Figure 9.(a) Gamma-ray and resistivity logs of an original field well (1956), San Andres “C” waterflood unit, Permian basin, Texas. Net pay is 7 m. (b) Gamma-ray neutron porosity and resistivity logs of a 1988 well drilled and cored in the same unit, about 9 m from the 1956 well.  Net pay in this well is about 20 m.