Finite element analysis of tubular ovality in oil well

This paper presents the finite element analysis of tubular expansion in oval bore holes such as those frequently observed in Upper Natih reservoirs. The minimum inner diameter of the expanded tubular must be larger than the drift diameter set by American Petroleum Institute (API) standards. If the minimum inner diameter is smaller than drift diameter, completion equipments can not be run successfully, which is necessary to complete an oil-well for production. The phenomenon of tubular ovality has been previously unknown to petroleum industry. Finite element model of tubular expansion in oval bore-holes is developed to determine the tubular ovality and compared with measured ovality. It was found that ovality increases linearly with tubular expansion ratio. With increase in expansion ratio, the tubular contact length with formation and developed contact pressure increases. Tubular ovality, if not considered in well design, may lead to premature tubular failure due to lower collapse rating and higher stresses.