Fracture effect limitation on residual oil saturation & visualization by computer tomography

Canbolat, Serhat
Recovery estimations of fractured reservoirs are considered to be extremely challenging due to complexity and heterogeneity of the geological patterns. Most reservoirs consist of natural and artificial fractures, including isolated microscopic fissures. These fractures form complicated paths for reservoir characterization and fluid movement that ultimately impacts production performance and ultimate recovery. In naturally fractured reservoirs, the matrix is the dominant storage area, while the main flowing channels are fractures. Oil production from fractured reservoirs results in varying saturation values throughout the reservoir. This is due to the microscopic fissures and heterogeneity of the fracture environment, which could not be swept thoroughly. Higher production / injection ratios also enhance the fingering effect by passing oil through the reservoir. To get rid off fingering or minimize, a polymer gel application is applied to the fractured cores to reduce residual oil saturation and to increase oil production. In this study, naturally and artificially fractured cores were used. Analytical and experimental calculations were performed in order to understand the physical vi structure of the cores. After the characteriztion of the fractured cores a polymer gel application is done to limit the fracture effect and increase oil recovery. Equivalent fracture aperture measurements were done by microscope and compared with the analytical calculations with cubic law. Using CT scanner images, matrix porosity and saturation calculations were done. Matrix permeability and fracture permeability values were found before and after the polymer gel injection application. Measurements of the fractures were completed by using microscope to verify the analytical calculations. Laboratory results were defined by the equation developed for predicting equivalent fracture apertures with and without polymer gel as Improved Cubic Law (ICL). Shrinkage in equivalent fracture aperture was also defined by ICL observed by microscope. Using ICL, analytical calculations were done in different environments. Equivalent fracture apertures were calculated for all the experimental flow rates under laminar flow. ICL has worked with the fractured cores flow definition whereas not for homogeneous cores. There is a direct relation between fracture permeability with equivalent fracture aperture. The experiments with different environments (initially oil saturated and water saturated) in the cores, with calculations of equivalent fracture aperture and fracture permeability, showed similar results. The effect of polymer gel conformance to increase recovery by decreasing equivalent fracture aperture plugging was proven. Moreover, the decrese in equivalent fracture aperture in the cores were resulted in decreasing fracture permeability respectively.


Polymer gel conformance on oil recovery in fractured medium: Visualization and verification
Canbolat, Serhat; Parlaktuna, Mahmut (Elsevier BV, 2019-11-01)
Due to complexity and heterogeneity of the geological patterns of fractured reservoirs recovery estimations are considered to be extremely challenging. These fractures form complicated paths for reservoir characterization and fluid movement that ultimately impacts production performance and recovery.
Use of voronoi gridding in well test design
Rahimov, Fuad; Sınayuç, Çağlar; Department of Petroleum and Natural Gas Engineering (2015)
One of the most efficient tools to accurately characterize the reservoir and its nature is well testing. In the literature, well testing sometimes is referred as Pressure Transient Analysis (PTA). For the development strategy of the field both technical and economic considerations are involved. In order to perform well testing, firstly it needs to be correctly designed, otherwise well testing will not yield reliable information about the reservoir. There are both analytical and numerical techniques for the ...
Discrete fracture network modeling in a carbon dioxide flooded heavy oil reservoir
Shiriyev, Javid; Akın, Serhat; Department of Petroleum and Natural Gas Engineering (2014)
Fracture analysis is crucial because of their abundance in reservoirs and can have a strong effect on fluid flow patterns. Accordingly, Discrete Fracture Network (DFN) model is an efficient alternative approach to modeling fractured reservoirs and it is a special tool that considers fluid flow and transport processes in fractured rock masses through a system of connected fractures. Unlike Dual Porosity Model, where a continuum approach is applied, DFN uses detailed information about fracture and fracture co...
Earthquake imprints on a lacustrine deltaic system: The Kurk Delta along the East Anatolian Fault (Turkey)
Hubert-Ferrari, Aurelia; El-Ouahabi, Meriam; Garcia-Moreno, David; Avşar, Ulaş; Altinok, Sevgi; Schmidt, Sabine; Fagel, Nathalie; Cagatay, M. Namik (2017-08-01)
Deltas contain sedimentary records that are not only indicative of water-level changes, but also particularly sensitive to earthquake shaking typically resulting in soft-sediment-deformation structures. The Kurk lacustrine delta lies at the south-western extremity of Lake Hazar in eastern Turkey and is adjacent to the seismogenic East Anatolian Fault, which has generated earthquakes of magnitude 7. This study re-evaluates water-level changes and earthquake shaking that have affected the Kurk Delta, combinin...
Seismic assessment of a monolithic RCC gravity dam including three dimensional dam-foundation-reservoir interaction
Yilmazturk, Sema Melek; Arıcı, Yalın; Binici, Barış (2015-10-01)
In this study, the seismic response of a tall roller compacted concrete gravity dam located in a highly seismic zone is investigated. The response of this monolithic RCC gravity dam is examined by conducting analyses including three dimensional dam-reservoir-foundation interaction. The effect of the foundation/structure moduli ratio, material damping, and bottom absorption and reservoir compressibility on the performance of the dam were investigated. Selection of an optimal downstream slope was discussed ba...
Citation Formats
S. Canbolat, “Fracture effect limitation on residual oil saturation & visualization by computer tomography,” Ph.D. - Doctoral Program, Middle East Technical University, 2018.