Experimental Study of Heterogeneity Effect on Strong Water Drive Gas Reservoirs

Gas recovery from strong water drive gas reservoirs (WDGR) may decrease because water influx may trap gas. WDGR performance is complicated and depends on many parameters.We investigated the effects of reservoir heterogeneity on WDGR recovery factor and aquifer performance in laboratory scale systems. In order to understand the uncertainty associated with reservoirs in complex geologic environments, it is critical to create porous media models that incorporate stratigraphic detail. The experimental models were contained distinct gas and water zone (aquifer portion) with thickness proportion of one to two. Aquifer permeability to gas zone was considered in three ranges: (Kaq/Kg=1 Kaq/Kg<1 Kaq/Kg>1).Gas zone was in initial water saturation in all of experiments. These permeable media were systematically characterized by Dykstra-Parsons coefficient. The Dykstra-Parsons coefficients were varied over reasonable ranges to cover the conditions normally encountered in gas reservoirs.We found that heterogeneity was not always detrimental to the recovery performance in WDGR.we explained this evidence by dimentinless number of Kaq /Kg .