Capillary Pressure

Pore Throat Size controls Sw & k.. so use Sw for k!

Think “Pore throat size distribution controls Sw AND k, so therefore..” k and Sw are both controlled by pore throat size. Porosity and NMR T2 distributions are not (surface area). Does your company use Sw or Ø*Sh’s stronger correlation with k to predict k? We pay for NMR logging, core analysis “flow zones” and “rock types” in attempts to address k variations with porosity.. but we often don’t need to. Sometimes we just need to look at what we already have for a cheaper, more powerful correlation of log analysis results with k.. (Reason: Service companies can’t make money out of data that already exists.. that is the task of the Interested Petrophysicist)


Capillary Pressure Mercury Injection Data (MCIP) for Saturation Height?

.. In addition mercury data generally cannot be used for Sw-Height in a clayey low permeability rocks unless Cation Exchange Capacity and Clay Bound Water corrections have been made. During a mercury experiment a water phase is not present to wet the clays and fine pores and the mercury bulldozer barges its way through delicate clay lined throats, so, unlike air-brine data, mercury saturations provide a poor analogue for reservoir saturations. Mercury data provides pore throat size information for rock typing. This lack of a water phase is especially important here where Clay + Capillary Bound Water is a significant fraction of total porosity, as implied here by the 100% + difference between the air-brine and mercury data sets for the same reservoir height. Hence, despite the need for a resistivity independent bulk volume hydrocarbon these data have limited ability to supply a usefully accurate dm-m scale whole rock storage capacity.