Study of Microfacies, Sedimentary Environment and Diagenesis of Sarvak Formation in well No. 6, Ahwaz Oilfield

رخساره‌های رسوبی

Article 2, Volume 9, Issue 2, October 2016, Pages 1-18   

Document Type: مقالات پژوهشی

DOI: 10.22067/sed.facies.v9i2.42257

Authors

Hamedeh Asadzadeh¹; Seyed Reza Moussavi-Harami¹; Mohammad Khanehbad^{* 1}; Asadollah Mahboubi¹; Mohammad Rahim Karimi²

¹Ferdowsi University of Mashhad

²National Iranian South Oil Company

Abstract

Intoduction
In the geological record of the Zagros fold-thrust belt and Dezful Embayment, Cretaceous successions consist of a thick sedimentary packages, which host numerous economically important hydrocarbon reservoirs such as Sarvak Formation (Ziegler, 2001; Ghabeishavi et al, 2010; Rahimpour-Bonab et al., 2012, Mehrabi et al, 2014). Sarvak Formation (Albian-Turonian) is one of the main reservoirs in Iran and is the second major hydrocarbon reservoir in southwest Iran. (James and Wynd, 1965; Alavi, 2007). Ahwaz Oilfield is one of the largest oilfield in Iran that is located in northern Dezful Embayment (Motiei, 1995).
In this research, petrographic studies and facies identification, for interpretation of sedimentary environment, have been carried out in order to understand the reservoir rocks of the Sarvak Formation. Furthermore, the influence of diagenetic processes on carbonate rocks of this formation in well No. 6 in the Ahwaz oil field, has been investigated which could be important in understanding of this formation for further development in this field.

Materials and Methods
205 thin sections, prepared from drilled cores, from Sarvak Formation in well No. 6 Ahwaz oil field have been studied in order to identify facies and interpret depositional environment as well as to investigate the diagenetic processes affected the Sarvak Formation.
The frequency of the components which constitute the studied carbonates have been estimated by Flügel chart (Flügel, 2010). Different researchers study, for example Boudagher-Fadel (2008), Ghabeishavi et al. (2010) and Rahimpour-Bonab et al. (2012), have been taken into consideration for identification of foraminifera which are important component in the studied carbonates. For classification of carbonate facies followed the nomenclature of Dunham (1962) and Embry and Klovan (1971).
The thickness of the Sarvak Formation in well No. 6 in the Ahwaz oilfield is 345 m that consists mainly of limestone. Since Sarvak Formation in the studied oilfield has not been completely drilled and with regard to the available data, the depth of 3310 to 3545 of this well which contains core has only been studied.

Discussion and conclusion
Petrographic studies of 205 thin sections from Sarvak Formation (235m thickness) in the studied well has led to identification of 7 carbonate facies including miliolid mudstone, packstone with highly diverse benthic foraminifera, bioclastic peloidal packstone, foraminiferal peloidal grainstone, rudist boundstone, rudist floatstone-rudstone, and planktonic foraminiferal wackestone. Based on identified of facies as well as vertical facies distribution and lack of slumping and turbidity deposits (Tucker and wright, 1990; Watts and Blome, 1990), gradual changes of facies, lack of aggregate grains, pisoids and oncoids (Burchette and Wright, 1992), the carbonate deposits of studied formation have been deposited in three environments including inner, middle and outer ramp, where sedimentation took place in a homoclinal ramp.
Carbonates of the Sarvak Formation in the studied well have been affected by various diagenetic processes such as micritization, compaction, cementation, neomorphism, dissolution, fracturing and replacement (dolomitization, hematitization and pyritization) that operated in diagenetic environments such as marine, meteoric, burial and uplifting. According to Petrographic studies, in carbonates of the Sarvak Formation, dissolution and cementation processes are more important than the other. In these carbonates, the dissolution process increased and the cementation decreased the reservoir quality.

Keywords: Ahwaz Oil field; Sarvak Formation; sedimentary environment; facies; diagenesis.

References
Alavi. M., 2007. Structures of the Zagros fold-thrust belt in Iran. American Journal of Science, 307: 1064 -1095.
Boudagher-Fadel. M.K., 2008. Evolution and geological significance of Larger Benthic Foraminifera. Developments in Paleontology & Stratigraphy 21, Amsterdam, Elsevier, 560 p.
Burchette. T.P., & Wright. V.P., 1992. Carbonate ramp depositional systems. Sedimentary Geology, 79: 3-57.
Dunham. R.J., 1962. Classification of carbonate rocks according to depositional texture. In: W.E. Ham. (ed.) Classification of carbonate rocks- A symposium. American Association of Petroleum Geologist Memoir 1: 108-121.
Embery. A.F., & Klovan. J.E, 1971. A Late Devonian reef tract on northeastern Banks Island, Northwest territories. Bulletin of Canadian Petroleum Geology, 19(4): 730-781.
Flügel. E., 2010. Microfacies of Carbonate Rocks: Analysis, Interpretation and Application. Second Edition, Springer, Heidelberg, 984 p.
Ghabeishavi. A., Vaziri-Moghaddam. H., Taheri. A., & Taati. F., 2010. Microfacies and depositional environment of the Cenomanian of the Bangestan anticline, SW Iran. Journal of Asian Earth Sciences, 37: 275-285.
James. G.A., & Wynd. J.G., 1965. Stratigraphic nomenclature of Iranian oil consortium, agreement area. American Association of Petroleum Geologists, Bulletin, 49: 2182–2245.
Mehrabi. H., Rahimpour-Bonab. H., Enayati-Bidgoli. A.H., & Navidtalab. A., 2014, Depositional environment and sequence stratigraphy of the Upper Cretaceous Ilam Formation in central and southern parts of the Dezful Embayment, SW Iran, Carbonates Evaporites, 29 (3), 263-278.
Motiei, H., 1995. Petroleum geology of Zagros. Geological Survey of Iran (in Percian), 1009 p.
Rahimpour-Bonab. H., Mehrabi. H., Enayati-Bidgoli. A.H., & Omidvar. M., 2012. Coupled imprints of tropical climate and recurring emergence on reservoir evolution of a Mid-Cretaceous carbonate ramp, Zagros Basin, southwest Iran. Cretaceous Research, 37: 15-34.
Tucker. M.E., & Wright. V.P., 1990. Carbonate sedimentology. Blackwell Science, Oxford, 482 p.
Vandeginste. V., John. C.M., & Manning. Ch., 2013. Interplay between depositional facies, diagenesis and early fractures in the Early Cretaceous Habshan Formation, Jebel Madar, Oman. Marine and Petroleum Geology, 43: 489-503.
Watts. K.F., & Blome. C.D., 1990. Evolution of the Arabian carbonate platform margin slope and its response to orogenic closing of a Cretaceous ocean basin, Oman. In: Tucker, M.E., Wilson, J.L., Crevello, P.D., Sarg, J.R., & Read, J.F., (eds.) Carbonate platforms: facies, sequences and evolution. Blackwell Scientific Publications, The International Association of Sedimentologists, 9: 291-323.
Ziegler. M.A., 2001. Late Permian to Holocene paleofacies evolution of the Arabian Plate and its hydrocarbon occurrences. GeoArabia, 3: 445-504.

Keywords

Ahwaz Oil field; Sarvak Formation; sedimentary environment; facies; diagenesis

References

مطیعی، ﻫ..، 1374. زمین شناسی نفت زاگرس (جلد 1 و 2). طرح تدوین کتاب زمین شناسی ایران. سازمان زمین شناسی و اکتشافات معدنی کشور، 1009 ص.

Alavi, M., 2007. Structures of the Zagros fold-thrust belt in Iran. American Journal of Science, 307: 1064 -1095.

Asadi-Mehmandosti, E., Adabi, M.H., & Woods. A.D., 2013. Microfacies and geochemistry of the Middle Cretaceous Sarvak Formation in Zagros Basin, Izeh Zone, SW Iran. Sedimentary Geology, 293: 9-20.

Bathurst, R.G.C., 1975. Carbonate Sediment and their Diagenesis. Second Edition, Elsevier: North Holland, 658 p.

Blomeier, D., Scheibner, Ch., & Forke, H., 2009. Facies arrangement and cyclostratigraphic architecture of a shallow-marine, warm-water carbonate platform: the Late Carboniferous Ny Friesland Platform in eastern Spitsbergen (Pyefjellet Beds, Wordiekammen Formation, Gipsdalen Group). Facies, 55: 291–324.

Boudagher-Fadel. M.K., 2008. Evolution and geological significance of Larger Benthic Foraminifera. Developments in Paleontology & Stratigraphy 21, Amsterdam, Elsevier, 560 p.

Burchette. T.P., & Wright. V.P., 1992. Carbonate ramp depositional systems. Sedimentary Geology, 79: 3-57.

Dickson, J.A.D., 1965. A modified staining technique for carbonate in thin section. Nature, 205: 587.

Dunham, R.J., 1962. Classification of carbonate rocks according to depositional texture. In: W.E. Ham. (ed.) Classification of carbonate rocks- A symposium. American Association of Petroleum Geologist Memoir, 1: 108-121.

Ehrenberg, S.N., 2006. Porosity destruction in carbonate platforms. Journal of Petroleum Geology, 29 (1): 41-52.

Embery, A.F., & Klovan, J.E, 1971. A Late Devonian reef tract on northeastern Banks Island, Northwest territories. Bulletin of Canadian Petroleum Geology, 19 (4): 730-781.

Flügel, E., 2010. Microfacies of Carbonate Rocks: Analysis, Interpretation and Application. Second Edition, Springer, Heidelberg, 984 p.

Ghabeishavi, A., Vaziri-Moghaddam, H., & Taheri, A., 2009. Facies distribution and sequence stratigraphy of the Coniaciane- Santonian succession of the Bangestan palaeo-high in the Bangestan Anticline, SW Iran. Facies, 55: 243-257

Ghabeishavi, A., Vaziri-Moghaddam, H., Taheri, A., & Taati, F., 2010. Microfacies and depositional environment of the Cenomanian of the Bangestan anticline, SW Iran. Journal of Asian Earth Sciences, 37: 275-285.

Gregg, J.M., & Sibley, D.F., 1984. Epigenetic dolomitization the origin of exenotopic dolomite texture. Sedimentary petrology, 54: 907-931.

Hajikazemi, E., Al-Aasam, I.S., & Conigilo, M., 2010. Subaerial exposure and meteoric diagenesis of the Cenomanian–Turonian Upper Sarvak Formation, southwestern Iran. In: Leturmy, P., Robin, C., (eds.) Tectonic and Stratigraphic Evolution of Zagros and Makran during the Mesozoic–Cenozoic, Geological Society, London, Special Publications, 330: 253-272.

Hood, S.D., Nelson, C.S., & Kamp, P.J.J., 2004. Burial dolomitisation in a non-tropical carbonate petroleum reservoir: the Oligocene Tikorangi formation, Taranaki Basin, New Zealand. Sedimentary Geology, 172: 117-138.

James, G.A., & Wynd, J.G., 1965. Stratigraphic nomenclature of Iranian oil consortium, agreement area. American Association of Petroleum Geologists, Bulletin, 49: 2182-2245.

Lucia, F.J., 1995. Rock–fabric/petrophysical classification of carbonate pore space for reservoir characterization. American Association of Petroleum Geologists, Bulletin, 79 (9): 1275-1300.

Makhloufi, Y., Collin, P.Y., Bergerat, F., Casteleyn, L., Claes, S., David, Ch., Menendez, B., Monna, M., Robion, Ph., Sizun, J.P., Swennen, R., & Rigollet, Ch., 2013. Impact of sedimentology and diagenesis on the petrophysical properties of a tight oolitic carbonate reservoir. The case of the Oolithe Blanche Formation (Bathonian, Paris Basin, France). Marine and Petroleum Geology, 48: 323-340.

Mehrabi, H., Rahimpour-Bonab, H., Enayati-Bidgoli, A.H., & Navidtalab, A., 2014. Depositional environment and sequence stratigraphy of the Upper Cretaceous Ilam Formation in central and southern parts of the Dezful Embayment, SW Iran, Carbonates Evaporites, 29 (3): 263-278.

Moore, C.H., & Wade, W.J., 2013. Carbonate reservoirs: Porosity evolution and diagenesis in a sequence stratigraphic framework. Developments in Sedimentology, 67: 1- 374.

Periere, M.D.D., Durlet, Ch, Vennin, E., Lambert, L., Bourillot, R., Caline, B., & Poli, E., 2011. Morphometry of micrite particles in cretaceous microporous limestones of the Middle East: Influence on reservoir properties. Marine and Petroleum Geology, 28: 1727-1750.

Rahimpour-Bonab, H., Mehrabi, H., Enayati-Bidgoli, A.H., & Omidvar, M., 2012. Coupled imprints of tropical climate and recurring emergence on reservoir evolution of a Mid-Cretaceous carbonate ramp, Zagros Basin, southwest Iran. Cretaceous Research, 37: 15-34.

Romero, J., Caus, E., & Rosell, J., 2002. A model for the palaeoenvironmental distribution of larger foraminifera based on late Middle Eocene deposits on the margin of the South Pyrenean basin (NE Spain). Paleogeography, Palaeoclimatology, Palaeoecology, 179 (1-2): 43-56.

Schlager, M., 2002. Sedimentology and Sequence Stratigraphy of Carbonate Rocks. Amsterdam (Vrije Universiteit/ Earth and Life Sciences), 146 p.

Tucker, M.E., & Wright, V.P., 1990. Carbonate sedimentology. Blackwell Science, Oxford, 482 p.

Vandeginste, V., John, C.M., & Manning. Ch., 2013. Interplay between depositional facies, diagenesis and early fractures in the Early Cretaceous Habshan Formation, Jebel Madar, Oman. Marine and Petroleum Geology, 43: 489-503.

Videtich, P.E., McLimans, R.K., Watson, H. K.S., & Nagy, R.M., 1988. Depositional, Diagenetic, Thermal, and Maturation Histories of Cretaceous Mishrif Formation, Fateh Field, Dubai. American Association of Petroleum Geologists, Bulletin, 72 (10): 1143- 1159.

Watts, K.F., & Blome, C.D., 1990. Evolution of the Arabian carbonate platform margin slope and its response to orogenic closing of a Cretaceous ocean basin, Oman. In: Tucker, M.E., Wilson, J.L., Crevello, P.D., Sarg, J.R., & Read, J.F., (eds.) Carbonate platforms: facies, sequences and evolution. Blackwell Scientific Publications. The International Association of Sedimentologists, 9: 291-323.

Ziegler, M.A., 2001. Late Permian to Holocene paleofacies evolution of the Arabian Plate and its hydrocarbon occurrences. GeoArabia, 3: 445-504.