Changes

Three major Mesozoic source rocks deposited during transgressive events. The Oxfordian Smackover Formation has limestones and marls with an average TOC of 3% and a type II kerogen. The Tithonian Cotton Valley- Bossier and Haynesville-Buckner super sequences are characterized by carbonate and some siliciclastic facies, where the TOC ranges 5 to 20% and kerogen is mostly type II. The Cenomanian-Turonian Eagle Ford- Tuscaloosa super sequence has black shales and 4-7% TOC. These rocks also work as unconventional reservoirs. Three main reservoirs are present in this basin. The Wilcox play (Cenozoic), characterized by its high porosity (15%-23%) and permeability (10-100 md), and reservoirs of Jurassic - Cretaceous age that include limestones from James and Andrew Formations and sandstones from the Norphlet Formation, the last one being the largest play in the basin. Retention of oil and gas is conducted by shales, limestones and evaporite seal rocks. Traps occur in diverse styles due to salt tectonics (salt canopy, faulting, diapirs, turtle structures).<ref name=Sneddenetal_2020 />

Three major Mesozoic source rocks deposited during transgressive events. The Oxfordian Smackover Formation has limestones and marls with an average TOC of 3% and a type II kerogen. The Tithonian Cotton Valley- Bossier and Haynesville-Buckner super sequences are characterized by carbonate and some siliciclastic facies, where the TOC ranges 5 to 20% and kerogen is mostly type II. The Cenomanian-Turonian Eagle Ford- Tuscaloosa super sequence has black shales and 4-7% TOC. These rocks also work as unconventional reservoirs. Three main reservoirs are present in this basin. The Wilcox play (Cenozoic), characterized by its high porosity (15%-23%) and permeability (10-100 md), and reservoirs of Jurassic - Cretaceous age that include limestones from James and Andrew Formations and sandstones from the Norphlet Formation, the last one being the largest play in the basin. Retention of oil and gas is conducted by shales, limestones and evaporite seal rocks. Traps occur in diverse styles due to salt tectonics (salt canopy, faulting, diapirs, turtle structures).<ref name=Sneddenetal_2020 />

The complexity in tectonics and geologic models in this basin led to necessary improvements in seismic imaging, drilling techniques and completion methods.<ref name=Sneddenetal_2020 />

The complexity in tectonics and geologic models in this basin led to necessary improvements in seismic imaging, drilling techniques and completion methods.<ref name=Sneddenetal_2020 />

===Permian Basin===

===Permian Basin===

It covers more than 220,000 km² and comprises several component basins and platforms, including the Midland Basin, the Delaware Basin, the Val Verde Basin and the Central basin platform ([[:file:GiacomoneEtAlFigure6.jpg|Figure 6]]).<ref name=Eia_2018 /> Recording the collision of North America and Gondwana during the middle Carboniferous, the Permian Basin developed as a foreland basin in the north of the Marathon Ouachita thrust belt.<ref name=Frenzeletal_1988>Frenzel, H. N., et al., 1988, The Permian basin region, in L. L. Sloss, ed., Sedimentary cover—North American craton; U.S.: Boulder, Colorado, Geological Society of America, The Geology of North America, v. D-2, p. 261– 306.</ref><ref name=Duttonetal_2005>Dutton, S.P., Kim, E.M., Broadhead, R.F., Raatz, W.D., Breton, C.L., Ruppel, S.C. and Kerans, C., 2005. Play analysis and leading-edge oil-reservoir development methods in the Permian basin: Increased recovery through advanced technologies. AAPG bulletin, 89(5), pp.553-576.</ref> The stratigraphy has been substantially influenced by sea-level changes. High sea levels are associated with carbonate shoals in platform margins, whereas lower sea levels were associated with aeolian and fluvial sediments at the shelf margins and  to thick turbidite deposits in deep marine environments.<ref name=Smith_2013>Smith, T., 2013. The Permian Basin – A Brief Overview. GEOExpro Vol. 9, No. 6, p. 64</ref>

It covers more than 220,000 km² and comprises several component basins and platforms, including the Midland Basin, the Delaware Basin, the Val Verde Basin and the Central basin platform ([[:file:GiacomoneEtAlFigure6.jpg|Figure 6]]).<ref name=Eia_2018 /> Recording the collision of North America and Gondwana during the middle Carboniferous, the Permian Basin developed as a foreland basin in the north of the Marathon Ouachita thrust belt.<ref name=Frenzeletal_1988>Frenzel, H. N., et al., 1988, The Permian basin region, in L. L. Sloss, ed., Sedimentary cover—North American craton; U.S.: Boulder, Colorado, Geological Society of America, The Geology of North America, v. D-2, p. 261– 306.</ref><ref name=Duttonetal_2005>Dutton, S.P., Kim, E.M., Broadhead, R.F., Raatz, W.D., Breton, C.L., Ruppel, S.C. and Kerans, C., 2005. Play analysis and leading-edge oil-reservoir development methods in the Permian basin: Increased recovery through advanced technologies. AAPG bulletin, 89(5), pp.553-576.</ref> The stratigraphy has been substantially influenced by sea-level changes. High sea levels are associated with carbonate shoals in platform margins, whereas lower sea levels were associated with aeolian and fluvial sediments at the shelf margins and  to thick turbidite deposits in deep marine environments.<ref name=Smith_2013>Smith, T., 2013. The Permian Basin – A Brief Overview. GEOExpro Vol. 9, No. 6, p. 64</ref>

Up to 8 petroleum systems and 32 plays have been defined in the basin.<ref name=Duttonetal_2005 /><ref name=Jarvie_2018>Jarvie, D.M., 2018. Petroleum systems in the Permian Basin: Targeting optimum oil production.</ref> The Guadalupian petroleum systems (Upper Permian, [[:file:GiacomoneEtAlFigure7.jpg|Figure 7]]) holds the major bulk of reserves with a cumulative production of 16 Bbbls of cumulative oil as of 2005 with main plays associated with shallow water carbonates and deep-water sandstones on stratigraphic traps.<ref name=Duttonetal_2005 /> Although this system holds the largest production, it is the Wolfcamp Shale that has lately drawn attention, arising as a prospective unconventional play revitalizing the basin. The Wolfcampian-age organic-rich shale formation extends over all three sub-basins in the Permian Basin.<ref name=Eia_2018 /> Hydrocarbon resources exceed 19 Bbbls of oil, 16 TCF of natural gas, and 1.6 billion barrels of natural gas liquids (NGL), making it one of the largest hydrocarbon plays in the country as of October 2018. TOC content ranges from less than 2% up to 8% and kerogen is mostly type II with a type III contribution.<ref name=Guptaetal_2017>Gupta, I., Rai, C., Sondergeld, C. and Devegowda, D., 2017, June. Rock typing in Wolfcamp formation. In SPWLA 58th Annual Logging Symposium. Society of Petrophysicists and Well-Log Analysts.</ref><ref name=Kvaleandrahman_2016>Kvale, E.P. and “Wahid” Rahman, M., 2016, August. Depositional facies and organic content of upper Wolfcamp Formation (Permian) Delaware Basin and implications for sequence stratigraphy and hydrocarbon source. In Unconventional Resources Technology Conference, San Antonio, Texas, 1-3 August 2016 (pp. 1485-1495). Society of Exploration Geophysicists, American Association of Petroleum Geologists, Society of Petroleum Engineers.</ref><ref name=Wardetal_1986>Ward, R. F., C. G. St. C. Kendall, and R. M. Harris, 1986, Upper Permian (Guadalupian) facies and their association with hydrocarbons—Permian basin, west Texas and New Mexico: AAPG Bulletin, v. 70, p. 239– 262.</ref> Fracture associated porosity varies between 2% and 12%; however, average permeability is as low as 10 millidarcies, which requires multistage hydraulic fracturing.<ref name=Duttonetal_2005 />

Up to 8 petroleum systems and 32 plays have been defined in the basin.<ref name=Duttonetal_2005 /><ref name=Jarvie_2018>Jarvie, D.M., 2018. Petroleum systems in the Permian Basin: Targeting optimum oil production.</ref> The Guadalupian petroleum systems (Upper Permian, [[:file:GiacomoneEtAlFigure7.jpg|Figure 7]]) holds the major bulk of reserves with a cumulative production of 16 Bbbls of cumulative oil as of 2005 with main plays associated with shallow water carbonates and deep-water sandstones on stratigraphic traps.<ref name=Duttonetal_2005 /> Although this system holds the largest production, it is the Wolfcamp Shale that has lately drawn attention, arising as a prospective unconventional play revitalizing the basin. The Wolfcampian-age organic-rich shale formation extends over all three sub-basins in the Permian Basin.<ref name=Eia_2018 /> Hydrocarbon resources exceed 19 Bbbls of oil, 16 TCF of natural gas, and 1.6 billion barrels of natural gas liquids (NGL), making it one of the largest hydrocarbon plays in the country as of October 2018. TOC content ranges from less than 2% up to 8% and kerogen is mostly type II with a type III contribution.<ref name=Guptaetal_2017>Gupta, I., Rai, C., Sondergeld, C. and Devegowda, D., 2017, June. Rock typing in Wolfcamp formation. In SPWLA 58th Annual Logging Symposium. Society of Petrophysicists and Well-Log Analysts.</ref><ref name=Kvaleandrahman_2016>Kvale, E.P. and “Wahid” Rahman, M., 2016, August. Depositional facies and organic content of upper Wolfcamp Formation (Permian) Delaware Basin and implications for sequence stratigraphy and hydrocarbon source. In Unconventional Resources Technology Conference, San Antonio, Texas, 1-3 August 2016 (pp. 1485-1495). Society of Exploration Geophysicists, American Association of Petroleum Geologists, Society of Petroleum Engineers.</ref><ref name=Wardetal_1986>Ward, R. F., C. G. St. C. Kendall, and R. M. Harris, 1986, Upper Permian (Guadalupian) facies and their association with hydrocarbons—Permian basin, west Texas and New Mexico: AAPG Bulletin, v. 70, p. 239– 262.</ref> Fracture associated porosity varies between 2% and 12%; however, average permeability is as low as 10 millidarcies, which requires multistage hydraulic fracturing.<ref name=Duttonetal_2005 />