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Williston Basin Report

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Introduction to the Williston Basin
The Williston Basin is an intracratonic sedimentary basin that occupies the majority of North and South Dakota, as well as, parts of Wyoming and Montana. The basin also stretches in parts of Canada, but this report will be focused on the United States portion of the basin. This portion of the basin is generally flat with average elevations ranging from 1500 feet to 3000 feet. Precipitation in the basin area ranges from 15 inches to 20 inches per year. The temperature averages approximately 65-70 degrees during the summer months, and 10-20 degrees in the winter.
Deposition of sediments began in the basin during the Cambrian era, but subsidence and basin filling occurred the most during the Ordovician, …show more content…

This geologic data has shown that the basin contains sedimentary rocks of Late Cambrian to the Tertiary age, and is more than 15,000 feet thick. The depo-center of the Williston Basin started its development during the early Paleozoic era in the northwestern part of North Dakota. The sedimentary rock thickness decreases to less than 10,000 feet in eastern Montana and to less than 5000 feet along the basin margin (Peterson & MacCary, 2009). Carbonate deposition occurred throughout the area during the early to middle Paleozoic era and changed to clastic deposition in the late Paleozoic era. During the Paleozoic era, more than 8000 feet of marine sediments accumulated at the basin center, but the shape of the basin remained the same. The basin depo-center has however shifted slightly over time. The Williston Basin sedimentation in the lower and middle Paleozoic is dominated by carbonates and evaporates, whereas upper Paleozoic and younger rocks are largely siliciclastic with small admixtures of carbonate (Anderson & Gerhard, …show more content…

The formation is located in western North Dakota, southern Saskatchewan, northeastern Montana, and southwestern Manitoba, and has a depth of approximately 130 feet to 12,000 feet deep. The upper and lower Bakken shale layers contain large amounts of organic-rich black mudstone. During the Lower Bakken Member deposition, an increase in the rate of siliciclastic sedimentation (quartz and orthoclase feldspar) caused more organic material to be preserved in bottom sediments. During Upper Bakken Member deposition, an increase in biological productivity in the water column resulted in more organic carbon reaching the bottom where it was subsequently preserved (Bustin & Smith, 1995). The middle layer is made up of mostly mudstone and sandstone. This layer can be tapped by both conventional and continuous oil

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