CO2 Accounting and Risk Analysis for CO2 Sequestration at Enhanced Oil Recovery Sites.

Area of Science:

• Geosciences
• Environmental Engineering
• Petroleum Engineering

Background:

• Enhanced oil recovery (EOR) using carbon dioxide (CO2) is a viable strategy for emissions management.
• CO2-EOR can significantly lower sequestration costs, especially without robust carbon capture and storage (CCS) policies.
• Depleted reservoirs present opportunities for large-scale CO2 sequestration.

Purpose of the Study:

• To develop a multiscale statistical framework for CO2 accounting and risk analysis in a CO2-EOR setting.
• To assess the environmental and economic risks associated with CO2 sequestration in depleted oil reservoirs.
• To evaluate the profitability of CO2-EOR at the Farnsworth Unit (FWU), Texas.

Main Methods:

• Geostatistical-based Monte Carlo simulations were employed to model CO2 flow and transport.
• Global sensitivity and statistical analyses were performed on key risk metrics.
• A response-surface-based economic model was developed to determine CO2-EOR profitability.

Main Results:

• The study estimated median values and confidence intervals for risk metrics including CO2/water injection/production rates, cumulative net CO2 storage, and CO2 breakthrough time.
• At current oil prices, approximately 31% of simulated CO2-EOR scenarios for the FWU were found to be profitable.
• Profitability increases with government carbon-tax credits, higher oil prices, or reduced CO2 capture and operating costs.

Conclusions:

• The developed framework provides valuable insights into CO2 storage potential within EOR operations.
• Understanding the interplay of environmental and economic risks is crucial for commercial-scale CO2 sequestration.
• CO2-EOR profitability is sensitive to market conditions and policy incentives, highlighting the need for supportive regulatory frameworks.