Organic geochemical characteristics of Jurassic petroleum system in Abadan Plain and north Dezful zones of the Zagros basin, southwest Iran

Abstract

Jurassic succession has resulted in prolific oil and gas reservoirs in southwest Iran. In order to geochemically investigate the Jurassic petroleum system and assess the source rock of these hydrocarbons, 32 source rock samples (from well cutting and surface section) and 4 condensate samples were analysed using geochemical approaches. Rock-Eval pyrolysis and vitrinite reflectance measurement were done on rock samples. Then, condensate samples and source rock extracts were subjected to gas chromatography, gas chromatography-mass spectrometry and isotopic analyses in order to establish oil-oil and oil-source rock correlation. The hydrocarbon generation prediction was then confirmed by petroleum system modelling. The results indicated that the middle Jurassic Sargelu Formation with average total organic carbon (TOC) and hydrogen index values of 3.8% and 600 mg HC/g TOC, respectively, can be classified as good to excellent source rock with kerogen of type II. The maturity indicators revealed late oil to wet gas generation window for the Jurassic Sargelu Formation. Biomarker parameters showed marine carbonate source rock with advanced level of thermal maturity for the source rock of the condensates. Furthermore, there were good correlations between Jurassic Sargelu Formation and the studied oil and condensate samples which proved the Sargelu Formation as the main source rock of the Jurassic petroleum system in the study area. The basin modelling results also confirmed late oil to wet gas window maturity for the Sargelu Formation enabling it as a source rock for generating gas condensate accumulation in southwest Iran. The hydrocarbon generation from Sargelu Formation began in the late Cretaceous and its peak expulsion occurred in the Miocene time.

Source Rocks’ Potentiality of the Sargelu Formation (Middle Jurassic) in the Taq Taq Oilfield, Kurdistan Region, Iraq

“…Generally, the Sargelu Formation in the northern parts of Iraqi Kurdistan Region (including Duhok, Tawke, and Atrush areas) and in the Makhule Field characterized by higher petroleum potentiality when compared with the other locations mentioned in Table 7. The most similar recorded source rock properties for the Sargelu Formation in the present study of Taq Taq Field are those been recorded in the Miran Field (Fatah and Mohialdeen, 2016) within Iraqi Kurdistan Region and in the Abadan Plain and north Dezful Zone of the Iranian Zagros Basin (Kobraei et al, 2019).…”

“…Regarding thermal maturity state, the Sargelu Formation showed a range of maturity between immature to post mature (gas generation). Highest maturity observed in the Taq Taq and Miran fields the Zagros Fold Belt (High Folded Zone), which shows similarity to the Abadan Plain and north Dezful Zone of the Iranian Zagros Basin (Kobraei et al, 2019). On the other hand, the formation reported immature to early mature in the uppermost part of Northern Iraq in the Twake Field and Duhok region.…”

“…In this study, an attempt is made to evaluate potentiality of the Sargelu Formation as a source rock from the well Tq-1 that has penetrated the formation in the Taq Taq Oilfield. Different tools are used in the evaluation process and the results compared with work previously done on the same formation in nearby areas (Ahmed, 2001;Pitman et al, 2004;Al-Ahmed, 2006;Al-Ameri et al, 2014;Abdula, 2015;English et al, 2015;Fatah and Mohialdeen, 2016;Najaf, 2018, Hakimi et al, 2018Kobraei et al, 2019;Mamaseni, 2020).…”

Evaluation of hydrocarbon generation potential of source rock using two-dimensional modeling of sedimentary basin: a case study in North Dezful Embayment, Southwest Iran

“…It is believed that most of Iran's oil and gas is generated during the Jurassic (e.g. Sargelu Formation) and Cretaceous (Garu and Kazhdumi formations), with the generated hydrocarbons trapped in the reservoirs across the Dezful Embayment and Abadan Plain during the Cretaceous and Cenozoic (Kobraei et al 2019). Kazhdumi Formation is believed to have served the Dezful Embayment as the main source of hydrocarbon generation.…”

Introducing a Novel Approach for Oil‐Oil Correlation based on Asphaltene Structure: X‐ray Diffraction

“…Most researchers have published their achievements based on these two aforementioned geochemical tools, which are measured in crude oil fractions or whole oil samples. Biomarker ratios and stable carbon isotope results are used extensively in oil-oil correlation studies (Telnaes and Dahl, 1986;Galimov and Rabbani, 2001;Rabbani, 2007Rabbani, , 2008; Kamali et al, 2013;Rabbani et al, 2014;Sourour et al, 2015;Rabbani and Baniasad, 2017;Alizadeh et al, 2018;El Diasty et al, 2019;Kobraei et al, 2019), whereas several authors have used trace elements (Hitchon and Filby, 1984;Ellrich et al, 1985;Filby, 1994;López et al, 1998;Akinlua et al, 2008Akinlua et al, , 2010Akinlua et al, , 2015Abdula et al, 2018) and diamondoids (Wang et al, 2006;Baniasad et al, 2014) to achieve this objective.…”