Streamline methods on fault adapted grids for risk assessment of storage of CO2 in geological formations

Abstract

Streamline methods have shown to be effective for reservoir characterization and simulation. In this work we will develop methodology which allows for tracing of streamlines in fractured or faulted media including anthropogenic faults such as abandoned wells. The basis for a streamline method is a sequential splitting of the coupled pressure and saturation equations. A mass-conservative discretization, which handles general faulted grids in a consistent manner, will be used for the pressure equation. The fact that the saturation equation is solved along the streamlines, makes accurate tracing of streamlines essential. In earlier work we have developed streamline tracing on structured and unstructured matching grids. Here we present an extension to grids adapting to faulted media. For CO2 injection, probabilistic analysis within a risk assessment framework requires multiple realizations. Therefore, fast numerical methods, such as streamline simulation, are needed for screening. The work is motivated in part by the need to assess potential of geological storage of CO2 and is also highly relevant for reservoir simulation.