The Persian Gulf Basin: Geological history, sedimentary formations, and petroleum potential
ABSTRACT The Persian Gulf Basin is the richest region of the World in terms of hydrocarbon resources. According to different estimates,
the basin contains 55–68% of recoverable oil reserves and more than 40% of gas reserves. The basin is located at the junction
of the Arabian Shield and Iranian continental block that belong to two different (Arabian and Eurasian) lithospheric plates.
Collision of these plates at the Mesozoic/Cenozoic boundary produced the Zagros Fold Belt and the large Mesopotamian Foredeep,
which is a member of the Persian Gulf Basin. During the most part of the Phanerozoic, this basin belonged to an ancient passive
margin of Gondwana, which was opened toward the Paleotethys Ocean in the Paleozoic and toward the Neotethys in the Mesozoic.
Stable subsidence and the unique landscape-climatic conditions favored the accumulation of a very thick sedimentary lens of
carbonate rocks and evaporites (up to 12–13 km and more). Carbonate rocks with excellent reservoir properties are widespread,
while the evaporites play the role of regional fluid seals. Organicrich rocks, which can generate liquid and gaseous hydrocarbons
(HC), are present at different levels in the rock sequence.
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ABSTRACT: There are several source rock units in the Zagros Basin, but the Cretaceous Kazhdumi and Paleogene Pabdeh formations probably have produced the majority of the commercial hydrocarbons in this area. Among the hydrocarbon provinces of Iran, the Dezful Embayment, which is located southwest of Zagros Mountains, is one of the most prolific regions in the Middle East. Numerous studies have been made in the northern part of the Dezful Embayment, but relatively few have been done in its southern part. The present study focuses on organic matter characterization of two potential source rocks (Kazhdumi and Pabdeh formations) in southern part of the Dezful Embayment. Cuttings samples (114) were collected from 10 wells and evaluated using Rock–Eval pyrolysis and organic petrography in order to characterize the content and type of organic matter and thermal maturity. The results showed that the average total organic carbon (TOC) content of Kazhdumi and Pabdeh formations are 2.48 and 1.62 wt%, respectively. The highest TOC contents for both formations are found in the northern compartment and decreased gradually toward the south. Pyrolysis data reveal that organic matter has a fair to very good hydrocarbon generation potential and are classified as Type II–III and Type III. Rock–Eval Tmax and vitrinite reflectance show that the majority of samples are in the early mature to mature stage of the oil generation window.Organic Geochemistry 49:36–46. · 2.52 Impact Factor
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ABSTRACT: The Persian Gulf is part of an asymmetric foreland basin related to the Zagros Orogen. Few published studies of this basin and associated onshore areas include seismic reflection data. We present a seismic-stratigraphic interpretation based on marine 2D seismic data, which reveals the presence of two types of compressional structures within the basin: (1) faulted domes related to salt movement and the offshore trace of a NNE–SSW-trending dextral basement fault (the Kazerun Fault); (2) long-wavelength (16 km), low amplitude (60 ms two-way travel time) folds relating to the advancing deformation front associated with the orogen. Thinning of age-constrained stratal units across structures related to the offshore trace of the Kazerun Fault implies a distinct pulse of uplift on this fault during the Maastrichtian. The geometry of growth strata across other intra-basin structures suggests a second, later stage of deformation, which began in the Middle Miocene. Thickening and folding of post-Middle Miocene stratal units towards the NE (i.e. towards the Zagros Orogen) is interpreted to reflect rapid loading, subsidence and compression related to southwestwards advance of the orogen. The results of this study have implications for the interaction between pre-existing structures and later compressional events both within the Persian Gulf and elsewhere.Journal of the Geological Society 01/2011; 168(2):485-498. · 2.58 Impact Factor
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ABSTRACT: The Middle Cretaceous–Early Miocene Petroleum System is the most important hydrocarbon system in the Zagros Basin. Rock-Eval pyrolysis, organic petrography and thermal 1D modeling were performed on wells located in the southern Dezful Embayment. The results provide information on organic matter quantity and quality as well as burial and thermal histories of source rocks in the framework of the basin evolution. A total of 98 cutting samples from BK-4, KK-1, SI-4 and RS-2 wells were pyrolyzed by Rock-Eval 6. Also thermal maturity of organic matter derived from Tmax of Rock-Eval was interpreted in conjunction with vitrinite reflectance data (50 samples). The TOC values of the sequences mainly range from 0.5 to 2.5 wt.%. The average values of Tmax and vitrinite reflectance indicate that samples from the wells have reached maturities corresponding to early/mid oil generation. Reconstruction of thermal history suggests that various steady heat flow values (62, 54, 50 and 56 mW/m2 for BK-4, KK-1, SI-4 and RS-2 wells, respectively) resulted in the best fit between the calculated and the observed vitrinite reflectance and bottom hole temperatures in our modeling. Thus, values of heat flow decrease from 60 mW/m2 in the southern basin margin to about 50 mW/m2 along the NE of the Dezful Embayment and the Zagros Basin. According to our modeling results, the onset of oil generation from source rocks in the studied area occurs well after deposition of the seal rock and formation of traps, ensuring entrapment and preservation of migrated hydrocarbons.International Journal of Coal Geology 12/2013; 120:1–14. · 3.31 Impact Factor