P008 ESTIMATE OF THE APERTURE OF WATER- SATURATED FRACTURES BY NUCLEAR MAGNETIC RESONANCE LOGGING Abstract 1 Nuclear magnetic resonance (NMR) well logging is a technique to measure the transport properties of fluid-saturated porous strata by analyzing the proton NMR signals from the hydrogen-bearing fluid molecules. We applied the technique to a borehole in an andesite lava formation (Akita Japan) to estimate the aperture of fractures embedded in the lava. A fracture (depth 61.2 m) responsible for the total loss of circulation during the drilling was scanned by a Schlumberger NMR sonde to obtain the bulk-fluid porosity of the fracture filled