Analysis of Snake Shape of Drillstring Constrained in Horizontal Well

Various types of drill pipes that connect with each other by connectors (called tool joints) to form a drillstring are widely used in oil exploration and development. Drill pipes are commonly modeled as pressurized thin homogenous rods constrained in a cylinder to investigate their snake shape (i.e. sinusoidal buckling) taking place during motion in a horizontal well. State of the art indicates few studies on the effect of the tool joints. This paper devotes to simulate sinusoidal buckling behavior of a rod constrained in a horizontal torus with respect of the connectors. In fact, this research concentrated on horizontal drilling aiming at approaching sustainable developments such as preventing drilling equipment failures, which are common due to magnifications of some mechanical phenomena like fatigue. The analysis of spatial buckling is divided into two separate planar states based on beam-column theory and the solutions are obtained by solving the governing equations. Some dimensionless terms are defined for the sake of equations simplification, which gives the effect of axial force rate on the radial, and axial deflections. The results demonstrate that the greater axial force, the larger deflections are. Also, the peak of the rod deflection curve deviates from the reference position, which lied on the bottom of the torus.

Keywords:

drillstring , buckling , snake shape , beam-column theory , horizental well