Petroleum system analysis of the northwestern part of the Persian Gulf, Iranian sector Alireza Baniasad a , Ahmad Reza Rabbani a,⇑ , Seyed Ali Moallemi b , Bahman Soleimany c , Mehrab Rashidi c a AmirKabir University of Technology, Faculty of Petroleum Engineering, Tehran, Iran b National Iranian Oil Company, IOR/EOR Institute for Oil and Gas Reservoirs, Tehran, Iran c National Iranian Oil Company, Exploration Directorate, Tehran, Iran article info Article history: Received 16 March 2016 Received in revised form 2 February 2017 Accepted 7 March 2017 Available online 16 March 2017 Keywords: Persian Gulf Binak Trough Biomarkers Oil family Inversion correlation Migration abstract Geochemical, geological, and geophysical data were used to identify and update genetic oil families, potential source rocks, and hydrocarbon generation kitchen as well as probable migration pathways in the northwestern part of the Persian Gulf. Rock-Eval analysis was performed on 52 cutting samples of prospective Cretaceous-Tertiary source rocks. According to the results, most of the samples have poor to fair potential for hydrocarbon generation, except for the Albian Formation which possesses good to excellent source rock characteristics in the study area. Two genetic oil families were identified based on source- and age-related biomarkers as well as stable carbon isotope ratios for 23 crude oil samples. Family I occurs in upper Jurassic-lower Cretaceous reservoirs mainly in the Surmeh-Hith Basin whereas family II occurs in lower Cretaceous-Tertiary reservoirs mainly in the Garau-Gotnia Basin. All attempts to correlate the identified families to prospective source rocks failed due to substantial maturity differences between the oils and rock samples. Inversion correlation based on detailed isotopic and biomarker analyses, however, confirms that the carbonates and marls of the Neocomian and Albian Formations are the main oil-generating facies for families I and II, respectively. The geographical exten- sion and composition of the identified oil families are highly affected by source rock facies distribution and migration pathways. 2D cross sections provided in the region indicate the dominance of lateral and vertical migration pathways from the Binak depression as the main hydrocarbon generation kitchen toward the structural highs in the study area. Ó 2017 Elsevier Ltd. All rights reserved. 1. Introduction The Persian Gulf is located in the foreland basin of the Zagros fold and thrust belt in the northeastern part of the Arabian Plate (Fig. 1). The northwestern part of the Persian Gulf (NWPG) is the most prominent hydrocarbon-bearing offshore area in Iran where recoverable oil reserves are reported to be more than 10,000 MMbbl (Alsharhan, 2014). Despite various previous studies (e.g. Bordenave and Hegre, 2010; Bordenave, 2014; Rabbani et al., 2014; Mashhadi and Rabbani, 2015; Mashhadi et al., 2015a, 2015b, Sefidari et al., 2015), a detailed understanding of the petroleum systems has not yet been obtained (i.e. the active petroleum sys- tems, hydrocarbon generation kitchen(s), and possible migration pathways). Our initial organic geochemical study indicated that there are at least two genetic oil families in the NWPG (Rabbani et al., 2014). These results showed that hydrocarbons in Jurassic-Cretaceous reservoirs of the H and G oilfields located in the Surmeh-Hith Basin (Family I) are genetically different from those in Cretaceous- Tertiary reservoirs of the A, B, D, E, F and H oilfields (Family II) located mainly in the Garau-Gotnia Basin (see Fig. 1 for the loca- tions). Enigmatically, hydrocarbons in the Tertiary reservoir of oil- field E show geochemical resemblances to family I, whereas those in the Cretaceous Burghan reservoir in this field are considered to be part of family II. This is an unlikely interpretation due to both geographic (Garau-Gotnia Basin) and stratigraphic (the Oligo- Miocene reservoir) considerations. Oil-source correlation was also not addressed in this previous study. For further comparison with our previous publication, 5 new oil and 52 drill cutting samples collected from Cretaceous-Tertiary source facies have been ana- lyzed to address these issues and to update the understanding of the petroleum systems in the NWPG. In addition, we have taken into account the evolution and structural settings of the basin using well and seismic data as well as the results of the basin mod- eling in the NWPG. The first objective of this study was to conduct a rigorous and defensible classification of genetic oil families on the basis of http://dx.doi.org/10.1016/j.orggeochem.2017.03.005 0146-6380/Ó 2017 Elsevier Ltd. All rights reserved. ⇑ Corresponding author. Fax: +98 21 64543535. E-mail address: rabbani@aut.ac.ir (A.R. Rabbani). Organic Geochemistry 107 (2017) 69–85 Contents lists available at ScienceDirect Organic Geochemistry journal homepage: www.elsevier.com/locate/orggeochem