AVA-anisotropy: spreadsheets program to model the variation of P-wave reflectivity with angle in VTI, HTI, and orthorhombic media

Spreadsheet-based programming has become a worldwide computational tool and a powerful platform for executing scientific calculations in different engineering disciplines. The inherent advantage of spreadsheets exists in integrated storage and the ability to manipulate matrices along with wide-ranging mathematical calculations, plotting, and diagrammatic presentation. This paper presents a user-friendly and interactive spreadsheet program “AVA-anisotropy” to characterize the primary P-wave amplitude versus incident angle (AVA) responses in vertically transverse isotropic (VTI), horizontally transverse isotropic (HTI), and orthorhombic media. The set of Rüger’s equations for isotropic, VTI, HTI, and orthorhombic media are solved to describe the seismic energy partitioning at an anisotropic interface. The spreadsheet program has three main sections: basic concepts, data input, and AVA modeling for anisotropic media. The interactive data input and on-screen mathematical and graphic presentation of the spreadsheet enables the students to have an in-depth examination of the effects of changing input data and the resulting model. This greatly helps them in understanding the energy partitioning in anisotropic medium.