A method can include accessing a depogrid generated via gridding of a structural model in a depositional space and transforming the gridded structural model to a geological space via an inverse mapping where the structural model represents structural features in a subterranean environment based at least in part on data acquired via at least one sensor; determining local u, v and w axes for a plurality of cells in the depogrid via volumetric centroids and vertices represented by coordinates in a depositional space coordinate system (u, v, w) and by coordinates in a physical coordinate system (x, y, z); defining directional geological grid properties based at least in part on the local u, v and w axes; and simulating physical phenomena of the subterranean environment via a simulator based at least in part on at least a portion of the directional geological grid properties.