The Fayetteville Shale is a geologic formation of Mississippian age (354–323 million years ago) composed of tight shale within the Arkoma Basin of Arkansas and Oklahoma. It is named for the city of Fayetteville, Arkansas, and requires hydraulic fracturing to release the natural gas contained within.
Nomenclature
Named by Frederick Willard Simonds in 1891, Simonds recognized what is now the Fayetteville Shale as three separate formations overlying the now abandoned Wyman Sandstone: the Fayetteville Shale, the Batesville Sandstone, and the Marshall Shale. In 1904, the name "Fayetteville Shale" replaced all three of these names. The Fayetteville Shale that Simonds recognized is now considered as the lower Fayetteville Shale. Simonds' Batesville Sandstone was found to be the same as the Wyman Sandstone, and replaced the name "Wyman Sandstone", while Simonds' Batesville Sandstone became known as the "Wedington Sandstone Member" presumably after Wedington Mountain. The name Marshall Shale was abandoned and is now known as the upper Fayetteville Shale.
Natural gas
The formation holds natural gas in a fine-grained rock matrix which requires hydraulic fracturing to release the gas. This process became cost-effective in some shales such as the Fayetteville after years of experimentation in the Barnett Shale in North Texas, especially when combined with horizontal drilling.
The Fayetteville Shale play began in July 2004 when Southwestern Energy drilled the Thomas #1-9 vertical well in Conway County, Arkansas. In February 2005, Southwestern Energy drilled the first horizontal well, the Seeco-Vaughan #4-22H, also in Conway County.
The US Energy Information Administration estimated that the shale play held 13,240 billion cubic ft (375 billion cubic meters) of unproved, technically recoverable gas. The average well was estimated to produce 1.3 billion cubic feet of gas.US Energy Information Administration, Annual Energy outlook 2012, accessed 14 Sept. 2013. As of 2018, new drilling in the Fayetteville Shale had ceased and almost 1/5 of wells were abandoned.
Paleontology Flora Because the Fayetteville Formation is a marine unit, most of the plants found in the black shales must have been washed into the Carboniferous sea from a landmass. However one unit within the formation, the Weddington Sandstone Member, is a series of river deposited sand beds. Fossil plants from this unit were probably deposited closer to their source.
Adiantites A. minima Ankyropteris Archaeocalamites A. fayettevillensis A. gracilentus A. umbralis A. wedingtonensis Bothrodendron Carpolithus C. inquirenda Cardiopteris C. hirta Chlamidostachys C. chesterianus Lepidocystis L. chesterensis Lepidodendron L. henbesti L. occidentale L. purduei L. wedingtonense Lepidophloios Lepidophyllum L. sagittatum Lepidostrobus L. occidentalis Lepidostrous Taylor, T., Eggard, D.,1967. Petrified Plants from the Upper Mississippian (Chester Series) of Arkansas. Transactions of the American Microscopical Society. 86: 4 Lyginopteris L. royaliiTomescu, A. 2001. Lyginopteris royalii sp. nov. from the Upper Mississippian of North America. Review of Paleobotany and Palynology. 116: 3-4 Medullosa Neuropteris Pachytesta Rhacopteris Rhynchogonium R. fayettevillense Rhynochosperma R. quinnii Dunn, M., Rothwell, G., Mapes, G. 2002.Additional observations on Rhynchosperma quinnii (Medullosaceae): a permineralized ovule from the Chesterian (Upper Mississippian) Fayetteville Formation of Arkansas. Journal of Botany. 89:11 Sphenopteris S. (Palmatopteris) erectiloba S. (Calymmatotheca) mississippiana Stigmaria S. arkansana S. wedingtonensis Tivena T. arkansanaDunn, M., Rothwell, G., Mapes, G. 2003. On Paleozoic plants from marine strata: Trivena arkansana (Lyginopteridaceae) gen. et sp. nov., a lyginopterid from the Fayetteville Formation (middle Chesterian/Upper Mississippian) of Arkansas, USA. Journal of Botany. 90:8
Fauna
Vertebrates Carcharopsis wortheniLund, R., Mapes, R. 1984. Carcharopsis wortheni from the Fayetteville Formation (Mississippian) of Arkansas. Journal of Paleontology. 58:3. "Cobelodus" (remains now attributed to Ozarcus) Maisey, J. G. (2007). The braincase in Paleozoic symmoriiform and cladoselachian sharks. Bulletin of the American Museum of Natural History, 2007(307), 1-122. Cosmoselachus mehlingi Ozarcus mapesae
Echinoderms
Acrocrinus constrictus Agassizocrinus conicus Alcimocrinus ornatus Allocatillocrinus carpenteri Ampelocrinus erectus Aphelecrinus exoticus A. planus Childonocrinus trinodus Cymbiocrinus gravis Dasciocrinus aulicus Heliosocrinus aftonensis Intermediacrinus modernus Linocrinus Mantikosocrinus castus OnchyocrinusBurdick, D., Strimple, H. 1973. Flexible Crinoids from the Fayetteville Formation (Chesterian) of Northeastern Oklahoma. Journal of Paleontology. 47:2 Onychocrinus pulaskiensis Ophiurocrinus hebdenensis Pentremites platybasis P. pulchellus Phacelocrinus Phanocrinus Strimple, H. 1948. Notes on Phanocrinus from the Fayetteville Formation of Northeastern Oklahoma. Journal of Paleontology. 22:4 P. alexanderi P. cylindricus P. formosus Scytalocrinus aftonensis Taxocrinus cestriensis T. whitefieldi. Ulrichicrinus chesterensis
Cephalopods
Arcanoceras furnishi Cluthoceras glicki Cluthoceras pisiforme Cravenoceras fayettevillae Cravenoceras lineolatum Dombarites mapesi Eurmorphoceras plummeri Fayettevillea planorbis Girtyoceras Doughouzhaeva L, Mapes, R., Mutvei, H. 1997. Beaks and radulae of Early Carboniferous goniatites. Lethia. 30:4 Goniatites granosus Lusitanites subcircularis Metadimorphoceras wiswellense Neoglyphioceras crebriliratum Paracravenoceras ozarkense Paradimorphoceras Pronorites baconi Rayonnoceras solidiforme Mapes, R. 1966. Late Mississippian Lycopsid Branch from Arkansas. Oklahoma Geology Notes. Tumulites varians
Corals Amplexus expansus Easton, W. 1945. Kinkaid Corals from Illinois and Amplexoid Corals from the Chester of Illinois and Arkansas. Journal of Paleontology. 19:4 Michelinia meekana Sando, W. 1969. Revision of Some of Girty's Invertebrate Fossils from the Fayetteville Shale (Mississippian) of Arkansas and Oklahoma: Part B- Corals. United States Geologic Survey Professional Paper 606 Palaecris carinata
Bivalves
Aviculopecten squamula Aviculopecten jennyi Aviculopecten multilineatus Aviculopecten morrowensis Aviculopecten inspeciosus Canyella peculiaris Cardiomorpha inflata Conocardium peculiare Cypricardia fayettevillensis Cyprecardella sublata Edmondia equilateralis Palaeoneilo sera Phestia stevensiana <ref name = pojeta/ Sanguinolites simulans Solenamorpha nitida Pojeta, J. 1969. Revision of Some of Girty's Invertebrate Fossils from the Fayetteville Shale (Mississippian) of Arkansas and Oklahoma: Part C- Pelecypods. United States Geologic Survey Professional Paper 606 Sphenotus branneri Sphenotus washingtonensis Sphenotus dubius Sphenotus meslerianus
Brachiopods Adairia adairensisM. Gordon Jr. and T. W. Henry. 1993. Late Mississippian Productoid Brachiopods Inflatia, Keokukia, and Adairia, Ozark Region of Oklahoma and Arkansas. Paleontological Society Memoir 30:1-29 Inflatia gracilis Inflatia cherokeensis Inflatia pusilla Inflatia inflata Orthotetes protensus Orthotetes subglobosus
Gastropods
Euconospira disjuncta Mourlonia lativittata Patellilabia laevigata Platyceras subelegans Platyceras compressum Sinuitina venata Yochelson, E 1969. Revision of Some of Girty's Invertebrate Fossils from the Fayetteville Shale (Mississippian) of Arkansas and Oklahoma: Part C- Pelecypods. United States Geologic Survey Professional Paper 606 Trepospira discus
Arthropods
Cyrtoproetus kerhini Paladin murconatus Gordon, M. 1969.Revision of Some of Girty's Invertebrate Fossils from the Fayetteville Shale (Mississippian) of Arkansas and Oklahoma: Part E- Trilobites. United States Geologic Survey Professional Paper 606 Paraparchites
Ostracods Amphissites Bairdia Cavellina Geisina Glyptopleura Graphiadactyllis Kegelites Kirkbya Sohn, I. 1969.Revision of Some of Girty's Invertebrate Fossils from the Fayetteville Shale (Mississippian) of Arkansas and Oklahoma: Part F- Ostracodes. United States Geologic Survey Professional Paper 606 Orthobairdia Roundyella Sansabella Sargentina Serenida
Bryozoans
Archimedes communis Archimedes compactus Archimedes confertus Archimedes distans Archimedes inflatus Archimedes intermedius Archimedes invaginatus Archimedes meekanus Archimedes owenanus Archimedes proutanus Archimedes sublaxus Archimedes terebriformis Batostomella parvula Fenestella cestriensis Fenestella compress Fenestella elevatipora Fenestella serratula Fenestella tenax
Leioclema Polypora cestriensis Polypora corticosa Polypora spinulifera Rhombopora tabulata Septopora cestriensis Streblotrypa nicklesi Streblotrypa subspinosa Sulcoretepora americana Sulcoretepora labiosa Sulcoretepora nitida Thamniscus turcillatus
Foraminifera Earlandia Eosigmoilina rugosa
Trace Fossils Cruziana Planolites Teichichnus
References