مجله پژوهش نفت
پیاپی 123 (خرداد و تیر 1401)

Shurijeh Formation with Early Cretaceous (Neocumin-Barmin) age is one of the most important clastic reservoir rocks in northeastern Iran. By combining core information, petrographic study and application of petrophysical logs and data obtained from core analysis (porosity and permeability) of hydraulic flow unit and Electrofacies in the sedimentary sequence of Shurijeh Formation in five wells field were identified. The purpose of this study is to survey relationship between hydraulic flow unit and Electrofacies with the position of sequences (sequences and system tracts) and zonation of sedimentary sequences of Shurijeh Formation in the study reservoir. Based on the porosity and permeability data obtained from the core analysis, four hydraulic flow units were determined using the Flow zone indicator method. The fourth Electrofacies was determined based on gamma, neutron, density, sound and effective porosity logs obtained from possible evaluations using MRGC clustering method. Afterwards, the Hydraulic flow units and Electrofacies determined in the framework of sedimentary sequences were used and their distribution in the reservoir and field was determined to provide a clear match between the reservoir zones and the sequence stratigraphic framework. Finally, petrophysics (micro conglomerates, sandstones, and Sandy Dolomitic Ooid Grainstone / Hybrid) are associated with high-energy braided river environments and the high-energy section of the lagoon to Barrier Tidal or shoal, the best reservoir units are in the sedimentary sequence of zone D, B and the middle part of zone C (C2). On the other hand, petrophysics (Claystone/shale, dolomadstone sandy) related to low-energy environments of Braided river (floodplain), meandering river and superatidal stream (above tidal), the Poorest reservoir unit of these sequences in zone A, E sediment sequence and alternately formed in zones C and D.

The oil spill into the oceans from oil tankers and oil pipelines has an ecological importance and a social and economic impact on coastal environments. Rapid detection of deliberate and accidental oil leaks can reduce serious risks to coastal residents and help pollutants be identified. The purpose of this research is to study the effects of thrust coefficient in wind under severe tidal conditions in the area of oil floods motion caused by oil tanker collision with a tower in Hebei typhoon in the western coastal zone of Korea. In order to separate oil from similar samples, Convolutional Neural Network (CNN) was used. The noise loss of the open data scattered by the Boxcar filter was modified and the motion of the oil flood was calculated by using a simple simulation model based on the experimental formula as the performance of surface water flow, wind speed and wind thrust factor. To simulate, the Environmental Fluid Dynamics Code (EFDC) and Automatic Weather Station (AWS) were used to generate tidal and wind fields. The simulated results were then compared with two samples of the data of the Synthetic Aperture Radar, Sentinel-1 and TerraSAR-X. From the present study, it is found that the highest match between the simulation results and the satellite images is obtained with different values of wind thrust and this factor is linearly proportionate to the wind speed.  According to the results, a new modified experimental formula is proposed to predict the flow of oil flood motion in the coastal zone.

Gas injection has been used as an enhance oil recovery (EOR) method over last decades. However, due to low viscosity of gas and reservoir heterogeneity, this method has low recovery factor. Foam injection has been introduced as a solution to decrease gas mobility, and improve the ultimate oil recovery. In this study, the impact of wettability and capillary pressure on the foam performance has been investigated. In this regard, a fractured reservoir is developed, and three different wettability and capillary pressure condition has been tested. These conditions are changing the wettability from water-wet to mixed wet, along with an assumption of considering the capillary pressure or not. For better accuracy, different foam models were devoted to fracture and matrix. These models are similar to porous medium, and foam model parameters are a result of an optimization algorithm. The simulation outcomes reveal that the generation of foam within the fracture creates a viscous crossflow which leads to displacement of oil and higher recovery factors. The wetting state of the matrix determines the quality of foam, and matrix foam becomes more water-base, as wettability is altered from water-wet to mixed-wet. The results also show that matrix capillary pressure can create a capillary crossflow and harms the efficiency of foam injection by drying out foam in the fracture.

Reservoir oil recovery and efficiency of EOR projects include designed water injection influenced by factors such as oil composition, porosity, permeability, rock mineral composition, porous space distribution, and pore size. The injection of designed water into the carbonate reservoir has always faced many ambiguities. This category of ambiguities has been further investigated and analyzed in this study by examining one of the influential factors, such as polar compounds of oil and its Physico-chemical interactions during the production process. Polar components in crude oil affect the electrostatic interactions at the mineral surfaces, affecting the wettability conditions. This study performed experiments measuring contact angle and spontaneous vascular process on limestone samples. For this purpose, cores with the same conditions are saturated in different oils regarding the percentage of polar compounds. Moreover, they are adjacent to specific components of active ions in designed water. In this regard, using the collected results, we can interpret and study how to participate in the reaction and the effectiveness of polar compounds in the oil. The results show that the amount of oil production due to water injection depends on the chemical composition of the oil and the interaction between water and oil, and in addition to the amount of asphaltene in the oil, it is also affected by the amount of organic carboxylic acids in crude oil.

The aim of the present study is to investigate the permeability changes and the ratio of horizontal to vertical permeability in Kangan and Upper Dalan carbonate reservoirs. The effect of geological parameters such as lithology, texture, facies and porosity has been investigated on the amount of horizontal and vertical permeabilities and their changes as well as the ratio of horizontal to vertical permeability in these formations in the central part of Persian Gulf. For this purpose, statistical methods have been used on the data obtained from the study of plugs and microscopic thin sections prepared from the 402 meters of cores. The results showed that the mean value of horizontal permeability is closed to the mean value of vertical permeability in the two types of dolomite and limestone lithology as well as crystalline carbonate and mudstone textures. By increasing porosity without considering other geological factors, permeabilities increase and the ratio of horizontal to vertical permeability decreases. Also, the two factors of heterogeneity and increase in the amount of grains (from mudstone to grainstone texture) are more effective in comparison with micrite and cement in the changes of permeabilities. The presence of grains increases heterogeneity. Horizontal permeability will be higher than vertical permeability in energetic sedimentary environments and in grain-supported facies. It was also observed that dolomitization increases the ratio of horizontal to vertical permeability due to increased mineralogical heterogeneity. The ratio decreases in very high amounts of this mineral (more than 90 percent) due to the homogeneity of rock texture. Therefore, this ratio depends on the degree of heterogeneity of rock, the amount of grain, and lithology. Increasing porosity and permeability, homogeneity of the sample both in terms of the type of mineral forming the rock and in terms of texture, causes closer horizontal and vertical permeabilities.

Orifices are simple devices without moving and electronic components that can be used in the enrichment industry and can be applied with a higher-pressure difference than control valves and it is very low-priced. The main goal of this research is the examination of different gas flow through an orifice and the determination of optimum conditions for the control application inside the inlet and outlet lines of the thermal diffusion column. Computational fluid dynamics was utilized to predict the behavior of gas flow through an orifice using COMSOL software. The three-dimensional orifice model with the compressible gas flow was applied in our model. To validate the model, the reliable and common correlations in this field, e.g., Singhal et al. and O’Hanlon were used. The results were presented in two sections: supersonic and subsonic flow. The result shows that in the supersonic flow, the temperature and velocity in the throat decrease sharply and the pressure drops. Also, in the subsonic flow at the throat, velocity increases, and accordingly pressure decreases. The results of the simulation of the supersonic and subsonic flow showed that the three-dimensional model can accurately predict the behavior of orifices.

In recent years, low salinity water-flooding has received much attention as one of the enhanced oil recovery methods because of its cheapness and low operating limitations. Tuning of injected water composition and concentration can induce a significant effect on the oil recovery during the spontaneous imbibition process and forced oil displacement in the fractured reservoirs. Numerous lab and field studies have been conducted to realize the mechanisms and factors affecting the low salinity and smart water injection. Despite these researches, some of the related mechanisms and determining factors in carbonate reservoirs, such as the initial water saturation and temperature, have not yet been fully understood. Therefore, extensive experiments are needed to optimize the conditions of injected water. In this study, the oil recovery of spontaneous imbibition by low salinity and smart water containing divalent ions has been investigated when the initial water saturations were in relatively small and high amounts in carbonate cores. Then, the coreflooding experiments were conducted with various temperatures, including equivalent and below the reservoir temperature. Based on relative permeability and capillary pressure measurements, the mechanism leading to higher oil recovery during smart water injection was also investigated. The results showed that the oil recovery was increased during spontaneous imbibition of low salinity and smart water under ambient conditions as the initial water saturation increased. It was also observed that elevating the temperature from 80 °C to 105 °C in secondary water injection could improve oil production significantly. The reduction of residual oil saturation in the relative permeability and capillary pressure diagrams due to the presence of sulfate and magnesium ions confirmed that the carbonate rock became more water-wet at the ambient temperature.

A significant part of Iranian hydrocarbon resources are located in fractured reservoirs. The existence of two different fracture and matrix systems creates two models for fluid storage and flow. Evaluation of the rock and fluid interaction and identification of micro-mechanisms at the pore scale is effective in better understanding the production mechanisms in these reservoirs. Pore network modeling makes it possible to simulate a wide range of different conditions, different flow regimes, and identifying micro-mechanisms at the pore scale. Since the injection of non-equilibrium gas into fractured reservoirs, a combination of gravity and molecular diffusion contribute to the production process, and so far, no pore-scale study involving the combined effects of both mechanisms has been performed, this study has examined this issue. In this research, by developing an exist pore network model based on the analogy between the isothermal drying process of a porous medium and the molecular diffusion process, by adding the effect of gravity in a single-block model and by sensitizing the various parameters of the porous medium and fluids in the process such as: fluid type, different pressures, pores and throats size, the gravity drainage and molecular diffusion mechanisms were evaluated. According to the results, at a pressure of 101.3 kPa, the desaturation time of the liquid phase of the Heptane-Nitrogen and Heptane-Carbon dioxide systems is about 18 and 170% longer than the Heptane-Methane system, respectively. This trend is also true at high pressures. By changing the liquid phase from Heptane to Octane and Decane, the desaturation time of the liquid phase occurs 3.6 and 19 times later, respectively. The results also showed that the effect of increasing the throat length does not prolong the depletion time of the liquid phase as much as increasing the throat radius.

Due to the high demand in the petrochemical industry, catalytic dehydrogenation of paraffins has received much attention in recent years. Modeling and simulation of propane dehydrogenation radial flow reactors has been studied in this research. This process is performed in 4 moving bed radial flow reactors and intermediate heaters are used to supply reaction heat, and a feed heat exchanger. The mass and energy equations were solved simultaneously with the kinetic equations of the reactions, which of results of reactor simulations in Polymath V6 software with an mean relative error of 7.2% are in good agreement with industrial data. Also, the selectivity of propylene to propane in the fourth reactor was 53%. By modeling and simulating the reactors, it was found that due to the coking of the catalysts and the decrease in the activity of the catalysts in each reactor, the conversion and temperature drop in each reactor gradually decreased and the propane conversion rate in the first reactor was 61%, in the second reactor 15%. It decreases by 11% in the third reactor and 5% in the fourth reactor.

Several problems may be encountered during recovery from reservoirs containing emulsified oil. Higher oil phase viscosity, pore throat blockage, and a much higher rate of pressure drop through the recovery period are among the most serious ones. A suitable way to overcome this issue is to investigate the behavior of this type of oil in the porous medium. This study aims to survey the effects of brine salinity on pressure behavior. Different brines with different salinities including low salinity brine, Persian Gulf brine, and South Pars formation brine was injected into the sand pack, and the pressure behavior and ultimate recovery were monitored. The results showed that Persian Gulf brine would cause more blockage of pore throats and formation of in-situ emulsion in the porous medium, hence, resulting in more fluctuation in the pressure response. Because of the formation of in-situ emulsion, the ultimate recovery of Persian Gulf water is the lowest recovery, and low salinity water is the best choice for water flooding in the emulsified reservoir.