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Experimental and Modeling Study of Two-Phase Relative Permeability at Near Miscible Condition

Parvazdavani, Mohammad | 2011

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 42189 (06)
  4. University: Sharif University of Technology
  5. Department: Chemical and Petroleum Engineering
  6. Advisor(s): Masihi, Mohsen; Ghazanfari, Mohammad Hossein; Rasaei, Mohammad Reza
  7. Abstract:
  8. One of the main parameters in modeling of two phase gas and oil flow is an accurate relative permeability functions. This importance will be more intensified when the miscibility condition approaches. In miscible condition due to reduction of interfacial tension between oil and gas phases, parameters of conventional relative permeability functions will change and this changing affects on production results such as oil and gas recovery and also pressure drop along the core. All of the previous studies could not present a unique and consistent model to show the effect of near miscibility condition on relative permeability curves. In this work, these changing of parameters will be investigated based on comparision of two phase oil and gas relative permeability at near miscible condition extracted from numerical implicit method to semi analytical conventional method. To minimise the errorness of production results, some experiments were done on two types of Iranian reservoir's core samples including fracture dolomite and sandstone by injection of almost pure CO2. In this study, conventional capillary dominant method such as Civan, Donaldson and also numerical implicit method were used in which the conventional methods are used as the initial guess of 1-D, two phase flow simulation code and then by optimizing the results of the code and experiments (History Matching), we approach to implicit permeability functions (Inverse Modeling). By having a fair relation between the criteria of approaching to near miscible and the errorness of conventional method in compare to implicit method, we modified the conventional method by consideration the term of dimension less minimum miscibility pressure (MMP), in order to have an accurate two phase gas/oil relative permeability functions at near miscible condition. To have a fairly accrate criteria of approaching to near miscible condition, the minimum miscibilty pressure (MMP) has been calculated based on various methods such as emperical corrolations and simulation of slim-tube experiment. As the conclusion by approaching in to near miscible and also miscible condition, the conventional method underestimates the values of wetting phase relative permeability which leads to errorful production results. Also by approaching in to near miscible and also miscible conditthe curvature of relative permeability curves of both implicit and conventional methods reduce and the intersection point of non-wetting and wetting phase relative permeability curves tends in to lower amount of non-wetting phase saturation. Another deduction is that approaching in to near miscibile condition has more effect on non-wetting phase relative permeability than the wetting-phase. Finally by using the well-known commercial software, we find that this model is fairly accurate and can be used in fluid flow simulators in order to have a better knowledge of fluid flow in low IFT regions during gas injection projects.
  9. Keywords:
  10. Inverse Modelling ; Relative Permeability ; Near Miscible Condition ; Unsteady State Displacement Experiments

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