Testing of Wettability Effects on Capillary Pressure and Electrical Conduction In Fluid-Saturated Rocks |

ABSTRACT:

The main goal of core analysis is toreduce uncertainty in reservoir evaluation processes created by the uncertaintydegree in the input parameters at the different levels from reserve estimatelevel to the enhancement of reservoir performance level. In order to reachthese targets, the exact determination of certain petro physical properties arenecessary such as rock porosity, relative permeability, water saturation, andcapillary pressure at all stages of reservoir life and rock wettability.Predicting reservoir wettability and its effect on fluid distribution andhydrocarbon recovery remains one of the major challenges in reservoirevaluation and engineering. Current laboratory based techniques require the useof rock-fluid systems that are representative of in situ reservoir wettability.Several parameters like relative permeability’s, residual saturations, andcapillary depressurization curves change with the wettability state of thereservoir. In addition all these parameters, can greatly impact oil recovery.Thus, there is a need to relate all these parameter to wettability state of thereservoir [Anderson, 1986]. In this study, irreducible oilsaturation and capillary pressures using rock centrifuge measurements for BereaSandstone rock samples. Thispaper summarizes and investigate the effects of wettability, pore geometry, andstress on electrical conduction in partially saturated porous media. Experimentsconducted on both glass-bead packs and Berea cores show that wettability has aprofound effect on the saturation exponent, consistent with theoreticalpredictions based on a network representation of the porous medium. The effect ofwettability is most pronounced when the pores are poorly connected. Theinfluence of stress is substantially smaller than the effect of wettability inthe relatively simple low-clay content intergranular-porosity systemsconsidered here. Small increases in the formation factor were observed for thecores and the water-wet beads, whereas larger increases were ob- served with the compressible asphaltene-coated oil-wet beads.