Depleted gas fields have a high potential for CAES service, although air has never been stored in a depleted gas reservoir.
Research conducted by team members at Hydrodynamics found that CAES in a depleted gas field has the following advantages:
- the structure can contain air
- the pressure history of the field is typically available, and
- the gas or airflow potential of individual wells are known.
A key issue for air storage in a depleted gas field is the mixing of air with residual natural gas in the storage reservoir. The potential for spontaneous combustion in the depleted gas/air storage reservoir, the combustibility of the air/natural gas mix in the turbine, and detrimental chemical reactions, such as oxygen depletion in the stored air must be resolved before a CAES facility can be commercially developed.
Hydrodynamics’ research on two depleted gas field in Montana, an abandoned gas storage field in Nebraska, and three depleted gas fields in California demonstrate that CAES is technically feasible. Our feasibility studies first involved the 3-D numerical simulation modeling of natural gas production from the field to provide reservoir properties and establish a starting point to simulate CAES development. The resulting models were then used to simulate the development of an air bubble in the depleted gas field. Our models simulated the displacement of natural gas to the parameter of the field. The chemical reactions between stored air and the natural gas, the connate water, and the reservoir rock was then modeled.
We know how to develop a depleted gas field for CAES that includes well field configuration design, air injection rates and schedules, and air injection and withdrawal well operating constraints.