Constitutive modeling of a laumontite-rich tight rock and the application to poromechanical analysis of deeply drilled wells

Abstract

Geological formations containing laumontite-rich rock are usually treated as problematic for geo-energy production projects because the presence of laumontite mineral can promote complex mechanical behaviors. Previous laboratory results indicate that rock formations with a higher laumontite content display severe stress sensitivity in poromechanical responses. With an increase in confining pressure, there is a transition from dilation to compression regime and the resulting localization styles range from shear dilation to compaction bands. In this study, we conduct finite element modeling of constitutive behaviors of rocks retrieved from the tight glutenite reservoir formation using a thermodynamic-consistent plasticity model. The shear dilation to compaction transition is well characterized. Poromechanical analysis is also conducted to analyze the plastic zone development around a borehole drilled in an over pressured reservoir. The simulated stress-paths of key points around the borehole are used to demonstrate the plastic strain development processes. The impact of in-situ stress on the wellbore stability is highlighted, and a comparison with the results from using the traditional plastic constitutive model is conducted.