Orhan Ozcelik

Source-Rock Hydrocarbon Potential of the Middle Triassic—Lower Jurassic Cudi Group Units, Eastern Southeast Turkey

The southern part of Southeast Turkey constitutes the northern margin of the Arabian plate. The region contains rock units ranging in age from Paleozoic to Mesozoic. The source-rock potential of the Middle Triassic-Lower Jurassic Cudi Group in the eastern part of Southeast Turkey was investigated. Samples were obtained from six wells (çilesiz-1, B. Yolaçan-1, G. Dinçer-1, çamurlu-101, çamurlu-102, and Yolaçan-3). The source-rock potential of these units was evaluated by organicgeochemical and petrographic analyses. Sediments have an average of 0.15% total organic carbon (TOC). Commonly, TOC is higher in carbonate-rich facies than in evaporitic deposits. TOC analyses of the Cudi Group shows that these formations are poor to moderate in organic matter. The S1 (average 0.25 mgHC/gTOC), S2 (0.40 mgHC/gTOC), hydrogen index (HI) (average 235 mgHC/gTOC), oxygen index (OI) (average 231 mgCO2/gTOC), and Tmax (average 422°C) values from the Rock-Eval pyrolysis indicate that the dominant organic matter consists of types II and III kerogen, which have gas generative potential. Production index (PI) values indicate samples containing secondarily migrated hydrocarbons. Optical investigation demonstrates that the organic matter is mainly amorphous (70-90%) and of marine origin, but includes small amounts of terrigenous organic matter (10-30%). Results suggest that these beds probably do not constitute a source of liquid hydrocarbons but may represent a source of gas.

Organic facies variation from well data on the Cudi Group, the eastern part of SE Turkey

South Turkey is situated on the transition zonebetween the Arabian–African plate and Alpine–Hima-layan orogenic belt. The eastern segment of South Tur-key is located at the northern margin of the Arabianplate (Fig. 1). This is the only tectonostratigraphic unitin Turkey where significant petroleum production istaking place. The region includes rock units, ranging inage from Cambrian to Miocene Derik, and HaburGroup strata are the basement of the autochthonousrock units of Southeast (SE) Turkey (Fig. 2).The Middle Triassic–Lower Jurassic Cudi Group(Figs. 2, 3) units are composed mainly of evaporiticdeposits in the west and marine carbonates in the eastpart of SE Turkey. During the detailed geological stud-ies, the geological structures and the tectonostrati-graphic relations that have developed at different geo-logical periods of the southeastern Anatolia are rela-tively well known and have been documented innumerous publications [1–16]. Also source rock poten-tial has been reported from several sedimentary unitswhich was deposited in the western and eastern part ofSE Turkey [17–34]. By contrast, only a few studieshave reported the organic facies in the Cudi Group. Inthis study, six geochemical logs from Cilesiz-1, B.Yolacan-1, G. Dincer-1, Camurlu-101, Camurlu-102, andYolacan-3 wells, which were drilled by the TurkishPetroleum Corporation in the same area, were used.The purpose of this work is to characterize the organicgeochemistry of the Middle Triassic to the LowerJurassic Cudi Group of the eastern part of SE Turkey, todetermine their kerogen type, and to assess theirorganic facies properties.Southeast Anatolia was situated in the southernhemisphere as a part of the Gondwanaland during thePaleozoic. The Arabian Plate and its northern edge (SEAnatolia) were affected by the epirogenic movementsof Caledonian and Hercynian orogenic events [35–38].All sediments were deposited on the continental shelf

Organic geochemical characteristics of the bituminous Eocene units in the Çorum–Suluova Basin, Central Anatolia, Turkey

In the Çorum–Suluova Basin (central Anatolia) the Eocene Çeltek and Armutlu formations consist of conglomerate, sandstone, siltstone, marl, mudstone, shale, limestone, clayey limestone, bituminous shale and coal. Total organic carbon (TOC) values in the Çeltek Formation range between 0.1 and 8%. Rock-Eval analyses on core samples with the highest TOC values give hydrogen index (HI) values from 45–846 mgHC g−1 TOC and oxygen index (OI) values from 9–64 mgCO2 g−1 TOC. The organic matter can be classified as Type I and Type II kerogen on the modified van Krevelen diagram. Tmax values vary between 428° and 440°C, with an average of 436°C, indicating the catagenesis stage. Based on the microscopic studies, organic matter is composed of predominantly autochthonous algal and amorphous material, with a minor contribution of terrestrial material. The Çeltek Formation can be regarded as a source rock for hydrocarbons. The TOC content of the Armutlu Formation is poor. Samples consist of terrestrial and reworked organic matter. Vitrinite reflectance values are between 0.27% and 0.43%, with an average of 0.34%. Tmax values are between 433°C and 436°C, with an average of 435°C. The HI value is between 29 mgHC g−1 TOC and 39 mgHC g−1 TOC. Considering the data, the Armutlu Formation cannot be the source rock.

Major and trace-element enrichments in the Karapınar coals (Konya, Turkey)

ABSTRACT Ten major oxides and 27 trace elements were determined in 21 samples collected from four holes that were drilled into the fault-controlled coals of the Karapınar (Turkey) basin. On the basis of X-ray diffraction analyses, the coals contain, in order of abundance, calcite, quartz, dolomite, feldspar, mica, clay minerals, and gypsum. In samples from the study area, a high level of correlation was determined between Mo, Sb, As, U, and V, and S and TOC (Mo, r = 0.697; Sb, r = 0.902; As, r = 0.927; U, r = 0.653; V, r = 0.721). Relative to coals of the world, USA, Turkey, and China, coals of the study area are seen to be enriched up to 1,000 times with respect to Mg, Ca, Na, and K. The Karapınar coals were determined to be enriched in Pb, U, Ba, Cs, Nb, Y, Sr, Rb, Ni, Co, V, and Sc relative to average Turkish coals; in Mn, Na, Ca, Mg, Cs, Sr, Ni, and Cr relative to average Chinese coals; in Ti, K, Na, Ca, Mg, U, Ta, Ba, Cs, Sr, Rb, As, Ni, Co, V, and Cr relative to average worldwide coals; in Mn, P, Ti, K, Na, Ca, Mg, Si, U, Ta, Ba, Cs, Nb, Zr, Sr, Ni, Co, V, and Cr relative to average USA coals; and in Mn, P, Ti, K, Ca, Mg, Fe, Sb, Nb, Zr, Sr, Rb, Zn, Cu, Ni, Co, and Sc relative to crustal averages (Clarke values). The aim of the present study was to determine the enrichment factors of the major- and trace-element contents of the Karapınar coals relative to coals of the world, USA, China, and Turkey, and to crustal averages.

Organic Facies Characteristics of Quaternary Sediments, Gulf of Izmit, Marmara Sea, Turkey

The classification of organic facies from samples obtained by submarine drilling between Hersek Burnu and Kaba Burun in the Gulf of Izmit was determined using organic geochemistry methods. The host sediment is composed of pebbles, sand, silt, and clay, some of which are rich in organic matter. Results indicate an early diagenesis stage according to total organic carbon (0.11-1.78%) and vitrinite reflectance (0.12-0.32%) values. Rock-Eval pyrolysis data display hydrogen indices (HI) of 3 to 97 mg HC/g TOC and oxygen indices (OI) of 29 to 245 mg HC/g CO2. Microscopic studies show that the dominant organic matter is oxic and terrestrial. These data demonstrate that the organic facies were developed in this environment. The CD facies reflects a mixture of source materials including terrestrial plant detritus, and reworked and fine-grained amorphous organic matter. The D facies consists of highly decomposed, reworked organic matter. These types of organic facies generally appear to be weakly sorted in marine and lake sediments.

Trace and Rare Earth Element Geochemistry of Black Shales in Triassic Kasimlar Formation, Anamas-Akseki Platform, Western Taurids, Turkey

The Triassic black shale sequence of Kasimlar Formation in the Anamas - Akseki Platform, Western Taurids, Turkey do not show any trace element enrichment. But trace element values of Black shales from the Kasimlar Formation are broadly comparable with those of the average upper continental crust. While there are slightly enrichments in As, Bi, Zn, Nb, Cu, Pb, Cs and Sb. The other elements are slightly depleted in black shales according to those of upper continental crust (UC). Organic carbon content of the black shales is between 05 and 0.71% but reach 3.78% (averaging as 0.52%). The black shales do not show metal/TOC correlation. Compared to the black shales of Kasimlar Formation and upper continental crust; The black shales show a significant increase in HREE and LREE. Our data show slightly negative Ce anomalies (Ce/Ce* as low as 0.94) and positive Eu anomalies (Eu/Eu* as high as 3.33). Ce/Ce* and Eu/Eu* values recorded in the depositional environment indicate low oxygenated and anaerobic (reducing) conditions.

Geochemical characteristics of major and trace elements in Sahinali Coals, Aydin, Turkey

ABSTRACT In this study, geochemical behavior of elements is investigated in 25 coal samples collected at 10 locations of Şahinli coaliferous units at southeast of Aydın, Turkey. In all the samples, X-ray powder diffraction and inductively coupled plasma mass spectrometry analyses were performed and element and mineral compositions were determined. Total organic carbon (TOC) values of coals are between 14.6 and 37.7 wt% with average of 28.5 wt%. Samples are composed of quartz, calcite, feldspar, dolomite, mica, gypsum, and salt minerals which are accompanied by illite-, kaolinite-, and smectite-type clay minerals. Comparison of average element contents of world coals and studied samples yields that K > Fe > As > U > Cs > Y > Er > Al > Th > Rb > Yb > W > Tb > Dy > Lu > Ce > Sm > La > Ho > Si > Nd > Gd > Tm > Eu > Nb > Pr > Pb > Sn > Ni > Cu > Ga > Ta > Sb > Zr > Cd > V > Zn > Co > Mo > P > Hf > Ba are found to be enriched, while Mn > Be > Ca > Sr > Bi > Mg are found to be depleted. Statistically elements are correlated with TOC.

Organic‐geochemical characteristics of the Miocene Lycian Basin, western Taurides, Turkey

In the Lycian Basin (SW Turkey), the Miocene Karabayır and Karakuştepe formations consist of algal limestone, conglomerate, sandstone, shale and limestone. Total organic carbon (TOC) analysis of the Miocene units show that these formations are poor in organic matter. TOC values are generally between 0.02 and 0.51%, but reach 3.47% in the Karabayır Formation. Hydrogen indices (HI) are mostly below 600 mgHC/gTOC, increasing to 1200 mgHC/gTOC in the Karabayır Formation. S2 vs. TOC diagrams are used to evaluate the sedimentary environments and hydrocarbon potential of the Lower–Middle Miocene sediments (the Isparta, Bucak and Korkuteli‐Elmalı areas). The organic material contains about 63 (type I), 35 (type II) and 29 (type II/III) pyrolysable hydrocarbons, respectively. The dominant organic matter is type II kerogens, and hydrocarbon generating potential is quite low. A positive x‐intercept has been calculated in analysed samples according to S2 vs. TOC diagrams; this value shows a rock‐matrix effect. Clay is the main agent of adsorption. Biomarker characteristics also verify these results. Isoprenoid rates are Pr/Ph: 2, Pr/n‐C17: 1.9, and Pr/n‐C18: 0.5, and a high Pr/Ph ratio (pristane/phytane) indicates an oxic environment; the terpane C29 NH/C30 H ratio is >1 for the Karabayır Formation, and this value indicates a carbonate lithology. On the other hand, the C25 NH/C30 H ratio is <1 for the Karakuştepe Formation; this indicates that the hydrocarbons were derived from terrestrial organic matter. According to m/z 191 mass fragmentograms, the Miocene units contain oleanane, indicating a Tertiary age. The abundance of sterane C29>C28>C27 shows that the kerogens formed from algal organic matter.