The main diagenetic processes affecting the Douleb reservoir. A: (Mf6) Dissolution of bioclasts and genesis of secondary porosity (a) in coarse rudist debris and peloids facies. B: (Mf9) Matrix dolomitization (a): Development of intercristalline porosity (b). C: (Mf4) Silicification of the compacted micritic matrix (a): the pores are filled by hexagonal quartz crystals (b). D: (Mf12) filling of pores with framboidal pyrite (a).