Research on torque and drag in extended-reach horizontal wells and its application in Chenghai-1 area

According to the “sea of oil land development” model, the extended-reach well technology is used for the development of the Zhuanghai 8 well of Chenghai-1 area in Dagang Oilfield. To solve the difficulties drilling extended-reach wells, technological research of predicting torque and drag is launched. In accordance with the torque and drag data of the Zhuanghai 8Nm-H3 extended-reach horizontal well, of which the H-V ratio is 3.92, the friction coefficient, under the existing condition and performance of the drilling fluid system, is confirmed, by establishing models for predicting torque and drag of extended-reach wells. The effect of friction-reducing tools, drilling fluid system, well trajectory, drill pipe system and hole cleaning on torque and drag is analyzed. The torque and drag of the extended-reach wells with the H-V ratio being 3.1, 3.5, 4, 4.5, and 5 respectively is calculated, by using the well structure, bottomhole assembly, drilling fluid system and its performance similar to that of Zhuanghai 8Nm-H3 well and the same pipe and open hole friction factors. Results show that the construction of extended-reach wells with H-V ratio higher than 5 may be fulfilled in Chenghai-1 area in Dagang Oilfield.