Method of modelling a sedimentary basin using a hex-dominant mesh representation

A method of modelling a sedimentary basin, the sedimentary basin having undergone a plurality of geological events defining a sequence of states of the basin, by means of a computer-executed numerical basin simulation, the numerical basin simulation solving at least one balance equation of poromechanics according to a face-based smoothed finite-element method for determining at least a stress field and a strain field, characterized in that the method comprises carrying out at least the following steps:

• A. performing physical quantity measurements relative to the basin by means of sensors and constructing a first mesh representative of the basin for each of the states of the basin, the first meshes of the basin for each of the states predominantly consisting of hexahedral cells,
• B. by means of the numerical basin simulation and the first meshes for each of the states, determining at least a strain field and a stress field for each of the states by carrying out at least the following steps for each of the first meshes representative of the states:
• a) determining a second mesh representative of the state by subdividing each of the hexahedral cells of the first mesh representative of the state into six pyramidal cells, the non-hexahedral cells of the first mesh being unchanged in the second mesh,
• b) modelling the basin by determining at least the displacement field and the stress field for the state by means of the numerical simulation applied to the second mesh representative of the state.