Modélisation de la circulation hydrothermale naturelle et simulations de perturbations de pression sur des failles lors d'injections en puits
Bérénice Vallier, actuellement en post-doctorat à l’Université de Strasbourg, viendra nous présenter ses travaux de recherche.
Abstract
Many numerical models studying the natural hydro-thermal circulation and the impact of industrial exploitations have been developed over the past decades. However, numerical methods which integrates several multi-physical and multi-scale measurements are under-represented. In the first part of the research, a natural large-scale hydro-thermal circulation is studied using a simplified thermo-hydro-mechanical model. Key rock physics properties are inverted from observed temperature and stress-depth profiles. On the other hand, this model with a complex coupling does not incorporate the details of the fluid flow along the major faults. The study provides new insights on the extension of the hydro-thermal convection cells through depth and on the up-scaling of rock physics properties from laboratory scale to field scale. In the second part, the anthropogenic impact on a natural large-scale system is analyzed. The aim of the study is to simulate far-field pore pressure disturbances from fluid injection in fractured porous medium. Studying the diffusion of pressure disturbances will allow to understand the evolution of the effective stress and to quantify the triggered seismicity. A large-scale homogeneous porous medium as a fault structure is represented. The pressure disturbances’ distribution is investigated under different states: (i) controlled injection; (ii) injection/production system. The numerical pressure perturbations are in good agreement with the analytical results. We develop alternative oscillating injection/production strategies and their influences are studied on the near-well and far-field pressure disturbances. The oscillating pumping strategy highlights apotential reducing of the induced seismicity on far-away faults.