A Abstractunlocking hidden potential:identification of remaining moveable oil potential area for optimal infill drilling strategies in heterogeneous multilayer fieldalfian ariantonim: 07200170007study program of petroleum enginering, faculty of earth technology and energy, universitas trisakti, jakarta, indonesiakr field is a mature oil field that has been producing since 1978, characterized by complex multilayer reservoirs consisting of 13 vertically separated zones isolated by shale layers. these reservoirs exhibit high heterogeneity in terms of permeability (ranging from 1 to 4000 md), porosity (0.1% to 27%), and reservoir thickness (4 to 30 ft). to date, the field has been developed under a primary recovery mechanism without water injection, utilizing commingled production through 39 wells, yielding a cumulative production of 31.2 mmstb from an estimated 118.5 mmstb of ooip, corresponding to a recovery factor of 26%. key challenges in multilayer reservoir development include production allocation uncertainty, pressure depletion, crossflow between reservoirs, inaccurate material balance calculations, and high water cut that limits oil recovery efficiency.this research aims to enhance oil recovery from kr field by identifying potential remaining oil and optimizing development strategies through reservoir simulation. a comprehensive subsurface evaluation was performed using a validated static and dynamic model incorporating data from core analysis, well logs, seismic interpretation, reservoir pressure, pvt, scal, and production history. the simulation focused on identifying remaining moveable oil potential area (rmopa) by filtering current oil-in-place using favorable reservoir properties: good permeability, porosity, and current oil saturation. these rmopa zones served as the primary reference in selecting optimal infill well locations.simulation results show that a development scenario consisting of continued production from 8 active wells, reactivation of 7 shut-in wells, and drilling of 21 new infill wells can improve the recovery factor from 26% to 36%, achieving an incremental oil gain of 11.7 mmstb. this optimized strategy demonstrates the effectiveness of integrating reservoir simulation into field development planning, especially in complex multilayer systems, and highlights the importance of rmopa-based infill well targeting in maximizing oil recovery during the primary recovery phase. the study provides a systematic approach to overcoming reservoir heterogeneity and commingled production challenges while maximizing the economic value of a mature oil field.keywords: kr field, multilayer reservoir, reservoir simulation, remaining oil, infill well, rmopa, recovery factor, primary recovery, development scenario