Effect of gravity drainage, miscibility, and relative permeability on tight matrix reservoir with low-quality natural fractures on carbon-dioxide injection

Date

2024-9-4

Author

Ülker, Murat Can

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Oil production in primary production phase declines continuously in the world. It is believed that there are very few fields that is not been discovered yet. The brown fields of the world are either abandoned with low recovery factors or they produce at low production rates due to reservoir pressure or water cut problems. Since the twentieth century, EOR techniques have been studied and applied in several fields. It has been observed that the oil production rate and the recovery factor can be increased and one way to do it is the injection of carbon-dioxide into the light-oil reservoir. Miscible carbon-dioxide injection in light-oil reservoirs is a way to enhance oil recovery and has gained attention since the 1970s from the industry. The advantage of carbon-dioxide injection to the light-oil reservoirs is the low viscosity levels of light oil. Oil interacts with low viscous carbon-dioxide resulting in moderate mobility and, thus, may prevent viscous fingering. Other advantages that carbon-dioxide injection brings are increasing reservoir pressure, trapping in the oil molecules, and sweeping them, thus oil production increases. It also helps matrix to drain oil to the fractures due to gravity drainage effect. Gravity drainage effect occurs due to the density difference between the fluids in the matrix and the fractures. In this thesis carbon-dioxide injection to the reservoir was studied in several aspects. The result indicates that the carbon-dioxide injection is feasible if some conditions are matched. This can be a turning point of Turkey’s petroleum production since there are a small number of fields that have been applied carbon-dioxide injection as a recovery method. In this study, the effects of gravity drainage, relative permeability and miscibility to the recovery factor of one of the Turkey’s tight matrix tight fracture oil reservoir are investigated. While miscible injection of carbon-dioxide increases the recovery factor significantly, the effect of relative permeability is very low using two different relative permeability models. The effect of the gravity drainage term in the dual-porosity formula is found lower than two other terms which are viscous displacement and imbibition term. However, it is proved that the effect of the gravity drainage can be increased if the injected carbon-dioxide is let to imbibe the matrix with shut-in periods.

Subject Keywords

Carbon-dioxide, Injection, Gravity, Miscibility

URI

https://hdl.handle.net/11511/111416

Collections

Graduate School of Natural and Applied Sciences, Thesis