A common observation in the majority of the studied wells.

Density (RHOB)

Usually, because of the low density in the FZs toward rocks, RHOB is lower in the fractured area.


The sonic log is based on wave arrival time. This time depends on P wave velocity that passes through lithology, porosity, and fluids. If the wave path passed a fracture zone, the time increases because P wave velocity is slower in porous and fluids rather than solids.

Gamma Ray (GR)

GR is natural radioactivity that comes from Uranium, Thorium, and Potassium that have accumulated in fractures.


Potassium is found in Feldspar and clay minerals. Because of the lake of Feldspar in the study formation, Potassium is due to clay formation. Clay has plasticity, therefore, it indicates the NFZ.


Claystone (shale) contains Thorium. Shale has plasticity properties and it is contrary to the properties of fractured rock.

Water Saturation (SW)

Higher water saturation usually indicates open fracture zones.


Uranium can dissolve in water and deposit in fractures.

Resistivity (RT)

By trapping brine in fractures, resistivity decreases. It means the NFZ has a high RT.

Photoelectric Factor (PEF)

FZs in some of the study wells indicate high PEF because of the tarp of water. It is because elements of connate water have a higher atomic number than rocks.


The Caliper tool reads the diameters of borehole more precisely when in FZ rock edge chipped away while drilling. Also, sometimes because of mud accumulation in open fractures a caliper log is even less than bit size.

Neutron Porosity (NPHI)

NPHI would increase if a fracture zone filled with fluid or Hydrogen content.

Geological Rock Types (dolomite, limestone, shale, and anhydrite)

Dolomite and limestone are brittle, with elastic behavior, capable of fracturing. Shale and anhydrite are ductile, capable of plastic behavior.