Abstract
Down-hole tubular technology plays an important role in enhanced oil recovery over last decades. Many unresolved issues in drilling and oil/gas well completion are properly addressed and solved through down-hole tubular technology. However, post-expansion properties of tubulars are always a concern in implementing them in an economic and viable framework. A thorough understanding of post-expansion material properties is required in successful implementation of tubulars in adverse and high formation pressure environment. This work investigates the consequences of expansion on microstructure, grain size, and crystallographic texture of tubular material. Firstly, multiple samples are taken from unexpanded and expanded sections of tubulars that are hydraulically expanded to a desired expansion ratio. Secondly, microstructure and fractographic analyses are performed through optical and scanning electron microscopy, respectively. Finally, electron back-scattered diffraction analysis is used to investigate grain morphology, grain size distribution, and crystallographic texture of samples. It is observed that the grain size is affected by excessive plasticity of tubular. It is also noted that the presence of elongated grains is due to the crystallographic reorientation of grains, existence or formation of secondary phases, and dislocation pileup at grain boundaries. Moreover, expansion process results in the variation of grain orientation. However, due to complex loading conditions, strong texture has not been observed.