Analysis of Factors Influencing Water Cone Progression in Horizontal Wells Targeting Loose Sandstone Reservoirs and Research on Compartmentalised Water Control Methods

Bottom-water reservoirs commonly suffer from severe water breakthrough during long-term production. In sand-prone formations with active bottom water, such as unconsolidated or weakly cemented sandstones, this issue is further complicated by a high risk of sand production. Water channeling promotes the rapid development of high-permeability flow paths, while sand production causes additional depletion and weakening of the reservoir skeleton. Their coupled effect leads to sand and water co-production at the wellbore and significantly degrades well performance. The study focuses on bottom-water-related controlling factors of sand and water co-production in sand-prone reservoirs. Using the commercial reservoir simulator CMG, an integrated wellbore–reservoir model is constructed for bottom-water drive development in sand-prone formations. The model is employed to systematically quantify the impact of key bottom-water and reservoir parameters—such as bottom-water drive strength, initial oil–water contact depth, permeability heterogeneity, completion strategy and production constraints—on sand and water production behavior, water-cut evolution and ultimate oil recovery. On this basis, a heterogeneous sand and water co-production profile and its dynamic evolution pattern are proposed to characterize the spatio-temporal distribution of sand and water production under different bottom-water conditions. Furthermore, the simulated sand and water production distribution is coupled with existing segmented water-control completion techniques for horizontal wells to identify sections prone to sand and water production and to provide a quantitative basis for compartmentalized water and sand control design. Finally, by integrating logging data and field observations of sand and water production, a case study of segmentation optimization for a horizontal well in a bottom-water reservoir is presented, demonstrating the practical applicability of the proposed workflow from the perspective of bottom-water controlling factors and providing a quantitative research basis and design guidance for sand and water co-control in bottom-water sand-prone reservoirs.