Abstract: During deepwater well completion in AKPO,Nigeria,low temperature,shale instability,formation of gas hydrate and other factors often cause problems.Because of high-rate filter loss,current completion fluids lead to formation damages to different degrees.Based on reservoir characteristics and potential damage factors,this paper selected key treatment agent and optimized three different formation-friendly deep water completion fluids which are prepared for different well completions.The performance evaluation results showed that,the optimized systems had better properties in rheological behavior,filter-loss reduction,clay hydration inhibition and gas hydrate inhibition,compared with current completion fluids.The reservoir core permeability recovery rate reached over 85%.Field application showed that the skin factor of AKPO-302 completed with optimized fluids was only 0.25,while in some intervals of Well AKPO-1 and Well AKPO-2,the skin factor reached 100.The results proved the completion fluids had remarkable reservoir protection results.