ROCK-PHYSICS MODELING: ESTIMATING THE EFFECTIVE BULK AND SHEAR MODULI OF LODGEPOLE FORMATION, WILLISTON BASIN

The seismic technique extensively uses rock physics modeling as an integral component of its research into reservoir features. The most accurate rock physics modeling must consider the research field and the effective medium's theory. The modeling of rock physics in real-world situations calls for using mineralogical composition data derived from XRD data and mineral elastic modulus values, which are often collected from the literature. The Williston Basin is an oval-shaped depression that stretches approximately 475 miles (764 km) north-south and 300 miles (480 km) east-west. It is named after the Williston River, which flows through the Basin. The Sauk, Tippecanoe, Kaskaskia, Absaroka, Zuni, and Tejas sequences are the six primary stratigraphic sequences that make up the Basin. Large unconformities separate each sequence within the 4,876.8 meters of Phanerozoic rocks. Unconventional reservoir rocks have a reputation for having multi-mineral compositions and intricate microstructures. Some examples of these rocks include tight sandstones and shales. The resulting strong heterogeneities and complicated mechanical properties create challenges in evaluating the effective moduli. In addition, XRD data is not continuous in every depth, and the elastic modulus information for minerals varies depending on the research region, so taking data from the literature can lead to mistakes. This study aims to estimate rock physics parameters such as elastic modulus of minerals and rock pore shape using Voigt-Reuss-Hill (VRH), Kuster-Toksoz (KT), Discrete Element Method (DEM), and Gassmann method in the Lodgepole formation, Williston Basin. This research used different scenarios considering the penny cracks and sphere inclusion. The findings of this research indicate that the intra-particle model fits the data well. Furthermore, the DEM model with a single inclusion provides the most accurate predictions of the rock physics parameters.