Abstract: The petroleum potential of the three forks formation (upper devonian) in North Dakota is poorly known due to limited stratigraphic, geochemical and petrophysical data. This study is an analysis of the stratigraphy, lithofacies distribution, petroleum potential and paleo-environments of the three forks formation using log and core data. About 5 major lithofacies are identified and the detailed lithology of the formation is computed by employing a probabilistic interpretation approach calibrated with lab results. These facies correlate well with electrofacies predicted by employing principal component analysis and clustering techniques to selected lithology-sensitive logs. Petrophysical examination of clay volume, porosity and fluid saturations plus hydrocarbon source rock analysis including type, quantity and thermal maturity of kerogen on all 5 facies using Rock-Eval 6 pyrolysis and LECO TOC show that these units have poor to fair petroleum potential and contain immature type II and III kerogens. About 6 members of the Three forks are identified and a proposed depositional model for the formation is constructed based on detailed core examination and petrographic evidences. Sufficient evidence is provided to show that the three forks formation is of peritidal to sabkha-like origin.