Drilling through depleted reservoirs presents significant operational challenges due to potentially reduced formation pressure, increased risk of lost circulation, and potential wellbore instability. These issues create further complexities when drilling across reservoir sections where formation damage and production impairments must be minimized. The research investigates a methodology for evaluating and optimizing drilling fluid additives for depleted sandstone reservoirs, using barite-weighted oil-based mud by performing high-pressure fluid loss tests with backflow analysis through production screens. A primary focus is placed on the selection and evaluation of wellbore strengthening materials and lost circulation materials, targeting sealing of matrix permeability up to 40 µm and fractures in the 500 – 600 µm range, under high differential pressures. Key considerations include the particle size distribution, particle mechanical strength, filter cake formation and removability, and the ability to maintain backflow through 230 µm production screens, which is critical for a successful completion and production phase. In anticipation of increased reservoir depletion, which may lead to the development of higher differential pressures and larger induced fractures, additional formulations were prepared by incorporating coarser wellbore strengthening materials with particle sizes approaching the target fracture widths of 1500 – 2500 µm. Results show that: •An improved fluid formulation, with bimodal particle size distribution, successfully achieved the design criteria of low fluid loss and reduced formation damage, unimpeded backflow through production screens and effective sealing of 500 µm sotted discs. •Enhanced sealing performance on wider fractures was most effectively achieved by introducing coarser bridging materials with a D90 approaching fracture width, rather than merely increasing the concentration of existing materials. This strategy enabled more stable seals and reduced fluid loss at high differential pressures. •Fluids with an insufficient content of fine bridging materials failed to establish stable seals, even when coarse particles closely matched fracture widths and created a particle bridge.