Multiscale pore structure characterization and pore network modeling of middle east carbonates

Gündoğar, Satı Aslı
The complex interplay between structural and wettability heterogeneities is responsible for the limited pore network modeling studies on carbonates. In this study, our purpose is to develop structurally representative pore networks of Middle East carbonates and to predict their macroscopic difficult-to-measure relative permeability and capillary pressure hysteresis curves and residual oil trends under mixed-wettability conditions. In comparison with the conventional pore-scale models, particular emphasis is put on multiscale pore structure characterization of complex carbonates. Scanning electron microscopy (SEM) imaging at multiple magnifications (75X and 750X) as well as physical core measurements, namely helium pycnometry and high-pressure (33,000 psi) mercury intrusion porosimetry (MIP) are employed to determine quantitative pore network descriptors. Mosaics constructed from overlapping low magnification (75X) views reveal abundant evidence of unresolved microporosity within the carbonate samples. Multiscaled SEM pore-size distributions incorporate microporous features as small as 0.077 μm and macropores as large as 310 μm into a single pore system. A pore body-throat classification method is developed with an initial premise of strong spatial size correlation between pore bodies and their connected throats. Six pore classes are identified with unique pore- and throat-size distributions. The average coordination number ranges mostly from 3 to 5, and irregular triangle-shaped cross-sections dominate the carbonate pore geometry. The pore body to throat aspect ratio is generally large (>2.5), indicating the potential for significant residual oil saturation. A novel quasi-static two-phase flow simulator is developed for a complete primary drainage-secondary imbibition-secondary drainage cycle with arbitrary wettability. Incorporating wettability alteration and contact angle hysteresis, the critical roles of corner wetting films and intermediate layers on fluid continuity and accordingly on recovery are investigated. The model predictions display a significant dependency on the interaction of pore structure, wettability, and saturation history. During spontaneous imbibition, snap-off becomes dominant in the systems with high aspect ratio and results in large amounts of trapped oil. It is shown that residual oil saturation is lower for more strongly oil-wet systems by means of the abundant presence of oil layers, while the endpoint water relative permeability increases gradually with the oil-wetness. The continuity of a phase is deduced to be the critical factor for its relative permeability rather than its abundance in the pore system. It is concluded that our newly proposed network model succeeds to represent experimentally hard-to-measure capillary pressure and relative permeability hysteresis trends for mixed-wet systems.  


Image-based extraction of material reflectance properties of a 3D rigid object
Erdem, ME; Erdem, IA; Yilmaz, UG; Atalay, Mehmet Volkan (2004-01-01)
In this study, an appearance reconstruction method based on extraction of material reflectance properties of a three-dimensional (3D) object from its two-dimensional (2D) images is explained. One of the main advantages of this system is that the reconstructed object can be rendered in real-time with photorealistic quality in varying illumination conditions. The reflectance of the object is decomposed into diffuse and specular components. While the diffuse component is stored in a global texture, the specula...
Dielectric matrix influence on the photoluminescence properties of silicon nanocrystals
Ferraioli, L.; Cazzanelli, M.; Daldosso, N.; Mulloni, V.; Bellutti, P.; Yerci, Selçuk; Turan, Raşit; Mikhaylov, A.n.; Tetelbaum, D.ı.; Pavesi, L. (null; 2006-12-01)
Photoluminescence properties of silicon nanocrystals embedded in five different oxide matrices are analyzed. Samples are silicon rich oxide and oxynitride produced by PECVD and ion implantation and crystalline and amorphous aluminum oxide implanted with silicon.
Unified theory of linear instability of anisotropic surfaces and interfaces under capillary, electrostatic, and elastostatic forces: The regrowth of epitaxial amorphous silicon
Ogurtani, Tarik Omer (American Physical Society (APS), 2006-10-01)
The first-order unified linear instability analysis (LISA) of the governing equation for the evolution of surfaces and interfaces under capillary, electromigration (EM), and elastostatic forces is developed. A formal treatment of the thermomigration (Soret effect) driven by the nonuniform temperature distribution caused by exothermic phase transformation (growth) at the surface and interfacial layers is presented and its apparent influence on the capillary force in connection with the stability is also esta...
Adsorption of water and ammonia on TiO2-anatase cluster models
Önal, Işık; Senkan, Selim (2006-06-15)
Density functional theory (DFT) calculations performed at B3LYP/6-31G** level are employed to study water and ammonia adsorption and dissociation on (101) and (001) TiO2 anatase surfaces both represented by totally fixed and partially relaxed Ti2O9H10 cluster models. PM3 semiempirical calculations were also conducted both on Ti2O9H10 and Ti9O33H30 clusters in order to assess the effect of cluster size. Following dissociation, the adsorption of H2O and NH3 by H-bonding on previously H2O and NH3 dissociated s...
Comparison of geostatistics and artificial neural networks in reservoir property estimation
Arzuman, Sadun; Karahanoğlu, Nurkan; Department of Geological Engineering (2009)
In this dissertation, 3D surface seismic data was integrated with the well logs to be able to define the properties in every location for the reservoir under investigation. To accomplish this task, geostatistical and artificial neural networks (ANN) techniques were employed. First, missing log sets in the study area were estimated using common empirical relationships and ANN. Empirical estimations showed linear dependent results that cannot be generalized. On the other hand, ANNs predicted missing logs with...
Citation Formats
S. A. Gündoğar, “Multiscale pore structure characterization and pore network modeling of middle east carbonates,” Ph.D. - Doctoral Program, Middle East Technical University, 2017.