Abstract: The conventional antiwear connector with strong rigidity is likely to cause wear to casing,inlaid wear jacket may fall off,causing downhole accident,and the position of inlaid wear jacket is difficult to detect.In view of these shortcomings,a solution of non-metallic antiwear connector combined with friction modifiers of drilling fluid was proposed,which was named as the double-effect antiwear technique,the non-metallic antiwear connector had good antiwear performance,and little wear to casing,friction modifiers would quickly be absorbed on the surface of drill pipe and casing to create a high-strength, low-friction organic antiwear layer once it entered the well.Using calculated lateral load of the drill string in the casing,and the increased flow resistance value measured on site,the number and location of antiwear connectors could be determined,and the dosage of friction modifier was calculated according to compatibility test of the friction modifier and drilling fluid.Field test in Well X202 indicated that the non-metallic antiwear connector used continuously for more than 500 h had an average wear rate of merely 6.5%,and the average amount of iron flowback from wellbore reduced from 124.64 g/h to 78.00 g/h,which showed significant wear reduction.The study showed it was feasible to reduce casing wear with this technique,opening a new way for reducing the wear of casing and drill string during the drilling of deep,directional and horizontal wells.