MECHANISM OF FORMATION OF GAS MIGRATION PATHS IN BOTTOM SEDIMENTS DURING THE DECOMPOSITION OF GAS HYDRATES

Abstract

The formation of gas filtration pathways on the seafloor resulting from gas hydrate decomposition is studied. It is shown that the plowing furrow formed by a stamukhi thrusting onto the seafloor disturbs the stress state of the bottom layers. It is established that the formation of gas migration pathways can be explained by the disturbance of the stress state of the bottom layers during furrow formation. A geomechanical model is developed for the formation of gas filtration pathways resulting from gas hydrate decomposition in an elastic-plastic medium with gas hydrate inclusions randomly distributed. The law of non-associated plastic flow with the Drucker–Prager limit condition and softening is used to describe the failure of the medium. Softening leads to the development of instability and localization of shear deformation in narrow zones. This results in localized cracking of the strata, which creates pathways for gas escape.