Fine Grid Simulation Study of Gas Injection In One of Iranian Carbonate Reservoirs

A typical Iranians carbonate matrix block surrounded by an open fracture was modelled in order to understand the fracture-matrix interaction and how to model the interaction best. This was modelled by using a fine-scaled Eclipse model in the single porosity mode . The model was extended to a stack of 6 matrix blocks to understand block-to-block interaction under gas injection scenarios. Results and conclusions from the single porosity single block and 6-block model were used in order to optimize the full field model, and these recommendations are described briefly in this paper.
The simulation results showed that gas injection works as a major recovery mechanism for medium and good rock types at all block heights; and for poor rock type with block heights of more than 2 meters. The oil recovery results are in the same range as for the single and six stack block model but the delay of oil recovery by gas gravity drainage is clearly seen in the six stack block results indicating at least 8-10 years to reach ultimate oil recovery for typical block heights