M Tajbakhshian; M.H Mahmudy; A Mahboubi; R Moussavi Harami; I Ejlali
Abstract
Hydrogeochemistry of surface and ground waters is a useful way to identify performing reactions in aquifers and also in recognizing effective natural and anthropogenic polluting factors in these sources. In order to study surface and ground waters quality of shahid Hashemi- Nejad gas refinery region, ...
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Hydrogeochemistry of surface and ground waters is a useful way to identify performing reactions in aquifers and also in recognizing effective natural and anthropogenic polluting factors in these sources. In order to study surface and ground waters quality of shahid Hashemi- Nejad gas refinery region, located 35 km south of Sarakhs town, 17 water samples were collected. Parameters of pH, temperature, electrical conductivity and total dissolved solids were measured in the field, and water samples were analyzed for major anions and cations concentrations in geochemical lab. Using Piper diagram, sodium sulfate and sodium chloride type and facies were determined for the water samples. Ca2+/Mg2+v.as Mg2+ ,Ca2+/Ca2++Mg2+v.as SO42-/SO42-+HCO3- compound diagrams, total hardness and PCO2 proved carbonates dissolution. Na+/Na++Cl-, Ca2+/Ca2++SO42-,HCO3-/Σ anions, HCO3-/SiO2 , SiO2/Na++K+-Cl-, Na++K+and SO42-+Cl-ionic ratios determined factors such as ion exchange, dissolution of Gypsum, Halite and sulfates of sodium-potassium, and weathering of carbonates and silicates as the most important effective parameters on chemical composition of water sources in this area. In Log(aCa2+/a(H+)2)andLog(aMg2+/a(H+)2) v.asLog (aNa+/a(H+)2) diagrams, which are used for specifying soluble silicate minerals in water, all water samples showed the dissolution of Kaolinite except two samples which were located at clinochlore mineral zone. Calculating saturation indices using PHREEQC software proved that Calcite and Dolomite mineral had supersaturation, Halite and Anhydrite undersaturation and Gypsum mineral supersaturation, undersaturation and equilibrium states in all samples. Schoeller and Wilcox diagrams pointed unsuitable quality for drinking and agricultural usages for these water sources. In fact, because of formations presence with high solubility that lay out in large amount of surface, water resources in this area have not suitable quality, and on the other hand shallow water level and high temperature intensify it. Based on obtained results, natural factors have major role in quality area’s water resources.
M Kavianpor sangno; A Namdarian; S.R mousavi-Harami; A Mahboubi; A Omidpour
Abstract
Evaporites include wide range of chemical deposits, which are precipitated in surface or near surface, from the concentrated brine by evaporation. Diagenetic processes are important factors can effect on reservoir quality. The Oligo-Miocene Asmari reservoir comprise of siliciclastic and carbonate sequences ...
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Evaporites include wide range of chemical deposits, which are precipitated in surface or near surface, from the concentrated brine by evaporation. Diagenetic processes are important factors can effect on reservoir quality. The Oligo-Miocene Asmari reservoir comprise of siliciclastic and carbonate sequences in the Mansouri Oil Field and reservoir quality of these rocks are affected by diagenetic processes during the time. One of the most important processes is anhydrite cement, which spread as layer, poikilotopic, pores filler and pervasive, early nodular, nodular- burial, scattered crystals, fracture and vein filler in the reservoir. Spread of anhydrite cement has a negative impact on the reservoir quality. On the other hand, the higher solubility of anhydrite cement than carbonate cement can have a positive effect on the reservoir quality. The Interplay of digenetic processes and anhydrite texture is visible in increasing or decreasing of characteristics of the Asmari reservoir. The result of this study shows that anhydrite (during diagenesis) as a cement with poikilotopic fabric and pervasive texture of porosity filler has the most important role in reduction of reservoir quality, but the processes such as dissolution has the main role in increasing of reservoir quality of the Asmari Formation in the Mansouri Oil Field.