رسائل ماجيستير
English
2023
Investigation Of Tti Anisotropy Of P-wave Velocities In Sand Dunes In Eastern Saudi Arabia
Abdullatif Al-Shuhail, خالد يسن مكي
كلية هندسة البترول وعلوم الأرض-جامعة الملك فهد للبترول والمعادن · السعودية
Unconsolidated dune sands pose unique challenges to geoscientists and seismic data, many of which lead to poor seismic images. This can be attributed to their complex topography, internal structure, and high attenuation effects, which are commonly overlooked during data processing. This study aims to investigate the azimuthal anisotropy of P-wave velocity in sand dunes through the design and deployment of a circular seismic array on a barchansand dune in Eastern Saudi Arabia. The studied sand dune exhibits dipping cross-strata and thus was viewed as a tilted transversely isotropic (TTI) medium.The acquisition geometry consists of 24 receivers placed on the circumference of a circle spaced at a polar (azimuthal) angle of 15° with a constant offset of 9 m from a source that is placed at the circle’s center. The measured velocity data show a sinusoidal behavior with a maximum velocity along an azimuth that is parallel to the slip face (cross-strata) of the dune. The measured velocity-azimuth data is fitted to a TTI model with four known parameters: azimuth (𝜑 = 0°, 15°, … , 330°, 345°), incidence angle (𝜃 = 71.33°), tilt of symmetry axis (𝜃0 = 30°), and velocity along symmetry axis (𝑉P0 = 274 𝑚/𝑠), and two unknown Thomsen parameters (𝜀, 𝛿). The best-fit values for 𝜀 and 𝛿 are 0.035 and 0.005, respectively, which proves that the studied sand dune has the characteristic of a weakly anisotropic TTI medium.
