PETROLEUM RESEARCH
Year:2012 | Volume:21 | Issue:68|Papers Count:9

Chitosan – Poly (N-isopropylacrylamide) hydrogels were synthesized by thermal and gamma irradiation methods. In the thermal method, initiators and crosslinkers were employed. It was found that the gamma irradiation method produced hydrogels of higher water swelling ratio. The hydrogels were used in drilling fluids and the important rheological properties of the muds such as apparent viscosity, plastic viscosity, and yield point as well as shear-shear rate diagrams were measured. Obtained results show that whereas linear polymer effects on mud properties are more significant in lower polymer concentrations, prepared crosslinked hydrogel effects are more significant at high concentrations. The hydrogel synthesized by gamma irradiation improved rheological properties of drilling fluids at higher concentrations of the hydrogel more effectively than the thermally produced hydrogel and linear polymers. It seems that addition of hydrogel to mud in powder form can increase the effects of rheological properties of drilling fluid. Thus, increase in gamma irradiation dose and monomer concentration, which rendered high swelling hydrogels, were more suitable for improving properties of drilling muds. In thermally synthesized hydrogels, increase in monomer and decrease in crosslinker concentration produced better hydrogels.

In this paper new equilibrium data has been obtained for methane hydrate in the presence of three thermodynamic mixed inhibitors: NaCl + DEG, NaCl + TEG and MeOH + TEG as well as for carbon dioxide simple hydrate in the presence of two glycols inhibitors, i.e. monoethylene glycol (MEG) and diethylene glycol (DEG) for various concentrations using constant volume method. In this work, measured equilibrium data has been reported for conditions, for which there is limited reported data. Thermodynamic model and general correlation of Heriot-Watt University have been applied for estimating the measured equilibrium data and good agreements between measured and predicted data were observed.

In this paper, CO2 adsorption isotherms at 273 K are measured on five commercial carbonaceous adsorbents using volumetric method and their pore size distributions are determined and compared using DA, DS and HK models. The results show that although the average pore diameter obtained from these models are almost the same, these models show different pore size distributions. Then obtained results from HRTEM images of one of samples and these model results are compared. The results also show that the average error for HK, DA and DS models are 2.04, 2.73 and 1.42, respectively. Thus, DS model is introduced as the best model for determination of pore size distribution, and DA model gets the third rank.

Effects of template type on the catalytic performance of SAPO-34 catalyst in conversion of methanol to light olefins (MTO) have been investigated. SAPO34 molecular sieves were synthesized by hydrothermal method, using morpholine tetraethyl ammonium hydroxide and dipropylamine as the template in the synthesis of gel with molar composition of Al2O3: P2O5: SiO2: template: H2O being 1:1:0.6:2:50, respectively. The produced samples were characterized by XRD, SEM, NH3-TPD and TGA-DTA techniques. These results showed that template type affects crystal size, morphology, crystallinity and purity of samples. It was found that the average SAPO-34 crystal size increased when morpholine was used as the template. Conversion of methanol to light olefins using acidic SAPO34 as the reaction catalyst was studied in a fixed bed reactor in the temperature range of 250–450oC, atmospheric pressure and WHSV=1 hr-1. Although all the catalysts showed similar activity and product distribution, the catalyst obtained using morpholine as the template, had the shortest lifetime.

Continuous gas lift process is used to boost oil production in many mature reservoirs, which can no longer produce under natural drive. In this article, application of mechanistic flow maps as well as the correlations estimating pressure drop in a gas lifted well, as the most complex and time consuming part of the gas lift modeling is examined. Using the black-oil model to compute the two-phase pressure drop in a gas lifted well leads to a substantial error due to the changes in composition and bubble point pressure along the well. In order to describe the thermodynamic behavior of the hydrocarbon fluid, a multicomponent compositional description has been applied using the reduced parameter method. The results show that the empirical maps and correlations lead to severe discontinuities at transition points between the different flow regimes. This causes an unacceptable error when computing the pressure drop.

Well logging tools are one of the most useful methods for formation evaluation in a sedimentary basin. Therefore, well log data could be used as an indicator for determination of source rock potential. Characterizations of Kazhdomi, Pabdeh and Gurpi source rocks have been determined by geochemical analyses in some of Iranian oil fields, but no TOC zonation and interpretation have been carried out in these formations yet. The aim of this study is to estimate the TOC content by means of combination of sonic and resistivity logs (DlogR method), which were run in Pabdeh and neural network method and then compare with TOC results from geochemical analysis (RockEval VI) in Ahwaz and Marun oil fields. Consequently, the results led to zonation of TOC in mentioned oil fields. Also, the intervals which Pabdeh formation has reached to oil generation window were determined with respect to TOC rich zone thickness changes and geothermal gradient of wells.

The objective of this study was to evaluate the feasibility of treating desalting plant wastewater to meet the applicable discharge limits and injection to well standard consistently using membrane processes to reduce the risk of clogging of the injection well. The effluent of sand filtration unit from Aghajari Maroon 2 was used as a feed. A pilot scale hybrid membrane unit consisting of a spun polypropylene 0.45 m pore size microfilter and a hollow fiber polypropylene 0.1 to 0.01 m pore size ultrafilter membrane was used in this study. Trials on different membrane fluxes were conducted for three processes, namely microfiltration, ultrafiltration and hybrid micro and ultrafiltration. Results have shown that the optimal values for flow rate and flux were 32 L/MIN and 120 LMH, respectively. The average values for percentage removal of turbidity, oil and grease, TSS and particle size were 98.53, 98.81, 98.23 and 99.93, respectively. The results showed that the quality of the product consistently met the requirement for injection to well. It was concluded that it is feasible to treat the wastewater using micro and ultra filter.

Aquifer displacement is one of the mechanisms of oil production in the reservoirs around the world as well as some reservoirs in Iran. A variety of parameters affect this mechanism, among which the most important ones are oil and water composition as well as the interactions between crude oil, brine and rock. When it comes to “Crude Oil-Brine-Rock” system, the evaluation of water injection is of much importance. The oil recovery based on water injection can be different in various compositions of “Crude Oil-Brine-Rock” system depending on the variety of oil, water composition and forces effective on displacement. In the conducted researches on oil reservoirs of Asmari and Bangestan formations, water injection has been reviewed under different compositions of fluids and rocks. The results have been outlined based on DLVO theory with regards to mechanical and colloidal forces. The study on various “Crude Oil-Brine-Rock” systems indicates that oil recovery depends on the interaction of rock and fluids and the superiority of different forces. The most notable among those forces are colloidal, capillary and viscosity. The interaction between fluid and rock is influenced by the circumstances of the incumbent “Crude Oil-Brine-Rock” system.