From deposition to final reservoir rock – diagenetic pathways in carbonates
The distribution of porosity and permeability in carbonate rocks is controlled by diagenesis, which affects fluid flow in subsurface environments. Quantifying the relationship between diagenetic petrographic characteristics and changes in permeability is challenging. In this presentation we utilise pore-scale models to demonstrate how typical carbonate sediments and their diagenetic histories can be used to quantify the evolution of petrophysical properties in carbonate rocks. The models were generated by creating 3D pore architecture models from 2D binarized images of typical textural changes of carbonate sediments following hypothetical diagenetic pathways. Flow properties were then calculated from the resulting network representation of the pore system. The evolution scenarios displayed "diagenetic tipping points," where permeability decreased dramatically for only a small decrease in porosity. The models also showed how diagenesis alters capillary entry pressures and relative permeabilities, providing trends that can be applied to real rocks. The values of porosity and permeability derived from these models were similar to those measured in nature. These diagenetic pathway models can be used to predict flow behaviour during burial and uplift scenarios by using "diagenetic back-stripping" of real carbonate rocks.
The distribution of porosity and permeability in carbonate rocks is controlled by diagenesis, which affects fluid flow in subsurface environments. Quantifying the relationship between diagenetic petrographic characteristics and changes in permeability is challenging. In this presentation we utilise pore-scale models to demonstrate how typical carbonate sediments and their diagenetic histories can be used to quantify the evolution of petrophysical properties in carbonate rocks. The models were generated by creating 3D pore architecture models from 2D binarized images of typical textural changes of carbonate sediments following hypothetical diagenetic pathways. Flow properties were then calculated from the resulting network representation of the pore system. The evolution scenarios displayed "diagenetic tipping points," where permeability decreased dramatically for only a small decrease in porosity. The models also showed how diagenesis alters capillary entry pressures and relative permeabilities, providing trends that can be applied to real rocks. The values of porosity and permeability derived from these models were similar to those measured in nature. These diagenetic pathway models can be used to predict flow behaviour during burial and uplift scenarios by using "diagenetic back-stripping" of real carbonate rocks.
