Source rock evaluation and burial history modeling of Cretaceous rocks at the Khalda Concession of Abu Gharadig Basin, Western Desert, Egypt
Introduction
In Egypt, the exploration and production of oil and gas began a long time ago and is ongoing at present with the discovery of the Zoher and Shrouk gas fields in the Mediterranean Sea. In the northern Western Desert of Egypt, exploration activities have led to the discovery of several oil and gas basins (e.g., Abu Gharadig, Gindi, Alamein, Beni Suef, and Matruh-Shushan) (EGPC, 1992; Abdel-Fattah et al., 2014, 2015; Abd-Allah et al., 2018). The study area (the Khalda Concession) is located northeast of the Abu Gharadig Basin in the north Western Desert (Fig. 1). Several hydrocarbon discoveries have been made in this highly faulted sedimentary basin. The Abu Gharadig Basin is considered to be one of the most prospective basins in the northern Western Desert of Egypt for oil and gas fields (El-Shaarawy et al., 1994) (Fig. 1). The Abu Gharadig Basin has been extensively studied by many groups (e.g., Abdel Aal and Moustafa, 1988; Bayoumi and Lotfy, 1989; EGPC, 1992; Hammad et al., 1992; Khaled, 1999; Nabawy and ElHariri, 2008; Moldowan, 2012; Teama and Nabawy, 2016; Abdel-Fattah et al., 2020). Schlumberger (1984) determined that the source rocks in the Abu Gharadig Basin are present within noncalcareous shale sequences that are associated with a transgressive event that occurred during the Late Jurassic and Cretaceous. The Abu Roash F member and the Bahariya Formation are thought to be the main oil source rocks in the Abu Gharadig Basin (Lüning et al., 2004; El Diasty and Moldowan, 2012; Abd-Allah et al., 2018).
The results from evaluations of the source rocks, including basin modeling, and seismic data interpretation reduce the risk of exploration and may lead to the discovery of new prospective areas. The source rocks were defined as sedimentary rocks having the ability to accumulate oil and/or gas. The hydrogen content of kerogen is thought to be the most important parameter controlling the generation of oil and gas (Maowen et al., 2006; Kamali and Mirshady, 2004).
The present study uses Rock-Eval pyrolysis and %Ro data for rock samples from the SPYGLASS-1X and AG-24 wells and two-dimensional (2D) seismic sections to evaluate the hydrocarbon potential, quality of kerogen, and thermal maturation history of the Cretaceous source rocks (the Abu Roash F and G members and the Bahariya Formation) in the Khalda Concession (Fig. 1). Two burial history models were constructed using the PetroMod software to determine the oil and gas window and the timing of the hydrocarbon generation using the modeled %Ro. In addition, the structural setting and the entrapment styles of the generated hydrocarbons were determined via an interpretation of 2D seismic lines using the Petrel software platform. Studying unconventional reservoirs has become the main object of exploration to increase crude oil reserves for many oil companies in Egypt, including Khalda and Apache. Accordingly, geochemical studies and basin modeling of the Abu Roash F and G members and the Bahariya Formation are a very important part of the future exploration of unconventional reservoirs in the Abu Gharadig Basin, especially the Abu Roash F member, which primarily consists of argillaceous limestone enrichment in organic matter with very low matrix permeability (Adly et al., 2016).
Section snippets
Lithostratigraphy
The lithostratigraphy of the Abu Gharadig Basin is composed of rock units ranging from the Precambrian to recent geologic time (Fig. 2) (EGPC, 1992). Its Paleozoic sediments vary from early Cambrian to Late Permian and un-conformably overlie a Precambrian basement and are in turn unconformably overlain with Jurassic sediments (the Eghei, Khatatba, and Masajid formations) and/or younger deposits (Fawzy and Dahi, 1992). During the Early Cretaceous, thick Neocomian–Albian marine sediments to
Tectonics and structures
The Abu Gharadig Basin is a part of the Egyptian Western Desert. This basin was affected by six major geotectonic cycles or phases, illustrated in Fig. 3, listed from younger to older as follows: the Red Sea phase (Oligocene–Miocene), Syrian Arc main phase (Paleogene), Sub Hercynian–Early Syrian Arc (Turonian–Santonian), Cimmerian/Tethyian (Triassic–Early Cretaceous), Variscan–Hercynian (Late Paleozoic), and Caledonian cycle (Cambrian–Devonian) (Meshref, 1990). The Western Desert is divided
Materials and methods
In this study, 36 cutting samples of the studied rock units from the SPYGLASS-1X and AG-24 wells (Table 2, Table 3, respectively) were analyzed for Rock-Eval pyrolysis and total organic carbon (TOC) by the StratoChem Services and EXLOG companies for the Khalda Petroleum Company. Subsequently, 12 ditch samples were selected and analyzed for %Ro based on the amount of TOC being equal to and/or greater than 0.5 wt% of the analyzed samples. These data were obtained from the Khalda Petroleum Company
Results and discussion
This study assessed the Abu Roash F and G members and the Bahariya Formation as the source rocks for produced hydrocarbons in the SPYGLASS-1X and AG-24 wells of the Khalda Concession at the Abu Gharadig Basin. The results of the TOC and Rock-Eval pyrolysis analyses of these formations are shown in Table 2, Table 3 Here, the hydrocarbon potentiality, types of kerogen, thermal maturation and generation, one-dimensional basin modeling, and the entrapment styles of the hydrocarbons are determined
Conclusions
The main conclusions of this study can be summarized as follows.
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Based on the TOC and Rock-Eval pyrolysis results, the Abu Roash F and G members have very good hydrocarbon potentiality while the Bahariya Formation has poor to fair hydrocarbon potentiality.
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The HI and QI values indicate that the kerogen is mainly Type II (Abu Roash F member) with a marine origin, mixed Type II/III (Abu Roash G member) with marine and terrestrial origins, and Type III (Bahariya Formation) with a terrestrial origin.
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Declaration of competing interest
The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
Acknowledgements
The authors submit deep thanks for the Egyptian General Petroleum Corporation (EGPC) for their permission to use these data to achieve this work. We are grateful to the Khalda Petroleum Company (KPC) for the materials of this paper. Profound thanks are extended to the StratoChem Services Company and EXLOG Company for analyzing the rock samples. Also, thanks are due to the Schlumberger Company for supplying us with the PetroMod and Petrel software used in this work. We thank Mr Brett Chamberlain
References (90)
- et al.
Assessment of eocene, paleocene and cretaceous source rocks in the West feiran area, offshore gulf of suez, Egypt
J. Petrol. Sci. Eng.
(2019) - et al.
Integrative 1D-2d basin modeling of the cretaceous BeniSuef basin, Western Desert, Egypt
J. Petrol. Sci. Eng.
(2017) - et al.
Integrated seismic attributes and stochastic inversion for reservoir characterization: insights from Wadi field (NE Abu-Gharadig Basin, Egypt
J. Afr. Earth Sci.
(2020) - et al.
3D seismic characterization of the polygonal fault systems and its impact on fluid flow migration: an example from the Northern Carnarvon Basin, Australia
J. Petrol. Sci. Eng.
(2018) - et al.
Modes of structural evolution of abu Gharadig basin, Western Desert of Egypt as deduced from seismic data
J. Afr. Earth Sci.
(1989) Organic maturity of late cretaceous and tertiary coal measures, Canadian arctic archipelago
Int. J. Coal Geol.
(1986)- et al.
Application of biological markers in recognition of the geochemical characteristics of some crude oils from Abu Gharadig Basin, North Western Desert, Egypt
Mar. Petrol. Geol.
(2012) - et al.
Seismic interpretation and tectonic re-gime of Sudanese Rift System: implications for hydrocarbon exploration in Neem field (Muglad Basin)
J. Petrol. Sci. Eng.
(2020) - et al.
Organic geochemical characteristics and oil generating potential of the Upper Jurassic Safer shale sediments in the Marib-Shabowah Basin, western Yemen
Org. Geochem.
(2013) - et al.
Pyrolysis analyses and bulk kinetic models of the Late Cretaceous oil shales in Jordan and their implications for early mature sulphur-rich oil generation potential
Mar. Petrol. Geol.
(2018)