The different types of porosity characterizing the Douleb reservoir. A: (Mf6) An intragranular (a) and intergranular (b) porosities observed between rudists. B: (Mf1) Rudist-rich packstone of Hippuritidae type (a) showing an important intergranular porosity (b). C: (Mf2) Packstone-grainstone with small rudist fragments and peloids showing an intergranular (a) and intragranular (b) porosity and oil-impregnation (c). D: (Mf2) SEM photography showing the matrix porosity (a) in fine grainstones with small debris of rudists and peloids. E: (Mf1) Radiolitidae type rudist (a) showing an important intragranular porosity (b). F: (Mf2) SEM photograph shows matrix (a) and intercrystalline porosity (b) between dolomite crystals (c).