Effect of Permeable Contacts on the Performance of a Gas-Oil Gravity Drainage Mechanism in a Stack of Matrix Blocks

In the gas invaded zone of a well fractured carbonate reservoir, gravity drainage mechanism plays the main role in expelling oil from dense, low permeability matrix blocks. Whenever the active mechanism is gravity drainage, reinfiltration and capillary continuity phenomena notably influence the rate and amount of oil recovery from matrix blocks. In the current research, six experiments were performed to study the efFects of a permeable contact area (between two blocks located on top of each other) on reinfiltration and capillary continuity. Two of the experiments were performed using single blocks of 30 and 60 cm height, whilst others were stacks of two 30 cm high blocks. Results of the experiments reveal that, by increasing the permeable contact area between blocks. due to capillary continuity and reinfiltration, there will be more communication between them, consequently, both ultimate oil recovery and production rate will improve. It is also noticeable that, if the permeable contact area is approximately greater than 20% of the total block surface area, the stack of blocks behaves analogous to a unique block with a height equal to that of the stack. The outcome of the present work, along with data from other studies, such as the efFects of horizontal fracture apertures and fracture dips. can be utilized in order to have a better understanding of block to block effects. By this, the modeling of the gravity drainage mechanism, while injecting gas into fractured carbonate formations. would be improved.