GAS-OIL GRAVITY DRAINAGE IN A FRACTURED RESERVOIR - EXPERIMENTAL STUDIES OF MECHANISMS OF THE BLOCK TO BLOCK PROCESS

In order to improve the understanding and the modelling of the flow mechanisms between the blocks of fractured reservoirs, a series of mainly experimental studies has been carried out in the Reservoir Division of Elf Aquitaine Production concerning capillary continuity and reimbibition during the cascade drainage. In simple experiments, clear observations of the phenomena have allowed identification of the essential points in the block to block process, such as conditions and characteristics of capillary continuity, and its effects on flow kinetics. Numerical simulations of these experiments have pointed out that Killough's formulation of capillary pressure hysteresis does not adequately show the reimbibition process on a block being simultaneously drained. Further modification of two-phase flows in a porous environment is necessary to simulate the reimbibition process and consequently the cascade drainage on a column of blocks.