(206e) CO2 Utilization for Enhanced Oil Recovery and Geologic Storage in Ohio

As public opinion and incentives shift toward a reduction of greenhouse gas emissions, coal fueled powerplants should seek to capture and sequester carbon dioxide (CO₂) emissions in order to better compete with natural gas and alternative energy sources on an emissions basis. There exists a need to reduce capture costs or generate a new revenue stream from the captured CO₂, since the costs of carbon dioxide capture without CO₂ utilization would currently render coal fueled generation non-competitive_. To that end, this project investigated the feasibility of capturing CO₂ from Ohio coal power plants and utilizing this CO₂ to recover additional oil from Ohio’s depleted oilfields, while concurrently sequestering CO₂ in the subsurface. Analysis of capture, transport, and storage cases indicated that it is technically feasible to capture CO₂ from a 550-megawatt coal electricity generating unit for 30 years and safely store it in nearby depleted Ohio oilfields. Economic analysis suggested that the revenues from the incremental oil recovery can prevent an increase in electricity costs to ratepayers, while providing a positive net present value to project developers from oil sales. These findings may enable the continued use of Ohio coal for electricity generation while competing on an emissions basis with natural gas or other alternative fuels.

This presentation will provide an overview of several technical issues that were addressed in the project, along with the corresponding key accomplishments:

• Characterization of oil fields with limited data – a methodology has been developed that enables the rapid estimation of geologic properties based on characteristics of geologically similar regions for performing assessments of CO₂-enhanced oil recovery (EOR) and geologic storage feasibility;
• Identification of fractures from well-log data with machine learning – a machine learning based approach has been developed for predicting fractures from common well log signatures when advanced logs and/or core samples are not available;
• Prediction of permeability with greater accuracy – new porosity-permeability transforms have been developed with larger data sets for both the Clinton sandstone and Copper Ridge dolomite oil-bearing formations to enable improved prediction of permeability;
• Prediction of CO₂-oil minimum miscibility pressure with greater accuracy – a new statistical correlation for predicting the optimal operating pressure for CO₂ floods, as a function of reservoir temperature and oil gravity, has been developed as an alternative to laboratory experiments;
• Understanding of core floods under CO₂ injection – first-of-a-kind laboratory experiments with core samples from the Clinton sandstone and Copper Ridge dolomite provide process understanding of CO₂-oil interaction in-situ without the interference from field-scale heterogeneities;
• Factors affecting fractured reservoir CCUS performance – detailed numerical simulations have been carried out to quantify the impact of natural fractures on CO₂ injection associated improved oil recovery and geologic storage volumes for the Clinton sandstone formation;
• Detailed mapping of CO₂ sources and sinks in Ohio – a detailed mapping of power plants (sources) and proximal oilfields (sinks) has been carried out for the largest coal-fired power plants in Ohio that helps identify promising candidates for a CCUS project;
• Techno-economic analysis of CCUS projects in Ohio – a detailed techno-economic analysis has been carried out for a representative source-sink pair that (a) shows how CO₂ storage credits can be critical for CCUS economics, and (b) identifies several feasible scenarios for which CO₂ capture costs can be offset from CO₂-EOR revenues;
• Framework for calculating risks from wellbore integrity issues – a detailed approach has been developed and applied to several depleted oilfields in Ohio to quantify wellbore integrity driven risks of CO₂ leakage and their associated cost impacts; and
• CO₂ injection into two different formations – CO₂ was successfully injected into wells in the Clinton sandstone formation and Copper Ridge dolomite formations – demonstrating acceptable injectivity and providing useful lessons on operational and cost issues for site preparation and monitoring.