ABSTRACT
This chapter focuses on both regional and local geologic factors. Included is discussion of the concept of porosity and permeability, sedimentary sequences and facies architecture, and fractured media in relation to preferred fluid migration pathways. Porosity can be individual open spaces between sand grains in a sediment or fracture spaces in a dense rock. A fracture in a rock or solid material is an opening or a crack within the material. Matrix is an important term referring to dominant constituent of the soil, sediment, or rock, and is usually a finer-sized material surrounding or filling the interstices between larger-sized material or features. Permeability is a measure of the connectedness of the pores. Thus, a glass with many unconnected air bubbles in it may have a high porosity but no permeability, whereas a sandstone with many connected pores will have both a high porosity and a high permeability.
