Application of Gray Analysis Method in Friction Coefficient Assessment for Extended Reach Well

Abstract

The friction & torque is a core issue in the process of extended reach well drilling. The friction coefficient has a great influence on friction & torque prediction. Reasonable and correct determination of the friction coefficient is an issue that must be addressed in the friction & torque analysis and prediction. The inverse model of friction coefficient was established based on extensive actual drilling data. On this basis, grey relational analysis is used to explore the potential factors influencing the friction coefficient and establish the association between friction coefficient and the relevant influencing factors. The studying result indicates that the main factors affecting friction coefficient in terms of importance are the average rate of overall angle change, the type of drilling fluid, well depth, hole diameter, drilling fluid density, drilling fluid loss, dynamic shear of drilling fluid, vertical depth, displacement, drilling fluid viscosity, drilling fluid plastic viscosity. The research results can provide a theoretical guide for reducing the friction and torque in the construction of extended reach wells. Key words: Extended reach well; Friction & torque; Grey relational analysis; Influencing factors; Drilling fluid