Analysis and Integration of Advanced Logs and Core Data: Characterization of the Copper Ridge Dolomite in Morrow County, Ohio

Abstract

The Morrow Consolidated oilfield, a Knox Group oil play in Ohio, produces from the Copper Ridge Dolomite, also known as the Trempealeau Formation. This prolific formation underwent large-scale erosion during the Knox unconformity of the Ordovician period, leaving behind carbonate remnants with relatively high porosities. As part of a regional characterization study of anthropogenic CO2 storage potential in these depleted oil fields, Battelle has collaborated with an industry partner/local well operator to collect whole and rotary sidewall cores in addition to a suite of advanced wireline logs. Analysis and integration of core data and wireline data provide the opportunity to conduct a detailed characterization of reservoir injection/storage potential and caprock properties. Additionally, establishing correlations between core and logs is essential in calibrating wireline logs in complex carbonate systems, allowing for better geologic and petrophysical characterization of potential reservoirs.

Two sections of whole core were recovered from the Upper Copper Ridge and Copper Ridge “B” formations. Rotary sidewall cores were collected from the Gull River formation, a potential caprock, and the Copper Ridge dolomite (Upper, “B”, and Lower). Whole and rotary sidewall core analyses consisted of core photography, helical computed tomography (CT) scans, grain density, porosity, permeability, X-ray diffraction (XRD), scanning electron microscopy (SEM), and thin-section petrography. Results were used to constrain key potential reservoirs and to analyze caprocks in south-central Ohio.

Comparison of core and advanced wireline log data from the Copper Ridge Dolomite suggests wireline logs underestimate porosity in these carbonates remnants. Core photography shows abundant vugs, corroborating high porosity and permeability core data. Grain densities derived from elemental spectroscopy capture (ESC) log data and bulk density logs are in good agreement with measured sidewall core values. The correlation of core to log data provides a better understanding of calibration of logging tools in the Morrow Consolidated oilfield and assists with better geologic characterization of potential reservoirs.

AAPG Datapages/Search and Discovery Article #90258 © 2016 AAPG Eastern Section Meeting, Lexington, Kentucky, September 25-27, 2016