Abstract:  Extended reach well is been drilled in many oilfields in Bohai. According to technical difficulties and stratigraphic characteristics of Bohai, a series of techniques such as well design, well trajectory control, drag and torque monitoring, drilling string optimization, drilling fluid technology, borehole cleaning, borehole wall stabilization, casing tripping in and so on, are researched and applied. Using these techniques combined with real-time decision system, a well horizontal displacement to vertical depth ratio of about 2.62 is realized.