Transforming Subsurface Insights: A Rock Physics Atlas for Enhanced Seismic and Geomechanical Analysis

ABSTRACT: Wireline log data is essential for subsurface characterization, but incomplete data, such as missing shear sonic logs, can limit our understanding of rock properties. In this study, we developed a rock physics model to predict shear sonic logs in wells with missing data. The predicted logs were then used to estimate geomechanical properties, which showed excellent agreement with measured values. To further explore the implications of our results, we conducted fluid and lithology substitution modeling using the predicted elastic logs. This allowed us to investigate how different fluid types and saturations affect seismic responses. Additionally, we constructed a rock physics template to integrate all relevant information for subsurface analysis, making it accessible to geologists, geophysicists, and geomechanical engineers. The predicted elastic logs can be applied to various subsurface characterization studies, including seismic reservoir characterization, 4D analysis, stress estimation, and wellbore stability assessment. Our research demonstrates the value of rock physics modeling in addressing data gaps and providing valuable insights into subsurface properties. 1. INTRODUCTION Rock physics has historically been crucial in linking geological characteristics with elastic and seismic parameters, enabling the precise interpretation of well logs and seismic data. This pilot study in the Sarawak Basin, Malaysia, advances the field by integrating rock physics with geomechanical principles. By developing and applying rock physics techniques, we significantly enhance subsurface modelling and prediction. We created a pilot rock physics atlas over the study area, incorporating geological, geophysical, well log, and reservoir engineering data. This atlas offers geoscientists detailed, accessible analyses, dramatically improving exploration and production efforts. One of the most discussing challenges in geophysics is tracking the most accurate relationship between elastic properties and pore structure of porous rocks. It is important to find the relations between fluids, pore space and rock, and how they modify the rock properties. The elastic bounds give the narrows of such a system without considering the interconnectivity details, pore shape, and size. Several analytical methods have been suggested to describe the dry rock/porous saturated elastic bounds. These methods depend on stress-strain investigation or are accurately based on the microstructural information. Recently, several elastic bounds such as Voigt-Reuss Bounds, Voigt-Reuss-Hill (VRH) approximation, and Hashin-Shtrikman (HS) Bounds etc.