COMPLICATIONS ARISING DURING OIL AND GAS WELL COMPLETION AND THEIR MITIGATION

Well completion is a critical stage in the development of oil, gas, and gas-condensate wells, as it directly determines the efficiency of fluid flow from the reservoir into the wellbore. During drilling operations, the near-wellbore zone is often exposed to drilling and completion fluids, which can lead to formation damage, permeability reduction, and deterioration of reservoir properties. As a result, the primary objective of well completion is to remove drilling-induced damage, restore natural reservoir permeability, and create favorable conditions for sustainable production. This study examines the main methods used to initiate and enhance reservoir inflow during well completion operations. Common techniques include gradual replacement of high-density drilling fluids with lower-density fluids, lowering the fluid level in the wellbore, aeration methods involving simultaneous injection of gas and liquid, gas lift systems, and mechanical activation methods such as swabbing and piston operations. Particular attention is given to deep and high-pressure offshore gas and gas-condensate wells, where hydrostatic pressure reduction through controlled fluid displacement represents the most widely applied completion approach. The paper also analyzes the potential complications that may arise during completion and clean-up operations. These include formation damage due to fluid incompatibility, wellbore instability caused by rapid pressure drawdown, sand production in unconsolidated formations, incomplete displacement of drilling mud, loss of well control, equipment failure, hydrate formation, and corrosion issues. Such complications can significantly reduce well productivity, increase operational costs, and pose safety risks if not properly managed. To address these challenges, various mitigation strategies are discussed, emphasizing the importance of proper fluid design, gradual pressure management, real-time monitoring, and reservoir-specific completion planning. The application of compatible completion fluids, optimized drawdown rates, sand control techniques, and well-designed gas lift or aeration systems can effectively minimize operational risks and enhance well performance. The results highlight that a systematic and integrated approach to well completion, tailored to specific reservoir conditions, is essential for ensuring long-term well integrity, stable production, and operational safety. The findings of this study may be useful for petroleum engineers involved in the planning and execution of completion operations, particularly in complex offshore and high-pressure reservoir environments. Keywords: well completion, reservoir inflow, formation damage, hydrostatic pressure reduction, gas lift, wellbore stability, offshore gas wells.