Naslov
Source rock characteristics of the Upper Cretaceous Soukhne and Shiranish Formations in the Hayan Block, Syria

Autori
Španić, Darko ; Troskot-Čorbić, Tamara ; Rumenjak, LJubica ; Stanković, Irenka ; Čuljak, Veronika

Vrsta, podvrsta i kategorija rada
Sažeci sa skupova, prošireni sažetak, znanstveni

Izvornik
62nd International Committee for Coal and Organic Petrology Meeting, Abstracts / Ercegovac, Marko - Beograd : Srpska akademija nauka i umetnosti (SANU), 2010, 52-53

Skup
62nd International Committee for Coal and Organic Petrology Meeting

Mjesto i datum
Beograd, Srbija, 26.09.2010. - 02.10.2010

Vrsta sudjelovanja
Poster

Vrsta recenzije
Međunarodna recenzija

Ključne riječi
Cretaceous, Source rock, Hayan, Syria

Sažetak
Exploratory wells drilled in the Hayan block, located in Palmyrides region in Central Syria, showed the oil condensate and gas discoveries. According to geochemical analyses, main source rock for these hydrocarbons is the middle Triassic Kurrachine Dolomite Formation. The objecticve of this paper is the geochemical characterization of the upper Cretaceous Soukhne (Santonian-early Campanian)and Shiranish (late Campanian-Maastrichtian) Formations in the Hayan Block, which are the main source rocks for oils in the nearby Euphrates Graben, one of the most important petroliferous basins in Syria (Litak et al., 1998). Soukhne Formation is composed of shale, marl and argillaceous limestone, with some chert and phosphate nodules. Lithology of Shiranish Formation is mainly argillaceous limestone. According to lithology, microfossil assemblage and organic geochemistry paleoenvironment of deposition is assumed as outer shelf to upper slope. In the exploatory wells in the Hayan Block area, thickness of the Soukhne Formation is 80 to 380m, whereas thickness of the Shiranish Formation is between 30 and 180 m. Seventy one cutting samples (58 from Soukhne and 13 from Shiranish Formation) from four exploratory wells were analyzed using Rock Evbal pyrolysis to determine quantity, quality and thermal maturity of the organic matter. Total organic carbon is between 0.61 and 7.45 % (mean 3.9%). Very high generative potential (up to 57 mg HC/g rock) indicates presence of kerogen type I-II (HI=360-90 mgHC/g TOC) in the diagenetic stage of thermal evolution. After chloroform extraction, organic carbon significantly decreased (mean 2.20%Toc) but hydrogen indices were almost unaffected. High quantity of soluble organic matter could be attributed to the short distance migration from deeper more mature source rock of the same formations, but also could be partly generated from associated kerogen. Very high amount (about 10% in both kerogen and extract) of organic bonded sulfur due to the weak carbon-sulfur bonds enables generation of bitumen in the diagenesis. Another evidence for this conclusion is over 90% of non-hydrocarbons in extract but it also could be the result of biodegradation. Microscopic examination of organic matter concentrate reveals mixture of amorphous, algal, bacterially degraded kerogen with some resistant dinocysts and bitumen. Very strong yellow fluorescence means excellent quality of kerogen for hydrocarbon generation as well as thermal immaturity. Bitumen is soluble in immersion oil with reflectance below 0.20%Ro and positive alteration in fluorescent light. Gas chromatograms of the alkane fraction of bitumen show big naphthenic “hump” as a result of biodegradation. Domination of phytane over pristane pointed out anoxic conditions of the source matter deposition.

Izvorni jezik
Engleski

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