Risk Analysis and Scheme Optimization of Sand Control String Running in Extended Reach Horizontal Well

Due to the structure of the wells and other factors, the sand control string in offshore extended-reach wells is subjected to great friction resistance and even buckling phenomenon when being lowered, which ultimately leads to the failure of the string to be lowered in place. Based on elastoplastic and other relevant theories, this paper took an extended reach horizontal well in an oilfield in the South China Sea as an example and analyzed the friction and wellhead suspension weight of different well structures and completion string combinations in the process of running and finally carried out the risk analysis of the running string and the optimization of completion scheme. The results show that the friction resistance of the four-hole structure (8 1/2″) is lower than that of the five-hole structure (6″). Among them, an 8-1/2″ open hole 5-1/2″ high-quality screen is preferred, and a 6″ open hole 4″ high-quality screen is preferred. The friction coefficient in the open hole section is less helpful in improving the running safety of the sand control string, while reducing the friction coefficient in the casing is more obvious to reduce the friction. The results can provide guidance for the running of the screen and control string in the extended reach horizontal well.