Sedimentology
Sara Ebrahimi Meymand; Hamed Zand-Moghadam; Mohammad Khanehbad; Asadollah Mahboubi Mahboubi; Gholamreza Hosseinyar
Abstract
Nebkhas are one of the aeolian dunes that play an important role in wind erosion by stabilizing sediments around plants. Due to the depression of northern Shahdad plain (eastern Kerman), the sever wind impact, high rate of sediment supply and the presence of desert plants, nebkhas have expanded. In this ...
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Nebkhas are one of the aeolian dunes that play an important role in wind erosion by stabilizing sediments around plants. Due to the depression of northern Shahdad plain (eastern Kerman), the sever wind impact, high rate of sediment supply and the presence of desert plants, nebkhas have expanded. In this study in order to achieve the formation of nebkha in the Shahdad plain, sedimentological parameters and the effect of vegetation on nebkha geomorphology have been investigated. Due to the expansion of the study area and the different geomorphology of the nebkha, 30 nebkha were sampled along with sediments between them. the analysis of these sediments shows that nebkha sediments are often fine sand sizes that are well-sorted and rounded. However, sediments between nebkha often have a range between gravel (pebble) and fine silt which are subdivided into either surface and sub-surface sediments (depth greater than 2 centimeters). Surface sediments are often coarse grains (granule to coarse sand) and have relatively well roundness and sorting. Field investigations and analyses have shown that genus and plant species are important in the geomorphology of nebkhas in the Shahdad plain but the effect of vegetation on the sedimentary parameters is insignificant. This is due to the fact that the three types of vegetation identified (Tamarix stricta, Seditzia rosmarinus, Prosopis farcta), the highest levels of nebkha is for Tamarix stricta but the sedimentary parameters with different vegetation are not significantly different.
Mostafa Moradi; Asadollah Mahboubi; Mohammad Khanehbad; Ali Ghabieshavi
Abstract
The Asmari Formation is the main reservoir rock for the Aghajari oilfieild. It is composed of about 400-meter limestone, dolostone and interlayers of sandstones. Study of 1200 meters drilling cores, 2800 microscopic thin sections, 12 SEM analyses along with 125 routine core tests in 5 cored wells indicate ...
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The Asmari Formation is the main reservoir rock for the Aghajari oilfieild. It is composed of about 400-meter limestone, dolostone and interlayers of sandstones. Study of 1200 meters drilling cores, 2800 microscopic thin sections, 12 SEM analyses along with 125 routine core tests in 5 cored wells indicate that the Asmari Formation was effected by various diagenetic processes such as micritization, compaction, cementation, fracturing, dissolution and dolomitization. Some of these processes (e.g. dissolution, dolomitization and fracturing) have constructive effects on the reservoir quality and created wide variety of porosity types including vuggy, intercrystaline and channel in upper parts of the Asmari Formation. Destructive diagenetic processes (micritization, compaction and cementation) have destroyed pore spaces and make the lower parts of the Asmari (specially zone 5) to a non-reservoir unit. Porosity-permeability plots on the Lucia's diagram show sandstones and carbonates rocks with interparticle porosities have good reservoir qualities and always plot on upper parts of classes 1-3. Samples with fracture porosity mainly plot on upper part of class 1. This shows fractures has no considerable role in promoting the porosity, but they strongly increase permeability. Dolostones and the rocks with vuggy porosity have plotted on classes 2 and 3 (high porosity, relatively high permeability). Paragenetic secession of the Asmari Formation shows the diagenetic processes occurred syn-sedimentary on sea floor, after sedimentation during the low-deep burry and uplift. The results of this study can be useful in detection of reservoir zones, increasing of hydrocarbon production and enhanced recovery of this oilfield.
Sedimentology
Ehsan Zamaniyan; Mohammad Khanehbad; Reza Mossavi-Harami; Asadollah Mahboubi
Abstract
Qadir Member of Nayband Formation in the eastern part of central Iran have a wide outcrop. Investigating the lithofacies and sedimentary environment of Qadir Member of Nayband Formation (Upper Triassic) in east central Iran, Tabas Block, resulted in identifying the coastal plain, deltaic and open marine ...
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Qadir Member of Nayband Formation in the eastern part of central Iran have a wide outcrop. Investigating the lithofacies and sedimentary environment of Qadir Member of Nayband Formation (Upper Triassic) in east central Iran, Tabas Block, resulted in identifying the coastal plain, deltaic and open marine deposits. Based onfield evidences, the facies features and the geometry of beds, this member consists of two lithofacies include carbonate and siliciclastic facies. The siliciclastic facies were identified as having four sandstone facies (medium-grained), including Sr, Sh, Sp, St and three fine-grained lithofacies, including FI, Fm, Fl (Sr) / Sr (FI) and one coal facies (C). Also carbonate facies are calcirudite and calcarenite. Regarding the field, laboratory studies and identifying the lithofacies, the coastal plain, deltaic (including deltaic plain, proximal delta front, distal delta front, and prodelta) and open marine environments were identified for Qadir Member on which it is under the impact of tidal currents.
