Investigation on oil reservoirs is up to several approaches under different aspects. oilreservoir is dependent on several approaches in different aspects. Distinct settings may be considered for the qualitative and quantitative reservoir evaluation. Control on potential reservoir accumulation is related to permeability and poroslty, in addition to diagenetic and petrographic effects. ln the case study, the considered reservoir is dealing with Cretaceous Carbonate series of ConiacianSantonian age located in the South East of Constantine area (Sud-Est Constontinois). From exploration and evaluation point of view, the oil potential, in the cited area levels, remains almost unexplored. Based on logging and drilling collected data indicates that the approached level of Coniancian -Santonian age can be a tight type. Evidences is from the permeability which is ranging from 0.1 md to 50 md and porosity stretching from lYo up to 16%o. Thus, contribution of tectonic effect is minimized. In the same harmony is the diagenetic and petrographic attitude which is responsible for the compaction and lesser dissolution with occlusion mostly of the intergranular.