Hydrocarbon Potential of the Middle–Late Jurassic Series of Northwestern Iraq: A Case Study in the Shaikhan Oil Field
The Middle–Late Jurassic Sargelu, Naokelekan, and Barsarin formations of northwestern Iraq have been investigated in the Shaikhan oilfield (well Shaikhan-8) to assess their potential for hydrocarbon generation.The results of total organic carbon analysis and rock-eval pyrolysis revealed a good-to-excellent hydrocarbon content and suggest that the depositional conditions were suitable for the production and preservation of organic matter. The thermal maturity proxy indicates that the studied formations were at the start of the hydrocarbon generation period. Most of the samples from the Sargelu and Barsarin formations belong to kerogen type II, whereas those of the Naokelekan Formation belong to kerogen type II/III. The Pr/Ph, Pr/n-C17, and Ph/n-C18 ratios of the extracted bitumen indicated that the organic matter originated from marine sources under reducing conditions. The stable carbon isotope composition of the saturated and aromatic hydrocarbon fractions ranged from –28.3 to –27.7 ‰ and –28.0 to –27.7 ‰, respectively. The biomarker results show a high contribution of marine organic matter that was preserved under relatively anoxic conditions. The profiles of the burial and thermal maturity history show that the simulated generation zones, based on the calculated vitrinite reflectance, indicate immature (0.44%–0.6%)-to-early oil generating (0.6%–0.75%) source rock. The low thermal maturity of the studied formations relative to the depth may be attributed to the low geothermal gradient and heat flow.
Al-Ameri, T.K. and Al-Nagshbandi, S.F. (2015). Age assessments and palynofacies of the Jurassic oil source rocks succession of North Iraq. Arabian Journal of Geosciences, 8, 759 – 771.
Al-Ameri, T.K. and Zumberge, J. (2012). Middle and upper Jurassic hydrocarbon potential of the Zagros fold belt, North Iraq. Marine and Petroleum Geology, 36, 13-34.
Al-Ameri, T.K., Najaf, A.A., Al-Khafaji, A.S., Zumberge, J. and Pitman, J. (2014). Hydrocarbon potential of the Sargelu Formation, North Iraq. Arabian Journal of Geosciences, 7, 987-1000.
Al-Atroshi, S.J., Sherwani, G.H. and Al-Naqshbandi, S.F. (2019). Assessment of the hydrocarbon potentiality of the Late Jurassic formations of NW Iraq: a case study based on TOC and Rock-Eval pyrolysis in selected oil-wells. Open Geosciences, 11, 1-11.
Al-Atroshi, S.J., Sherwani, G.H. and Al-Naqshbandi, S.F. (2020). Assessment the hydrocarbon potentiality of the Middle Jurassic Sargelu Formation in NW Iraq. Iraqi Geological Journal, 53(1A), 1-15.
Al-Azzawi, N.K. and Hamdoon, A.N. (2008). Structure and Geomorphology of Shaikhan Anticline-Northern Iraq. Iraqi National Journal of Earth Sciences, 8,54-63.
Ameen, M.S. (1992). Effect of basement tectonics on hydrocarbon generation, migration, and accumulation in Northern Iraq. AAPG Bulletin, 76(3), 356-370.
Aqrawi, A.A.M., Goff, J.C., Horbury, A.D. and Sadooni, F.N. (2010). The petroleum geology of Iraq. Scientific Press, Beacon Field.
Bellen, V.R.C., Dunnington, H.V., Wetzel, R. and Morton, D.M., 1959. Lexique stratigraphique International. Fasc.10a, Iraq, Paris, 333p.
Buday, T., 1980. The Regional Geology of Iraq, Stratigraphy and Paleogeography, Dar Al-Kutub Publication House, Mosul, Iraq, 351 p.
Demaison, G., and Huizinga, B. J. (199). Genetic classification of petroleum systems. American Associations of Petroleum Geologists Bulletin, 75, 1626-1643.
El Nady, M.M. and Hakimi, M.H. (2016). The petroleum generation modeling of prospective affinities of Jurassic-Cretaceous source rocks in Tut oilfield, Northwestern Desert, Egypt: an integrated bulk pyrolysis and 1D-basin modeling. Arabian Journal of Geosciences, 9,430-442.
English, J.M., Lunn, G.A., Ferreira, L. and Yacu, G. (2015). Geologic evolution of the Iraqi Zagros, and its influence on the distribution of hydrocarbons in the Kurdistan Region. American Associations of Petroleum Geologists Bulletin, 99, 231-272.
Espitalié, J., Laporte, J.L., Madec, M., Marquis, F., Leplat, P. (1977). Rapid method for source rocks characterization and for determination of petroleum potential and degree of evolution. Revue De L’institut Francais Du Petrole, 32,23-42.
Espitalie, J., Madec, M. and Tissot, B. (1980). Role of mineral matrix in kerogen pyrolysis: influence on petroleum generation and migration. American Associations of Petroleum Geologists Bulletin, 64, 59-66.
Espitalie, J., Deroo, G. and Marquis, F. (1985). Rock-Eval pyrolysis and its applications. Revue De L’institut Francais Du Petrole, 40, 563-579.
Hakimi, M.H., Abdullah, W.H. and Shalaby, M.R. (2012). Molecular composition and organic petrographic characterization of Madbi source rocks from the Kharir Oilfield of the Masila Basin (Yemen): palaeoenvironmental and maturity interpretation. Arabian Journal of Geosciences, 5(4), 817-831.
Hakimi, M.H., Al-Matary, A.M. and Ahmed, A.F. (2018). Bulk geochemical characteristics and carbon isotope composition of oils from the Sayhut sub-basin in the Gulf of Aden with emphasis on organic matter input, age and maturity. Egyptian Journal of Petroleum, 27(3), 361-370.
Hantschel, T. and Kauerauf, A.I. (2009). Fundamentals of basin and petroleum systems modeling. Springer Science and Business Media, 476.
Hunt, J.M., (1996). Petroleum Geochemistry and Geology. Second edition. Freeman, New York.
Jalees, M.I., Tahira, F. and Saleem, H., (2010). Study on the geochemical correlation of crude oils of Paleocene and Jurassic ages from the Potowar Indus Basin in northern Pakistan. Chinese Journal of Geochemistry, 29,82-93.
Jarvie, D.M. and Tobey, M.H. (1999). TOC, Rock-Eval and SR Analyzer Interpretive Guidelines. In: Application Note 99-4. Humble Instruments and Services, In: Geochemical Services Division Texas.
Jassim, S.Z. and Al-Gailani, M. (2006) Hydrocarbons. In: Jassim, S.Z. and Goff, J.C. (Eds.), Geology of Iraq (pp 232-250). Dolin, Prague and Moravian Museum, Brno, Czech Republic.
Jassim, S.Z. and Buday, T. (2006). Late Toarcian-Early Tithonian (Mid-Late Jurassic) Megasequence AP7, Chapter 10. In: Jassim, S.Z. and Goff, J, 2006 (Eds.), Geology of Iraq (pp 117-123). Dolin, Prague and Moravian Museum, Brno, Czech Republic.
Jassim, S.Z. and Goff, J.C., (2006). Geology of Iraq. Dolin, Prague and Moravian Museum, Brno, Czech Republic.
Mohialdeen, I.M.J., Mustafa, K.A., Salih, D.A., Sephton, M.A. and Saeed, D.A., (2018). Biomarker analysis of the upper Jurassic Naokelekan and Barsarin formations in the Miran Well-2, Miran oil field, Kurdistan Region, Iraq. Arabian Journal of Geosciences, 11(51), DOI: 10.1007/s12517-018-3405-x
Moldowan, J.M., Seifert, W.K. and Gallegos, E.J. (1985). Relationship between petroleum composition and depositional environment of petroleum source rocks. American Associations of Petroleum Geologists Bulletin, 69, 1255-1268.
Obermajer, M., Fowler, M.G. and Snowdon, L.R. (1999). Depositional environment and oil generation in Ordovician source rocks from southwestern Ontario, Canada. Organic geochemical and petrological approach. American Associations of Petroleum Geologists Bulletin, 83, 1426-1453.
Osuji, L.C. and Antia, B.C. (2005). Geochemical implication of some chemical fossils as indicators of petroleum source rocks. Jour. Appl. Sci. Environ. Mgt., 9,45-49.
Peters, K.E. and Cassa, M.R. (1994). Applied source rock geochemistry: Chapter 5: Part II. Essential elements, 60:93-120.
Peters, K.E., Walters, C.C. and Moldowan, J.M. (2005). The biomarker guide: Biomarkers and isotopes in petroleum systems and earth history, Vol 2, Cambridge University Press.
Pitman, J.K., Steinshour, D. and Lewan, M.D. (2004). Petroleum generation and migration in the Mesopotamian basin and Zagros Fold Belt of Iraq, result from a basin modeling study. GeoArabia, Gulf Petrolink, Bahrain, 9, 41-72.
Sharland, P.R., Archer, R., Cassey, D.M., Davies, R.B. and Hall, S.H. (2001). Arabian plate sequence stratigraphy. special publication no. 2, Gulf PetroLink, Bahrain, 371.
Sofer, Z. (1984). Stable carbon isotope compositions of crude oils: application to source depositional environments and petroleum alteration. American Associations of Petroleum Geologists Bulletin, 68, 31-49.
Ten Haven, H.L., De Leeuw, J.W., Rullkötter, J. and Damsté, J.S. (1987). Restricted utility of the pristane/phytane ratio as a palaeoenvironmental indicator. Nature, 330, 641-643.
Tissot, B.P. and Welte, D.H. (1984). Petroleum Formation and Occurrence. 2nd edition. Berlin, Germany: Springer-Verlag, Berlin.
This work is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License.
Authors who publish with this journal agree to the following terms:
1. Authors retain copyright and grant the journal right of first publication with the work simultaneously licensed under a Creative Commons Attribution License [CC BY-NC-ND 4.0] that allows others to share the work with an acknowledgment of the work's authorship and initial publication in this journal.
2. Authors are able to enter into separate, additional contractual arrangements for the non-exclusive distribution of the journal's published version of the work (e.g., post it to an institutional repository or publish it in a book), with an acknowledgment of its initial publication in this journal.
3. Authors are permitted and encouraged to post their work online (e.g., in institutional repositories or on their website) prior to and during the submission process, as it can lead to productive exchanges, as well as earlier and greater citation of published work (See The Effect of Open Access).