Abstract: In view of the difficulty of producing for bottom water reservoirs and low resistance oil layers, the VisiTrak long-distance detection technology has been applied in horizontal wells for the first time in Bohai Oilfeild. This technique effectively increases the detection range of the tool, which can predict the depth of the reservoir in advance, help to make judgments calmly, and reduce the risk of landing failure. The application results of Well A in the research shows that in the ultra deep boundary detection, the tool detects the top interface of the reservoir 7 meters ahead of time in the mudstone, landing precisely 0.7 m below the reservoir interface even when the reservoir is shallower, the implementation space for subsequent drilling has been greatly increased and the water avoidance height is ensured. VisiTrak long-distance detection technology has a large detection depth, accurate prediction of the reservoir interface, and effective implementation in areas with uncertain structures.