This paper is based on the work performed during the design, implementation and operation of Cascade and Chinook fields and it provides an overview of the Cascade and Chinook fields' reservoirs, part of the emerging Ultra-Deepwater Wilcox Trend in the Gulf of Mexico. A general picture of the structure, stratigraphy, depositional facies, and petrophysics of each field will be given. Reservoir engineering parameters will also be discussed as well as the initial field development. The main result of this work is a consistent integration of all available data, following a recommended workflow process, aiming to build a geologically coherent and realistic reservoir models for these fields. The match of real field production information with the dynamic flow models allows the reduction of uncertainties of the scenarios and better support for the production forecast. From the integration of seismic, logs, fluids, cores and production data has emerged structural models similar for both fields: a faulted salt-cored anticline divided roughly into western upthrown and eastern downthrown blocks, populated with amalgamated-to-stacked turbidite sands. The petrophysical model developed considers the geologic background and supports the dynamic flow model. The main technical contribution of the work presented in this paper is an overview of the reservoirs that have pioneering production from the Lower Tertiary (Wilcox) Ultra-Deepwater trend (Walker Ridge area). These fields are the first analogues for a mostly untested trend which is still projected to have significant production potential. Currently, numerous oil & gas companies have several Wilcox fields, prospects, and plays in varying stages of development in the area. The information provided and the modeling approach used in this paper can be applied as guidelines for similar Lower Tertiary reservoirs developments in the deepwater Gulf of Mexico.