The aim of the study is to investigate matrix-fracture interaction, gas oil gravity
drainage (GOGD) and diffusion mechanisms with CO2, N2 and CH4 gas injection
in a fractured system. Effects of injected gas type, initial gas saturation and
diffusion coefficient on oil recovery are studied by an experimental and
simulation work.
In the experimental study, Berea sandstone cores are placed in a core holder and
the space created around the core is considered as a surrounding fracture. System
is kept at a pressure of 250 psi by CO2, N2 and CH4 gases and at a reservoir
temperature of 70 ° / C.
Experiments with cores having similar initial saturations resulted in the highest ndecane
recovery in CO2 experiment followed by CH4 and N2. The highest solubility of CO2 in n-decane and density difference between CO2 and CO2-ndecane
mixture are considered as the reason of results.
CO2 injection tests with n-decane and brine saturated core with and without initial
gas saturation indicate that availability of initial gas saturation in matrix increased
recovery.
A simulation study is continued using CMG (Computer Modeling Group Ltd.)
WinProp (Microsoft Windows&trade / based Phase-Behavior and Fluid Property
Program) and GEM (Generalized Equation-of-State Model Compositional
Reservoir Simulator). Simulation results of CO2 experiment with initial gas show
that dominant effect of GOGD decreases and diffusion becomes more effective at
final production stages. Simulation study indicates an immediate, sharp decrease
in oil saturation in matrix. Oil in matrix migrates into fractures and moves
downward as a result of GOGD with gas injection.
| Identifer | oai:union.ndltd.org:METU/oai:etd.lib.metu.edu.tr:http://etd.lib.metu.edu.tr/upload/12614449/index.pdf |
| Date | 01 June 2012 |
| Creators | Bulbul, Sevtac |
| Contributors | Parlaktuna, Mahmut |
| Publisher | METU |
| Source Sets | Middle East Technical Univ. |
| Language | English |
| Detected Language | English |
| Type | Ph.D. Thesis |
| Format | text/pdf |
| Rights | To liberate the content for public access |
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