We measured capillary pressure,relative permeability,electrical resistivity and NMR response on carbonate samples from a producing field in the Middle East.The pore throat distribution from mercury injection was successfully compared with the pore size distribution inferred from the NMR T2 relaxation curve.Some samples were aged in crude oil at elevated temperature and underwent the same experiments to evaluate the influence of wettability changes on these properties. The experimental data show that there is a significant difference in the relative permeability and capillary pressure of clean and aged samples;the results are explained in terms of the pore-scale configurations of fluids.In contrast,electrical resistivity did not encounter significant changes for different wettability,suggesting that electrical properties in these carbonates are mainly affected by the porosity that remains waterwet, or is only neutrally-wet.This conclusion is supported by the significant displacement that is observed in the aged sample at capillary pressures close to zero.
展开▼
