Abstract
Combined (ultra-) small angle neutron scattering measurements [(U)SANS] and a contrast matching technique were employed to quantify the porosity and pore size distribution from 1 nm to 10 μm and to differentiate accessible (open) pores and inaccessible (closed) pores with respect to organophilic and hydrophilic fluids for two Utica and two Bakken shale samples. The results indicate that around 40–70% of the pores in the Utica oil shales (mixed carbonate mudstone) are accessible to oil, and 34–37% of the pore surfaces are water-wet. In contrast, the Bakken oil shales (mixed siliceous mudstone and carbonate/siliceous mudstone), which have high total organic carbon contents, have a higher proportion of isolated pore space that is not preferentially wet by oil or water, with less than 36% of the pores accessible to both fluids. In addition, for both formations, pores less than 3 nm in diameter are not oil accessible (organic matter related) but water accessible (clay tactoids related).
| Original language | English |
|---|---|
| Article number | e2020GL087896 |
| Journal | Geophysical Research Letters |
| Volume | 47 |
| Issue number | 14 |
| DOIs | |
| State | Published - Jul 28 2020 |
Funding
We acknowledge the funding support from AAPG Foundation's Grants‐in‐Aid Program, National Science Foundation Graduate Research Fellowship, and the Nuclear Energy University Program coordinated by the Office of Nuclear Energy at U.S. Department of Energy (award number DE‐NE0008797). Work by L.M.A. was supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, Chemical Sciences, Geosciences, and Biosciences Division. The authors greatly thank Aaron Evelsizor of the Ohio Geological Survey for Utica, and the late Julie LeFever of the Wilson M. Laird Core and Sample Library and the North Dakota Geological Survey for the Bakken, samples used in this work. Access to SANS NG7‐30 and USANS BT5 instruments was provided by the Center for High Resolution Neutron Scattering, a partnership between the National Institute of Standards and Technology (NIST) and the National Science Foundation under agreement No. DMR‐1508249. A portion of this research used resources at the Spallation Neutron Source, a DOE Office of Science User Facility operated by the Oak Ridge National Laboratory (ORNL). Any opinions, findings, and conclusions or recommendations expressed in this study do not necessarily reflect the views of DOE or NIST. We also thank Tomasz Blach, Katherine Gioseffi, and Jeff Krzywon for their help during the (U)SANS experiments at NIST.
| Funders | Funder number |
|---|---|
| Nuclear Energy | |
| National Science Foundation | |
| U.S. Department of Energy | DE‐NE0008797 |
| Office of Science | |
| Basic Energy Sciences | |
| American Association of Petroleum Geologists | |
| Chemical Sciences, Geosciences, and Biosciences Division | DMR‐1508249 |