فهرست مطالب r. moussavi-harami

The Sarvak formation (Cenomanian-Turonian) has one of the main stratigraphical units in SW of Iran oil fields and Abadan plain due to huge amounts of trapped oil. Investigation of Sarvak Formation based on 3 wells data including core, petrographical analysis, petrophysical logs, and POROPERM data which was received from the core laboratory, led to recognized seven microfacies in this succession. The identified facies were deposited in five sub-environments; restricted lagoon, shoal rudist biostromes, and open marine. The situation of each facies and their depositional setting proposed the homoclinal carbonate ramp platform.Petrographical investigation shows the several diagenetic realms that affected this formation. the main diagenetic process identified in this research are, micritization, mechanical and chemical compaction, dissolution, cementation, stylolitization, dolomitization, silicification, and fracture. The depositional environment of Sarvak formation affected by a sea-level change in Cenomanian-Turonian time which is affected the reservoir section by several diagenetic phenomena. To investigate the reservoir rock typing two methods were analyzed. One of them is based on microfacies analysis and diagenetic process investigation and the other is based on RQI/FZI index. integration data and analysis show that dissolution has a positive effect, especially in grain-supported facies and cementation has a negative impact on reservoir quality index. the result of this study could be implemented in the planning of hydrocarbon exploration and development stage.

Lithofacies analysis and interpretation of architectural elements of Oligocene silisiclastic deposits in Binaload Zone were investigated in Baghshan-Gach area, north of Neyshabour. This study led to identification of 14 lithofacies and 4 architectural elements in the sequence of 150 meter thick. Lithofacies are classified into three categories including coarse grain (Gmg, Gcm, Gmm, Gh, Gp and Gt), medium grain (Sh,Sp,St,Sr,Sm and Sl), and fine grain (Fl,Fm). The architectural elements are CH, SB, LV and SG. It is interpreted that Oligocene silisiclasic sediments have been deposited in braided river system, based on lithofacies analysis and architectural elements. Petrofacies analysis indicates that these rocks had oroigin from the magmatic arc and deposited under arid climatic condition. paleocurrent analysis represents that the river was flowing from NE to SW direction.

Ilam Formation is the reservoir rock of Maleh-Kuh oilfield located in folding-thrusting Zagros zone in Lurestan province. It is mainly composed of mud-supported lithofacies varying from mudstone to wackestone. The most important identified diagenetic processes are compaction (physical and chemical), aggrading neomorphism, different replacement (pyritization, dolomitization, glauconitization and silicification), cementation, several generations of fracture, and burial dissolution. The main recognized pore types are moldic, vuggy, stylolitic, intercrystalline, and intragranular. Paregenetic sequence interpretation of Ilam Formation indicates that a set of diagenetic processes such as syndepositional diagenesis in marine environment, as well as post-depositional shallow to deep burial diagenesis, and uplift have affected this reservoir rock. Porosity and permeability data plots show that these facies have very low reservoir quality and most diagenetic processes have not had a major effect on increasing reservoir quality, and, only in some cases, permeability has been increased by stylolitization and fracturing.

Aitamir Formation (Albian–Cenomanian) crops out in the Kopet-Dagh basin in north-east Iran.This formation is mainly composed of sandstone, shale, siltstone, and several shellbeds. One of the major components in all of the siliciclastic facies is glaucony. They are autochthonus and parautochthonus types which have formed in suitable physico-chemical conditions and replaced quartz, chert, feldspar, mica and carbonate cement. Nonselective replacement, poorly sorted, along with phosphate, fish teeth and morphological shrinkage are major evidences of autochthonus glaucony. These glauconies are pale green nascent, evolved and highly evolved. Glaucony within marine deposits (suitable host rock), associate with bioturbation, presence of pellets of nascent glaucony and debris of sparse glaucony within the matrix forms of greenhalo are others evidences of autochthonus glauconites. Characteristics of paraautochtonus glaucony, including: ooidal rims around rounded peletic glauconites, well sorted glauconys, presence of glauconites within cross lamination and low fractures in peletics glauconites due to local reworking into in early transgressive surface.

The Sachun Formation (Paleocene-Lower Eocene) is mainly composed of carbonates and evaporates that were deposited in shallow-marine evaporitic mudflat environments. The Sachun Formation in the study area has been divided into three units including: lower evaporate; middle bioclastic limestone and upper evaporate. It is mainly composed of diagenetic gypsum, which originated from dehydration of anhydrite precursor. This gypsum in the Sachun Formation generally displays alabastrine and porphyroblastic textures with corroded anhydrite relics. Petrological studies reveal that the most important diagenetic processes affected the middle Part of the Sachun Formation are dolomitization and evaporate mineralization. Four types of dolomite, ranging from early to burial diagenetic environments, were identified. These are including very fine-to-fine crystalline (D1), neomorphic dolomite (D2), fine-to-medium crystalline euhedral to subhedral dolomite (D3) and pore- and fracture-filling dolomite (D4).

The 50 meters thick Top Quartzite sediments in Kerman area is laid between siliciclastic red beds of the Dahu Formation and carbonate deposits of the Kuhbanan Formation. Three stratigraphy sections were measured at Gazuieh, Katkuieh and Dahuieh in eastern Zarand for analysis of depositional environment. Field and petrographic studies led to identification of a conglomerate petrofacies and three sandstone petrofacies (chert arenite, quartz arenite, sublitharenite) with high textural and compositional maturity. Lithofacies analysis resulted in recognition of three coarse grain (Gcm, Gms, Gt), seven medium grain (Sp, St, Sh, Sl, Sr, Sm, Se), one fine grain (Fl) and three intermediate sand-mud lithofacies (Sr(Fl), Sr/Fl, Fl(Sr)). Structural and textural evidences as well as predominant bimodal paleo-currents in most facies show that these sediments have been deposited in the tidal flat environment. The coarse, medium and fine grain sediments are deposited in tidal channels, intertidal flats, supratidal flats, respectively. We hope represented data in the study improve the basin analysis and paleogeographical reconstruction of Cambrian sedimentation.

Two stratigrphic sections from Dahu Formation (Early Cambrian), at Gezuieh and Dahuieh (type section) in E and SE Zarand, NW Kerman, with thickness of 227 and 240 meters respectively, were measured. These data have been used for interpretation of provenance of these siliciclastic sediments. Lithofacies, architectural elements and petrofacies analysis show that Dahu Formation has been deposited in meandering river system when the river was flowing from south toward the north. Provenance studies and depositional history, using petrography frameworks characteristics, paleocurrent analysis and tectonic setting (using the triangle diagram Qt-F-L and Qm-F-Lt), show that the sediments of Dahu Formation may have been derived from alkali granite related to Pan-African orogeny from Saudia Arabian train. These sediments may have been deposited as post rift sediments in Kerman region. We hope that this information can be used for paleogeographical reconstruction of the Early Cambrian time in local and regional scales.

Siliciclastic sediments of the Cheleken Series (Lower to Middle Pliocene) are exposed along the northern flank of Elburz Mountain Range. The goal of this study is to identify the clay mineral type in these siliciclastic sediments in Mazandaran and Golestan regions, because this can help in the prediction of drilling mud type that can be used. 23 samples have been collected from Neka, south of Ghaem Shahr and Alamdeh regions. Petrographic and XRD analysis revealed that sandy siliciclastic sediments with conglomerate interbeds are mainly consists of quartz, calcite and clay minerals. Illite and kaolinite is the major and monmorilonite and chlorite are the minor clay minerals in these sediments. Based on these types of clay minerals in study area, we suggest that the best drilling mud for using in these sediments are salt/polymer water – based mud with a suitable amount of potassium salts. Because these materials are available in Iran and they are relatively less expensive as well as potassium with low ionic diameter has the least problems during cation exchange in clay minerals that present in cheleken series.