Figure 3.3. Isopach map of upper Seven Rivers dolomite “net porosity volume” (porosity x feet of thickness). Pore volumes were estimated from gamma ray/neutron logs of various vintages (1950’s to 1990’s). A conservative method of estimating pore volume was utilized that ignored porosity less than 4% and tended to focus on the probable grainstone/packstone higher-energy facies.