Method and system for determining streamlines in a reservoir geological formation by dual front propagation

A computer implemented method for determining streamlines between a source and a target in a reservoir geological formation, based on a reservoir grid corresponding to a 3D grid of cells wherein each cell represents a respective portion of the reservoir geological formation, wherein said method comprises:

• front-propagating from a source cell of the reservoir grid, which corresponds to the source in the reservoir geological formation, to determine front propagation paths originating from the source cell,
• front-propagating from a target cell of the reservoir grid, which corresponds to the target in the reservoir geological formation, to determine front propagation paths originating from the target cell, and
• determining a contact set which is composed of contact cells of the reservoir grid at which the front propagation paths originating from the source cell meet the front propagation paths originating from the target cell,
• and, for at least one contact cell of the contact set:
• determining a partial streamline by back-propagating along the front-propagation paths originating from the source cell, from said at least one contact cell up to the source cell,
• determining a partial streamline by back-propagating along the front-propagation paths originating from the target cell, from said at least one contact cell up to the target cell, and
• determining a streamline of the reservoir geological formation by combining the partial streamlines originating from respectively the source cell and the target cell which reach said at least one contact cell.