--> --> Pore Characterization of Bakken Shales (Mississippian-Devonian) in the Williston Basin

AAPG Foundation 2019 Grants-in-Aid Projects

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Pore Characterization of Bakken Shales (Mississippian-Devonian) in the Williston Basin

Abstract

Oil and gas production from the unconventional resources has increased over the last decade. Despite the significant production from the middle siliciclastic/carbonate member of the Bakken Formation in the Williston Basin, little has been produced from the upper and lower shales. Understanding the pore geometry and structures as it relates to porosity in organic material is essential. Thus it is important to develop an approach to characterize the pores within the shale to better understand how oil is expelled from these shales. We propose to test the idea that Nuclear Magnetic resonance (NMR) transverse relaxation time (T2) reflect the development of porosity in organic material in shales. Five wells from North Dakota and one well each from Montana, Saskatchewan and Manitoba will be utilized for this study. Preliminary result of the NMR on samples from North Dakota shows that the pores within Bakken Shales are predominantly micropores with thermally matured samples having the least percentage. The objective of this study is to use NMR T2 to determine how the porosity of NMR is evident in organic pores and link its porosity to porosity seen in the field emission scanning electron microscope (FE-SEM) on ion milled samples to understand the nanometer and micrometer scale pore properties and pore geometry. I expect that with maturation, pores within the kerogen marcerals will change in size, frequency and shape. NMR and FE-SEM pores will provide an understanding of the pore properties and geometry which is important in evaluating and developing of Bakken Shales, thus maximize production.