Application of the Velocity-deviation Log in Determining Pore Types and Permeability Trends of Nubia S.S Formation

velocity-deviation log is calculated by converting porosity-log to a synthetic velocity log using the time-average equation.The difference between the real sonic log and the synthetic sonic log can be plotted as a velocity-deviation log.The deviation log reflects the different rock physical signatures of the pore types.Positive velocity deviation mark zones where frame forming pore types dominate.Zero deviations show intervals like interparticle or microporosity.Negative deviations mark zones caused by a cavernous,fracturing,or by a high content of gas.By tracing the velocity deviations continuously down hole,one can know the diagenetic zones,that are characterized by these varying pore types.In addition,this method can be used to observe permeability trends.The velocity–deviation log is applied on the Nubia sandstone Formation for nine wells distributed in the study area of Abu Rudeis-Sidri Field located on the eastern coast of the Gulf of Suez.This study showed that the major pore type for the studied Fm.is the dissolution porosity,this means that the S.S rock of this Fm.is affected by leaching processes which,lead to the presence of the unconnected pores so this Fm.can not be acted as a good reservoir rock.