A pseudo-kinetic model to simulate phase changes in gas hydrate bearing sediments

by Teymouri, M, Sanchez, M, Santamarina, J.C
Article Year: 2020 DOI: doi: https://doi.org/10.1016/j.marpetgeo.2020.104519.


Mehdi Teymouri., Marcelo Sánchez and J. Carlos Santamarina (2020).  A pseudo-kinetic model to simulate phase changes in gas hydrate bearing sediments, Marine and Petroleum Geology


Modeling of the phase transitions anticipated in gas hydrate bearing sediments (GHBS) is critical for a 31 proper understanding of time-dependent changes in states and volumes (e.g. the production of methane 32 from this type of soils). We propose a new pseudo-kinetic approach to simulate the typical phase changes 33 anticipated in GHBS, using published experimental results involving gas hydrate dissociation that are the 34 basis of a widely used kinetic model. The proposed pseudo-kinetic model is formulated in the pressure35 temperature (P-T) plane and assumes a rate of gas hydrate dissociation (or formation) proportional to the 36 distance between the current state and the phase boundary. The model consists of only one parameter and 37 is simple to implement in numerical simulators. A similar concept is used to model ice formation/thawing 38 phenomena, but based on the ice/liquid-water phase boundary. We implemented the pseudo-kinetic model 39 in a fully coupled thermo-hydro-chemo-mechanical (THCM) finite element code and validated it against 40 experimental results performed on the dissociation of synthetic gas hydrate. We also evaluated the 41 pseudo-kinetic model using synthetic cases covering several scenarios associated with gas hydrate 42 formation/dissociation and ice formation/thawing. The model successfully reproduced the gas production 43 test from a natural GHBS core from Korea (scaled gas venting experiment over 14hours), and also the formation of gas hydrate and ice in permafrost in Alaska (over 2x106 44 years). We show the versatility of 45 the proposed approach by applying it to model the different phase transitions typically encounter in 46 GHBS. The simple formulation, easy implementation in numerical simulator, and reduced number of 47 parameters (only one per phase change) make this model an attractive option for simulating phase 48 transformations in problems involving GHBS.


gas hydrate hydrate dissociation hydrate formation ice formation/melting phase transitions numerical modeling validation