title: Low magnetic fields for flow propagators in permeable rocks.
abstract: Pulsed field gradient NMR flow propagators for water flow in Bentheimer sandstone are measured at low fields (1H resonance 2 MHz), using both unipolar and bipolar variants of the pulsed gradient method. We compare with propagators measured at high fields (1H resonance 85 MHz). We show that (i) measured flow propagators appear to be equivalent, in this rock, and (ii) the lower signal to noise ratio at low fields is not a serious limitation. By comparing different pulse sequences, we study the effects of the internal gradients on the propagator measurement at 2 MHz, which for certain rocks may persist even at low fields.
authors.affiliation: Schlumberger-Doll Research, 36 Old Quarry Road, Ridgefield, CT 06877, USA. psinger@slb.com
authors.forename: Philip M
authors.initials: PM
authors.lastname: Singer
authors.forename: Gabriela
authors.initials: G
authors.lastname: Leu
authors.forename: Edmund J
authors.initials: EJ
authors.lastname: Fordham
authors.forename: Pabitra N
authors.initials: PN
authors.lastname: Sen
mesh_terms: D004867:Equipment Design; D019544:Equipment Failure Analysis; D019015:Geologic Sediments / Q000032:analysis* / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy / Q000295:instrumentation* / Q000379:methods; D008280:Magnetics / Q000295:instrumentation*; D044085:Microfluidics / Q000295:instrumentation* / Q000379:methods; D010539:Permeability; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D014867:Water / Q000737:chemistry
chemical_list: D014867:Water