Region: Northern Midcontinent
Sedgwick Basin ProvinceThis description of the Sedgwick Basin Province is from the U. S. Geological Survey 1995 National Assessment of United States Oil and Gas Resources (available on CD-ROM from the U.S.G.S. as Digital Data Series DDS-30, Release 2).
The Salina Basin Province, covers an area of about 45,000 sq mi, consisting of the eastern half of Nebraska and the north-central portion of Kansas. The basin lies between the Cambridge Arch-Central Kansas Uplift Province on the west, the Nemaha Uplift Province to the east, the Sioux Arch Province to the north, and a poorly defined structural saddle, separating the Salina Basin and the Sedgwick Basin Province, to the south. In addition to the structural boundaries, the basin is further defined by the zero isopach of Mississippian rocks.
Most of the Salina Basin is nonproductive. Maturity of potential source rocks (Simpson, Chattanooga) decreases in a northwest direction from the Forest City Basin. Although large areas of the Salina Basin remain untested, 600 wildcat wells have been drilled in the nonproductive portion, and despite numerous oil shows, there has been no commercial discovery in over 60 years of exploration. The lack of an organic-rich facies (due to thinning of the Simpson westward from the Forest City Basin towards the Central Kansas Uplift) and lack of sufficient burial depth or local heat source in most of the Salina Basin suggests little to no hydrocarbon potential. Only Saline and Dickinson Counties, Nebr., at the extreme southern end of the basin have significant production. Production in the southwest corner of Osborne County, (Natoma and Ruggels fields) is properly assigned to Cambridge Arch-Central Kansas Uplift Province, while production in Clay and Geary Counties is assigned to the Nemaha Uplift Province.
The Sedgwick Basin, a broad south-plunging shallow embayment of the Anadarko Basin covers an area of about 8,500 sq mi in south-central Kansas encompassing 9 counties. It is bounded by the Central Kansas Uplift to the west, the Nemaha Anticline to the east, and the Anadarko Basin to the south. The northern margin is the poorly defined structural saddle dividing it from the Salina Basin. A series of narrow anticlines that are subparallel to the Nemaha Anticline provide the primary traps.
Exploration in both provinces is in the mature stage, most of the larger accumulations were discovered in the 1930s and 1940s using magnetics and core-drilling techniques, and all plays are nearly exhausted. Stacking of reservoirs is common and structural relief appears to increase with depth. The southward plunge of the Sedgwick Basin results in increasing depth to productive horizons towards the south. However, because of the relatively thin stratigraphic section, about half of the many exploratory wells have tested the entire stratigraphic section to the Cambrian.
Plays in the Salina Basin Province are extensions of those in the adjacent Sedgwick Basin Province, to the south, and are combined in the following play descriptions. The geographic play boundaries for the three plays described below are identical. The plays, all conventional, are Lower Paleozoic Combination Traps Play, Mississippian Combination Traps Play, and Pennsylvanian Combination Traps Play.
Scientists affiliated with the American Association of Petroleum Geologists and from various State geological surveys contributed significantly to play concepts and definitions. Their contributions are gratefully acknowledged.
Hatch, J.R., Jacobson, S.R., Witzke, B.J., Risatti, J.B., Anders, D.E., Watney, W.L., Newell, K.D., and Vuletich, A.K., 1987, Possible Late Middle Ordovician organic carbon isotope excursion--evidence from Ordovician oils and hdyrtocarbon source rocks, Mid-Continent and east- central United States: AAPG Bulletin, v. 71, no. 11, p. 1342-1354.
Newell, K.D., 1990, Lindsborg field--U.S.A., Salina basin, Kansas, in Beaumont, E.A., and Foster, N.H., compilers, Structural traps IV, tectonic and nontectonic fold traps: AAPG Treatise of Petroleum Geology, Atlas of Oil and Gas Fields, p. 347-382.
Newell, K.D., Lambert, M., and Berendsen, P., 1988, Oil and gas shows in the Salina basin: Kansas Geological Survey Subsurface Geology Series No. 10, 36 p.
Newell, K.D., Watney, W.L., Cheng, S.W.L., and Brownrigg, R.L., 1987, Stratigraphic and spatial distribution of oil and gas production in Kansas: Kansas Geological Survey Subsurface Geology Series No. 9, 86 p.
Newell, K.D., Watney, W.L., Hatch, J.R., and Ziazhong, G., 1986, Theraml maturation and petroleum source rocks in Forest City and Salina basins, Mid-Continent, U.S.A. [abs.]: AAPG Bulletin, v. 70, no. 5, p. 625.