Аннотация
Abstract Excessive water production is a major problem in mature oil fields because it reduces oil-production efficiency and increases lifting, separation, and water-handling costs. This issue is especially relevant for Kazakhstan reservoirs, many of which are characterized by high water cut after long-term waterflooding. Relative permeability modifiers (RPMs) are chemical treatments intended to reduce water permeability more strongly than oil permeability and are therefore considered promising for selective water control. This work evaluated the performance of RPMs under laboratory conditions representative of selected Kazakhstan fields. Two RPM candidates were first compared in single-phase water-flow tests, after which the more suitable chemical was selected for detailed study. Two-phase coreflood experiments were then carried out on sandstone core samples from four field systems using field-specific formation waters, crude oils, and reservoir-representative temperature and pressure conditions. Water and oil permeabilities were measured before and after treatment to determine the selectivity of the RPM. In addition, a simplified CMG IMEX simulation was performed for one representative field case to examine the possible reservoir-scale effect of the experimentally observed permeability changes. The results showed that the selected RPM reduced water permeability substantially more than oil permeability in all tested cores. It confirms its selective behavior. The best result was obtained for Field A, where water permeability was reduced by 67.9% while oil permeability decreased by only 5.2%. For other fields water-permeability reduction ranged from 50.8% to 54.5% and oil-permeability reduction remained limited. The simulation results supported the laboratory findings and showed that selective permeability reduction could lead to lower cumulative water production.