AN IN-DEPTH LOOK AT THE POINT PLEASANT FORMATION IN SOUTHEASTERN OHIO USING PETROGRAPHIC ANALYSIS AND ANALYTICAL INSTRUMENTATION

The Point Pleasant Formation was deposited during the Katian, Late Ordovician Period. The formation is underlain by the Trenton Limestone and overlain by the Utica Shale. Increasing demand for shale gas and other unconventional resources has made the Point Pleasant Formation a major prospect in the Appalachian Basin. Wireline log analysis has revealed a significant spike in resistivity, as much as 1 million ohms in some wells. This spike also displays a significant separation between the deep and shallow resistivity; a phenomenon typically associated with increased permeability. However, initial core description and petrographic analysis of these mixed fine to very fine siliciclastic and carbonate sediments do not indicate the presence of fractures or secondary porosity that might influence permeability trends. We hypothesize that micro-porosity associated with organics preserved along bedding planes may preserve permeability in the Point Pleasant Formation. This study will use petrography and analytical instruments to determine if the resistivity anomaly is related to the formation of micro-porosity.

The research project focuses on two cores on loan from EMF Geoscience Inc. and ARTEX Energy Group LLC. The cores, from Noble and Muskingum Counties, Ohio, will be described and correlated with well log readings, with emphasis placed on the unique response found in the resistivity log that can be correlated both east-west and north-south across the study area of southeast Ohio. Initial analysis has identified a coarsening upward interval in the Gamma curve coinciding with the resistivity anomaly. Detailed analyses of the core will be done using thin-section description, grain size analysis, XRD, carbon isotope analysis, TOC, and FIB-SEM to better understand pore size/ distribution, mineralogy (clay, framework, etc.) and organic material characterization and distribution. The results of this project will help to improve our understanding of unconventional mudstone reservoirs in Southeastern Ohio and could be applied to targeting similar unconventional plays.