نشریه علوم زمین خوارزمی
سال هشتم شماره 2 (پاییز و زمستان 1401)

Accurate reservoir description in hydrocarbon and water bearing zones is one of the most important steps in reservoir characterization and modeling. Information about reservoir properties can be obtained from different sources such as geological data, seismic data, well logging data, core measurement data, well test data and reservoir production history. Well test data contain valuable information on the dynamic behavior of reservoirs. It is essential to integrate all sources of information for a successful description of a reservoir. However, it is a relatively difficult task to integrate all sources of information quantitatively, since these sources of information have different resolutions.  The main objective of the third phase of this project is to find fine-scale permeability profile in the gas and water zones of the studied field. For this purpose, in a history matching process of the bottomhole pressure, the permeability distribution estimated from petrophysical and core data has been corrected by the calculated permeability from analytical well test interpretation. Of course, the other effective parameters to be adjusted during the history match of the bottomhole pressure are the skin factor and the rate-dependent skin. Capillary pressure and relative permeability should also be used for matching of DST water production data. In this study, 6 DSTs from two wells were investigated. In this report the methodology of single well simulation study including model construction, initialization and history matching for 6 DSTs has been described. The results of this study will be used as input data for the sector simulation modeling.

Based on tectonic and sedimentological characteristics, Neogene deposits were chosen to review due to their high extent in the Eshtehard area (Alborz Province) and lack of previous information. These sediments were not determined in the area due to an indistinct lower boundary and the absence of the Qom Formation, and they were attributed to the Neogene. The clastic-evaporitic continental deposits in the north of Eshtehard, Mard Abad, Salt Mine and Rud Shur sections were divided into five sedimentary units (M1 to M5) based on facies and lithological characteristics. Lithological studies showed that the composition of the sediments of the M1 to M4 units is very different from that of the M5 unit. Field observations reveal an erosional unconformity between M4 and M5 units, and the salt dome has pierced M4 but has no effect on unit M5. Comparing the Neogene units of the Eshtehard area with equivalent sedimentary deposits in the Avaj area, it seems that the deposits of the M1 to M4 units in the Eshtehard area are equivalent to the Upper Red Formation, and the M5 unit belongs to the Pliocene and suggests that it should be considered as a new formation.

One of the most important concerns in aquifers adjacent to oil facilities is pollution caused by LNAPL leaks. Because these compounds have less weight than water, they float on the surface of the water as a layer and move along with the water flow. Recovery of LNAPLs is always difficult and expensive. This study aims to manage the recovering costs by determining the hydrodynamic coefficients of LNAPL. The hydrodynamic coefficients include transmissivity and specific yield. In this study, for the first time, instead of the term specific yield, the term oil specific yield has been used according to the type of fluid in the aquifer. The Rockwork model was used to calculate the oil specific yield and LDRM (LNAPL Distribution and Recovery Model) model was used to calculate LNAPL transmissivity coefficient. The inputs of the LDRM model include soil and LNAPL parameters, porosity, hydraulic conductivity of water saturation, van Genuchten parameters, mass densities of water and LNAPL, surface tensions of water-LNAPL, LNAPL-air and water-air, viscosities of water and LNAPL. From the inputs, LNAPL transmissivities and recoverable and total LNAPL specific volumes were extracted as output results. With the help of the obtained results, maps of LNAPL transmissivities, thickness and recoverable volume of LNAPL were prepared and the best recovery locations were introduced.

The Gooreh Mountain is located about 55 km northwest of Anarak (northeast of Isfahan) and in the western margin of the Central-East Iranian microcontinent (west of the Yazd block). The field studies show that the Eocene volcanic rocks in this area present two lithologies of gray-colored dacite and light-colored rhyolite. Dacite lavas cross-cut the rhyolite ones and are younger. Petrography indicates that dacites contain the major minerals of plagioclase (labradorite and bytownite), clinopyroxene (augite) and quartz, and rhyolites are mainly composed of plagioclase, sanidine and quartz. Chlorite, calcite, hematite and limonite are the secondary minerals in both rock units, formed by the alteration of clinopyroxene, plagioclase and magnetite. The main textures of these rocks are porphyritic, glomeroporphyritic, anti-rapakivi, sieved and poikilitic. The crystallization order of minerals in dacites is magnetite, clinopyroxene, plagioclase and quartz, and in rhyolites, is plagioclase, sanidine and quartz. Whole rock geochemical analyses show that the studied volcanic rocks of the Gooreh Mountain are sub-alkaline (calc-alkaline magma series) in nature. Moreover, the chondrite and primitive mantle-normalized diagrams are characterized by the enrichment of LREEs and LILEs and depletion of HFS elements (e.g., Ti, Nb and Ta). The negative TNT (Ti, Nb and Ta) anomalies probably indicate subduction-related volcanic arc magmatism. The dehydration of subducting slab and partial melting of the mantle wedge spinel peridotites produced a basic magma that, during ascent through the lower and middle continental crust, led to melting of amphibolites and formation of acidic magmas.

Today, extensive studies are conducted to provide a suitable plan for the maintenance of underground spaces. The results show that the appropriate method, in addition to being safe, should also be economically reasonable. The engineering classification of rock masses can be useful in the feasibility and initial design stage of a project, when little information is available regarding the geotechnical properties of rock masses, stress state and hydraulic characteristics. The main purpose of using a classification system is to be able to categorize parameters and understand the nature of rock mass behavior using their results. In this research, firstly, by using the data bank collected from authentic articles about RMR, Q, BQ, and JH classifications, and also by using 331 geological mappings of various excavated tunnels, rock mass classification by RMR, Q, BQ, and JH methods. It is estimated. Then, these methods were compared with each other during a statistical operation and their correlations were evaluated. In the next step, according to the information extracted from 331 geological mappings of different dug tunnels, during a statistical operation, the stabilization method implemented in the geological mapping of each tunnel and the stabilization method proposed by each of the classification methods presented together Their comparison and relationship and correlation coefficient are evaluated and finally the best relationship with high correlation coefficient is introduced.

One of the most important issues in urban areas is the stabilization of vertical and sloping earth walls. Nailing technique used for slope stabilization, has become popular day by day in urban environments, around the world.  Normal drilling wells, even at shallow depths, have collapsed many times when subjected to applied loads, resulting in reduced work progress, loss of life and unpredictable economic costs. On the other hand, the collapse of drilling holes causes to loosen the soil structure and reduce its density, which in turn causes more horizontal and vertical deformations to occur in the earth’s surface. This research, introduces the deep excavation stabilization with the aid of laboratory and numerical modeling and presents the effect of overburden and soil density on the nails behavior. It was observed that under the conditions of the same soil density, the pullout capacity of all types of nails increases with the increase of the overburden pressure applied on the soil. For example, by increasing the overburden from 0.2 to 0.5 kg/cm2, in a soil sample with a specific weight of 1.4 gram/cm3, it causes a 100% increase, and in a soil sample with a specific weight of 1.6 gram/cm3 causes a 150% increase in the nail pullout capacity. Also, under the same conditions of the applied overburden pressure, the pullout capacity of the nails will increase due to the increase in the specific dry weight of the soil, which is an increase in the density of the soil. In other words, by increasing the specific dry weight of the soil from 1.4 to 1.6 gram/cm3, by applying overburden of 0.2, 0.5, and 0.8 kg/cm2, the pullout capacity of the nail increases by 16, 35, and 40 percent compared to the initial state.

In western Alborz zone (N-Iran), there are two adjacent bentonitic deposits in the same stratigraphic level (epiclastic deposits), but different in mineral assemblages of alteration zones. The unaltered tuffs belong mainly to lithic-crystal tuffs and crystal-vitric tuffs and are composed of quartz, plagioclase, biotite, K-feldspar and opaque as well as lithic clasts and a considerable amount (up to 40 vol. %) of glassy matrix. The XRD analysis results show that montmorillonite + alkali feldspar + plagioclase + quartz ± illite ± kaolinite, are the mineral assemblages in the alteration zones of the study area. However, due to the greater abundance of illite in the Nyagh district, its bentonitic deposit is of higher quality than the Ardebilak deposit. Major element data suggest that Na2O, K2O and to a lesser extent Al2O3 and Fe2O3 are depleted in the alteration zones. Whereas, SiO2 and CaO show different behavior in two study districts. It means that in the Nyagh area, SiO2 is enriched and CaO is depleted. While, in the Ardebilak area, SiO2 and CaO are depleted and enriched, respectively. In both areas, REEs show enrichment in the alteration zones, while Eu has a prominent depletion (especially in Nyagh) that may be due to alteration of feldspars and leaching of Eu in the aqueous fluids. Except for Zr that shows a considerable depletion (ΔCi = -53 in Ardebilak and ΔCi = -64.91 to -84.97 in Nyagh), other HFSEs (especially Nb, Ta, Hf) were immobile during alteration event. It seems that the hot and very acidic (pH < 4) or alkali fluids may be responsible for Zr depletion in the altered zones. In conclusion, it seems that a hidden granitic intrusion in the fractured zone of Nyagh could be responsible for heating the circulating fluids in the tuffaceous rocks. Such a conclusion is verified by more altered tuffs (montmorillonite + illite + kaolinite), the basic dyke swarms and a dacitic dome near the Nyagh area.

The Chore-Nab iron deposit is located in the northwest of the Zanjan-Zaker district. The deposit was formed in quartz monzonite, syenogranite, and granodiorite bodies introded into Lower Cambrian volcanic (andesite) and sedimentary units (siltstone, tuff, and ignimbrite) in the Tarom-Hashtjin metallogenic province. Iron mineralization occurs as brecciated, massive, disseminated, and vein-veinlet types. Major alteration minerals include actinolite, albite, magnetite, epidote, phlogopite, k-feldspar, and biotite. The main sulfide minerals are pyrite, chalcopyrite, and bornite. Based on field and mineralogical studies, sodic-calcic, potassic, propylitic, sericitic, siliceous, and argillic alterations have been identified in the deposit. Sodic-calcic alteration (albite-actinolite-magnetite), characterized by massive and brecciated magnetite in the depth, calcic (actinolite) and potassic (secondary biotite) alteration in the middle levels associated with vein-veinlet sulfide mineralization and finally propylitic alteration (chlorite-epidote) in the shallow levels are observed. Based on the results of chemical analyses, the clinopyroxenes in the alteration zones (mainly sodic-calcic) are mostly augite and less commonly diopside. Plagioclase has a range of albite compositions. Amphiboles are calcic and often tremolite and magnesio-hornblende. Finally, the absence of Cl in the composition of the amphiboles of the Chore-Nab deposit and the presence of at least two Cl-rich amphiboles in all the IOCG deposits of the Carajas mineral province can be attributed to the lack of influence of replacement mechanisms generated by Cl-rich hydrothermal fluids during sodic-calcic alteration.

The eastern Iranian ranges appearing with a NS-trending strike on the satellite images, were already known as the Sistan suture zone, but have recently been identified as the eastern Iranian orogen. The N40E first-generation folds and thrusts with slaty cleavage (parallel folds) have appeared parallel to the NE edge of the Lut block. The structural analysis shows that most of the thrusts dip to the northwest, so that the Permo-Triassic and Jurassic microdiorite units in Lut have been thrusting on the younger rocks. The structural studies show that the tectonic vergence in this deformation event is northwest to the southeast and from the outside (hinterland) to the inside (foreland) of this orogen in the Sechengi area. Younger thrusts of the second deformation event were either directly formed due to the second deformation event, or they were older thrusts that reactivated and folded, so that often two sets or more slickenlines can be recognized on the thrust plane. The recent N44W thrusts have been redistributed in perpendicular to the edge of the Lut block and parallel to the axial plane of the northwest second-generation large-scale folds (radial folds). Both the northwest folds' axial plane and penetrative shear cleavage, have dips to the northeast and southwest. These structures are parallel to the axial planes of the second-generation folds and younger thrusts. Such consecutive deformation events perpendicular to each other are inconsistent with the models of simple linear orogens presented for eastern Iran (i.e., rifting of eastern Iran continental crust and subsequent linear collision) and seem more consistent with the buckling orogens (Orocline).

Amphibolites are a major component of the northern Makran ophiolite belts. They include both foliated and massive types. They are diverse in mineralogy and include amphibolite, garnet-pyroxene amphibolite, and epidote-garnet amphibolite. In addition to plagioclase and amphibole, which are the main constituent phases, other minerals such as zircon, sphene and quartz are also found in amphibolites. According to mineral chemistry, the amphiboles in these rocks are calcic type, and compositionally range from magnesian to ferrohornblende. Geothermobarometry of the amphiboles indicates a pressure ≤ 7 kbar (4-6 kbar) and a temperature range of 750-800°C. Thus, geothermobarometry of amphiboles shows that the Makran amphibolites were metamorphosed at high-temperature and low to medium pressure metamorphic facies (Abukuma-type metamorphism).