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==Geological Settings==
==Geological Settings==
The geological history of the [[Arabian Basin]], which is a part of the [[Arabian Plate]] ([[:file:M114CH01FG01.jpg|Figure 1]]), has been discussed in detail (e.g., Powers et al., 1966<ref name=Powersetal1966>Powers, R. W., L. F. Ramirez, D. D. Redmond, and E. L. Elberg Jr., 1966, Geology of the Arabian peninsula, sedimentary geology of Saudi Arabia: USGS Professional Paper, 560-D, 150 p.</ref>; McGillivray and Al-Husseini, 1992<ref name=McGillivrayandalhusseini1992>McGillivray, J. G., and M. I. Al-Husseini, 1992, The Paleozoic petroleum geology of central Arabia: AAPG Bulletin, v. 76, p. 1473–1490.</ref>; Alsharhan and Nairn, 1997<ref name=Alsharhanandnairn1997>Alsharhan, A. S. and A. E. M. Nairn, 1997, Sedimentary basins and petroleum geology of the Middle East: Elsevier Science B.V., Amsterdam, 843 p.</ref>; Wender et al., 1998<ref name=Wenderetal1998>Wender, L. E., J. W. Bryant, M. F. Dickens, A. S. Neville, and A. M. Al-Moqbel, 1998, Paleozoic (Pre-Khuff) hydrocarbon geology of the Ghawar Area, eastern Saudi Arabia: GeoArabia, v. 3, p. 273–302.</ref>; Al-Hajri and Owens, 2000<ref name=Alhajriandowens2000>Al-Hajri, S., and B. Owens, 2000, Sub-surface palynostratigraphy of the Palaeozoic of Saudi Arabia, in S. Al-Hajri and B. Owens, eds., Stratigraphic palynology of the Palaeozoic of Saudi Arabia: GeoArabia Special Publication 1, Gulf PetroLink, Bahrain, p. 10–17.</ref>; Al-Husseini, 2000<ref name=Alhusseini2000>Al-Husseini, M. I., 2000, Origin of the Arabian plate structures: Amar collision and Najd rift: GeoArabia, v. 5, no. 4, p. 527–542.</ref>; Konert et al., 2001<ref name=Konertetal2001>Konert, G., A. M. Afifi, S. A. Al-Hajri, and H. J. Droste, 2001, Paleozoic stratigraphy and hydrocarbon habitat of the Arabian plate: GeoArabia, v. 6, no. 3, p. 407–442.</ref>; Sharland et al., 2001<ref name=Sharlandetal2001>Sharland, P. R., R. Archer, D. M. Casey, R. B. Davies, S. H. Hall, A. P. Heward, et al. 2001, Arabian plate sequence stratigraphy: GeoArabia Special Publication 2, Gulf PetroLink, Bahrain, 371 p.</ref>; Ziegler, 2001<ref name=Ziegler2001>Ziegler, M. A., 2001, Late Permian to Holocene paleofacies evolution of the Arabian Plate and its hydrocarbon occurrences: GeoArabia, v. 6, p. 445–504.</ref>; Faqira et al., 2009<ref name=Faqiraetal2009>Faqira, M., M. Rademakers, and A. M. Afifi, 2009, New insights into the Hercynian orogeny, and their implications for the Paleozoic hydrocarbon system in the Arabian plate: GeoArabia, v. 14, no. 3, p. 199–228.</ref>; Cantrell et al., 2014<ref name=Cantrelletal2014>Cantrell, D. L., P. G. Nicholson, G. W. Hughes, M. A. Miller, A. G. Bhullar, S. T. Abdelbagi et al., 2014, Tethyan petroleum systems of Saudi Arabia, in L. Marlow, C. Kendall, and L. Yose, eds., Petroleum systems of the Tethyan region: AAPG Memoir 106, p. 613–639.</ref> and references cited therein).
The geological history of the [[Arabian Basin]], which is a part of the [[Arabian Plate]] ([[:file:M114CH01FG01.jpg|Figure 1]]), has been discussed in detail (e.g., Powers et al., 1966<ref name=Powersetal1966>Powers, R. W., L. F. Ramirez, D. D. Redmond, and E. L. Elberg Jr., 1966, Geology of the Arabian peninsula, sedimentary geology of Saudi Arabia: [https://pubs.er.usgs.gov/publication/pp560D USGS Professional Paper 560-D], 150 p.</ref>; McGillivray and Al-Husseini, 1992<ref name=Mcgillivrayandalhusseini1992>McGillivray, J. G., and M. I. Al-Husseini, 1992, The Paleozoic petroleum geology of central Arabia: [http://http://archives.datapages.com/data/bulletns/1992-93/data/pg/0076/0010/0000/1473.htm AAPG Bulletin], v. 76, p. 1473–1490.</ref>; Alsharhan and Nairn, 1997<ref name=Alsharhanandnairn1997>Alsharhan, A. S. and A. E. M. Nairn, 1997, Sedimentary basins and petroleum geology of the Middle East: Elsevier Science B.V., Amsterdam, 843 p.</ref>; Wender et al., 1998<ref name=Wenderetal1998>Wender, L. E., J. W. Bryant, M. F. Dickens, A. S. Neville, and A. M. Al-Moqbel, 1998, Paleozoic (Pre-Khuff) hydrocarbon geology of the Ghawar Area, eastern Saudi Arabia: GeoArabia, v. 3, p. 273–302.</ref>; Al-Hajri and Owens, 2000<ref name=Alhajriandowens2000>Al-Hajri, S., and B. Owens, 2000, Sub-surface palynostratigraphy of the Palaeozoic of Saudi Arabia, in S. Al-Hajri and B. Owens, eds., Stratigraphic palynology of the Palaeozoic of Saudi Arabia: GeoArabia Special Publication 1, Gulf PetroLink, Bahrain, p. 10–17.</ref>; Al-Husseini, 2000<ref name=Alhusseini2000>Al-Husseini, M. I., 2000, Origin of the Arabian plate structures: Amar collision and Najd rift: GeoArabia, v. 5, no. 4, p. 527–542.</ref>; Konert et al., 2001<ref name=Konertetal2001>Konert, G., A. M. Afifi, S. A. Al-Hajri, and H. J. Droste, 2001, Paleozoic stratigraphy and hydrocarbon habitat of the Arabian plate: GeoArabia, v. 6, no. 3, p. 407–442.</ref>; Sharland et al., 2001<ref name=Sharlandetal2001>Sharland, P. R., R. Archer, D. M. Casey, R. B. Davies, S. H. Hall, A. P. Heward, et al. 2001, Arabian plate sequence stratigraphy: GeoArabia Special Publication 2, Gulf PetroLink, Bahrain, 371 p.</ref>; Ziegler, 2001<ref name=Ziegler2001>Ziegler, M. A., 2001, Late Permian to Holocene paleofacies evolution of the Arabian Plate and its hydrocarbon occurrences: GeoArabia, v. 6, p. 445–504.</ref>; Faqira et al., 2009<ref name=Faqiraetal2009>Faqira, M., M. Rademakers, and A. M. Afifi, 2009, New insights into the Hercynian orogeny, and their implications for the Paleozoic hydrocarbon system in the Arabian plate: GeoArabia, v. 14, no. 3, p. 199–228.</ref>; Cantrell et al., 2014<ref name=Cantrelletal2014>Cantrell, D. L., P. G. Nicholson, G. W. Hughes, M. A. Miller, A. G. Bhullar, S. T. Abdelbagi et al., 2014, [http://http://archives.datapages.com/data/specpubs/memoir106/data/613_aapg-sp1960613.htm Tethyan petroleum systems of Saudi Arabia], in L. Marlow, C. Kendall, and L. Yose, eds., [http://http://store.aapg.org/detail.aspx?id=1139 Petroleum systems of the Tethyan region]: AAPG Memoir 106, p. 613–639.</ref> and references cited therein).
[[file:M114CH01FG01.jpg|300px|thumb|{{figure number|1}}Oil and gas fields in the [[Arabian Plate]] and distribution of [[Silurian]] Qusaiba [[shale]]s beneath [[Hercynian]] unconformity (after Faqira et al., 2009<ref name=Faqiraetal2009 />). MA-I and MA-II show the two areas selected for a 2-D basin modeling study. The [[Unayzah]] fields contain oil sourced by Qusaiba shales.]]
[[file:M114CH01FG01.jpg|300px|thumb|{{figure number|1}}Oil and gas fields in the [[Arabian Plate]] and distribution of [[Silurian]] Qusaiba [[shale]]s beneath [[Hercynian]] unconformity (after Faqira et al., 2009<ref name=Faqiraetal2009 />). MA-I and MA-II show the two areas selected for a 2-D basin modeling study. The [[Unayzah]] fields contain oil sourced by Qusaiba shales.]]
Therefore, only a brief summary will be presented in this chapter, and for details the reader is referred to previous publications. The main tectonic phases that shaped the [[Arabian Plate]] include:
Therefore, only a brief summary is presented in the [http://http://archives.datapages.com/data/specpubs/memoir114/data/1_aapg-sp2030001.htm full paper] associated with this Wiki article, and for details the reader is referred to previous publications. The main tectonic phases that shaped the [[Arabian Plate]] include:
* [[Precambrian]] (formation of the [[basement]])
* [[Precambrian]] (formation of the [[basement]])
As evidenced from the [[sediment]]ary succession ([[:file:M114CH01FG02.jpg|Figure 2]]), throughout the [[Paleozoic]] [[era]], clastic [[continent]]al and shallow-marine [[sediment]]ation prevailed on a stable passive margin on the northeastern [[Gondwana]]. The [[Hercynian]] events of the [[Carboniferous]] affected the area, creating regional uplift, widespread erosion, and basement [[tectonic|tectonism]] due to rejuvenation of the preexisting weaknesses in the basement (Konert et al., 2001<ref name=Konertetal2001 />). From the [[Permian]] to the [[Eocene]], the area was a broad stable passive margin where the deposition of mainly shallow-water [[carbonate]]s with minor [[anhydrite]]s and [[shale]]s occurred (Cantrell et al., 2014<ref name=Cantrelletal2014 />). Since the [[Oligocene]], the northeastern part of the basin has been undergoing shortening as a consequence of collision of the [[Arabian Plate]] with [[Laurasia]] ([[Zagros]] [[Orogeny]]). The resulting flexure of the [[Arabian Plate]] underneath the [[Zagros]] fold-and-thrust belt created a wedge-shaped, low-angle (less than 2°) [[foreland]] basin ([[:file:M114CH01FG03.jpg|Figure 3]]), that has been the site of mixed evaporitic, [[carbonate]], and [[clastic]] sedimentation.
As evidenced from the [[sediment]]ary succession ([[:file:M114CH01FG02.jpg|Figure 2]]), throughout the [[Paleozoic]] [[era]], clastic [[continent]]al and shallow-marine [[sediment]]ation prevailed on a stable passive margin on the northeastern [[Gondwana]]. The [[Hercynian]] events of the [[Carboniferous]] affected the area, creating regional uplift, widespread erosion, and basement [[tectonic|tectonism]] due to rejuvenation of the preexisting weaknesses in the basement (Konert et al., 2001<ref name=Konertetal2001 />). From the [[Permian]] to the [[Eocene]], the area was a broad stable passive margin where the deposition of mainly shallow-water [[carbonate]]s with minor [[anhydrite]]s and [[shale]]s occurred (Cantrell et al., 2014<ref name=Cantrelletal2014 />). Since the [[Oligocene]], the northeastern part of the basin has been undergoing shortening as a consequence of collision of the [[Arabian Plate]] with [[Laurasia]] ([[Zagros]] [[Orogeny]]). The resulting flexure of the [[Arabian Plate]] underneath the [[Zagros]] fold-and-thrust belt created a wedge-shaped, low-angle (less than 2°) [[foreland]] basin ([[:file:M114CH01FG03.jpg|Figure 3]]), that has been the site of mixed evaporitic, [[carbonate]], and [[clastic]] sedimentation.
With respect to the [[Paleozoic Petroleum System]] (PPS), early [[Silurian]] time has prime importance due to deposition of organic-rich (hot) [[shale]]s in a large shelf area of the [[Gondwana]] covering present-day [[North Africa]] and the [[Arabian Peninsula]] (Klemme and Ulmishek, 1991<ref name=Klemmeandulmishek1991>Klemme, H. D., and G. F. Ulmishek, 1991, Effective petroleum source rocks of the world: Stratigraphic distribution and controlling depositional factors: AAPG Bulletin, v. 75, p. 1809–1851.</ref>). Lower [[Silurian]] organic-rich (hot) [[shale]]s have generated about 80–90% of the [[Paleozoic]] sourced [[hydrocarbon]]s in [[North Africa]] and the [[Arabian Peninsula]] (Klemme and Ulmishek, 1991<ref name=Klemmeandulmishek1991 />). The lower hot [[shale]]s, of the [[Qusaiba Formation]] of the [[Qalibah Group]] in [[Saudi Arabia]], are major source rocks of the [[Paleozoic]] oil and gas accumulations in the [[Arabian Peninsula]] (Alsharhan and Nairn, 1997<ref name=Alsharhanandnairn1997 />). In most cases, the shales were deposited directly above upper [[Ordovician]] [[periglacial]] [[sandstone]]s during the initial early [[Silurian]] [[transgression]] that was a result of the melting of the late [[Ordovician]] [[ice cap]] (Lüning et al., 2000<ref name=Luningetal2000>Lüning, S., J. Craig, D. K. Loydell, P. Storch, and B. Fitches, 2000, Lower Silurian “hot shales” in North Africa and Arabia: Regional distribution and depositional model: Earth Science Reviews, v. 49, p. 121–200.</ref>).
With respect to the [[Paleozoic Petroleum System]] (PPS), early [[Silurian]] time has prime importance due to deposition of organic-rich (hot) [[shale]]s in a large shelf area of the [[Gondwana]] covering present-day [[North Africa]] and the [[Arabian Peninsula]] (Klemme and Ulmishek, 1991<ref name=Klemmeandulmishek1991>Klemme, H. D., and G. F. Ulmishek, 1991, Effective petroleum source rocks of the world: Stratigraphic distribution and controlling depositional factors: [http://http://archives.datapages.com/data/bulletns/1990-91/data/pg/0075/0012/0000/1809.htm AAPG Bulletin], v. 75, p. 1809–1851.</ref>). Lower [[Silurian]] organic-rich (hot) [[shale]]s have generated about 80–90% of the [[Paleozoic]] sourced [[hydrocarbon]]s in [[North Africa]] and the [[Arabian Peninsula]] (Klemme and Ulmishek, 1991<ref name=Klemmeandulmishek1991 />). The lower hot [[shale]]s, of the [[Qusaiba Formation]] of the [[Qalibah Group]] in [[Saudi Arabia]], are major source rocks of the [[Paleozoic]] oil and gas accumulations in the [[Arabian Peninsula]] (Alsharhan and Nairn, 1997<ref name=Alsharhanandnairn1997 />). In most cases, the shales were deposited directly above upper [[Ordovician]] [[periglacial]] [[sandstone]]s during the initial early [[Silurian]] [[transgression]] that was a result of the melting of the late [[Ordovician]] [[ice cap]] (Lüning et al., 2000<ref name=Luningetal2000>Lüning, S., J. Craig, D. K. Loydell, P. Storch, and B. Fitches, 2000, Lower Silurian “hot shales” in North Africa and Arabia: Regional distribution and depositional model: Earth Science Reviews, v. 49, p. 121–200.</ref>).
[[file:M114CH01FG04.jpg|300px|thumb|{{figure number|4}}Petroleum systems of the [[Arabian Basin]] (modified after Cantrell et al., 2014<ref name=Cantrelletal2014 />).]]
[[file:M114CH01FG04.jpg|300px|thumb|{{figure number|4}}Petroleum systems of the [[Arabian Basin]] (modified after Cantrell et al., 2014<ref name=Cantrelletal2014 />).]]
[[Paleozoic Petroleum System]]s: A summary of the PPS is shown in [[:file:M114CH01FG04.jpg|Figure 4]]. This petroleum system contains the basal [[Silurian]] Qusaiba hot [[shale]], and to a lesser extent the Qusaiba warm [[shale]]s, as its principal source rocks, with reservoirs extending from the [[Ordovician]] to the early [[Triassic]]. [[Seal]]s occur at different stratigraphic levels, with the evaporitic [[Sudair Formation]] of the early [[Triassic]] age serving as the regional top seal of the PPS. Hanadir and Ra’an shales of the [[Ordovician]] [[Qasim Formation]] may also present some source potential.
[[Paleozoic Petroleum System]]s: A summary of the PPS is shown in [[:file:M114CH01FG04.jpg|Figure 4]]. This petroleum system contains the basal [[Silurian]] Qusaiba hot [[shale]], and to a lesser extent the Qusaiba warm [[shale]]s, as its principal source rocks, with reservoirs extending from the [[Ordovician]] to the early [[Triassic]]. [[Seal]]s occur at different stratigraphic levels, with the evaporitic [[Sudair Formation]] of the early [[Triassic]] age serving as the regional top seal of the PPS. Hanadir and Ra’an shales of the [[Ordovician]] [[Qasim Formation]] may also present some source potential.
Source Rocks: Although several intervals of fine [[clastic]]s (e.g., [[shale]]s and [[mudstone]]) are potential source rocks of various organic richness, the basal hot [[shale]] member of the [[Qusaiba Formation]] of the [[Qalibah Group]] ([[:file:M114CH01FG02.jpg|Figure 2]]) shows a basin-wide occurrence ([[:file:M114CH01FG01.jpg|Figure 1]]) and is organic rich (Cole et al., 1994<ref name=Coleetal1994 />). Termination of [[glaciation]] at the end of the [[Ordovician]] resulted in a major sea-level rise during the early [[Silurian]] time, leading to deposition of the upward-coarsening [[progradation]]al [[Qalibah Group]]. This rapid [[transgression]] caused displacement of earlier shallow marine [[siliciclastic]]s and resulted in the deposition of organic-rich sediments within [[anoxic]] intra-shelf depressions of the northern [[Gondwana]] (Jones and Stump, 1999<ref name=Jonesandstump1999>Jones, P. J., and T. Stump, 1999, Depositional and tectonic setting of the Lower Silurian hydrocarbon source rock facies, Central Saudi Arabia: AAPG Bulletin, v. 83, p. 314–332.</ref>). As these intra-shelf depressions were filled with [[anoxic]] [[sediment]]s, more [[oxic]] depositional environment led to a widespread deposition of warm, organic-lean [[shale]]s of the [[Qusaiba Formation]] (Lüning et al., 2000<ref name=Lüningetal2000>Lüning, S., J. Craig, D. K. Loydell, P. Storch, and B. Fitches, 2000, Lower Silurian “hot shales” in North Africa and Arabia: Regional distribution and depositional model: Earth Science Reviews, v. 49, p. 121–200.</ref>). The organic-rich basal hot [[shale]] of the [[Qusaiba Formation]] is best developed in the subsurface of east-central [[Saudi Arabia]], as well as in the northwest Saudi Arabia, and has an average [[TOC]] content of about 5 wt.%, with maximum values as high as 20 wt.% (Cole et al., 1994<ref name=Coleetal1994 />). Several [[Paleozoic]] oil and gas fields in [[Saudi Arabia]] are known to have been sourced from the basal Qusaiba hot [[shale]] (AbuAli et al., 1991<ref name=Abualietal1991>AbuAli, M. A., U. A. Franz, J. Shen, F. Monnier, M. D. Mahmoud, and T. M. Chambers, 1991, Hydrocarbon generation and migration in the Paleozoic sequence of Saudi Arabia: Society of Petroleum Engineers, SPE 21376, p. 345–356.</ref>, 1999<ref name=Abualietal1999>AbuAli, M. A., J. L. Rudkiewicz, J. G. McGillivray, and F. Behar, 1999, Paleozoic petroleum system of Central Saudi Arabia: GeoArabia, v. 4, no. 3, p. 321–335.</ref>; Mahmoud et al., 1992<ref name=Mahmoudetal1992>Mahmoud, M. D., D. Vaslet, and M. I. Al-Husseini, 1992, The Lower Silurian Qalibah Formation of Saudi Arabia: An important hydrocarbon source rock: AAPG Bulletin, v. 76, p. 1491–1506.</ref>; McGillivray and Al-Husseini, 1992<ref name=Mcgillivrayandalhusseini1992>McGillivray, J. G., and M. I. Al-Husseini, 1992, The Paleozoic petroleum geology of central Arabia: AAPG Bulletin, v. 76, p. 1473–1490.</ref>; Cole et al., 1994<ref name=Coleetal1994 />; Jones and Stump, 1999<ref name=Jonesandstump1999 />). This hot shale unit contains type II amorphous organic matter, with [[graptolite]] and [[chitinozoan]]s, and ranges in thickness from 10 to 250 ft (3–70 m) as given by Mahmoud et al. (1992)<ref name=Mahmoudetal1992 />, Wender et al. (1998)<ref name=Wenderetal1998 />, AbuAli et al. (1999)<ref name=Abualietal1999 />, and AbuAli and Littke (2005)<ref name=Abualiandlittke2005>AbuAli, M. A., and R. Littke, 2005, Paleozoic petroleum systems of Saudi Arabia: A basin modeling approach: Geo-Arabia, v. 10, no. 3, p. 131–168</ref>. Within the [[Qusaiba Formation]], a thick sequence of nonradioactive, light to medium gray [[shale]] overlies the basal hot shale. This lean shale still contains poor to moderate [[organic]] richness (up to a few weight percent [[TOC]]) with mixed oil and gas potential (Cole et al., 1994)<ref name=Coleetal1994 />, and due to its thickness, it can also be a volumetrically important source rock for [[hydrocarbon]] resources in [[Saudi Arabia]].
Source Rocks: Although several intervals of fine [[clastic]]s (e.g., [[shale]]s and [[mudstone]]) are potential source rocks of various organic richness, the basal hot [[shale]] member of the [[Qusaiba Formation]] of the [[Qalibah Group]] ([[:file:M114CH01FG02.jpg|Figure 2]]) shows a basin-wide occurrence ([[:file:M114CH01FG01.jpg|Figure 1]]) and is organic rich (Cole et al., 1994<ref name=Coleetal1994 />). Termination of [[glaciation]] at the end of the [[Ordovician]] resulted in a major sea-level rise during the early [[Silurian]] time, leading to deposition of the upward-coarsening [[progradation]]al [[Qalibah Group]]. This rapid [[transgression]] caused displacement of earlier shallow marine [[siliciclastic]]s and resulted in the deposition of organic-rich sediments within [[anoxic]] intra-shelf depressions of the northern [[Gondwana]] (Jones and Stump, 1999<ref name=Jonesandstump1999>Jones, P. J., and T. Stump, 1999, Depositional and tectonic setting of the Lower Silurian hydrocarbon source rock facies, Central Saudi Arabia: [http://http://archives.datapages.com/data/bulletns/1999/02feb/0314/0314.htm AAPG Bulletin], v. 83, p. 314–332.</ref>). As these intra-shelf depressions were filled with [[anoxic]] [[sediment]]s, more [[oxic]] depositional environment led to a widespread deposition of warm, organic-lean [[shale]]s of the [[Qusaiba Formation]] (Lüning et al., 2000<ref name=Lüningetal2000>Lüning, S., J. Craig, D. K. Loydell, P. Storch, and B. Fitches, 2000, Lower Silurian “hot shales” in North Africa and Arabia: Regional distribution and depositional model: Earth Science Reviews, v. 49, p. 121–200.</ref>). The organic-rich basal hot [[shale]] of the [[Qusaiba Formation]] is best developed in the subsurface of east-central [[Saudi Arabia]], as well as in the northwest Saudi Arabia, and has an average [[TOC]] content of about 5 wt.%, with maximum values as high as 20 wt.% (Cole et al., 1994<ref name=Coleetal1994 />). Several [[Paleozoic]] oil and gas fields in [[Saudi Arabia]] are known to have been sourced from the basal Qusaiba hot [[shale]] (AbuAli et al., 1991<ref name=Abualietal1991>AbuAli, M. A., U. A. Franz, J. Shen, F. Monnier, M. D. Mahmoud, and T. M. Chambers, 1991, Hydrocarbon generation and migration in the Paleozoic sequence of Saudi Arabia: Society of Petroleum Engineers, SPE 21376, p. 345–356.</ref>, 1999<ref name=Abualietal1999>AbuAli, M. A., J. L. Rudkiewicz, J. G. McGillivray, and F. Behar, 1999, Paleozoic petroleum system of Central Saudi Arabia: GeoArabia, v. 4, no. 3, p. 321–335.</ref>; Mahmoud et al., 1992<ref name=Mahmoudetal1992>Mahmoud, M. D., D. Vaslet, and M. I. Al-Husseini, 1992, The Lower Silurian Qalibah Formation of Saudi Arabia: An important hydrocarbon source rock: [http://http://archives.datapages.com/data/bulletns/1992-93/data/pg/0076/0010/0000/1491.htm AAPG Bulletin], v. 76, p. 1491–1506.</ref>; McGillivray and Al-Husseini, 1992<ref name=Mcgillivrayandalhusseini1992 />; Cole et al., 1994<ref name=Coleetal1994 />; Jones and Stump, 1999<ref name=Jonesandstump1999 />). This hot shale unit contains type II amorphous organic matter, with [[graptolite]] and [[chitinozoan]]s, and ranges in thickness from 10 to 250 ft (3–70 m) as given by Mahmoud et al. (1992)<ref name=Mahmoudetal1992 />, Wender et al. (1998)<ref name=Wenderetal1998 />, AbuAli et al. (1999)<ref name=Abualietal1999 />, and AbuAli and Littke (2005)<ref name=Abualiandlittke2005>AbuAli, M. A., and R. Littke, 2005, Paleozoic petroleum systems of Saudi Arabia: A basin modeling approach: Geo-Arabia, v. 10, no. 3, p. 131–168</ref>. Within the [[Qusaiba Formation]], a thick sequence of nonradioactive, light to medium gray [[shale]] overlies the basal hot shale. This lean shale still contains poor to moderate [[organic]] richness (up to a few weight percent [[TOC]]) with mixed oil and gas potential (Cole et al., 1994)<ref name=Coleetal1994 />, and due to its thickness, it can also be a volumetrically important source rock for [[hydrocarbon]] resources in [[Saudi Arabia]].
Reservoir Rocks: The main reservoirs of the [[Paleozoic Petroleum System|PPS]] are the sandstones of the [[Devonian]] [[Jauf Formation]], sandstones of the [[Permian]] [[Unayzah Formation]], and [[carbonate]]s of the [[Permian]] [[Khuff Formation]] ([[:file:M114CH01FG02.jpg|Figure 2]]). The [[Ordovician]] [[Sarah Formation]], underlying the regional Qusaiba hot [[shale]] source rock, consists mainly of fine- to coarse-grained [[sandstone]] sequences of glacial and glacio-fluvial origin. The formation is widely distributed in central and northwestern [[Saudi Arabia]]. Cantrell et al. (2014<ref name=Cantrelletal2014 />) has noted that pre-Qusaiba clastics (e.g., [[Sarah sandstones]]) are generally considered to be tight due to advanced [[diagenesis]], particularly cementation by [[quartz]] overgrowths, which has reduced reservoir quality.
Reservoir Rocks: The main reservoirs of the [[Paleozoic Petroleum System|PPS]] are the sandstones of the [[Devonian]] [[Jauf Formation]], sandstones of the [[Permian]] [[Unayzah Formation]], and [[carbonate]]s of the [[Permian]] [[Khuff Formation]] ([[:file:M114CH01FG02.jpg|Figure 2]]). The [[Ordovician]] [[Sarah Formation]], underlying the regional Qusaiba hot [[shale]] source rock, consists mainly of fine- to coarse-grained [[sandstone]] sequences of glacial and glacio-fluvial origin. The formation is widely distributed in central and northwestern [[Saudi Arabia]]. Cantrell et al. (2014<ref name=Cantrelletal2014 />) has noted that pre-Qusaiba clastics (e.g., [[Sarah sandstones]]) are generally considered to be tight due to advanced [[diagenesis]], particularly cementation by [[quartz]] overgrowths, which has reduced reservoir quality.
==See also==
==See also==
* [[asdf]]
* [[Barmer basin]]
* [[Llanos basin]]
* [[Hammerfest basin]]
==References==
==References==