Geomechanical Analysis of Liner Deformation in Deep Gas Wells

Abstract

Liner deformation is a challenging problem in deep gas wells that are normally associated with poor borehole structural integrity. It occurs usually during the hydraulic fracturing process when the tensile strength of cement around the liner is compromised, and is most likely to occur due to the void structure inside the cement sheath. In routine hydraulic fracturing design, the evaluation of cement and its interaction with the liner and formation is normally not conducted to assess the liner mechanical integrity. Therefore, liner deformation may occur in poorly constructed boreholes, which could lower the cement strength on the external boundary of the liner by allowing air voids to form. This paper presents numerical analysis of liner structural integrity based on the presence of voids in the cement sheath. A better understanding of the liner mechanical integrity in smaller gauge boreholes is key to minimizing and/or avoiding liner deformation in deep gas wells.