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In borehole geophysics, a tube wave is an interface wave traveling along the steel-cased borehole at a relatively fixed velocity, about 5.5 km/s, as reported by Gal'Perin (1974). Tube wave occurs when a Rayleigh wave encounters the wellbore and perturbs the wellbore fluid. It propagates along the cylindrical fluid-solid boundary of the borehole and has no spherical divergence. Tube waves often have larger amplitudes than that of body waves in the surrounding rocks due to little energy loss during their propagation.,
Tube wave modes
The classic tube wave can be observed as the lowest order trapped mode. The higher modes of tube waves may be generated depending on the rock properties and source frequency. The fundamental tube wave mode is often called Stoneley wave. However, tube wave is a solid-liquid interface wave, the term Scholte wave is more appropriate than Stoneley wave.
In some applications, tube waves could be considered as a useful seismic signal. We can use the information obtained from tube waves to determine some properties of the rock formation near the borehole. Due to the coupling property of tube wave with the rock formation where it travels through, tube wave can perturb the formation across open fractures intersecting the borehole. This effect is called squeezing effect. This effect can generate secondary tube waves traveling both up and down the wellbore from the fractures. Therefore, tube waves can be used to study the presence of open fractures. In addition, the length and the width of the fractures can be qualitatively assessed based on the amplitude of the tube waves.
However, in vertical seismic profile (VSP), tube waves are considered as the most damaging noise because of their coherency feature. They interfere with the reflected body waves which occur later in time on VSP data.
- Gadallah, M.R.; Fisher, R. (2008). Exploration Geophysics. Springer Science and Business Media. p. 76.
- "Tube wave". http://www.glossary.oilfield.slb.com/Terms/t/tube_wave.aspx. Retrieved May 15, 2018.
- Schoenberg, M.; Marzetta, T.; Aron, J.; Porter, R.P. (1981), "Space–time dependence of acoustic waves in a borehole", Journal of the Acoustical Society of America 70 (5): 1496-1507
- Daley, T.M.; Gritto, R.; Majer, E.L.; West, P. (2003), "Tube-wave suppression in single-well seismic acquisition", Geophysics 68 (3): 883-869
- White, J.E. (1965), "Seismic waves: Radiation, transmission, and attenuation", McGraw-Hill