Seismic analysis of fluid mud

Seismic analysis of fluid mud: Detection of shear parameters in fluid mud and the relation between seismic velocities and yield stresses

Buisman, Menno (TU Delft Civil Engineering and Geosciences)

Kirichek, Alex (mentor)
Draganov, D.S. (mentor)
Maurer, H (mentor)

Delft University of Technology

Applied Geophysics

MUDNET

2019-08-17

In this research, a new measuring method to detect shear parameters in fluid mud is proposed, namely using shear waves, or S-waves opposed to the conventional pressure waves, or P-waves. Currently, detecting fluid mud is done by the use of P-waves. This paper shows that conventional P-waves velocity measurements are unsuitable for linking velocities to the yield stress, which is likely caused due to gas in the mud. Opposed to this, S-wave velocities do show an logarithmic increase, which most likely can be linked to the yield stress development of fluid mud. Both S-wave velocities and yield-point measurements show an exponential increase over time and, because of this, it could be that there is a linear relation between them. The difference why S-waves are more suitable for shear-strength measuring is due to their nature of propagation. S-waves do not propagate through gas and are therefore hardly effected by gas production, opposed to P-waves. For this research, both P-and S-wave velocities are estimated from a transmission seismic experiment. Also, a frequency analysis has been conducted showing large similarities over time and for dissimilarities between different mud samples. The yield-point measurements are derived from a rheometer with the same mud sample used for the seismic experiments. Besides a velocity analysis from the transmission measurements, also a reflection measurement has been conducted. The aim for this is to detect converted P-to S-waves and to detect the Scholte wave. Furthermore, a dispersion analysis has been conducted, which is likely important since the relative change in S-wave velocities is small and the velocities are frequency-dependent.

fluid mud
rheology
Yield Stress
Seismic
shear wave

http://resolver.tudelft.nl/uuid:1c2af380-8dd4-4321-9f78-e5cb66def6d2

Student theses

master thesis

© 2019 Menno Buisman