Halliburton Energy Services, Inc.

Gabriela Singer

Songhua Chen

Shouxiang Mark Ma

Lilong Li

A method comprises determining a Nuclear Magnetic Resonance (NMR) response of a subsurface formation that is based on an NMR response signal that traversed through the subsurface formation and that is result of a magnetic field being emitted into the subsurface formation; determining an Archie cementation exponent for an Archie equation based on the NMR response; and determining a property of the subsurface formation based on the Archie cementation exponent.

Nuclear magnetic resonance based Archie parameter determination

To separate porosity from surface roughness, length scales for pore size and surface roughness are identified. These length scales are determined from surface roughness measurements and confirmed via NMR pore body calculations and pore size capillary pressure measurements. A filter removes pore contribution to surface roughness measurements and delivers intrinsic surface roughness. Additional filters and methods determine the minimum magnification on which to base surface roughness calculation, based on size of the field of view and where measured surface roughness approaches intrinsic surface roughness as magnification increases but larger magnification increase sampling time and difficulty. Sample irregularities, such as saw marks, are also filtered out or determined to be too large to remove via filter and another area of measurement is located. With the pore corrected quantification of surface roughness, surface relaxivity and pore distribution can be calculated with greater accuracy.

Pore contribution corrected quantifying of surface roughness

Measurements of a core sample at scales of measurement that differ by multiple orders of magnitude can be used to calculate a value that fairly represents surface roughness of the core sample. This surface roughness value can be used to determine petrophysical properties of the subsurface formation from which the core sample was obtained. The measurements can be nuclear magnetic resonance (NMR) diffusion-relaxation and gas-adsorption measurements. Surface relaxivities at the different scales are determined from the measurements and a ratio those surface relaxivities can be used to calculate the surface roughness value.

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Richmond, TX, United States of America

Gabriela Singer