Improving Matrix Recovery Using Chemicals and Thermal Methods in Fractured Heavy-Oil Reservoirs

To increase the effectiveness of heavy-oil recovery from matrix by capillary imbibition, surfactant and polymer solutions or hot water can be used as an aqueous phase. The effect of them on the matrix fracture transfer performance was investigated in this article. The observations and analysis of the laboratory scale experimentation on these three methods were reported. Experiments were conducted on water-wet (Berea sandstone) and oil-wet samples (Indiana limestone) using engine oil and heavy crude oil. Different boundary conditions were created so that both co and counter-current type matrix-fracture transfers took place. Performances were compared in terms of ultimate recovery, recovery rate and the cost of the process. It was observed that all three aqueous phases yielded higher and faster recovery compared to waterflooding with some exceptions. This difference was more prominent for counter-current capillary imbibition. The exceptional cases were scrutinized and the possible reasons were discussed. Based on these observations, suggestions were made for the most suitable aqueous phase yielding the best performance for different rock wettabilities and oil types.     

Heavy oil and bitumen recovery by hot solvent injection

Thermal and miscible methods are commonly used for in situ recovery of heavy oil and bitumen. Both techniques have their own limitations and benefits. However, these methods can be combined by co-injecting solvent with steam or injecting solvent into a pre-heated reservoir. The current work was undertaken to study the performance of solvents at higher temperatures for heavy oil/bitumen recovery. Glass bead packs and Berea sandstone cores were used in the experiments to represent different types of pore structures, porosity and permeability. After saturating with heavy oil, the samples were exposed to the vapor of paraffinic solvents (propane and butane) at a temperature above the boiling point of the solvent, and a constant pressure of 1500 kPa. A mechanical convection oven was used to maintain constant temperature across the setup. The setup was designed in such a way that a reasonably long sample (up to 30 cm) can be tested to analyze the gravity effect. The oil recovered from each of these experiments was collected using a specifically designed collection system and analyzed for composition, viscosity and asphaltene content.The final amount of oil recovered in each case (recovery factor but not extraction rate) was also analyzed and the quantity and nature of asphaltene precipitated with each of the tested solvents under the prevailing temperature and pressure of the experiment was reported. Optimal conditions for each solvent type were identified for the highest ultimate recovery. It was observed that recovery decreased with increasing temperature and pressure of the system for both solvents, and that the best results were found when experimental temperature is only slightly higher than the saturation temperature of the solvent used. It was also noticed that butane diluted the oil more than propane which resulted in lower asphaltene content and viscosity of oil produced with butane as a solvent.     

Effect of dust content on some properties of concrete

Summary The region mapped is located in the north-eastern part of the Parana basin in Brazil. The area contains sedimentary rocks and large flows and intrusions of basaltic rocks. As a result of transcurrent faulting due to the displacement of Atlantic plates to the west, followed by uplift, flexuring and normal faulting, the most important rivers draining the region flow out of the basin over fractured zones following the dip of the beds from SE to NW. Study of the frequency of occurrence of erosion surfaces in the more fractured zones offers a means of studying the structural conditions in the area and the degree of fracturing of rock masses. Geomorphological mapping, together with statistical surveys of erosion surfaces and regions with high and low degrees of depression and tilting, permits the localisation of areas more suitable for civil engineering works because of reduced seismicity, slope instability and water flows.

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Cartographie morphotectonique pour la construction d'ouvrages d'art dans la partie nord-est du bassin du parana, Bresil

Résumé La région cartographiée est située dans la partie nord-est du bassin du Parana, au Brésil. Elle comprend des roches sédimentaires et des roches basaltiques en grandes coulées et en intrusions. Du fait de la présence de failles de décrochement dues au déplacement des plaques atlantiques vers l'ouest, puis à leur soulèvement, à leur flexure et à la formation de failles normales, les principaux cours d'eau qui drainent cette région sortent du bassin en traversant des zones fracturées et en suivant le pendage des couches du sud-est vers le nord-ouest. L'étude de la fréquence des surfaces d'érosion dans les zones les plus fracturées constitue un moyen d'étude des conditions structurales de la région et du degré de fracturation des masses rocheuses. La cartographie géomorphologique, associée à une enquête statistique sur la surface d'érosion et sur les régions comportant de hauts degrés ou de bas degrés de dépression et d'inclinaison, permet de localiser comme aires les plus favorables à la construction de grands ouvrages celles qui présentent une moindre sismicité, une moindre instabilité des talus et moins d'inondations.

     

A comparison for Turkish provinces’ performance of urban air pollution

The objective of this paper is to assess the environmental performance of Turkish provinces by using a non-parametric method, Data Envelopment Analysis. The results of ranking are based on the provinces’ ability to produce the largest equi-proportional increase in the desirable output-gross domestic product and decrease in the undesirable output namely, air pollutants. The results indicate that 7.41% of the sample provinces are relatively efficient. The results also show that, regions with the highest level gross domestic product per capita have the highest efficiency scores. New industrial districts have lower efficiencies in spite of relatively higher income per capita. In the second stage of the study the possible relationship between environmental efficiency scores and input, output variables are investigated by a regression analysis. According to the results, there is a positive relationship between gross domestic product and efficiency scores.     

Fluid–structure interaction modeling of clusters of spacecraft parachutes with modified geometric porosity

To increase aerodynamic performance, the geometric porosity of a ringsail spacecraft parachute canopy is sometimes increased, beyond the “rings” and “sails” with hundreds of “ring gaps” and “sail slits.” This creates extra computational challenges for fluid–structure interaction (FSI) modeling of clusters of such parachutes, beyond those created by the lightness of the canopy structure, geometric complexities of hundreds of gaps and slits, and the contact between the parachutes of the cluster. In FSI computation of parachutes with such “modified geometric porosity,” the flow through the “windows” created by the removal of the panels and the wider gaps created by the removal of the sails cannot be accurately modeled with the Homogenized Modeling of Geometric Porosity (HMGP), which was introduced to deal with the hundreds of gaps and slits. The flow needs to be actually resolved. All these computational challenges need to be addressed simultaneously in FSI modeling of clusters of spacecraft parachutes with modified geometric porosity. The core numerical technology is the Stabilized Space–Time FSI (SSTFSI) technique, and the contact between the parachutes is handled with the Surface-Edge-Node Contact Tracking (SENCT) technique. In the computations reported here, in addition to the SSTFSI and SENCT techniques and HMGP, we use the special techniques we have developed for removing the numerical spinning component of the parachute motion and for restoring the mesh integrity without a remesh. We present results for 2- and 3-parachute clusters with two different payload models.     

OPTIMUM STEAM INJECTION STRATEGIES FOR NATURALLY FRACTURED RESERVOIRS

ABSTRACT

This study aims to identify the effective parameters on matrix oil recovery and the efficiency of this process while there is a continuous flow of steam in fracture. Single matrix system is studied first. The critical injection rate is defined for laboratory scale simulation for different matrix properties. It is observed that there is a critical injection rate optimizing the process and the critical injection rate for an efficient matrix oil recovery is defined for different matrix sizes and matrix heat transfer coefficients.

In the second part of the study, similar analysis is performed to investigate the effect of injection rate on the oil recovery for field scale. Critical rate concept is evaluated for different number of horizontal fractures and steam qualities. Finally, the economics of steam injection in the field scale is studied. The optimum injection strategies determined by the adjustment of injection rates are discussed based on the fracture properties such as density and permeability. The approach and results can be used in further studies to analyze the efficiency of thermal applications and to obtain correlations for steam injection performances in naturally fractured reservoirs.     

Bond strength of polymer lightweight aggregate concrete

Bond strength, physical, and mechanical properties of lightweight PC were investigated with inclusion of pumice lightweight aggregate in maximum size of 12 mm. As binder material, epoxy resin‐based polymer was used with its hardener. The binder to aggregate ratio was 30% by weight. In addition, steel fibers were added to lightweight PC mixtures in ratio of 0, 0.5, and 1%. After lightweight PC mixture was prepared, it was poured in the molds with different type of steel‐bars in size of 100 × 100 × 100 mm³. The steel‐bars centered in the cubic molds, and they were in size of Ø12, Ø14, and Ø16. The specimens were cured at 60°C for 2 h. On the hardened polymer lightweight concrete (PLC), pull‐out test for bond strength and compressive strength tests were performed. Moreover, ultrasonic pulse velocity, water absorption by weight, specific porosity, and density experiments were carried out. The relation between physical and mechanical properties showed that PLCs become more durable when using ratio of steel fibers. POLYM. COMPOS., 34:2125–2132, 2013. © 2013 Society of Plastics Engineers     

Space–time interface-tracking with topology change (ST-TC)

To address the computational challenges associated with contact between moving interfaces, such as those in cardiovascular fluid–structure interaction (FSI), parachute FSI, and flapping-wing aerodynamics, we introduce a space–time (ST) interface-tracking method that can deal with topology change (TC). In cardiovascular FSI, our primary target is heart valves. The method is a new version of the deforming-spatial-domain/stabilized space–time (DSD/SST) method, and we call it ST-TC. It includes a master–slave system that maintains the connectivity of the “parent” mesh when there is contact between the moving interfaces. It is an efficient, practical alternative to using unstructured ST meshes, but without giving up on the accurate representation of the interface or consistent representation of the interface motion. We explain the method with conceptual examples and present 2D test computations with models representative of the classes of problems we are targeting.