Electric lineation and tortuosity for assigning fracture porosity in Nukhul formation, north of the gulf of Suez, Egypt

An integrated interpretation of petrographical, petrophysical and anisotropic fabric studies has been carried out for assigning fracture porosity of Nukhul Formation in north of the Gulf of Suez. Petrographically, the available Nukhul core samples are composed mainly of clastic rocks as glauconitic and dolomitized quartz wacke, echinoidal and foraminiferal dolomitic quartz wacke, and calcareous quartz arenite. Beside to some microfacies, they could be assigned as sandy dolopackstone microfacies, sandy molluscan packstone microfacies and dolomitic packstone microfacies. The 2-D porosity determination in the thin section revealed negligible porosity values mainly dishanced by compaction and pressure solution, silicification and cementation by calcite. Some other diagenetic processes slightly/hardly enhanced porosity as dolomitization, dissolution, replacement and aggrading neomorphism. Petrophysically, porosity and permeability are poor due to the tight cementation mostly by silica, which obliterated the primary porosity and also the diagenetic porosity formed after the dolomitization process. Permeability values decrease with increasing the irreducible water saturation and the tortuosity values in perpendicular direction to the bedding plane, whereas it increases by increasing porosity. Both the petrographical and petrophysical studies showed the presence of some fracture and channel porosity in the field scale, assigned from the well-log data, and hardly assigned by using the traditional petrophysical and petrographical methods. Using the electric fabric parameters and measuring tortuosity in 3-D is a useful tool for assigning fracture and channel porosity at the upper and middle parts of the studied rock unit