Buckling of Tubulars in Actual Field Conditions

Abstract

Abstract Buckling of tubulars inside wellbore has been the subject of many researches and articles in the past. However, these theories have always followed the same assumptions: the wellbore has a perfect and unrealistic geometry (vertical, horizontal, deviated, curved) and the friction is ignored, conditions relatively far from actual field conditions. How do tubulars buckle in actual field conditions, that is, in a naturally tortuous wellbore with friction and rotation ? Can we apply conservatively theories developped for perfect well conditions (no tortuosity, no friction) to actual well conditions ? This paper gives answers to these questions in comparing results obtained from existant models with results obtained from an advanced model dedicated to drillstring mechanics. Firslty, this paper presents the new developements integrated in a recently advanced model for drillstring mechanics and enabling to take into account the buckling phenomenom in any actual well trajectory. Secondly, this paper shows the influence of tortuosity and friction on the buckling phenomenom for some practical and critical case met in the drilling industry. These tortuosity and friction effects are demonstrated with an experimental set up that enables to confirm theoretical features. Lastly, we compare results obtained from existant models with results obtained from our new model to evaluate the tortuosity and friction effects on the critical buckling load found in the litterature.