The contribution is devoted to the numerical calculation of the frequency-dependent complex-valued vectorial amplitudes of S waves in weakly anisotropic media by the coupling ray theory. The efficient and accurate method of numerical integration of the coupling equation is proposed, and the accuracy of the method is estimated in order to control the integration step so, that the relative error in the wavefield amplitudes due to the integration is kept below a given limit. Several quasi-isotropic approximations of the coupling ray theory are briefly discussed and a numerical example is presented.
Edited and anisotropy-corrected sonic logs from deepwater Gulf of Mexico (GOM) have been used in combination with mostly published core velocity measurements and Biot-Gassmann modeling to determine shale and oil sand trends in low-frequency Vs-Vp space. These trends equally apply to the shear (SI) and acoustic (AI) impedance crossplot. Then (in Part II), using simultaneous inversion of 3D seismic, we demonstrate how the petrophysically defined SIAI trends can be used to deterministically map net-to-gross away from well control.
Detailed mapping of Moho relief, crustal thickness, detailed basement structure, and a tectonic framework for the deepwater Gulf of Mexico has recently been completed. Input data for this work includes a 100 deepwater well velocity database, 95,000 line miles of newly acquired high-resolution gravity and bathymetry data, and 268,000 line miles of detailed aeromagnetics. The interpretation includes over three man-years of effort by senior project geophysicists. This poster presents a review of input data, interpretation flowchart, and a statistical analysis of deepwater discovery locations versus basement structure.
Detailed mapping of the deep structures in the U.S. Gulf of Mexico has been a challenge for as long as exploration has been undertaken, primarily due to a lack of detailed and high quality data. Industry’s need for accurate crustal thickness, composition, and basement structure has driven the acquisition of new detailed gravity, bathymetry and magnetic data sets.