ABSTRACT

An upper Hunton reservoir in the southwest Ringwood area is composed of two distinct porosity zones. The porosity zones are referred to as the Hunton "C" and "D"; the Hunton "C" is the deeper of the two zones. The Hunton "C" porosity zone is composed of fine- to medium-crystalline dolostone that contains silt, mica, illite, and microporosity. Log analyses indicate that the zone should be water-productive, but it produces gas with little or no water. These log calculations are affected by the low resistivity measurements caused by the irreducible water present in the micropores and in the illite clay. The upper porosity zone, Hunton "D," is a clean dolostone that contains vugular and inter-crystalline porosity along with microporosity. Core, geophysical-log analyses, and pressure-transient analyses indicate that both porosity zones average ~12% porosity and 0.10 millidarcy (md).