that was snuffed out by a strong fresh-water flow. The Twin Creek was not tested. Data are from mud log and personal notes of Doug Sprinkel.

Figure 11. Other notable wells. The Placid WXC-Barton 1, Williams Exploration Monroe Fee 1, and Phillips Petroleum US-E 1 are other wells with key shows in reservoirs older than the Jurassic Navajo Sandstone, most commonly in the Triassic Sinbad Limestone Member of the Moenkopi Formation. The Barton well is also noted for being the only well in central Utah to contain deadly concentrations of hydrogen sulfide gas and very high down-hole temperatures. Data are from mud log and personal notes of Doug Sprinkel.

Figure 12. Conclusions from drilling.

  • Structural geometries similar to northern Utah thrust belt

  • Jurassic Twin Creek and Navajo reservoirs

  • No marine Cretaceous source rocks in subthrust position

  • What was source of oil and gas shows?

    • Jurassic Arapien Shale

    • Permian Park City-Phosphoria Formation

    • Permian Toroweap Formation

    • Mississippian strata

As the result of Placid’s drilling program and wells drilled by other operators, we could not demonstrate marine Cretaceous source rocks in a subthrust position. Placid began investigating other possible source rocks in Mississippian, Permian, and Jurassic strata.

Figure 13. Stratigraphic chart of central Utah thrust belt. Stratigraphic correlation chart showing potential source and reservoir rocks of each stratigraphic region.

Figure 14. Covenant oil analysis. Collecting oil from the Covenant field and the gas chromatograph (GC) analysis of oil (Baseline DGSI, 2005).

Figure 15. Basic oil characteristics. Basic geochemical characteristics of the oil from the Covenant field. Production is from the Navajo Sandstone but the source of the oil is Mississippian.

Figure 16. Saturated vs. aromatic hydrocarbons. C13 aromatic versus saturated hydrocarbons plot shows the oil from the Covenant field is geochemically different from the well-known Phosphoria source of Rangely field, Colorado, the Cretaceous source of fields in northeastern Utah, and the mixed Cretaceous-Phosphoria source of Ashley Valley field in eastern Utah. The age of the oil is likely Mississippian.

Figure 17. Potential Mississippian source rocks for central Utah. The possible source rocks for the Covenant field is likely one of the three Mississippian formations given above.

Figure 18. Thickness and distribution of Manning Canyon Shale, Doughnut Formation, and Chainman Shale (modified from Moyle, 1958). The Doughnut Shale is the principal source rock for this time slice; however, the Manning Canyon Shale could be a significant source rock if it is preserved in a subthrust position along the edge of the Oquirrh Basin where much thinner Oquirrh Formation would have been deposited.

Figure 19. Distribution of Delle Phosphatic Member (modified from Sandberg and Gutschick, 1984). Delle Phosphatic Member of the Deseret Limestone could be the dominant source rock during this time slice. The Delle on the hanging wall of the Nebo thrust would likely be “over cooked” but should be in an optimum thermal regime in the central area. Note that the Chainman Shale is restricted to western Utah and eastern Nevada, and is not likely a viable source for the Mississippian oil in central Utah. 

Click to view in sequence Figures 18 and 19 (distribution of Manning Canyon Shale and Delle Phosphatic Member).

Figure 20. Reservoir - Navajo Sandstone. The Navajo Sandstone is the main reservoir for the Covenant field. The Navajo is dominantly a quartz sandstone, but the reservoir is likely heterogeneous with varying porosities and fine-grained baffles (Figure 22) that could affect production. Detailed reservoir characterization studies are needed to understand better the reservoir characteristics.

Figure 21. Navajo/Nugget Sandstone thickness map (Picard, 1975). Isopach map of the Navajo/Nugget Sandstone. Arrows indicate paleowind directions.

Click to view in sequence Figures 18, 19, and 21 (distribution of potential source rocks and reservoir).

Figure 22. Interdune oasis deposit, Killpecker Dunes, Wyoming (Ahlbrandt and Fryberger, 1981). Interdune oasis and wadi deposits are potential baffles to production within the Navajo Sandstone.

Figure 23. Arapien Shale exposed in Salina Canyon. The principal seal is likely the Jurassic Arapien Shale as oil migrated along thrust faults.

Figure 24. Sevier thrust belt (modified from Witkind, 1982). Structural history of the central Utah thrust belt. The key items include thrusting that was sequential and began in Late Jurassic to late Early Cretaceous. Thrusting ended in Eocene and was likely coincident with Laramide deformation. Neogene extension is also a part of the structural history.

Figure 25. Central Utah thrust belt play area. Exploration summary of central Utah play.

  • Thrust-related anticlines

  • Multiple reservoirs

    • Twin Creek Limestone

    • Navajo Sandstone

    • Sinbad Limestone Member of Moenkopi Formation

  • Arapien is main seal

    • Twin Creek

    • Interdunal zones in Navajo

    • Shale zones in Moenkopi

Click to view in sequence Figures 5, 6, 20, and 25 (exploration history, key shows, reservoir—Navajo Sandstone, and play area).

Figure 26. Idealized cross section, showing the structural style of traps and relation to source rocks and seals.

Figure 27. Source of oil and hydrocarbons shows is key! Key to central Utah is understanding the location and maturation of the source rocks. That information combined with timing and migration pathways will lead to additional discoveries.

Figure 28. UGS source-rock assessment. The Utah Geological Survey (UGS) source-rock assessment will sample surface exposures and collect cuttings from wells in the UGS Core Research Center for geochemical biomarker analysis.

Figure 29. UGS outcrop analog studies. The Utah Geological Survey is planning to conduct detail reservoir characterization studies of the Navajo Sandstone.

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Funded in part by U.S. Department of Energy's Preferred Upstream Management Program (PUMPII), National Petroleum Technology Office, Tulsa, Oklahoma, Contract No. DE-FC26-02NT15133.



Ahlbrandt, T.S., and Fryberger, S.G., 1981, Introduction to eolian deposits, in Scholle, P.A., and Speraring, D., eds., Sandstone depositional environments: AAPG Memoir 31, p. 11-47.

Baseline DGSI, 2005, Basic crude oil characteristics and biomarker analysis from the Kings Meadow Ranches no. 17-1 well, covenant field, Sevier County, Utah: Utah Geological Survey Open-File Report 467, 15 p.

Chidsey, T.C., Jr., Wakefield, Sharon, Hill, B.G., and Hebertson, Michael, 2005, Oil and gas fields map of Utah: Utah Geological Survey Map 203DM, scale 1:500,000.

Moyle, R.W., 1958, Paleoecology of the Manning Canyon Shale in central Utah: Brigham Young University Research Studies, v. 5, no. 7, 86 p., 7 plates.

Picard, M.D, 1975, Facies, petrography and petroleum potential of Nugget Sandstone (Jurassic), southwestern Wyoming and northeastern Utah, in Bolyard, D.W., ed., Symposium on deep drilling frontiers of the central Rocky Mountains: Rocky Mountain Association of Geologists Guidebook, p. 109-127.

Poole, F.G., and Claypool, G.E., 1984, Petroleum source-rock potential and crude-oil correlation in the Great Basin, in Woodward, J., Meissner, F.F., and Clayton, J.L., eds., Hydrocarbon source rocks of the greater Rocky Mountain region: Rocky Mountain Association of Geologists, p. 179-230.

Sandberg, C.A., and Gutschick, R.C., 1984, Distribution, microfauna, source-rock potential of Mississippian Delle Phosphatic Member of Woodman Formation and equivalents, Utah, in Woodward, J., Meissner, F.F., and Clayton, J.L., eds., Hydrocarbon source rocks of the greater Rocky Mountain region: Rocky Mountain Association of Geologists Guidebook, p. 135-178.

Swetland, P.J., Clayton, J.L., and Sable, E.G., 1978, Petroleum source-bed potential of Mississippian-Pennsylvanian rocks in parts of Montana, Idaho, Utah, and Colorado: The Mountain Geologist, v. 14, p. 79-87.

Witkind, I.J., 1982, Salt diapirism in central Utah, in Nielson, D.L., editor, Overthrust belt of Utah: Utah Geological Association Publication 10, p. 13-30.

Villien, A., and Kligfield, R.M., 1986, Thrusting and synorogenic sedimentation in central Utah, in Peterson, J.A., ed., Paleotectonics and sedimentation in the Rocky Mountain region: AAPG Memoir 41, p. 281-306.

Willis, G.C., 1999, The Utah thrust system – an overview, in Spangler, L.W., ed., Geology of northern Utah and vicinity, Utah Geological Association Publication 27, p. 1-9.


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