Research on Buckling Behavior and Analysis of Sensitive Factors in Horizontal Well Drilling

Abstract

Buckling behavior of the drill string in the wellbore is one of the key issues in the oil and gas well engineering, which has been investigated by many theoretical and experimental studies in recent years. In order to study the buckling characteristics of drill string in the horizontal well, the factors of gravity, friction, and boundary conditions were taken into account, and a numerical simulation model of horizontal drill string was built up. The buckling critical load of numerical simulation was proven to be in good agreement with the experimental results; that is to say the simulation result is reliable. The key factors of friction coefficient, length of horizontal well section, and radial clearance between drill string and wellbore annular which affect buckling critical load of drill string were discussed. The results show that the angular displacement of horizontal drill string changes in the form of sine when sinusoidal buckling occurs. The pipe string buckling critical load increases with the increasing of friction coefficient. Under the same condition, the buckling critical load of horizontal drill string decreases approximately linear with the raise of horizontal well length, and declines in exponential trend with the increasing of the annular clearance. The research can provide theoretical reference for the optimal design of horizontal well string and practical drilling operation.