title: Developments in core analysis by NMR measurements.
abstract: For a large suite of consolidated sandstone samples low in shale content we have measured the permeability k, irreducible water saturation Swi, porosity phi, electrical-resistivity formation factor F, porosity by NMR, geometric-mean relaxation times T1g, and stretched-exponential relaxation times T1s. We find that T1g (or T1s) is the decisive parameter for the estimation of k or Swi of porous sandstones by other than direct measurements of these quantities. The additional use of phi or F brings appreciable, but not decisive, improvement. We show isovalue maps of the error factor delta, which show substantial regions of near-minimum values of delta and show basic compatibility of our estimators for permeability with different published estimators. The exponents of T1g (or T1s) in our power-law estimators and those of various published estimators for k are not very far from 2.0 if either or both of phi and F are also used in the estimators.
authors.affiliation: University of Bologna, Department of ICMA, Italy.
authors.forename: G C
authors.initials: GC
authors.lastname: Borgia
authors.forename: V
authors.initials: V
authors.lastname: Bortolotti
authors.forename: A
authors.initials: A
authors.lastname: Brancolini
authors.forename: R J
authors.initials: RJ
authors.lastname: Brown
authors.forename: P
authors.initials: P
authors.lastname: Fantazzini
mesh_terms: D009682:Magnetic Resonance Spectroscopy; D010539:Permeability; D016062:Porosity; D014867:Water
chemical_list: D014867:Water