Journal of Petroleum Science and Technology
Volume:2 Issue: 2, Summer 2012

Among the methods available to reduce water production, injecting a gelling system composed of a polymer and a crosslinker has been widely used. In this work, a hydrogel was prepared by crosslinking of an aqueous solution containing hexamethylenetetramine (HMTA) as crosslinker, hydrochloric acid (HCl) as an activator, and the co-polymer of 2-acrylamido-2methyl-propanesulfonic-acid sodium salt (AMPS) and acrylamide (PAMPS). In order to indicate the effective factors on the gelation time and also to develop the quadratic mathematical models, central composite design (CCD) was applied. Therefore, the main purpose was to establish functional relationship between the three factors (polymer concentration, HMTA, and hydrochloric acid) and a response (gelation time) by using a statistical technique. In order to determine the optimum value of these factors for maximum gelation time, a simultaneous optimization was also applied. The results of the analysis of variance (ANOVA) of the developed model illustrated that the fitted model was significant in a 99% confidence limit. The results showed that hydrochloric acid was identified as the main factor effecting the gelation time and there was also an interaction between HMTA and hydrochloric acid. Finally, a mechanism for the reaction between PAMPS and HMTA were presented.

The slurry polymerization of ethylene was studied by employing a (TiCl4/Mg(OEt)2/TEA) catalyst system in hexane. The effects of triethylaluminum concentration and temperature on polymer yield and polymer viscosity average molecular weight, Mv, were investigated. The maximum polymer yield was obtained at an Al/Ti molar ratio of 124. The highest yield and Mv were achieved at 60 °C. The concentration of active sites of the obtained catalyst system for ethylene polymerization was evaluated as a function of Al/Ti molar ratio and polymerization temperature. Increasing Al/Ti molar ratio from 62 to 124 raised the active site concentration of catalyst, [C*], from 0.0003 to 0.0017, whereas a further increase in Al/Ti molar ratio from 124 to 231 reduced [C*] from 0.0017 to 0.0013. Similarly, increasing the temperature from 40 °C to 60 °C increased the [C*] from 0.0002 to 0.0017, but when temperature was increased above the optimum value, [C*] decreased.

The aim of the current study is to evaluate the effects of inhibitors or solvents on asphaltene precipitation under reservoir conditions. To this end, the interaction between live oil and solvent, and its side effects on precipitated/dissolved asphaltene were predicted via Miller’s entropy modified polymer solution theory under reservoir conditions. Then, the adjustable parameters of the model were tuned using experimental the data of asphaltene precipitation within a live oil sample. The obtained adjusted parameters were considered to monitor the effects of solvent injection, miscible gas injection, and natural depletion on asphaltene deposition through an oil sample. Finally, Peng-Robinson equation of state was applied to calculate vapor-liquid equilibrium conditions. The results showed that the output of the model was really in good agreement with all experimental, field, and theoretical data.

In the present work, for the first time, a palladium-silver membrane has been prepared by electroless plating on the surface of a porous stainless steel disk by using ethylene glycol as a new reducing agent and polyol process. The reducing action of ethylene-glycol in the presence of PVP as a protecting surface agent produces a membrane with finely divided powder and nano-sized pores. Furthermore, the hydrogen separation ability of the membrane confirmed that the membrane with Pd77Ag23 is highly selective towards hydrogen compared to other prepared membranes. This is mainly related to the formation of dense and homogenous microstructure of the coating. Moreover, according to Graham’s law, the tests showed that hydrogen purity rises by increasing the applying temperature.

A heat exchanger network (HEN) for the process of methanol synthesis has been studied by combination of pinch design method and the application of “Twisted Tube” heat exchanger units as a new technology. The HEN is reconstructed based on the full utilization of maximum allowable pressure drops for the process hot and cold streams. An algorithm is developed to generate design procedure for twisted tube application. The algorithm needs to extend and develop correlation among the pressure drops, heat transfer coefficients, and required surface area through a simple relationship for twisted tube exchangers. It is revealed that a great economic, energy savings and process improvement are realized by using pinch analysis and applying twisted tube units in comparison to existing plants. The paper reveals highly potential benefits of this technology in design and replacement of twisted tube heat exchangers with the conventional shell and tubes type. The HEN is reconstructed by adding 4 new twisted tube units with their detail design in methanol process as a case study. The results show that the application of twisted tube exchangers may achieve significant energy saving for the methanol process with a one-year payback. Moreover, these units may result in a great reduction of carbon emission, operational problems such as heat exchanger fouling, and tube bundle vibration of heat exchangers.

Applying corona wind as a novel technique can lead to a great level of heat and mass transfer augmentation by using a very small amount of energy. The enhancement of forced flow evaporation rate by applying electric field (corona wind) has been experimentally evaluated in this study. Corona wind produced by a fine wire electrode charged with positive high DC voltage impinges on water surface and leads to an evaporation enhancement by disturbing the saturated air layer over water surface. The study was focused on the effect of corona wind velocity, electrode spacing, and air flow velocity on the level of the evaporation enhancement. Two sets of experiments, i.e. with and without electric field, have been conducted. The data obtained from the first experiment were used as a reference for the evaluation of the evaporation enhancement in the presence of electric field. The applied voltages ranged from corona threshold voltage to spark over voltage with increments of 1 kV. The results shows that corona wind has a great enhancement effect on water evaporation rate, but its effectiveness gradually diminishes by increasing air flow velocity. The maximum enhancements are 7.3 and 3.6 times for air velocities of 0.125 and 1.75 m.s-1 respectively.

Permeability, the ability of rocks to flow hydrocarbons, is directly determined from core. Due to high cost associated with coring, many techniques have been suggested to predict permeability from the easy-to-obtain and frequent properties of reservoirs such as log derived porosity. This study was carried out to put clustering methods (dynamic clustering (DC), ascending hierarchical clustering (AHC) self organizing map (SOM) and multi-resolution graph-based clustering (MRGC)) into practice in order to predict the permeability of a heterogeneous carbonate reservoir in southwest of Iran. In addition, the results are compared with three conventional approaches, empirical models, regression analysis, and ANN. The performance of all the examined methods was compared in order to choose the best approach for predicting permeability in un-cored wells of the studied field. For all clustering methods, selecting the optimal number of clusters is the most important task. The optimal values for the number of clusters are selected by iteration. The optimal number of clusters for MRGC, SOM, DC, and AHC are 7, 9, 9, and 8 respectively. Empirical equations and regression analysis weakly predict permeability and the value of R2 parameters of both approaches are around 0.6. Generally the performance of clustering techniques is acceptable in Fahliyan formation. These techniques predict permeability between 1 and 1000 mD very well and just overestimate permeability values less than 1 mD. SOM performed the best among all examined techniques (R2=0.7911). The constructed and validated SOM model with 9 clusters was selected to predict permeability in one of un-cored wells of the studied field. In this well, the predicted permeability was in good agreement with MDT derived permeability.

A newly phenol-degrading bacterium, identified as Ralstonia sp. strain PH-S1, was isolated from oil-contaminated soil in Khark Island. It was isolated by a multistep enrichment and screening technique on mineral medium (MM) containing 100 mg.l-1 of phenol as the sole source of carbon. The bacterium was able to degrade up to 1100 mg.l-1 of phenol but the cell growth decreased with higher concentrations of phenol. The PH-S1 strain grew well in the pH range of 4 to 9 and in the temperature range of 30 to 40 °C. Different concentrations of NaCl ranging from 10 to 20% on the growth of bacteria was studied and it was found that this strain was able to grow well in 10% NaCl; but, higher concentrations of NaCl decreased the growth of the strain. The laboratory scale results indicated the potential application of the strain in the treatment of low saline industrial wastewaters. However, further investigations are required to confirm the ability of the strain.