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Experimental and Simulation Study to Determine the Fracture Flow Functions in Two Phase Systems at Core Scale

Goodarzi, Matin | 2024

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 56977 (06)
  4. University: Sharif University of Technology
  5. Department: Chemical and Petroleum Engineering
  6. Advisor(s): Ghazanfari, Mohammad Hossein
  7. Abstract:
  8. Fractured reservoirs have allocated a significant portion of Iran's and the world's oil and gas reserves, underscoring the importance of predicting the performance of these reservoir types in the oil and gas industry. Predicting the performance of fractured reservoirs by professional reservoir simulators, especially in enhanced recovery conditions, requires precise information on fracture flow functions, which is often limited. These functions vary for each reservoir based on the distinct characteristics of the rock and fluid, and the only way to determine them is through appropriate laboratory experimentation and modeling of the results. Currently, in simulation models, the relative permeability of fractures is typically assumed to be linear, and the fracture capillary pressure is considered zero. However, this is not the case in reality, as some studies in subsequent chapters have indicated that fracture flow functions depend on fluid saturation. Therefore, the main objective of this research is to investigate and determine fracture flow functions as a function of fluid saturation for a sample of rock and fluid from one of the oil reservoirs in the southern part of the country. In summary, this study comprises two phases: laboratory experimentation and modeling. In the laboratory phase, displacement phase experiments in a two-phase nitrogen-oil system are investigated. Then, the output data from the experiments are used in the commercial simulator CMG, and the results are compared with simulations using the CMOST module. The CMOST module adjusts the fracture flow functions (relative permeability and capillary pressure) in the simulator to match the experimental results closely. It selects the best flow functions that agree with the experimental results. It's worth mentioning that in this research, the history-matching method based on the Brooks-Corey relationship is employed. Furthermore, in this study, existing models that have investigated the relative permeability of fractures are reviewed, as mentioned in the literature review chapter. The best model that matches the output results from the history matching method and close experiments is selected. Finally, using a well-known model based on fracture surface roughness and fractal dimension, the history-matching process is conducted, and in addition to relative permeability below the fracture surface, fracture capillary pressure is calculated separately. Moreover, in another part of the results, the validity of the conducted method is verified by applying it to two samples from articles published in references on the topic of fracture relative permeability. As stated in the results chapter, the obtained relative permeability plots for fractures are not linear, and likewise, the obtained capillary pressure plot for fractures indicates that fracture capillary pressure is considerable and not zero. Therefore, it can be said that assuming linearity in fracture relative permeability and assuming zero fracture capillary pressure is not accurate
  9. Keywords:
  10. Fractured Reservoirs ; Modeling ; Flow Functions ; Core-Scale ; Laboratary Study ; Two Phase Systems

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