Hydraulic Fracturing and Flowback in the Heterogeneous Unconventional Formation: Do Water Blocks Still Play a Role?

Abstract

Abstract Understanding the dynamics of water blocks in reservoir formations is crucial for optimizing hydrocarbon production in unconventional reservoirs. This study investigates the impact of heterogeneity on water block behavior through experimental analysis using a composite heterogeneous two-layer core sample. The experimental results reveal that the presence of high permeability layers mitigates the severity of water blocks compared to homogeneous low permeability layers. During hydraulic fracturing, fracturing water primarily invades the high permeability layer, resulting in uneven water saturation distribution across the core sample. Pressure drop analysis during flowback and hydrocarbon production indicates rapid normalization of pressure drop in heterogeneous unconventional formations, contrasting with prolonged normalization in homogeneous formations. These findings underscore the importance of reservoir heterogeneity in minimizing water block impact and optimizing hydrocarbon production. By elucidating the mitigating effect of high permeability layers on water block behavior, this study provides valuable insights for reservoir management strategies in unconventional reservoirs.