Oil recovery by miscible gas injection process has been a topic of research, development, and field testing for more than 40 years. There is still some disagreement in the interpretation of laboratory, field-test data and selection of predictive methods. Field experiments, however, have disclosed a number of problems with hydrocarbon miscible flooding that limit the oil recovery and diminish the economic attractiveness of these processes. Due to the fact that there is no generalized engineering method or model that adequately accounts for all the factors, each model tends to emphasize one or more aspects of the displacement while neglecting other aspects for the sake of tractability.

A parametric study is done, using a 3-D, compositional numerical simulator "VIP" in order to design the model and analyze the results and performance of miscible gas injection in Hassi Berkine South field. A 9-component PR EOS was used to describe the phase behavior using IMPES formulation. The process of simulation study to design and optimize the full field model included the following steps:

  1. Start with a basic run, used as a reference case.

  2. Compare the base case (miscible gas injection) with water injection process.

  3. Consider the phase behavior effect.

  4. The reservoir description effect.

  5. Vertical sweep out.

  6. Partial recovery of miscible flood.

  7. Influence of grid variation.

A cross sectional model was used to represent the simulation domain that covered about 5000 ft² in area and 100 ft in thickness. All the runs consisted of two wells, penetrating the entire layers, the injector in the first cell and the producer in the last one.

From the results it has been concluded that the use of horizontal well data has compensated for lack of information about reservoir heterogeneity in lateral direction of the interwell locations.

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