The Effects of Macropores in Heterogeneous Porosity Systems on Electrical Resistivity Behavior

To better understand the petrophysical properties, such as electrical resistivity behavior, capillary pressures and displacement behavior, of hydrocarbon bearing carbonate rocks with a macropore system, a porous plate capillary desaturation cell was built. Lucia's carbonate classification was selected to be used in this research. Electrical end effects were minimized by utilizing a four-electrode system. An oil/ water system and a gas/ water system have been studied.

The effects of vugularity on the petrophysical properties were evident from the experiments. For a constant porosity, as vugularity increases, cementation exponent (m) and saturation exponent (n) increase systematically. The irreducible water saturation, the capillary pressure curves and the displacement behaviors are also substantially different from homogeneous sandstone experiments.

Keywords:

• capillary pressure
• displacement behavior
• electric resistivity
• macropore
• petrophysical properties