A. Bavi Ovaydi; M. H. Adabi; A. Sadeghi; H. Amiri Bakhtiar
Abstract
Dolomitic limestone and dolomite comprise the most part of Ghorban member of the Sachun Formation (Paleocene-early Eocene) in Ghareh Anticline section in southeast Shiraz. Geochemical and petrographic studies of these deposits indicate that these dolomites have formed in marine, meteoric and burial diagenetic ...
Read More
Dolomitic limestone and dolomite comprise the most part of Ghorban member of the Sachun Formation (Paleocene-early Eocene) in Ghareh Anticline section in southeast Shiraz. Geochemical and petrographic studies of these deposits indicate that these dolomites have formed in marine, meteoric and burial diagenetic environments. According to these studies, three types of dolomites have been recognized including dolomicrite (less than 16 µm), dolomicrosparite (16-62 µm) and dolosparite (more than 62µm). Evidences such as fenestral porosity, evaporate minerals (gypsum and anhydrite), intraclast and lack of fossil show that dolomicites have been deposited in supratidal environment. Dolomicrosparites which been formed due to recrystalization of dolomicrites and replacement of micrite, have higher amount of Fe and Mn, and lower amounts of Na, Sr and Mg. Quantities and contributions of the above mentioned elements are related to more diagenetic effect on dolomicrites and formation of these dolomites in medium to deep burial diagenesis environment. Dolosparites have been seen in three forms. The first form includes euhedral crystals of dolomite that have been replacement of red algae and micrite. Second form of dolosparites that consist of crystals with syntexial overgrowth, luminescence with zones consisting of light and dull bands and fluids inclusion are pore filling cements which form in burial diagenetic environment. Euhedral-subhedral, porous, destructive fabric with sucrose texture Dolosparites (the third form) in Sachun-Jahrum formations boundary have been interpreted as meteoric-marine mixing zone environment product.
M Mohammadi; H Amiri Bakhtiar; F Amraee
Abstract
This study aimed to compare Asmari Formation in two sections in Maleh-Kuh and Amiran anticlines based on benthonic foraminifera. In this study, 26 species and 16 genera of benthonic foraminifera from the Maleh-Kuh section yielded 2 biozones of Elphidiumsp. 14 – Peneroplis, farsenensisandBorelismelocurdica ...
Read More
This study aimed to compare Asmari Formation in two sections in Maleh-Kuh and Amiran anticlines based on benthonic foraminifera. In this study, 26 species and 16 genera of benthonic foraminifera from the Maleh-Kuh section yielded 2 biozones of Elphidiumsp. 14 – Peneroplis, farsenensisandBorelismelocurdica – Borelismelomeloweresuggesting an age of Aquitanian – Burdigalian for the formation. In Amiran anticline based on 27 species and 20 genera only the biozone of Borelismelocurdica – Borelismelomelo (Burdigalian)was recorded.Based on this study, the Asmari sequence in Maleh-kuh Section (with a thicknessof 310m) deposited earlier In Aquitanian. But in Amiran section (with a thickness 162m) deposition started in Burdigalian and ended synchronously in both sections. In both sections the Asmari Formation overlain Shahbazan Formation disconformably and is in turn under lain by Ghachsaran Formation concordantly-transitionally in Maleh-Kuh and by a sharp contact in Amiran Section.
A Ahifar; A Kani; H Amiri Bakhtiar
Abstract
Pabdeh Formation has been investigated in three sections viz. the Type Section, Tang-e Hatti and the northern limb of Gurpi Anticline within the ZagrosSedimentaryBasin with emphasis on calcareous nannofossils. Study of microscope slides prepared from the 1508 collected samples resulted in determination ...
Read More
Pabdeh Formation has been investigated in three sections viz. the Type Section, Tang-e Hatti and the northern limb of Gurpi Anticline within the ZagrosSedimentaryBasin with emphasis on calcareous nannofossils. Study of microscope slides prepared from the 1508 collected samples resulted in determination of 256 species belonging to 59 genera from 22 families of nannofossils and biostratigraphic classification was carried out based on their stratigraphic distribution. According to Martini (1971) zonal scheme, presence of NP4-NP23 nannofossil zones at the Type Section, and NP5-NP23 nannofossil zones at both Tang-e Hatti and northern limb sections have been ascertained thus indicating Early Paleocene to Early Oligocene age for the Pabdeh Formation at these three localities. Calcareous nannofossil assemblages reveal sedimentation of Pabdeh Formation occurred in an oligotrophic, warm water environment during Paleocene-Eocene which was later on replaced by a relatively cooler water condition in Oligocene times.
Kh Noraei Nezhad; H Amiri Bakhtiar; R Mohammadian; A Azizi
Abstract
Marun Oil Field is located in the southern part of Dezful embayment, in the mid part of the zagros simple folded mountain range and along the Ramin and Aghajari anticlines. In this study, based on the subsurface data and using subsurface analytical methods the folding mechanism and fractures of this ...
Read More
Marun Oil Field is located in the southern part of Dezful embayment, in the mid part of the zagros simple folded mountain range and along the Ramin and Aghajari anticlines. In this study, based on the subsurface data and using subsurface analytical methods the folding mechanism and fractures of this anticline has been studied. In this research, using the primary results of geophysical data, analysis methods, geometric curvature changes, mud loss and reservoir engineering data, geometry of anticline and fractures associated with folding have been analyzed. Folding mechanisms in this anticline is a combination of flexural-sliding folding and folding with neutral surface. In other words, the Marun subsurface anticline is a thrust fault- related fold and also a faulted detachment fold. Seismic profiles showthat the Marun anticline as a concentric fold that from surface to depth space has been decreased. This decrease of space associated with faulting in the southern flank and these faults disappear in the Gachsaran formation. A good conformity among geometric analytical methods, mud loss data, index productivity on bending region in the Marun anticline and presence of fractures in this region exist. The data analysis shows that the highest density of fractures is related to the bending region in the Marun Oil Field. Finally, using these parameters, it is recommended that for further drilling of development and production wells these parameters must be regarded and the northeastern part of the Oil Field as well as southern flank of the anticline must be given full consideration.
