Study on Spatial Configuration of Operating Pipe String in Wellbore

Abstract

Abstract The buckling of operation pipe string may occur under complex load in deep well. The serious buckling of the string will lead to partial wear, break or even self-locking, which is detrimental to the downhole operation. At present, most of the studies have focused on the string buckling stability and characteristics of single buckling pattern, and the spatial configuration of entire operation pipe string was seldom studied. In fact, the entire operation pipe string of deep well under complex loads may present a complex configuration consisted of non-buckling, sinusoidal buckling and helical buckling. In this study, the smooth connection condition of different deformation states of pipe string is proposed, and combining the buckling stability analysis and boundary influence characteristics, the spatial configuration of the entire operation pipe string in the borehole could be solved. A field example was given, and the variation of the spatial configuration of the entire operating string with injection pressure is analyzed in detail. The results showed that the calculation method proposed is very useful and important to determine the operation parameters in-situ, to know the working state of the downhole operation string. This works is helpful to avoid the complex situation or accidents in completion practices.