This chapter provides an in-depth analysis of the Bakken Petroleum System (BPS) in the Williston Basin, focusing on Improved Oil Recovery (IOR) techniques. It explores the significant advancements in drilling, completion designs, and artificial lift methods that have markedly boosted oil recovery in this prime unconventional resource basin. The chapter traces the history of oil production in the Williston Basin, highlighting the transformative impact of horizontal drilling and multistage fracturing. It delves into advanced drilling operations, emphasizing the role of high-performance motors, geosteering, and real-time downhole data in enhancing drilling efficiency. Additionally, the chapter examines the evolution of well-completion strategies, from traditional to innovative horizontal completions, and assesses their effectiveness through data analytics, numerical modeling, and field studies. The vital role of artificial lift systems in combating rapid production decline in shale formations is analyzed, comparing the efficacy of ESPs, Sucker Rod Pumps, and Gas Lifts. The interconnectivity between operational aspects is discussed, providing a unified view of how integrated strategies and technological advancements drive optimized oil recovery in the Bakken formation. This study aims to offer insights and strategic guidance for industry stakeholders, particularly concerning IOR in unconventional oil resources.