# Estimating Biot-Willis coefficient

The Biot-Willis coefficient is a key component associated with the effective stress field, where it represents the proportion of fluid pressure that counteracts the confining stress. To properly estimate the Biot-Willis coefficient, we require knowledge of the more fundamental building blocks of a rock mass that go beyond the elastic domain. These include the petrophysical properties from which components of the rock mass such as its pore space, frame and solid phase can be assembled from its constituent parts. In this study, we estimate the Biot-Willis coefficient from seismic data. First, we derive a calibrated rock physics model to provide a set of relationships between our elastic and petrophysical properties.

Subsequently, we perform an AVO inversion followed by a rock physics inversion to determine the total porosity and mineral fractions. This was used to compute the Biot-Willis coefficient to better understand how pressurized fluids interact with the rock mass to determine the effective stress.