Reidar I. Korsnes

Porosity and permeability development in compacting chalks during flooding of nonequilibrium brines: Insights from long‐term experiment

We report the complete chemical alteration of a Liege outcrop chalk core resulting from a 1072 flow-through experiment performed during mechanical compaction at 130°C. Chemical rock-fluid interactions alter the volumetric strain, porosity, and permeability in a nontrivial way. The porosity reduced only from 41.32% to 40.14%, even though the plug compacted more than 25%. We present a novel analysis of the experimental data, which demonstrates that the geochemical alteration does not conserve the volume of the solids, and therefore, the strain is partitioned additively into a pore volume and solid volume component. At stresses beyond yield, the observed deformation can be explained by grain reorganization reducing the pore space between grains and solid volume changes from the rock-fluid interactions. The mechanical and chemical effects are discussed in relation to the observed permeability development.

A mathematical model relevant for weakening of chalk reservoirs due to chemical reactions

In this work a mathematical model is proposed for modeling of coupled dissolution/precipitation and transport processes relevant for the study of chalk weakening effects in carbonate reservoirs. The model is composed of a number of convection-diffusion-reaction equations, representing various ions in the water phase, coupled to some stiff ordinary differential equations (ODEs) representing species in the solid phase. More precisely, the model includes the three minerals

Evaluation of the compositional changes during flooding of reactive fluids using scanning electron microscopy, nano-secondary ion mass spectrometry, x-ray diffraction, and whole-rock geochemistry

\text{CaCO}_3

How Stress and Temperature Conditions Affect Rock-Fluid Chemistry and Mechanical Deformation

(calcite),

Evaluation of porosity change during chemo-mechanical compaction in flooding experiments on Liège outcrop chalk

\text{CaSO}_4

Comparative Study of Five Outcrop Chalks Flooded at Reservoir Conditions: Chemo-mechanical Behaviour and Profiles of Compositional Alteration

(anhydrite), and

Tracing Fluid Flow in Flooded Chalk under Long Term Test Conditions

\text{MgCO}_3

The Dynamic Stability of Chalks During Flooding of Non-equilibrium Brines and CO2

(magnesite) in the solid phase (i.e., the rock) together with a number of ions contained in the water phase and essential for describing the dissolution/precipitation processes. Modeling of kinetics is included for the dissolution/precipitation processes, whereas thermodynamical equilibrium is assumed for the aqueous chemistry. A numerical discretization of the full model is presented. An operator splitting approach is employed where the transport effects (convection and diffusion) and chemical reactions (dissolution/precipitation) are solved in separate steps. This amounts to switching between solving a system of convection-diffusion equations and a system of ODEs. Characteristic features of the model is then explored. In particular, a first evaluation of the model is included where comparison with experimental behavior is made. For that purpose we consider a simplified system where a mixture of water and

Induced Shear Failure by Temperature Reduction at Uni-axial Strain Conditions

\text{MgCl}_2

Comparative Studies of Mineralogical Alterations of Three Ultra-long-term Tests of Onshore Chalk at Reservoir Conditions

(magnesium chloride) is injected with a constant rate in a core plug that initially is filled with pure water at a temperature of