Sharif Digital Repository

The partitioning of penicillin G acylase in aqueous two-phase systems (ATPS's) containing poly(ethylene glycol) (PEG) 20000 or 35000 and potassium dihydrogen phosphate (KH2PO4) or sodium citrate (C 6H5Na3O7 ·5H2O) has been measured at three temperatures, (301.2, 307.2, and 310.2) K. The effects of temperature, polymer molecular weight, and polymer and salt concentrations on the partitioning of penicillin G in the ATPS were studied. The experimental data showed that the composition of salt has a large effect on partitioning of penicillin G in ATPS, and the temperature of the system has a small effect on the partitioning. The UNIFAC-FV group contribution model (Pazuki et al., Ind. Eng. Chem.... 

As expounded, the precipitation and deposition of asphaltene particles in pipelines has been proved to be the most challenging flow assurance problem due to its unknown and complex behaviors. In this work, a new multicomponent, multiphase and dynamic tool was developed to model the aggregation and deposition of asphaltene particles in a bulk medium. The multiphase and dynamic asphaltene deposition tool, shortened as MAD-ADEPT is, in fact, a modified version of the previously developed ADEPT. The new tool was developed to make the asphaltene deposition and aggregation concepts in oil production wells more predictable. To tackle the complexity of the asphaltene problem, a bespoke algorithm was... 

The GV-MSA, the BMCSL-MSA and the Pitzer models were used to correlate the individual, the mean ionic activity coefficients and the osmotic coefficients of symmetric and asymmetric electrolyte solutions. In order to compare the results obtained from the GV-MSA with those obtained from the Pitzer and the BMCSL-MSA models, the same experimental data and the same minimization procedure were used and the new sets of parameters for the BMCSL-MSA and the Pitzer models were also reported. The values for the osmotic coefficients of electrolyte solutions were calculated directly using the values of the mean ionic activity coefficients obtained from the models studied in this work. The results for the... 

The diffusion and deposition of TiO2 nanoparticles in EOR application was investigated in this paper. TEM image of nanoparticles showed that the particles are elongated with average long and short axis sizes of 54 and 15 nm. Water flooding tests showed that the recovery factor can be improved from 49% to 80% using TiO2 nanoparticles. Viscosity and interfacial tension measurements showed that by using TiO2 nanoparticles the viscosity of injected fluid and interfacial tension do not change significantly and can not explain the change in recovery factor. Contact angle measurements showed that nanoparticles deposition changed the wettability of the rock surface from oil-wet to water-wet. SEM... 

CO2 sequestration in geological formations, such as aquifers, is known to be the best short-term solution to CO2 mitigation. Accurate description of CO2 solubility in brine is important for evaluating the capacity of aquifers to sequester CO2. Currently, EOS-based models are widely used in reservoir compositional simulators for this purpose. However, most of these models involve complex and iterative calculations which take too much time in case of large-scale flow simulation of geological CO2 storage. In this study, a neural network model is presented for prediction of CO2 solubility in brine which is highly accurate with less computational overhead  

Although application of nanoparticles in enhanced oil recovery has been reported, understanding the transport and retention of nanoparticles in the oilfield reservoir is still a crucial issue. In this research, behavior of low concentration of TiO2 nanoparticles in core plug porous media and the mechanism of increasing oil recovery were investigated. Flooding test with a concentration of 0.01% TiO2 nanoparticles showed improvement in sweeping heavy oil from 41% to 55%. Inductively coupled plasma results on the exiting effluent of the flooding test with a concentration of 0.05% TiO2 nanoparticles showed the presence of only 0.5% of injected nanoparticles, which indicates high affinity of the... 

A new two-parameter model based on the perturbation of a hard-sphere reference has been developed to correlate the activity coefficients of several amino acids and simple peptides in aqueous solutions. The hard-sphere equation of state used as the reference in the model was proposed recently by Ghotbi and Vera. The perturbation terms coupled with the reference hard-sphere equation of state are attributed to the dispersion forces and the dipole-dipole interactions. The Lennard-Jones and Keesom potential functions are used to represent the dispersion and dipole-dipole interactions, respectively. The results of the new model are compared with those obtained by other models. It is shown that the... 

Gel flooding is one of the most important cEOR methods. In this study, a Co[AM-AMPS-MA-AAC]/PEI-MBA nanocomposite, using zirconium or zinc nanoparticles, was synthesized to improve the performance of traditional hydrogels. FTIR and XRD tests confirmed the three-dimensional structure and homogeneous distribution of nanoparticles. The SEM and ESEM images revealed a homogeneous and 3D structure with an average pore size of 35 nm. The sweep strain test showed that the maximum storage moduli of Zr and Zn nanocomposites are 21,300 and 7700 Pa, respectively. The frequency sweep test showed linear viscoelastic behavior at various frequencies. According to TGA results, less than 1% of the... 

In this study, the performance of preformed dual crosslinked nanocomposite hydrogels (PNCH) consisting of acrylamide, 2-acrylamide-2-methylpropane sulfonic acid, maleic acid, and acrylic acid in sand control was investigated. Also, the effects of three nanoparticles (NPs) of iron (PNCH1), silicon (PNCH2), and bentonite (PNCH3) on the PNCH structure were studied. The morphology, equilibrium swelling ratio (ESR), rheology, thermal strength, zeta potential, and compressive strength were experimentally analyzed. According to the XRD results, the NPs were completely dispersed in all three samples. The results of SEM and EDS tests confirmed the presence of NPs within the PNCHs with a dense,... 

Over the past years, oil and gas research works have been concentrated in the enhanced oil recovery methods through injection of chemical materials. In this work, Co[AM-AMPS-MA]/PEI-MBA(Ben) nanocomposite hydrogel was designed and synthesized. To characterize the synthesized nanocomposite hydrogel, TGA, DTG, XRD, FTIR, SEM, and ESEM techniques, and equilibrium swelling, frequency and temperature sweep, and micromodel tests were applied. Based on TGA and DTG data, thermal stability of the sample was confirmed at the reservoir temperature. The XRD analysis confirmed the amorphous structure of the nanocomposite hydrogel and the homogeneous distribution of the nanoparticles in its structure. SEM... 

Simultaneous water and CO2 injection has been performed on a sandstone core to evaluate oil recovery under the secondary and tertiary near-miscible injection modes. It is demonstrated that secondary SWACO2 injection as well as tertiary flood is an effective method for the oil/residual oil recovery from oil saturated/water-flooded porous media. In the secondary SWACO2 injection, the ultimate oil recovery increases by increasing SWAG ratio from 0.2 to 0.4 but due to some limits, e.g. topological effects, prohibiting contacting of injected gas with residual oil in pores, altering SWAG ratio from 0.4 to 0.6 showed no effect on ultimate oil recovery. Secondary SWACO2 injection can recover higher... 

The formation of condensate banking in the near well-bore region will lead to the reduction in gas relative permeability and loss of well deliverability. This loss is investigated by conducting a series of fine grid numerical compositional simulation with the gas condensate and dry gas reservoir data. Also, a method for calculation of condensate blockage skin factor is introduced in which the skin factor is calculated using dry gas and gas condensate simulation production data. The authors also found that absolute permeability and pressure drawdown of the producing well have significant influence on the well gas deliverability and condensate blockage skin factor  

Relative permeability curves of two-phase flow in a fracture have been a subject of study in recent years. The importance of these curves have been widely observed in multidisciplines, such as water subsurface resources, geothermal energy and underground hydrocarbon resources, especially fractured oil and gas reservoirs. Extensive experimental studies have been cited alongside the numerical studies in this area. However, simple analytical and practical solutions are still attractive. In the current study, wettability effects and phase interference explicitly were tried to be implemented in a simple analytical formula. The wettability effects are represented by residual saturations which... 

A method based on the Genetic Algorithm (GA) was developed to study the phase behavior of multicomponent and multiphase systems. Upon application of the GA to the thermodynamic models which are commonly used to study the VLE, VLLE and LLE phase equilibria, the physically meaningful values for the Binary Interaction Parameters (BIP) of the models were obtained. Using the method proposed in this work the activity coefficients for components at infinite dilution, obtained from the local composition based models, can be accurately predicted comparing to the experimental data available in the literature. In this work, a Global Optimization Procedure (GOP) based on the GA was developed to obtain... 

The objective of this work is to extend the Kelvin mean spherical approximation (K-MSA) model to correlate the mean and individual ionic activity coefficients for symmetric and asymmetric electrolyte solutions at different concentrations and at different temperatures. Revised values of the parameters for the mean and individual ionic activity coefficients of 1:1 electrolytes and new values of the parameters for the mean ionic activity coefficients of asymmetric electrolytes are presented. The effect of the short-range electrostatic term (Pn) at different size ratios of the ions is examined. Assuming a constant anion diameter and a composition-dependent diameter for the cation, the K-MSA... 

Two different models based on Guggenheim's renormalized canonical partition function proposed by Wang and Vera, the generalized quasi-chemical model (GEM-QC) and the generalized regular solution model (GEM-RS), have been used in molecular form to correlate the liquid-liquid equilibrium (LLE) of experimental data for ternary systems containing water, propionic acid (PA) and organic solvents. Both the GEM-QC and the GEM-RS models have nine adjustable parameters for a ternary system, which are obtained from a least square fit of the models to the LLE experimental data. In this work the same assumptions made to develop the simplified GEM-RS model (GEM-RS2) by Wang and Vera, have been applied to... 

The non-primitive mean spherical approximation (NP-MSA) based models were used to correlate the individual and the mean ionic activity coefficients of the symmetric and asymmetric aqueous electrolyte solutions. The results of the models for the mean ionic activity coefficients were directly used to calculate the osmotic coefficient for the electrolyte solutions studied in this work. In the NP-MSA models, the Ghotbi-Vera and the Boublik-Mansoori-Carnahan-Starling- Leland hard sphere equation of state as the reference system coupled with the non-primitive mean spherical approximation model (NP-GV-MSA and NP-BMCSL-MSA models, respectively). In correlating the mean ionic activity coefficients of... 

Introduction: One of the main objectives of reservoir engineering studies is to increase the production of hydrocarbon reservoirs with an optimal method. One of the artificial lift methods in wells is the gas lift. This system increases the oil production flow rate by reducing the pressure at the bottom of the well and increasing the pressure at the wellhead. In this method, by injection of high-pressure gas into the well's column, the average density of the well fluid is reduced, and through this, the well is reactivated. Method: In the current study, the simulation of a gas lift system in the horizontal and inclined wells was investigated. The pressure changes at the end of a simulated... 

The experimental study and modeling of gravity drainage during Water Alternative Gas Injection, WAG process, in carbonate rock for one of the Iranian off-shore reservoir at lab-scale were carried out. The mechanism of gravity drainage during the WAG process, and its contribution to the oil recovery in the fractured carbonate reservoirs were also studied. In the WAG process alternatively gas is injected during the process and gravity drainage could be happened. Changes in the block dimensions, rock properties, oil properties, gas properties, and fractures properties and their effect on the amount of oil recovered during the gravity drainage mechanism were studied. It would be worth mentioning... 

In this work, a new model based on multilayer kinetic adsorption mechanism has been proposed to account asphaltene adsorption in porous media under dynamic condition and the model was verified using experimental data obtained in this work and also with those reported in the literature. In the proposed model two steps are considered for asphaltene adsorption. The first step is taken as adsorption of asphaltenes on the surface of the porous media and the second step is taken as adsorption of asphaltenes on the asphaltenes already adsorbed on the porous media. The Crank-Nicholson method, central difference in space and trapezoidal rule in time, giving second order convergence in time was...