Fig. 12

a Relationship between stress sensitivity coefficients and the porosity sensitivity coefficient \(\beta \). The stress sensitivity coefficients \({S}_{s}^{\varPhi }\) for porosity and \({S}_{s}^{k}\) for permeability are compared with a set of data from different authors. While \({S}_{s}^{\varPhi }\) shows no significant correlation with \(\beta \), \({S}_{s}^{k}\) is clearly increasing with increasing \(\beta \). Higher values of \(\beta \) indicate a progressively increasing contribution of fracture pores and micro-fractures to the effective permeability network and result in higher \({S}_{s}^{k}\) values. Data for sandstone are taken from Xu et al. (2018) and for limestone compiled from Meng et al. (2019), Teklu et al. (2018), and Dautriat et al. (2011). b Porosity sensitivity is related to the effective pore throat size controlling the flow through the pore network. The exponent \(\beta \) increases with decreasing pore throat size, which indicates a decoupling of the stress sensitivity from porosity and permeability