Abstract: Bi-416 well is a key preliminary prospection well in Liyuan nose-like structure of Southern steep slope belt in Henan oilfield.From top to bottom,the formation contains gravel stratum,it is of strong polishing property and poor drilling ability and it brings the difficulty for drilling construction.Through some technical measures,such as the selected drill bit and the optimization of drilling fluid,some technical difficulties,namely the low rate of penetration,drilling fluid pollution and friction have been overcome.Therefore,the successful drilling of Bi-416 has been guaranteed and valuable experience in the block drilling has been obtained.