The Assessment of Fracture Geometrical Properties on the Performance of Conventional In Situ Combustion

Abstract

The aim of the present work is to evaluate the effect of fractures geometrical properties such as orientation, density, location, and networking on the conventional fire flooding (CFF) process performance through simulation analysis. Combustion parameters of a fractured low-permeable carbonate heavy oil reservoir in Iran called Kuh-E-Mond (KEM); applied for simulation study and simulator has been validated with KEM combustion tube experimental data. The validated model was modified to study CFF in 3D semi-scaled combustion cells. Simulation results confirmed that CFF is more feasible in the case of densely fractured reservoirs such as those in the Middle East.     

A game equilibrium model of a retail electricity market with high penetration of small and mid-size renewable suppliers

Game theory has provided a practical tool to model players' strategic behavior in electricity markets, particularly as the world moves towards a more competitive market. A game theoretic approach can be used to find the clearing electricity price in a retail electricity market with a high penetration of small and mid-size renewable suppliers.     

Effect of gravity in wheel/terrain interaction models

Predicting the motion of wheeled robots in unstructured environments is an important and challenging problem. The study of planetary exploration rovers on soft terrain introduces the additional need to consider the effect of nonterrestrial gravitational fields on the forces and torques developed at the wheel/terrain interface. Simply reducing the wheel load under Earth's gravity overestimates the traveled distance and predicts better performance than is actually observed in reduced‐gravity measurements. In this paper, we study the effect of gravity on wheel/terrain interaction. Experiments were conducted to assess the effect of reduced gravity on the velocity profile of the soil under the wheel, as well as on the traction force and sinkage developed by the wheel. It was shown that in the velocity field of the soil, the decay of the tangential velocity component becomes gradual with reducing gravity, and the decay of the normal to rim velocity is slower in Lunar gravity. It was also found that wheel flexibility can have an important effect on the dynamics as the contact patch and effective radius vary periodically. These results were then used together with traditional semiempirical terramechanics models to determine and validate the simulated drawbar pull values. The developed simulation model includes the effect of wheel flexibility, dynamic sinkage, and gravity.     

Application of a Coordination Model for a Large Number of Stakeholders with a New Game Theory Model

Water Resources Management - Water allocation is an important issue for systems with multiple stakeholders. Individual and collective decisions are very important for such systems. Thus, a new...     

Quantifying the Role of Ultrasonic Wave Radiation on Kinetics of Asphaltene Aggregation in a Toluene–Pentane Mixture

Abstract

Recently, ultrasonic wave technology has received much attention as a method for removal of asphaltene deposits from the near wellbore region. However, very little is known about another feature of this technology on the kinetics of asphaltene molecules aggregation. In this work, the kinetics of asphaltene flocculation in several crude oil samples exposed to ultrasonic waves for different time intervals is studied by confocal microscopy. The colloidal structural evolutions of flocks are described by analysis of size distribution of flocculated asphaltene particles. The results show that for the first 90 min of flocculation time, the size of aggregates increases rapidly, and a reaction-limited aggregation model matches well with the experimental data for all samples. But, after 90 min, a reduction in aggregate size of sonicated samples is observed, whereas the aggregate size of nonsonicated oil samples increases in close agreement with the diffusion-limited aggregation model. It has been found that asphaltene flocculation of sonicated samples cannot obey classic Derjaguin-Ladau-Verwey-Overbeek (DLVO) theory of colloidal dispersions due to partial reversibility of flocculation. An optimum value for ultrasonic radiation time, at which the viscosity and flocculation rate of asphaltenic crude oils reduce to a minimum, is found to be close to 10 min for Sarvak crude oil. The results of this study illustrate two different behaviors associated with asphaltene aggregation in the case of sonicated oil samples.     

Effective factors in the treatment of kerosene-water emulsion by using UF membranes

The effects of different parameters including membrane type (regenerated cellulose and polysulphone), transmembrane pressure (TMP), the content of oil in the feed, the flow velocity of the feed and pH on the ultrafiltration of an emulsion of kerosene in water were studied. It was found that the important factors affecting ultrafiltration were, in order, membrane type, pressure and oil concentration. The greatest flux at the optimum conditions here of 3 bar, an oil content of 3% (v/v) and with membrane type C30F was predicted as 108 L/(m(2)h) that was within the range of the confidence limit of the measured value of 106 L/(m(2)h). The normalised FTIR results of the virgin cellulosic membranes C30F and C100F showed more abundant OH groups. The bigger number of OH groups implies a greater hydrophilicity. The larger observed flux in the C30F is related to a higher number of pores as well (surface porosity) compared with the C100F membrane. In the "polarised regime" from 3 bar upwards, flux was independent of pressure for all membranes and was assumed to be determined by the back diffusion transport. Despite the fact that both the PS100H and C100F membranes had the same cut-off (100 kg/mol), the hydrophilic C100F showed a superior permeate flux. The strongest drop of flux with time due to oil fouling was observed for the C100F although it was hydrophilic. In the case of the PS100H, both FTIR and SEM showed that cake layer formation was not the cause of fouling. Meanwhile the SEM and FTIR results of fouled C100F provided evidence of adsorptive and gel formation fouling.     

Nanocrystalline copper doped zinc oxide produced from copper doped zinc hydroxide nitrate as a layered precursor

Undoped and copper doped nanostructured zinc oxides were synthesized by using a series of synthetic layered material, undoped and copper doped zinc hydroxide nitrates at various molar percentages of copper (2–10) within the layers as precursors. The layered materials were heat-treated at 500 °C to produce zinc oxide nanostructures with crystallite sizes in the range of 23–35 nm. Optical studies of the nanostructured copper doped zinc oxides showed the decrease in band gap with increasing content of the doping agent, copper.     

Optimization of Gas Allocation to a Group of Wells in Gas Lift in One of the Iranian Oil Fields Using an Efficient Hybrid Genetic Algorithm (HGA)

A hybrid genetic algorithm (HGA) was introduced to allocate optimum amount of gas. This method was applied to a group of wells in gas lift in the case of availability limited amount of gas. For testing the ability of the proposed HGA, the results of this work with those of previous works in a field with six wells were compared. Then for an Iranian southern west oil field with nine wells, gas allocation is performed using different amount of available gas. The results show that the introduced method (HGA) is very efficient tool in gas allocation issue.     

Reservoir Characterization by a Combination of Fuzzy Logic and Genetic Algorithm

Reservoir characterization is the basis of almost all aspects of well drilling and oilfield managements and therefore the precise determination of the reservoir properties has a massive profound impact on the success of the operations. Different methods have been suggested by previous authors for this purpose but complexity of the procedures, lack of precision, and time-consuming nature are the major weak points of such procedures, especially when uncored intervals are intended. In order to defeat such problems, a novel hybrid computational intelligence system is developed through which the optimum inputs (features) are investigated by a combination of genetic algorithm and adaptive network-based fuzzy inference system and then the cluster center's range of influence in each of the data dimension is optimized by the same algorithm. The resulting performances of the modeled cases are then compared by other methods. The considerable improvement in the system accuracies and achieving mean standard error of .00007 and .00033 for the porosity and water saturation models, substantiates the power, efficiency, and precision of the stated novel method.     

Relationship Between Wetting Properties and Macroscale Hydrodynamics During Forced Gravity Drainage and Secondary Waterflood

Abstract

In order to relate the wetting properties at the pore scale to the macroscale prevailing forces, a series of experiments was performed in vertical porous media under forced gas invasion at various wettability conditions with partially spreading oil. To describe the dynamics of oil recovery in a three-phase flow condition, the downward gas flood experiments were continued by water injection from the bottom. Experimental results obtained in situations where the magnitudes of viscous, capillary, and gravity forces are comparable. We study the transition from flow configurations where the interface is stable with respect to viscous instability to flow configurations where viscous fingering occurs. The results also have been analyzed using a dimensionless number.