Effect of non-linear elasticity on stress paths in depleted reservoirs and their surroundings

Abstract

The prediction of stress and strain changes in and around reservoir using numerical simulators is often based on assumption of linear elasticity before reaching yield point. However, it is known that rocks are generally behaving non-linearly and a deviation from purely elastic response begins already at micro-strain level. In this work, we performed multi-scenario numerical modelling of hydrocarbon reservoir depletion using a non-linear elastic model. The model has been calibrated based on the laboratory test results with both sandstone and shale. The non-linear elastic modelling is then compared to purely linear-elastic cases. We found that assumption of pure elasticity could lead to a strong underestimation of stress and strain changes in and around the reservoir. In addition, stress path (direction of stress changes) may significantly deviate when non-linear elasticity is not accounted for.