In this North China Basin field, the evaluation of newly drilled in-fill wells oil saturation, capillary-bound water volume and permeability is difficult. Conventional saturation evaluation is hampered by constantly varying water salinities due to the fresh water flooding EOR program. NMR-derived effective porosity, capillary-bound water volume and permeability are adversely affected by the extreme viscosity of the crude oil.

This paper presents a synergistic evaluation approach, combining conventional open hole data with NMR data corrected for viscous oil effects and cased hole gamma-ray spectroscopy data for complete evaluation of Phie, Sw, Sxo, Swirr and Kint. A new technique is developed to derive Sxo exclusively from NMR data and clay volume.

This synergistic approach overcomes salinity and crude oil viscosity problems, it also allows more accurate lithology and reservoir producibility estimation, but, the Sxo derivation from NMR data is only valid if crude viscosity is very high.

Keywords:
viscosity, well logging, water saturation, reservoir, correction, salinity, log analysis, clay content, vxoi, contribution
Subjects:
Reservoir Fluid Dynamics, Improved and Enhanced Recovery, Formation Evaluation & Management, Flow in porous media, Waterflooding, Open hole/cased hole log analysis, Core analysis
Copyright 1998, Society of Petroleum Engineers
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