G. H. Movazi.
S.R Jaberi

In a fractured reservoir that has a gas cap, pressure reduction results from oil production causes the gas cap to expand and hence the gasoil contact moves downward. Because of its high mobility, gas moves much faster than oil in the fractures to form a gas invaded zone right above the oil column. As such all matrix blocks located in the invaded zone are partially or totally surrounded by the gas within the fractures. The difference between oil and gas density results in gravity forces that push gas into the matrix blocks and drain oil from them under a mechanism that known as "gravity drainage". The question is whether the drained oil flows through the fracture network characterized with its high permeability or reinfiltrate into the lower matrix blocks in a process known as blocktoblock interaction? The answer to this question is crucial to decide about the reliability of the oil production rate predicted by dual porosity simulation which assumes that there is no block to block interaction and the drained oil from the gas invaded zone moves through the fracture network. In this study by using a fine single porosity simulation, firstly it is shown that blocktoblock interaction is a dominant process within the gas invaded zone of fractured reservoir and secondly the rate of reinfiltration in dense fractured reservoir is calculated.