This document describes in detail the organic petrology and maturation of the Bakken Formation located in the Williston Basin. This report is organized into five sections. Section I will introduce the Bakken Formation in reference with the Williston Basin. It will also address sedimentary and structural aspects of the Bakken Formation. Section II outlines the processes that formed the Bakken Formation that occurred during the Devonian/Mississippian age. Section III will summarize organic components and influence within the Bakken Formation. Furthermore Section IV will address the nature of inorganic constinuents that influence the Bakken Formation. Section V will discuss production history and current production of oil and gas found within the Bakken Formation. This report concludes in Section VI with a complete analysis of the Bakken Formation summarizing the four main sections of this paper.
I. The Bakken Formation, an Introduction
The Bakken Formation is a clastic unit measuring to be around 45 meters thick that stretches across the Williston Basin that was deposited during the Late Devonian to the Early Mississippian. The Bakken Formation consists of three primary members that onlap (in some places lower member is absent due to non-deposition or over step of the middle member); the upper, middle, and lower members. Both the upper and lower members within the Bakken Formation are black shales (Jiang, 2001). The black shales in the upper and lower members formed offshore in anoxic condtinos. The shales in the upper and lower members of the Bakken Formation are composed of hard silicous and pyritic components (Webster, 1984). These members are also fissile and non calcareous and contain numerous amounts of conodonts and other organic constituents, such as tasmanites. These shales represent high resistivity that reads around 100 ohms-meters in the lower shale specifically, and high gamma ray measurements in both shales around 200 API units (Webster, 1984). The black shale in the Bakken Formation contains the hydrocarbons that migrate and are stored in the sandstone that is the middle member.
The middle member of the Bakken Formation is a calcareous sandstone that formed offshore in a regressional environment that formed with a rapid lowering of sea level.
One of the primary structures in the Bakken Formation is the Nesson Anticline which lies in the northwestern part of North Dakota (Schieber, 2001). The Nesson Anticline in North Dakota trends North for 176 km.
The Williston Basin as a whole is a sedimentary basin that is located west on the North American craton that dates Paleozoic in age, making the Bakken Formation an intracratonic formation. The Williston Basin is located in North Dakota, South Dakota, Montana, Saskatchewan, and Manitoba. However, the Bakken Formation is not the only formation within the Williston Basin, however it will be the only formation discussed in this paper.
II. Formation of the Bakken