Clay mineralogy and geochemistry of three offshore wells in the southwestern Black Sea, northern Turkey: the effect of burial diagenesis on the conversion of smectite to illite

The conversion of smectite to illite has long been studied by numerous researchers because of its importance as a diagenetic metric. Interpreting the pressure, temperature, and age of the sequences in which this conversion occurs provides the possibility to identify the historical maturation parameters of hydrocarbon sources. The Black Sea Basin is known to be an area that can provide source rocks for oil and gas production. The purpose of this study was to determine the clay minerals and their abundances, to establish a stratigraphic correlation among three wells, which is useful to select specific stratigraphic horizons for hydrocarbon exploration, and to predict paleotemperature ranges in the wells by using the conversion of clay minerals. The determination of the clay mineralogy and chemical composition of the three wells in the Black Sea Basin was done by several methods of analysis. These methods include powder X-ray diffraction (XRD), X-ray fluorescence spectroscopy (XRF), and environmental scanning electron microscopy (ESEM). All 54 samples were processed by XRD and XRF and 6 representative samples were selected for ESEM analysis. Based on the XRD results, the clay minerals determined in the samples are illite, smectite, and mixed-layer illite/smectite (I/S), which are the most abundant minerals calculated by the method described in Underwood and Pickering, plus kaolinite and chlorite. The chemical results of major oxides acquired from XRF analyses show that the changes in Na2O and K2O, which are the main actors in the conversion of smectite to illite, do not gradually increase or decrease. Since the Black Sea Basin is considered a rift basin, the maximum temperature ranges of the conversion were calculated by considering the maximum and minimum depths of the samples. These temperature ranges are 111 154 °C, 147 208 °C, and 48 59 °C for Well-1, Well-2, and Well-3, respectively.

PDF

___

Burst JF (1959). Postdiagenetic clay mineral environmental relationships in the Gulf Coast Eocene. Clay Clay Miner 6: 327-341.
Chen F, Siebel W, Satir M, Terzioğlu N, Saka K (2002). Geochronology of the Karadere basement (NW Turkey) and implications for the geological evolution of the İstanbul Zone. Int J Earth Sci 91: 469-481.
Drits VA, Lindgren H, Sakharov BA, Jakobsen HJ, Salyn AL, Dainyak LG (2002). Tobelitization of smectite during oil generation in oil-source shales: application to North Sea illite-tobelite-smectite-vermiculite. Clay Clay Miner 50: 82-98.
Dunoyer de Segonzac G (1964). Les Argiles du Cretace Superior dans le bassin de Douala (Cameroun): Problems de diagenese. Alsace-Lorraine Service Carte Geologie Bulletin 17: 287-310.
Fowler AC, Yang XS (2003). Dissolution/precipitation mechanism for diagenesis in sedimentary basins. J Geophys Res 108 (B10): 2509.
Freed RL, Peacor DR (1992). Diagenesis and the formation of authigenic illite-rich I/S crystals in Gulf Coast shales: TEM study of clay separates. J Sediment Petrol 62: 220-234.
Görür N (1988). Timing of opening of the Black Sea basin. Tectonophysics 147: 247-262. Hamilton PJ, Kelley S, Fallcik AE (1989). K-Ar dating of illite in hydrocarbon reservoirs. Clay Miner 24: 215-231.
Hoffman J, Hower J (1979). Clay mineral assemblages as low grade metamorphic geothermometers: application to the thrust faulted disturbed belt of Montana, in Aspects of Diagenesis. In: Scholle PA, Schluger PS, editors. SEPM Special Publications 26: pp. 56-79.
Hower J, Eslinger EV, Hower ME, Perry EA (1976). Mechanism of burial metamorphism of argillaceous sediment: mineralogical and chemical evidence. Geol Soc Am Bull 87: 725-737.
Jaboyedoff M, Bussy F, Kübler B, Thelin P. (2001). Illite crystallinity revisited. Clay Clay Miner 49: 156-167.
Jiang S (2012). Clay minerals from the perspective of oil and gas exploration. In: Valaskova M, Martynkova GS, editors. Clay Minerals in Nature - Their Characterization, Modification and Application. 1st ed. Rijeka, Croatia: InTech, pp. 21-38.
Kelly J, Parnell J, Chen HH (2000). Application of fluid inclusions to studies of fractured sandstone reservoirs. J Geochem Explor 69: 705-709.
Kübler B (1967). La cristallinité de lillite et les zones tout à fait supérieures du métamorphisme. In: Etages tectoniques, Colloque de Neuchâtel 1966, Edition de la Baconniére. Neuchâtel, Switzerland: 105-121.
Liewig N, Clauer N, Sommer F (1987). Rb-Sr and K-Ar dating of clay diagenesis in Jurassic sandstone oil reservoir, North Sea. AAPG Bull 71: 1467-1474.
Moore DM, Reynolds RC (1997). X-Ray Diffraction and the Identification and Analysis of Clay Minerals. 2nd ed. New York, NY, USA: Oxford University Press.
Nadeau PH, Wilson MJ, McHardy WJ, Tait JM (1985). The conversion of smectite to illite during diagenesis: evidence from some illitic clays from bentonites and sandstones. Mineral Mag 49: 393-400.
Okay AI (2008). Geology of Turkey: a synopsis. Anschnitt 21: 19-42.
Okay AI, Tüysüz O (1999). Tethyan sutures of northern Turkey. In: Durand B, Jolive L, Horvath F and Serrane M, editors. The Mediterranean Basins: Tertiary Extensions within Alpine Orogen. 1st ed. London, UK: Geological Society Special Publications 156, pp. 475-515.
Okay AI, Şengör AMC, Görür N (1994). Kinematic history of the opening of the Black Sea and its effect on the surrounding regions. Geology 22: 247-270.
Okay AI, Satır M, Maluski H, Siyako M, Monie P, Metzger R, Akyüz S (1996). Paleao- and neo-Tethyan events in northwestern Turkey: geologic and geochronologic constrains. In: Yin A, Harrison TM editors. The Tectonic Evolution of Asia. 1st ed. London, UK: Cambridge University Press, pp. 420-441.
Pearson MJ, Small JS (1988). Illite/smectite diagenesis and palaeotemperatures in Northern North Sea Quaternary to Mesozoic shale sequences. Clay Miner 23: 109-132.
Perry E, Hower J (1970). Burial diagenesis in Gulf Coast pelitic sediments. Clay Clay Miner 18: 165-177.
Underwood MB, Pickering KT (1996). Clay-mineral provenance, sediment dispersal patterns, and mudrock diagenesis in the Nankai Accretionary Prism, Southwest Japan. Clay Clay Miner 44: 339-356.
Ustaömer PA, Mundil R, Renne PR (2005). U/Pb and Pb/Pb zircon ages for arc-related intrusions of the Bolu Massif (W Pontides, NW Turkey): evidence for Late Precambrian (Cadomian) age. Terra Nova 17: 215-223.
Velde B (editor) (1995). Origin and Mineralogy of Clays: Clays and the Environment. 1st ed. Heidelberg, Germany: Springer. Weaver CE (1958). Geologic interpretation of argillaceous sediments. AAPG Bull 42: 254-309.
Weaver CE (1960). Possible uses of clay minerals in search for oil. AAPG Bull 44: 1505-1518.
Winchester JA, Floyd PA (1977). Geochemical discrimination of different magma series and their differentiation products using immobile elements. Chem Geol 20: 325-343.
Yariv S (1976). Organophilic pores as proposed primary migration media for hydrocarbons in argillaceous rocks. Clay Sci 5: 19-29.
Yiğitbaş E, Kerrich R, Yilmaz Y, Elmas A, Xie QL (2004). Characteristics and geochemistry of Precambrian ophiolites and related volcanics from the İstanbul-Zonguldak Unit, Northwestern Anatolia, Turkey: following the missing chain of the Precambrian South European suture zone to the east. Precambrian Res 132: 179-206.
Yilmaz Y, Tüysüz O, Yiğitbaş E, Genç ŞC, Şengör AMC (1997). Geology and tectonic evolution of the Pontides. In: Robinson AG, editors. Regional and Petroleum Geology of the Black Sea and Surrounding Region. 1st ed. Tulsa, OK, USA: AAPG Memoir 68: pp. 183-226.