مجله پژوهش نفت
پیاپی 102 (آذر و دی 1397)

Using diverter agents in matrix acidizing is one of the common techniques in the heterogeneous reservoirs. These agents temporary block the high-permeability layer by increasing the viscosity and thus diverting the acid to the low-permeability layer. Here, a rheological model that was developed by previous researchers is used for in-situ gelled acids by considering the main parameters such as shear rate, pH, and temperature. Then, the rheological model is combined with the extended two-scale continuum model to describe the underlying reactive transport mechanisms. The results were compared with the Newtonian acid. Furthermore, the apparent viscosity of the in-situ gelled acid is estimated and updated at each time step of the modeling. In this study, the results of the linear and radial system were compared with each other. The results show that in the linear model, the growth and propagation of acid in high permeability region is stopped due to high viscosity. Therefore, acid starts diverting from high permeability zone to low permeability zone. However, several wormholes are formed in a radial model; moreover, the wormholes prevent diverting acid from high permeability region to low permeability region. In other words, the existing model could not respond to divert acid from high-perm region to low-perm region in the radial system.

Corrosion inhibition of aryl-triazino-benzimidazole-2-thiones on carbon steel in 2 M HCl solution was investigated using quantum mechanical, polarization, and electrochemical impedance methods. Moreover, the polarization curves show that these compounds act as a mixed inhibitor. The results of electrochemical impedance indicated that Bode-phase curves have a time constant in the concentrations less than 50 mg.L-1 of inhibitor, but Bode plots show two time-constants in the concentrations which are more than 50 mg.L-1. Adsorption of these aryl-triazino-benzimidazole-2-thions on the carbon steel surface obeyed Langmuir’s adsorption isotherm. The values of indicate that adsorption of inhibitors on the metal surface is possibly chemisorption. In addition, the geometric structures of all the compounds were optimized, and their performances were structurally compared with the DFT quantum method. Finally, the results obtained from quantum mechanical, electrochemical impedance and polarization measurements were in good agreement with each other.

Casing collapse is one of the costly and safety-threatening incidents in the oil industry. For example in Kupal oil field, Iran, approximately, a third of the wells have been removed from the production cycle due to casing collapse, which in some cases have led to the total loss of those wells. Since most of these cases have occurred in Gachsaran Formation, it is necessary to use an appropriate method to determine the geomechanical characteristics of this formation, especially, the layer considered as caprock for the underlain Asmari reservoir under the real conditions of temperature and pressure at real depths. In this paper, after discussing the effect of temperature, loading rate, and confining pressure on general geomechanical behavior of rocks, and in particular, the caprock of the Asmari reservoir, the results of geomechanical experiments performed under different temperature and pressure conditions on this type of rock are presented, and their comparison with the corresponding results determined by other researchers are discussed. The obtained results from the experiments demonstrate that under constant loading rate, each 1.0 MPA increase in confining pressure increases the strength of the caprock about 1.0 MPa. Conversely, every 1 °C increase in temperature decreases the caprock strength almost 0.2 MPa.

In this study, the UVM-7 at ZIF-8 hybrid nanoparticle was synthesized using hydrothermal method, and its application was investigated to remove the sulfur compound of Dibenzothiophene in the liquid phase at R. T. To study the efficiency and DBT removal capacity of the as-prepared nano-adsorbent, various factors such as the amount of adsorbent, time and selectivity toward aromatic compound of naphthalene have been investigated. According to the results, the UVM-7@ZIF-8 showed high selectivity and good recycling ability to eliminate DBT under mild conditions. In addition, removal of DBT has been reported with a maximum absorption of 299.2 mgS/g for UVM-7@ZIF-8. Due to the high adsorption capacity and absence of π-π interactions, it has been suggested that the presence of non-saturated sites around metal centers were responsible for the absorptive desulfurization process. For determining the desulfurization mechanism, we characterized the exhausted samples through FTIR, and XRD measurements were characterized.In addition, the results against fresh samples were compared with each other.

According to increasing human energy requirements and energy source limitation, production of fossil energy is an important issue. Enhanced oil recovery techniques have been developed for increasing the amount of crude oil that can be extracted from oil fields. Recently, the application of nanoparticles (NPs) suspension flooding for EOR purposes has been proved. In addition, NPs can improve fluid-rock interaction characteristics such as wettability. In this work, alpha-Alumina nanofluid effects have been investigated in wettability alteration of carbonated rocks. Contact angle is used to analyze the alteration of surface wettability. Different nanofluids concentration in the range from 0.1 to 0.5 wt.% is used. Finally, the result clearly indicates the improvement wettability of reservoir to highly water-wet when it is treated with nanofluids.

A simple and economical thermochemical method was used for synthesis of MgAl2O4 spinel for the first time. After dispersion of MgO over the spinel surface as active phase, the new MgO/MgAl2O4 nanocatalyst was successfully used for the biodiesel production as a green fuel. The prepared nanocatalyst was analyzed by XRD, FESEM, EDX-Dot Mapping, BET-BJH and FTIR analyses. Finally, the synthesized sample was used for the biodiesel production for reaction conditions at 110 °C, catalyst to the feed ratio being 3%wt., molar ratio of alcohol to oil equals to be 12 for 3 hours reaction time. The results of the XRD analysis confirmed the successful synthesis of MgAl2O4 spinel and the FESEM images of the synthesized sample showed a uniform morphology with the formation of clusters. The BET-BJH analysis has shown that the synthesized sample had a pore size diameter and surface area of 5.9 nm and 84.76 m2/g respectively which are appropriate for the biodiesel production reaction. The results of these analyzes were in good agreement with the results of the synthesized nanocatalyst activity in the biodiesel production reaction, so that this sample achieved a good conversion of 92.6%. Also, after six times usage in the mentioned reaction conditions, the conversion for the synthesized sample was about 64%. However, it should be noted that the conversion remained almost constant in the third to sixth cycles. The results of this paper has shown that thermochemical-impregnation method, in addition to its simplicity and low cost, leads to synthesis of catalyst with favorable characteristics and industrialization capability.

Accurate evaluation of pore pressure and fracture pressure are key parameter in well planning and drilling operation. Estimation of these parameters has an important role in reduction in well costs. An inaccurate estimation of fracture gradient may jeopardize whole drilling operation and cause serious problems such as loss circulation and blowout. In this paper, the method of Gene Expression Programming (GEP) has used for developing a mathematical model for prediction of formation fracture pressure. Overburden pressure, pore pressure and Poisson ratio are independent variables in this model. Studied areas include two oil-bearing formations: Kangan and Upper-Dalan in an onshore field which is located near Persian Gulf. A separate model is presented for each formation by using well logging data from two wells. Models developed by using more than 4,300 well logging data from a well. Verification of these models is done with 6,000 data from second well in same formation. Statistical analyses confirm that the models are suitable for fracture gradient prediction so we can use them for estimation of fracture pressure.

One of issues preventing utilization of sodium hydroxide, as H2S absorbent in this oil/gas industries, is its recovery, because of an irreversible reaction between NaOH and H2S. In this work, ozone and natural zeolite (clinoptilolite) were used for oxidation of sulfide to sulphate ions and adsorption of sulfate ions from alkaline solution, respectively. A synthetic solution of sodium sulfide in sodium hydroxide was prepared. The effect of three operating variables at three levels including ozonation time, hydrogen peroxide dosage, and initial concentration of sodium sulfide was investigated on conversion of sulfide ion to sulfate ion. The design of experiments was performed utilizing response surface method (RSM) in Design Expert software to find optimum condition of oxidation process. Under optimum condition, i.e., ozonation time: 60 min, hydrogen peroxide dosage: 5 mL and sodium sulfide concentration: 0.03 M, a conversion 72.11% was achieved. In the next step of experimental runs and for the removal of produced sulfate ion in oxidation step, an adsorption process using natural zeolite and surface modified zeolite with barium chloride was applied. The highest adsorption efficiency of sulfate ion (91%) was achieved at the highest level of modified zeolite dosage (8 g zeolite/100 mL of solution). Total removal efficiency 65.7% was reported in whole process of oxidation-adsorption, whereas no significant changes in pH were observed. The present method could be a notable alternative to replace ethanol amines with NaOH solution in oil and gas industries.

More than 60% of the world’s discovered oil reservoirs are stored in carbonate rocks. In most cases, oil-wetness of these formation has led to low recovery factor in the water-flooding process. Due to the negative effect of capillary forces, injected water cannot easily penetrate the oil-wet matrices and push oil to leave the matrix. Wettability alteration of the rock in relatively oil-wet formations has been considered as an approach to improve oil recovery. There are various methods for changing the wettability of reservoirs, among them, surfactants and low salinity waters are mentioned. Both of these methods have been studied in a wide variety of separate studies. In this study, the effect of hybrid low salinity surfactant was investigated. For this purpose, samples of oil and reservoir rock were prepared from one of the Iranian south oil reservoirs and their characteristics have been measured. Then, imbibition experiments of formation brine, low salinity water and low salinity water in the presence of AOT surfactants have been done. Results showed an improvement in the oil recovery in the low salinity surfactant formulation. The anionic surfactant in the low salinity environment has resulted in the recovery of 56% of crude oil C1 and 37% of crude oil C2.

In this study, steam methane reforming was investigated by using Ni-Al-Zn catalyst. This process carried out at 750-900 °C in the industrial plants. From the economical and operational point of view, the reduction of operational temperature is important. Therefore, the Ni-Al-Zn catalyst was studied to decrease the operational temperature. This catalyst was synthesized by coprecipitation method. The results of XRD, ICP, and BET revealed that catalyst were appropriately synthesized. Then, this catalyst was used in the steam methane reforming process and 15% nickel was obtained as optimum value. The performance of optimum catalyst at 650 °C was similar to industrial catalyst at 750 °C, so that the methane conversion was about 75 %. This catalyst showed high carbon resistance at temperatures above 600 °C. Kinetic study of optimum catalyst was performed. Moreover, the activation energy for reaction of methane to CO and H2, water gas shift and methane to CO2 and H2 were 219.4 kJ/mol, 71.90 kJ/mol, and 221.04 kJ/mol, respectively. The results of kinetic experiments on the synthesized catalyst showed that the activation energy for the first and third reactions of reforming (hydrogen production via methane and steam) was less than the activation energy on the industrial catalyst which reveals higher activity of the synthesized catalyst. Furthermore, the adsorption parameters in the kinetics equations were obtained and thermodynamically verified.

One of the efficient methods for enhanced oil recovery from a petroleum reservoir is the surfactant injection in the presence of alkaline material. Moreover, the contact angle of water and reservoir rock is reduced in the presence of surfactants. On the other hand, this material changes the interfacial tension. The alkaline materials in the present of surfactants also help the reduction of interfacial tension and the wettability alteration of reservoir rock. In this research, the effect of concentration (0.05, 0.1, 0.3, 0.5 wt %) and shelf-life of surfactant dodecyltrimethylammonium bromide in the presence of different concentrations of sodium carbonate (0.5, 1, 1.5, 2, 2.5 wt %) on the interfacial tension and wettability alteration of carbonated rocks of the Asmari petroleum reservoir were analyzed. The results of these experiments showed that surfactant dodecyltrimethylammonium bromide reduces the interfacial tension and alters the wettability of reservoir rock to the water-wet state. Furthermore, the interfacial tension and contact angle is reduced in the presence of sodium carbonate to a great extent which is one of the effective factors in the amount of oil recovery. By increasing the shelf life of the reservoir rock in contact with the solution containing surfactant and sodium carbonate for 7 days, the minimum contact angle was reduced from 59 to 46 degrees. At 0.3 wt.% micelle concentration of dodecyltrimethylammonium bromide and sodium carbonate with an optimum concentration of 0.5 wt.%, the most reduction in interfacial tension was obtained.

In this study, extractive desulfurization of dibenzothiophene from n-hexane as model fuel using 1,10-phenantroline 2,9-dicarboxamide-FeCl3-based choline chloride as a green, novel and efficient deep eutectic solvent (DES) was considered. FT-IR, 1H NMR, and 13C NMR were used for the characterization of the synthetized DES. The effect of influential parameters of the mass ratio of fuel to DES, temperature, and time was investigated. Moreover, for 10 mL solution containing 500 mg L-1 dibenzothiophene in n-hexane, at obtained optimum conditions of mass ratio of fuel to DES (equal to) 33.5, temperature (equal to) 25 °C, and time (equal to) 15 min, the maximum sulfur removal percent of 93.5 ± 0.5 was achieved. The obtained experimental results were optimized by Genetic algorithm based on artificial neural network (GA-ANN). By using GA-ANN, the optimum conditions of 34.4, 27.33 °C, and 16.99 min were acquired for the mass ratio of fuel to DES, temperature, and time which showed high potential and ability of the applied model in the optimization of the proposed process.