Computed Tomography Scan Image Analysis of Michigan Niagaran Reef Cores for Improved Reservoir Characterization

Abstract

Whole core is a valuable dataset that facilitates a better understanding of variations in geology, environmental setting, and reservoir properties. Many core analyses provide single, localized measurements that are not representative of highly heterogeneous reservoirs. In recent years, image analysis of computed tomography (CT) scans has emerged as a mechanism for reservoir characterization and allows for examination of reservoir properties in 3- dimensions (3D). However, CT data analyses are often constrained to qualitative assessments and limited by software catered specifically to medical applications. Battelle has developed an interactive tool for CT scan data that allows the interpreter to process, view, and analyze core data for reservoir characterization in both 2-dimensions (2D) and 3D. Battelle’s CT scan analysis tool also quantifies the volume of selected features, generates a curve of percent of the selected features with depth and displays digital well log data. Battelle was involved in the collection of two whole cores from reservoirs in the Northern Niagaran Pinnacle Reef Trend (NNPRT) that are currently undergoing carbon dioxide enhanced oil recovery (CO2-EOR). With the objective of enhancing CO2-EOR operations via improved geologic characterization and understanding of the reef systems, dual energy CT scan data was collected over both cores and processed in Battelle’s CT scan analysis tool. Density thresholds were identified to denote selected features such as secondary porosity, salt, anhydrite, and carbonate matrix. Volumes were rendered for the features of interest and statistics were calculated for each resulting feature volume. Results were then compared to wireline logs and other core-measured properties. The CT scan analysis tool successfully captured variability in the heterogeneous reservoirs which improved understanding of the reservoir properties. Understanding the variability in reservoir properties is critical when constructing geologic models and when analyzing the differences in CO2-EOR performance among reefs along the NNPRT, as it allows for optimization of CO2 storage and oil production. This study is part of the Midwestern Regional Carbon Sequestration Partnership Michigan Basin Large-Scale Injection Project under DOE/NETL Cooperative Agreement # DE-FC26-0NT42589 with co-funding by Core Energy, LLC, and several other partners.

AAPG Datapages/Search and Discovery Article #90335 © 2018 AAPG 47th Annual AAPG-SPE Eastern Section Joint Meeting, Pittsburgh, Pennsylvania, October 7-11, 2018