Saturation-Height Modeling: Assessing Capillary Pressure Stress Corrections

Hulea, Iulian N. (Shell Global Solutions International B.V.)


While permeability modeling follows a wellestablished approach in converting laboratory properties to subsurface conditions, ambiguity remains over the approach to be followed by laboratory-acquired capillary pressures (under ambient conditions, like most mercury injection capillary pressures (MICP) measurements). One approach (developed by the earlier work of Juhasz) recommends that capillary pressures be stress corrected (prior to modeling) according to a correlation. Another approach suggests the saturation-height model (SHM) be built with ambient measurements that when supplied with corrected properties (porosity and permeability) would generate in-situ saturations. The effect of stress correction applied to porosity and permeability data (as part of routine core analysis (RCA) is not easily compared against the capillary pressure correction, potentially leading to inconsistencies. The work presented here uses a recent methodology that aims at ensuring consistency between permeability and SHMs to provide guidance on the best approach to be followed in the process of building a SHM. The MICP or SHM carries an intrinsic permeability that can be compared to the permeability model. The results show that signicant inconsistency can occur between the porosity-permeability data (a reliable, well-controlled and measurable property under stress) on one hand, and the MICP-/SHM-inferred permeability on the other.