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Experimental Investigation of the Role of Fracture Geometrical Characteristics and Injection Scenarios on Heavy Oil Recovery during Hydrocarbon Solvent Flooding

Saidian, Milad | 2010

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 40906 (06)
  4. University: Sharif University of Technology
  5. Department: Chemical and Petroleum Engineering
  6. Advisor(s): Masihi, Mohsen; Ghazanfari, Mohammad Hossein; Kharrat, Riyaz
  7. Abstract:
  8. Due to the importance of enhanced oil recovery of heavy oil fractured reservoirs, in this work micromodel setup has been used to study the miscible solvent injection in five-spot fractured reservoirs with different fracture geometrical characteristics. Due to the visual nature and flexibility of the micromodel patterns it is a subject of interest to be used in different studies. Different patterns has been constructed by chemical etching and controlled laser etching and saturated with displaced fluid and flooded by constant rate injection of hydrocarbon solvent in abient temperature and pressure. At first, effect of fracture’s length, numbering, orientation, discontinuity and scattering on the final recovery of miscible injection has been studied. Then using the qualitative and quantitave experimental results of previous part has been used to investigate the effect of geometrical characteristics of fracture on finger initiation and development. In the third part of study a new pattern constructed specifically to study the effect of injection rate, viscosity ratio and solvent type on the matrix-fracture interaction as well as fingering in matrix and channeling in fracture. Finally with a matlab code, pictures has been analysed and using a newly developed iterative algorithm which coupled numerical and experimental results, dispersivity coefficient has been calculated in the fracture. Results revealed that fracture length, numbering, scattering and discontinuity are directly proportional to the oil recovery and it maximizes in 45 degree fracture and minimizes in 0 degrees fracture. Higher dispersion coefficient in fracture rather than matrix in both longitudinal and transverse direction cause fingers to be affected by fracture geometrical characteristics. This may cause fingers to be mixed and make a unit sheilding finger. Fractures act as heterogeneity in porous media and cause finger tips to be splitted. Dispersion in longitudinal direction improves shielding and in transverse direction increases splitting and spreading probability. Fracture scattering, discontinuity and numbering are directly proportional with finger tip splitting before and after breakthrough and spreading around fractures as well. Sheilding is directly affected by fracture orientation and maximixes at zero degrees fracture. Numerical modeling revealed that fracture dispersivity affects oil recovery curve during process but matrix dispersivity affects later part of recovery curve. In the case of high viscosity ratio, the injection rate improved the oil recovery at early times due to the breakthrough and drainage of the fracture. However, at later times as diffusion became dominant the recovery decreased. Higher viscosity ratio increases the fingering probability in matrix and channeling in fracture and consequently decreases the breakthrough time and final recovery of oil. Developed algorithm to calculate the fracture dispersivity coefficient is not sensitive to initial guess and using both experimental and numerical to calculate reliable results for this coefficient
  9. Keywords:
  10. Heavy Oil ; Numerical Modeling ; Dispersion ; Fractured Reservoirs ; Fracture Geometrical Properties ; Fingering ; Matrix-Fracture Interaction

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