Comparison of methods for predicting shear-wave velocities of unconsolidated shallow sediments in the Gulf of Mexico
Scientific Investigations Report
2013-5141
By: Myung W. Lee
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Abstract
Accurate shear-wave velocities for shallow sediments are important for a variety of seismic applications such as inver-sion and amplitude versus offset analysis. During the U.S. Department of Energy-sponsored Gas Hydrate Joint Industry Project Leg II, shear-wave velocities were measured at six wells in the Gulf of Mexico using the logging-while-drilling SonicScope acoustic tool. Because the tool measurement point was only 35 feet from the drill bit, the adverse effect of the borehole condition, which is severe for the shallow unconsolidated sediments in the Gulf of Mexico, was mini-mized and accurate shear-wave velocities of unconsolidated sediments were measured. Measured shear-wave velocities were compared with the shear-wave velocities predicted from the compressional-wave velocities using empirical formulas and the rock physics models based on the Biot-Gassmann theory, and the effectiveness of the two prediction methods was evaluated. Although the empirical equation derived from measured shear-wave data is accurate for predicting shear-wave velocities for depths greater than 500 feet in these wells, the three-phase Biot-Gassmann-theory -based theory appears to be optimum for predicting shear-wave velocities for shallow unconsolidated sediments in the Gulf of Mexico.
Study Area
| Publication type | Report |
|---|---|
| Publication Subtype | USGS Numbered Series |
| Title | Comparison of methods for predicting shear-wave velocities of unconsolidated shallow sediments in the Gulf of Mexico |
| Series title | Scientific Investigations Report |
| Series number | 2013-5141 |
| DOI | 10.3133/sir20135141 |
| Year Published | 2013 |
| Language | English |
| Publisher | U.S. Geological Survey |
| Publisher location | Reston, VA |
| Contributing office(s) | Central Energy Resources Science Center |
| Description | iii, 11 p. |
| Country | United States |
| Other Geospatial | Gulf Of Mexico |
| Online Only (Y/N) | Y |
| Google Analytic Metrics | Metrics page |