A Model To Estimate Carbon Dioxide Injectivity and Storage Capacity for Geological Sequestration in Shale Gas Wells

Area of Science:

• Geosciences
• Environmental Engineering
• Petroleum Engineering

Background:

• Shale gas formations are being explored for large-scale carbon dioxide (CO2) sequestration.
• Concerns exist regarding the dynamic response and practical injection limits of CO2 into these wells.

Purpose of the Study:

• To investigate the dynamics of CO2 injection into shale gas formations.
• To assess the feasibility and capacity of CO2 sequestration in depleted shale gas wells.

Main Methods:

• A two-component (CO2 and CH4) gas flow model was developed, incorporating adsorption effects.
• History-matching of gas production data was used for formation parameter estimation.
• The model was applied to analyze CO2 injection in three major shale gas-producing regions.

Main Results:

• CO2 injection rates into individual wells are limited to low levels.
• Individual well storage capacity is relatively small, with significant variations between shale plays.
• Estimated average capacities: Marcellus Shale well (0.5 million metric tonnes CO2), Barnett Shale well (0.15 million metric tonnes CO2).

Conclusions:

• CO2 sequestration in shale gas wells is possible but constrained by injection rates and well capacity.
• Total estimated capacity for Marcellus Shale (PA) is 7200-9600 Mt, and for Barnett Shale is 2100-3100 Mt (as of March 2015).
• Results highlight the importance of formation-specific parameters in determining sequestration potential.