Facies Analysis and Depositional Sequences of the Upper Jurassic Mozduran Formation, a Carbonate Reservoir in the Kopet Dagh Basin, Ne Iran

Abstract

Upper Jurassic carbonates of the Mozduran Formation constitute the principal reservoir intervals at the giant Khangiran and Gonbadli gasfields in the Kopet Dagh Basin, NE Iran. These carbonates were investigated using detailed field studies and petrographic and wireline log analyses in order to clarify their depositional facies and sequence stratigraphy. Facies were interpreted to reflect deep basin, fore-shoal, shelf margin, lagoon, tidal flat and coastal plain depositional systems.The Mozduran Formation is composed of six depositional sequences. Thickness variations were controlled by differential subsidence. Aggradation on the platform margin and reduced carbonate production in the deep basin together with differential subsidence resulted in the creation of a narrow seaway during the late Oxfordian. Petrographic studies suggest that Mozduran Formation carbonates had a low-Mg calcite mineralogy during the Oxfordian, and an aragonite to high-Mg calcite mineralogy during the Kimmeridgian. Reservoir pay zones are located in highstand systems tracts within the lower and middle Kimmeridgian depositional sequences. The rapid lateral thickness variations of these sequences were controlled by tectonic factors, leading to compartmentalization of the Mozduran Formation reservoir with the possible creation of stratigraphic traps, especially at the Khangiran field.

Sedimentary facies and depositional environments of the neoproterozoic sediments of the Gambaga-Nakpanduri massifs, Voltaian Basin

“…The presence of burrows without sediment filling supports their development in consolidated sediments. The evidence of their intense bioturbation reflects low/break in sedimentation rate according to Kavoosi et al (2009), moderate sediment supply rate is also reported by Odumoso et al (2013) and this is indicative of sediments of foreshore/shoreface environments. The presence of wavy laminations with relatively high feldspar content supports sediments deposition under turbulence in a continental shelf environment.…”

“…The interpretation of facies can be by considering the depositional environments, processes and the prevailing conditions at the time of deposition. Different energy levels of the depositional media could reflect variable sedimentary facies as the sedimentary structures will be different with a possible similar composition of the sediments, hence, the grouping of the sediments into facies is principally based on the observed sedimentary structures, which reflects the depositional environments, conditions and processes, the composition and the texture of the sediments (Tucker, 2004;Kavoosi et al, 2009).…”

Depositional characteristics and constraints on the mid-Valanginian demise of a carbonate platform in the intra-Tethyan domain, Circum-Rhodope Belt, northern Greece

“…In both cases they were characterized as shallow marine sediments deposited above fair-weather wave base. Also, Kavoosi et al (2009) interpreted the same microfacies association from Upper Jurassic rocks of NE Iran as fore-shoal deposits. The non-fossiliferous calcimudstones forming uppermost levels of the Porto Koufos Limestones (interval IV, Fig.…”

The Carbonate Platform Model and Reservoirs’ Origins of the Callovian-Oxfordian Stage in the Amu Darya Basin, Turkmenistan

“…Hereafter, the Amu-Darya Basin entered the development stage of rift basin [63] and a period of stable settlement. In Lower-Middle Jurassic, there were the clastic sediments with greater thickness [64], which were unconformably contacted with the underlying stratum [65]. In Middle Jurassic Bathonian Stage/Callovian Stage, there was large-scale transgression, and the successive paleo-uplifts (e.g., Chardzhou, Dengizkul, Sandykly) and basement faults in the basin controlled the deposition of …”