A NEW APPROACH FOR OBTAINING SWIR FROM NMR LOGWITHOUT REQUIRING T_(2CUTOFF)

摘要

The Coates permeability equation is dependent onporosity correlation and a reliable T_(2cutoff) to partition T_2relaxation time distribution into movable andirreducible fluid volumes. When a formation rockexhibits neither good permeability-porosity correlationnor a consistent and reasonable T_(2cutoff), the Coatesequation won’t be a good choice for permeabilityestimation and BVI can not be reliably and/or easilyobtained with a fixed or variable T_(2cutoff). We developeda new S_(wir) (and BVI) model by combining the Leverett Jfunction and the SDR permeability model. Uponvalidation of this Swir model for its applicability to theformation under investigation, we are able to justifyusing a modified SDR model for permeabilityestimation. With this approach, both S_(wir) andpermeability can be obtained using NMR-derivedporosity and T_(2GM), without requiring a T_(2cutoff).