SEDL / STP / STP883-EB / STP36335S

Pressure Release Disturbance in Simulated Marine Cores as Indicated by a Laboratory Gamma-Ray Densitometer

Chace, AB
Supervising ocean engineer, Brown and Caldwell, Consulting Engineers, Walnut Creek, CA

Pages: 12    Published: Jan 1985

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Abstract

A gamma-ray density gage showed that under simulated marine conditions standard Ottawa sand decreased in bulk density as indicated by the closely related linear attenuation coefficient on release of 10.3-MPa (1500-psi) confining pressure. This simulated recovery of a marine core from a depth of 1050 m. Expansion of the sand samples in one holder continued an average of 17 h. Samples repressurized within 4 h regained their original density while those left unpressurized for over 5 h did not. Density variation in marine cores following retrieval is significant and results primarily from effervescence and expansion of gas bubbles.