Dissociation of methane hydrates sediments. Coupling heat transfer / mass transfer

• Main Author: Tonnet, Nicolas
• Other Authors: Centre Sciences des Processus Industriels et Naturels (SPIN-ENSMSE), École des Mines de Saint-Étienne (Mines Saint-Étienne MSE), Institut Mines-Télécom Paris (IMT)-Institut Mines-Télécom Paris (IMT), Département Géochimie, environnement, écoulement, réacteurs industriels et cristallisation (GENERIC-ENSMSE), Institut Mines-Télécom Paris (IMT)-Institut Mines-Télécom Paris (IMT)-SPIN, Laboratoire des Procédés en Milieux Granulaires (LPMG-EMSE), Institut Mines-Télécom Paris (IMT)-Institut Mines-Télécom Paris (IMT)-Centre National de la Recherche Scientifique (CNRS), Ecole Nationale Supérieure des Mines de Saint-Etienne, Jean-Michel HERRI([e-mail])
• Format: Doctoral or Postdoctoral Thesis
• Language: French
• Published: HAL CCSD 2007
• Subjects: gas hydrate; mass transfer; heat transfer; kinetics of dissociation; porous media; permeability; experimental device; parametric study; hydrates de gaz; transfert de chaleur; transfert de masse; cinétique de dissociation; milieu poreux; perméabilité; dispositif expérimental; étude paramétrique; [SPI]Engineering Sciences [physics]; Methane hydrate
• Online Access: https://theses.hal.science/tel-00326878; https://theses.hal.science/tel-00326878/document; https://theses.hal.science/tel-00326878/file/N-Tonnet-071204.pdf

226 pages The production of methane gas from methane hydrate bearing sediments is a process which is considered to reach an industrial scale in the next decades. However the first tests to recovery methane gas have appeared to be not completely fruitful, and difficult to carry out. In fact, the dissociation of methane hydrate in a porous medium is still bad known and controlled : the melting of methane hydrate involves fluids flows and heat transfer through a porous medium that properties evolves in function of the disappearance of the hydrate phase, and potential appearance of an ice phase . Mass and heat transfers can be coupled in a complex way, firstly because of the permeability changes, and secondly due to material conduction changes. In our work, mass and heat transfers have been studied both experimentally and numerically. A 2D numerical model is proposed in which heat and mass transfers govern dissociation of methane hydrate. The results of simulation show us the evolution of the interfaces, and gradients of pressure and temperature. This model has been used to dimension an experimental device. Then the model has been then used to model the experimental results. The experimental set-up consists of five cylindrical zones of same diameter (1/2 inch) but different length, for a total of 2.6 meters. Each zone is temperature and pressure controlled. Each experiment consists firstly in crystallizing a hydrate phase in a porous media (from 65 to 75 % of the porosity). Then the material I dissociated by controlling the pressure at one side of the zone. The kinetics of dissociation is also monitored by controlling pressure in exiting ballast. The dissociation limiting step reveals to be thermal transfer, or mass transfer depending on the initial permeability, and conductivity of the porous media. The role of ice is also identified: it reveals to be different depending on porous media properties. La production de méthane à partir des champs hydratifères des fonds océaniques est un procédé promis à se ...