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


1 Department of Reservoir Engineering,Iranian Offshore Oil Company

2 -------,Arvandan Oil and Gas Producing Company


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, rein ltration and capillary continuity phenomena notably
uence the rate and amount of oil recovery from matrix blocks. In the current research, six
experiments were performed to study the e ects of a permeable contact area (between two blocks
located on top of each other) on rein ltration 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 rein ltration, 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 e ects of horizontal fracture apertures and fracture dips, can be utilized in order to have
a better understanding of block to block e ects. By this, the modeling of the gravity drainage
mechanism, while injecting gas into fractured carbonate formations, would be improved.