SIMULTANEOUS MEASUREMENT OF MULTIPLE CAPILLARY PRESSURE CURVES FROM WETTABILITY AND ROCK PROPERTY VARIATIONS WITHIN SINGLE ROCK PLUGS

摘要

The high definition capability of Magnetic Resonance Imaging(MRI)makes it suitable for imaging fluids in porous rock on a fraction of a millimeter scale.Under the right circumstances,MRI images of heterogeneous rock containing fluids can become an asset for obtaining data.By using MRI,it was possible to obtain multiple capillary pressure curves simultaneously from core plugs containing immiscible fluids.One example shows how independent and distinct primary drainage capillary pressure curves were obtained for each rock type within a single plug.Another example using the Direct Measurement of Saturation Method for capillary pressure found multiple spontaneous and forced imbibition capillary pressure curves within a single plug that had been aged under crude oil for wettability alteration.Amott indices calculated from these Direct Measured imbibition curves indicated that wettability varied from moderately to highly water-wet conditions within the plug with the least water-wet rock toward the outside of the plug.The variation of wettability within the plug could not be discerned from an Amott test on the full plug.Analysis of such wettability variations within a single plug was only possible by the Direct Measurement of Saturation Method.