Graphical analysis of laminated sand-shale formations in the presence of anisotropic shales

Laminated sand-shale models with anisotropic shales have been discussed extensively. The interpretation methods are written in elaborate mathematical equations. However, there has not been a clear procedure to determine key parameters such as shale anisotropy, to guide the choice of solution, and, more importantly, to recognize the circumstances in which a solution is robust or sensitive to errors. A graphical crossplot gives better insights into petrophysics than a set of equations, while interactivity allows instant visualization of the solutions, thereby helping the petrophysicist in the most effective way. Objectives of graphical analysis are: To determine the shale anisotropy parameters and whether it is necessary to create multiple zones To define the region boundaries where each analytical solution is applicable To illustrate the effect of data outliers on the results To quickly perform sensitivity tests.