Abstract: Calculated cementation index(m), saturation index(n)and formation constants(a, b)from the measured resistance increasing rate and formation factor under high temperature and high pressure are different from those under ambient conditions.Study showed that it results from different electrical conductivity of ions under different temperatures. Moreover, it is pointed out that the parameters measured at ambient conditions must be corrected for log interpretation.

Key words: Sandstone, Temperature, Pressure, Cement index, Water saturation, Index, Formation, Constant