--> ABSTRACT: Pore Distribution in the Ordovician Shale of the Utica/Point Pleasant Sub-Basin, by Murphy, Michael; Daniels, Jeffrey ; Cole, David R.; Sheets, Julie; Welch, Sue; #90142 (2012)

Datapages, Inc.Print this page

Pore Distribution in the Ordovician Shale of the Utica/Point Pleasant Sub-Basin

Murphy, Michael *1; Daniels, Jeffrey 1; Cole, David R.1; Sheets, Julie 1; Welch, Sue 1
(1) Subsurface Energy Materials Characterization & Analysis Laboratory (SEMCAL) in the School of Earth Sciences, The Ohio State University, Columbus, OH.

Shale and mudstones are potential reservoir seals for geologic sequestration of carbon dioxide. When rich in organic matter, they are critical in the creation and distribution of hydrocarbons. The objective of this investigation is to characterize and image pore networks in shale. The techniques used in this study characterize porosity in small samples at the nanometer to micron scale. Linking pore types to depositional environments can help to scale up laboratory measurements. Pore types were classified by their size, shape, and connectivity, and then analyzed in relation to facies distributions in the Utica/Point Pleasant sub-basin. The sub-basin is an Ordovician feature in the Midcontinent United States flanked by carbonate platforms to the northwest and southwest, and the Taconic foreland basin to the east. Core samples from six wells were used to investigate porosity in the Utica Shale, the Point Pleasant Formation, and the Logana Member of the Lexington Limestone. Mercury intrusion porosimetry was used to estimate total pore volume, pore size distribution, connectivity, and capillary breakthrough pressure. Pulse and probe permeameters were used to measure permeability. A scanning electron microscope with Quantitative Evaluation of Minerals by Scanning Electron Microscope (QEMSCAN) software was employed to image pores and for quantitative analysis of mineralogy, texture, and porosity. Two samples were analyzed with a dual beam focused ion beam scanning electron microscope (FIB-SEM). The FIB-SEM analysis produced 3D representations of pore networks and organic matter distribution. Initial results indicate that pore size, shape, and connectivity vary with the distributions of clay and carbonate matrix and organic matter. These differences correspond to location within the sub-basin and to stratigraphic position. The matrix pores tend to be larger and more connected, but with narrow pore throats. Pores are smaller in organic matter and fossil fragments, but in some cases are locally highly connected. Pore distribution shows a high correlation to rock texture and fabric. Maps of pore networks will be compared with organic matter and other mineral distributions.

 

AAPG Search and Discovery Article #90142 © 2012 AAPG Annual Convention and Exhibition, April 22-25, 2012, Long Beach, California