PETROLEUM RESEARCH
Year:2010 | Volume:20 | Issue:61|Papers Count:10

The amount of resin existing in crude oil highly affects the asphaltene precipitation values and results in formation of precipitation, asphaltene and resin and also pressure and temperature variations in such reservoirs. According to the literature, the effect of resin content has not been studied. The equation of state (AEOS) is one of the most applicable models which was also used in this study. The compressibility factor was assumed to be made of physical and chemical components. SRK equation of state was used in physical component. Considering the fact that asphaltene and resin do not interact in gas phase and that asphaltene and resin precipitations are in liquid state, vapor-liquid and liquid- liquid equilibrium calculations were applied. Asphaltene precipitation values were calculated from simulations the results were then compared to experimental data. Finally the resin precipitation values were measured.

In this study the effects of dodecylbenzenesolfonic and dodecylresorcinol acids (as alkyl-benzene derivatives inhibitors) on asphaltene precipitation of three Iranian crude oil were investigated. Near infrared spectroscopy technique and heptane titration were used to detect the onset of asphaltene precipitation in presence and absence of inhibitors. The displacement of asphaltene precipitation at the presence of inhibitors was considered as the delay criteria of asphaltene formation and structural stability. The relation between structural parameters of asphaltene and onset precipitation displacement in presence of inhibitors was studied. The inhibition effect of dodecylbenzenesolfonic acid was revealed to be more effective than dodecylresorcinol in the three crude oil samples. The suitable concentration of dodecylbenzenesolfonic acid was measured as 500~1000 ppm. The onset precipitation displacement constantly decreases at higher concentrations in presence of both inhibitors.

In this study, perovskite Ba0.5Sr0.5Co0.8Fe0.2O3-d and SrCo0.8Fe0.2O3-d were synthesized by EDTA and citrate complexing methods. The microstructural studies were carried out using X-Ray Diffraction (XRD) and Scanning Electron Microscopy (SEM) to investigate the crystal structure and also structural stability. Oxygen permeation through BSCF and SCF membranes were measured at elevated temperatures (700oC to 950oC). XRD re-suits showed that both specimens possess perovskite and cubic structure. A relatively high permeation value (2 cc/min.cm2 at 950oC) were reported for both specimens. The results indicated that oxygen permeation of BSCF is higher than that of SCF through a wide range of temperature. Also, the effect of upstream partial pressure of oxygen (0-1 atm) on oxygen flux was studied at various temperatures. The increase in oxygen partial pressure significantly increases the oxygen flux which suggests that these membranes may be used for industrial application. Activation energy results revealed that permeation of SCF membrane at low temperatures is more sensitive to temperature than BSCF which is contrary to observations at high temperatures. It was concluded that Oxygen permeation flux is controlled by both surface exchange kinetics and bulk diffusion. XRD patterns after (adsorption-desorption treatment) indicated that BSCF has a more stable structure at high-temperatures than SCF and also possesses lower oxygen partial pressures.

In this study, a method for evaluation of pressure drop of air cooler heat exchangers was developed which is based on the maximum pressure drop value. Due to the procedure used in full pressure drop absorption, the heat exchanger designed in this study are smaller than most common procedures which leads to lower capital investment of heat exchangers. It was concluded that the proposed procedure can be successfully used in high efficiency enhanced heat exchangers, where tube inserts are employed as the enhancement element.

Determination of different facies is one of the most important and fundamental tasks of geological arid engineering characterization of reservoir rocks. The neural network method is one of the new techniques used in identification of facies. The objective of the present study was to identify and measure different facies of Southern Pars gas and oil fields (Iran) using back-propagation neural networks in order to develop static and dynamic models. Modeling was carried out using three different techniques. Also network parameters were optimized in order to improve the network performance including number of layers and neurons, transfer function, training algorithm, dividing and performance functions. The results indicate that the back-propagation neural network is a powerful method for identification and modeling of the facies.

History matching is considered as one of the most important simulations in reservoir description. In other words, reservoir simulation results are not reliable without history matching due to uncertainties of the input data. However, in some cases there may not be enough data for history matching and few tricks may be re-quired Studied field is an abandoned oil field that has no water and gas production history. After reviewing the history of the field in this study, it was revealed that a blowout had occurred in a well for three months which was due to BOP (Blow Out Preventer) problem and water-oil surface had risen in this well. As the result, a history of water-oil interface movement exists which can be used in history matching. W-C movement was successfully simulated in this well and the results showed good agreement with experimental results. After history matching, various techniques including drilling infill (vertical and horizontal), water and gas injection were applied and results were then compared. It was revealed that horizontal drilling causes water breakthrough and low recovery values. Also the same results were observed for water injection method. The gas injection was selected as the optimum method in which 20 MMSCF/D gas was injected into the two wells (10 MMSCF/D for each) and consequently an overall increase of 18 MMSTB was reached in oil production from these two wells in 10 years. Gas injected wells are rarely of any importance due to high water cut problem and investment on drilling of new gas injected wells is not suggested.

In the present study, injection of different gases in a fractured reservoir of Iran were simulated by various techniques. Science natural, nitrogen, separator and miscible gases were injected, also an economic evaluation was done in this field. Results indicate that the miscible gas exhibited the highest recovery factor (57.2%). This value for natural gas N2 were nearly the same. Using the Eclipse commercial simulator, the composition of black oil was simulated and economic calculations were carried out by measruing the amount of inection gas of the reservoir. The recovery factor of two gases were almost the same, however amount of methane is lower than N2. Based on economic calculations, it was revealed that methane is the most suitable injection gas for this field.

In this study, a thermal modeling was carried out in surface outcropped-formations in Kuh-e Khami and Kuh-e Mish, Iran. The formations were studied by two sets of experiments obtained from three different locations. Lithology, thickness, dip and azimuth of strata were measured. Also the eroded parts of these formations were reconstructed. A cross section of Kuh-e Khami and Kuh-e Mish were prepared from NE-SW direction and was used for the simulation software. Finally maturity model and history of Kazhdumi were established based on the results. It was included that erosion had a significant impact on maturation rate of organic materials. Initiation of erosion from burial depth resulted in lower temperatures and oil production rates.