Abstract

The development of the Bakken petroleum system in North Dakota provides an interesting insight into the interplay of innovations in geologic thought and advances in drilling and completion technologies. The earliest oil production from the Bakken petroleum system was from vertical wells drilled into fractured portions of the Bakken and Three Forks formations along the crest of the Antelope Anticline. This production compared to other later vertical wells drilled on smaller structures illustrates an important relationship between structure, reservoir fracturing and production.

Production statistics from the earliest phase of horizontal drilling show that this technology compensates for the lack of structurally induced fracturing when wells targeted the oil-saturated, upper Bakken shale. Additional improvements in production occurred after drilling tested the idea that tight, mechanically competent units adjacent to the source beds are charged with oil expelled from the source beds. Significant production over much of the Williston Basin shows production from these oil-charged units is largely independent of structurally controlled natural fracturing. However, the mechanical properties of the units next to the Bakken source beds allow for drilling long laterals, which when stimulated by large scale hydraulic fracture treatments, result in significant oil production.