Sonic while drilling has long been considered a major goal by the industry because of its potential applications: real-time determination of pore pressure and overburden gradients, improved lithology change determination, seismic calibration, and detection of seismic reflectors ahead of the bit. Until now, only two methods were available to perform sonic measurements while drilling—the use of continuous coring or a specific measurement while drilling (MWD) tool. Unfortunately, both methods remain very expensive and suffer from technical limitations. A new technology [named pulsed ultrasound on cuttings (PUC)] has been developed to measure both compressional and shear-wave velocities directly on cuttings with dimensions as low as 1 mm. Laboratory and field implementations of the method are presented along with its validation against reference measurements.

Keywords:
puc method, puc measurement, reservoir characterization, transducer, overburden gradient, laboratory, well logging, sonic log, fragment, compressional
Subjects:
Exploration, development, structural geology, Formation Evaluation & Management, Open hole/cased hole log analysis, Reservoir Characterization, Reservoir geomechanics, Seismic processing and interpretation
Copyright 1997, Society of Petroleum Engineers
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