Geochemical evaluation and thermal modeling of the Eocene–Oligocene Pabdeh and Middle Cretaceous Gurpi Formations in the northern part of the Dezful Embayment

Rock–Eval pyrolysis analysis, burial history, and 1D thermal maturity modeling have allowed the evaluation of the source rock potential, thermal maturation state, and impacts of the Pabdeh and Gurpi Formations in Cretaceous–Miocene petroleum system in the Naft Safid (NS) and Zeloi (ZE) oilfields, North Dezful Embayment. The total organic carbon (TOC) content of the Pabdeh and Gurpi Formations ranges from 0.2 to 4.7 wt% and 0.3 to 5.3 wt%, respectively. S2 values of the Pabdeh Formation in the ZE and NS oilfields vary from 0.41 to 13.77 and 0.29 to 14.5 mg HC (Hydrocarbon)/g rock, with an average value of 4.48 and 4.14 mg HC/g rock, respectively. These values for the Gurpi Formation in the ZE and NS oilfields range from 0.31 to 16.96 and 0.26 to 1.44 mg HC/g rock, with an average value of 8.54 and 2.43 mg HC/g rock, respectively. The S2 versus TOC diagram reveals a fair to good hydrocarbon generation potential of the Pabdeh Formation and poor to fair potential of the Gurpi Formation. The high values of S2 (S2 > S1) for samples of the both formations in the ZE and NS oilfields show that the samples are not contaminated with petroleum generated from underlying source rocks. The samples of the Pabdeh Formation in the ZE oilfield are characterized by a relatively narrow range of activation energy values with principal activation energy of 46 kcal/mol and frequency factor of 5.27 × 10⁺¹¹ s^?1. It seems that the high sulfur content of the Pabdeh organic matter probably caused the frequency factor and principal activation energy to be lower than usual. Hydrogen index (HI) values of the Pabdeh and Gurpi Formations in the ZE oilfield vary from 71 to 786 and 97 to 398 mg HC/g TOC, with an average value of 310 and 277 mg HC/g TOC, respectively. These values in the NS oilfield range from 66 to 546 and 51 to 525 mg HC/g TOC, with an average value of 256 and 227 mg HC/g TOC, respectively. Plot of HI vs. T _max value indicates that the majority of the Pabdeh and Gurpi samples contain predominantly type II kerogen and their organofacies are directly related to the more homogeneous precursor materials. Based on thermal maturity modeling results, kinetic parameters, and Rock–Eval analysis, both formations in the ZE and NS oilfields are thermally mature and immature or early mature stage, respectively.     

Identification and determination of PAHs compounds in Anzali International Wetland

The worst environmental pollutants in Anzali International Wetland are oily hydrocarbons especially aromatic and poly aromatic compounds (PAHs). The existence of oily compounds with approximate limit of concentration of 0.1 μg/l in aquatic environment bans the growth of fish larva and causes the generic state manner of animals. Anzali International Wetland, which is situated in the west — southern part of Caspian Sea where has environmental importance in life of living organisms and ecosystems. In this reseach, four sites, Pirbazar, Pasikhan, west and central parts, where are situated in Anzali International Wetland, have been studied in 2002. Waste sedimentation soil Sampling was performed during winter and spring in the above-mentioned regions. In the first stage, the purpose of sampling was to access optimum instrumental conditions and correct and precise procedures. Oily pollutants were extracted from water and it was done by using CC1₄ solvent after cleaning and concentrating. The extracted samples were identified with gas chromatographic method with using polyaromatic standard solutions. By the powerful GC/MS method; results of qualitative analysis were confirmed. Also by GC/MS using SIM mode quantitative analysis were performed. Quantitative study of polyaromatic compounds has also been done by luminescence spectrophotometry. Some compounds which were identified in the water samples were: olifinic, aromatic and poly — aromatic compounds such as: antracene, fluourine, xylene, methylbenzene, naphthalene and acenaphtylene. Finally, the degree of biodegradation of compounds such as pristan (C₁₉H₄₀) and phytan (C₂₀H₄₂) in water samples was integrated.     

Response surface methodology approach to the optimization of oil hydrocarbon polluted soil remediation using enhanced soil washing

One of the environmental concerns in recent decades is the prevalence of different pollutants in soil. Hence, the importance of remediation has led to the development of various methods to remediate polluted soil. Among these methods, soil washing has gained significant attention to treat polluted soils. In this paper, the response surface methodology was applied in order to determine the optimal conditions for total petroleum hydrocarbon remediation using nonionic surfactant Brij35 in soil environment. The effect of different factors in soil washing process including surfactant solution concentration and volume, washing time, age of pollution and frequency of washing are evaluated. The predicted values for total petroleum hydrocarbon remediation efficiency by the response functions are in a very close agreement with experimental data (R-2= 98.75 %). The second order model was developed as experimented response and optimal conditions were obtained by analyzing the contour and surface plots and also by solving the regression equation using LINGO 9.0 software. The optimal concentrations (8 g/L), volume of surfactant solution (500 mL), washing time (75 min), age of pollution (29 days) and frequency of washing (three times) are determined. In this optimal condition, the removal efficiency has been observed to be 93.54 % which conforms to the results of process optimization using response surface methodology. Based on the results, it can be concluded that the response surface methodology is a suitable approach to determine the optimal conditions of soil washing to remediate organic hydrophobic pollutants using the nonionic surfactant Brij35 from the soil.