Crystallisation induced damages in confined reservoir conditions

David Gregoire and Jean-Paul Callot – LFCR, E2S UPPA Hannelore Derluyn – LFCR, CNRS 
Eric Gaucher and Sylvain Calassou – Total, CSTJF, Pau

Major Results

  1. Experimental proof of crystallisation induced damages in porous sandstones confined in reservoir conditions
  2. In situ ultrasonic monitoring of salt hydration reaction in porous sandstone
  3. Unclassical barite precipitation in sedimentary rock


Veins in geological reservoir settings are mineral filled fractured long being associated with the model of ‘crack seal’. However, some veins exhibit features that are difficult to explain with the model of ‘crack seal’ but would better fit with a ‘seal-crack’ model driven by the concept of crystallisation pressure. From this, two main experimental tests were conducted. First, we started with an experiment of counter diffusion to precipitate a barite front in two sedimentary rock. In fact, we did not observe damage but a barite nucleation and crystallisation behaviour linked to the pore distribution, the matrix mineral crystallisation state and an interaction between barite and clay minerals.


Second, a new protocol salt hydration protocol was tested in a sandstone under hydrostatic reservoir confinement. Damages were monitored at a confining pressure up to 10 MPa. In addition homogenesisation method modelled the effective medium properties of the reacted sandstone that fit with the evolution of the elastic properties of the sandstone during salt hydration.

Precipitation of hydrous phases with high molar volumes in the porosity of a rock and generation of cracks