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.     

Surface damage of poly(methylmethacrylate) under fretting loading

The initial fretting damage in a glass/PMMA contact was investigated by means of experiments and numerical (F.E.M.) simulations. Both micro-crack nucleation at the contact edges and particle detachment were identified on the PMMA's surface. Micro-crack initiation was related to the combination of high tensile stresses and positive hydrostatic pressures which are known to enhance crazing. During the early stages of the fretting tests, the distribution of the detached particles within the contact was correlated to the spatial distribution of the cumulative interfacial energy dissipated by friction. As the number of cycles was increased, it was observed that detached particles moved toward the middle of the contact. On the basis of FEM simulations, this particle displacement within the contact was attributed to the existence of differential micro-displacements during the fretting cycle.     

Optimizing the location of the gas injection well during gas assisted gravity drainage in a fractured carbonate reservoir using artificial intelligence

Gas assisted gravity drainage (GAGD) is a novel subdivision of gas injection method. In this method the injection wells are located in the upper bed of the oil zone, and the production wells are drilled at the bottom bed of the oil zone. Reservoir simulation is among the decision tools for investigating production rate and selecting the best scenarios for developing the oil and gas fields. Selecting the location of the injection wells for reaching the optimized pressure and production rate is one of the most significant challenges during the injection process. Recent experiences have shown that artificial intelligence (AI) is a reliable solution for taking the mentioned decision appropriately and in a least possible time. This study is attributed to the investigation of applying the artificial neural network (ANN) as an artificial intelligence method and a potent predictor for choosing the most proper location for injection in a GAGD process in a fractured carbonate reservoir. The results of this investigation clearly show the efficiency of the ANN as a powerful tool for optimizing the location of the injection wells in a GAGD process. The comparison between the results of ANN and black oil simulator indicated that the predictions obtained from the ANN is highly reliable. In fact the production flow rate and pressure can be obtained in every possible location of the injection well.     

Visualization and Quantification of Asphaltinic-Heavy Oil Displacement by Co-Solvents at Different Wettability Conditions

Abstract

Despite numerous experimental studies, there is a lack of fundamental understanding on how the chemical composition of a co-solvent at different wettability conditions might affect the pore-scale events and oil recovery efficiency in 5-spot models. In this study visualization of solvent injection experiments performed on a one-quarter five spot glass micromodel, which was initially saturated with the crude oil. One hydrocarbon solvent was considered as base, and four other groups of commercial chemicals, as well as their mixtures, were used as co-solvents. Microscopic and macroscopic displacement efficiency of solvent mixtures in both strongly water-wet and oil-wet media has been studied. It has been observed that small aggregates of asphaltene can improve oil recovery to some extent during early stages of solvent injection. Different groups of chemicals showed various effects on oil recovery based on their nature. An optimum mixture with some percent of commercials containing alcohol group with greatest sweep efficiency was found. The observations confirmed that the presence of connate water in strongly water-wet medium could improve the final recovery, while the effect of wettability in absence of connate water was at minimum.     

Structural,Micromechanical and Tribological Characterization of Zn–Ni Coatings: Effect of Sulfate Bath Composition

Zn and Zn–Ni alloy coatings were electrodeposited on mild steel from sulfate-based bath containing Sn as additive. The effect of Ni content on the microstructure, morphology, microhardness and the tribological behavior of these coatings were studied and discussed. Adding Sn in the sulfate bath had a significant effect on the surface morphology, particularly on the Zn–8 wt% Ni coatings. By increasing the Ni concentration from 8 to 14 wt%, the X-ray patterns showed that the phase structure of Zn–Ni alloy coatings was changed from η-phase Ni₃Zn₂₂ to γ-phase Ni₅Zn₂₁. The plastic deformation and delamination were found to be wear mechanisms for the investigated coatings. While the Zn–14 wt% Ni alloys had the best wear resistance, Zn films had the most severe wear volume loss and the highest friction coefficient.     

Asphaltene Precipitation During Different Production Operations

Asphaltene precipitation due to enhanced oil recovery (EOR) methods or natural depletion is a serious technical problem at petroleum industry. The authors present the result of asphaltene precipitation during associated gas injection, CO₂ injection, and natural depletion in reservoir condition. In addition, the effect of variations in operation pressure, injection gas concentration, and production rate on asphaltene precipitation and difference between slope of precipitation graph due to various method of EOR or natural depletion were investigated. The results revealed that temperature has an efficient role on result of asphaltene deposition through associated gas and CO₂ injection. By decreasing temperature, the amount of asphaltene precipitation due to associated gas injection was increased. In fact, recovery of gas injection was decreased at lower temperatures, hence; solubility has an important rule on asphaltene precipitation.     

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.     

Experimental and numerical investigation of intermittent drying of timber

Intermittent drying may be of interest in the future to address energy issues. Such drying conditions are also likely to help stress relaxation through mechanosorptive creep. The influence of applying oscillations of temperature and relative humidity during the drying of beech timber on time and drying stresses is discussed in the paper by means of nonsymmetrical and loaded drying. Experimental data were used to validate a numerical model in the case of intermittent drying. The model was then used to perform a numerical investigation of the possibility of using an intermittent energy source to dry wood.     

Dynamic replication factor model for Linux containers-based cloud systems

The Journal of Supercomputing - Infrastructure-as-a-service container-based virtualization is gaining interest as a platform for running distributed applications. With increasing scale of cloud...