Experimental Study on Water Drive Performance and Water Cut Rise Law of Rhythmic Edge Water Drive Reservoir

To explore the water breakthrough patterns in rhythmic heterogeneous edge water drive reservoirs, the L block of the Bohai layered edge water drive reservoir was taken as the research object. A three-dimensional physical simulation experimental device for edge water drive reservoirs was used, and a three-layer design was adopted to simulate rhythmicity. The electrical method was used to monitor the oil saturation field of the three layers, and the dynamic evolution law of edge water drive reservoirs was simulated. Simulated and analyzed the evolution law of water drive front under different rhythm combinations, reservoir dip angles, and different mining systems. Experiments have found that interlayer displacement differences caused by rhythmicity significantly reduce the recoverability of the upper layer after the breakthrough of the lower layer water. The analysis results indicate that in various rhythmic patterns, the water under the surface first breaks through the lower layer; Rhythm has a significant impact on the efficiency of reservoir water flooding. In the presence of low, medium, and high permeability zones, positive rhythm is prone to premature water breakthrough, while reverse rhythm reservoir water flooding has the best development effect. The larger the permeability gradient under reverse rhythm, the longer the waterless oil recovery period, and the gradient determines the length of the “step” in the water breakthrough mode. Experimental measurements show that the step phenomenon gradually disappears when the gradient is greater than 1.8. This article proposes experimental simulation methods under multi-layer conditions of rhythmic reservoirs, elucidating the impact of rhythmicity on edge water drive development and providing guidance for the development of rhythmic edge water reservoirs.