Scientific drilling in the campus: Almera-1 borehole, unraveling urban subsurface geology in Barcelona (Spain)

Abstract

Almera-1 borehole was drilled to provide a borehole geophysical logging and downhole monitoring research and training facility. Also a main objective was the exploration of the urban subsurface geology adjacent to the Institute of Earth Sciences Jaume Almera (CSIC) in Barcelona the University of Barcelona Pedralbes. Wireline drilling continuous coring was successfully applied to recover cores from the entire section (214m). Since 2011 Almera-1 hole has been extensively used for slim hole logging, coring and monitoring. Total depth was reached after drilling a Quaternary to Paleozoic section. The upper section of Almera-1 hole is cased with PVC and the lowermost is an open hole section within the Paleozoic section. A complete set of geophysical logging measurements and oriented borehole images was acquired with CSIC own slim hole logging equipment both in open hole mode and through the PVC casing. Logging measurements were acquired over the entire section. Open hole measurements included acoustic and optical imaging, spectral natural gamma ray, full wave acoustic logging, magnetic susceptibility, hydrochemical-temperature logs and fluid sampling. Through casing (PVC casing) measurements included spectral gamma ray logging, full wave sonic and acoustic televiewer