Experimental Evaluation of Reducing Water Cut and Increasing Oil Recovery Using Multiphase Mixed Fluid.

Chemical profile control has long been an effective method for reducing water cut and increasing oil production in heterogeneous reservoirs. However, its application has been limited due to high costs, economic constraints, and difficulties in adapting to complex reservoir environments characterized by high temperatures and high salinity. To address this, this paper proposes a multiphase mixed fluid system in which the aqueous phase serves as the continuous phase and high-viscosity oil droplets as the dispersed phase. Through parallel sand pack and transparent visualization plate displacement experiments, the mechanisms by which this multiphase mixed fluid system enhances oil recovery in heterogeneous reservoirs were systematically investigated. Experimental results indicate that the multiphase mixed fluid system forms dynamic blockages in high-permeability channels via the Jamin effect. In the plate experiments, the permeability of the high-permeability layer decreased from 2227 to 178 mD, effectively achieving fluid redirection and increasing the recovery factor in the low-permeability zone by 8.5%; the system continues to function during the subsequent accelerated displacement phase; visualization experiments intuitively revealed the dynamic process of "water channeling-blockage-redirection," while sand pack experiments confirmed the significant increase in recovery factor through precise measurement. The study confirms that multiphase mixed fluid technology, through intelligent blockage and energy redistribution, can effectively address the challenge of low sweep efficiency in heterogeneous reservoirs, providing a new technical direction for the development of high-water-cut oilfields.