Karen Frantz
GHG Monitor
1/31/2014
The Environmental Protection Agency released a finalized rule and a guidance document this month that raised questions among some enhanced oil recovery industry officials over various regulatory issues surrounding the injection of CO2 into the ground—including whether the EPA recognizes that incidental geologic storage of CO2 can occur during EOR operations—prompting the agency to respond to industry questions late last week. The EPA’s guidance document is designed to provide direction to injection well owners or operators and Underground Injection Control Program Directors regarding when Class II wells—in which CO2 is injected for the purpose of EOR—must be re-permitted as Class VI wells—in which CO2 is injected for the purpose of geologic sequestration. The guidance document was released at the same time as the EPA finalized a rule that conditionally excludes CO2 injected into Class VI wells from the definition of hazardous waste under the Resource Conservation and Recovery Act, although the EPA said the guidance and the regulation are not meant to complement each other and they are for two different programs.
Steve Melzer, owner of Melzer Consulting, which has done much of the pioneering research on EOR in west Texas, told GHG Monitor that the EPA needed to clarify issues surrounding transition so that it doesn’t preclude ongoing projects from getting “incidental storage,” in which some CO2 that is injected into already developed oil fields in order to extract additional oil is left in the ground during the process. However, another industry executive said the EPA had been clear that incidental storage can occur in Class II wells.
An EPA spokesperson sought to clarify the confusion in comments e-mailed to GHG Monitor this week. “The Underground Injection Control Program regulates the injection of fluids to ensure protection of underground sources of drinking water,” the spokesperson said. “While the UIC Program acknowledges, from a technical perspective, that some CO2 is left behind/not recovered (i.e., ‘incidentally stored’) in enhanced recovery operations, the focus of the program is ensuring that the appropriate requirements apply to wells injecting fluids. As such, whether ‘incidental storage’ is occurring does not factor into the appropriate permitting of wells to address risks to underground sources of drinking water.”
Is Guidance Relevant for Existing Operations?
The EPA also addressed other industry concerns, including that of an official who said that the guidance document was confusing because it was unlikely a Class II operation would ever convert into a Class VI operation and that the conditions and hypothetical risks the document lays out that could spur conversion aren’t relevant for existing CO2-EOR operations. Melzer and the official also said there are complications associated with the process of converting from a Class II well to a Class VI well that would be onerous for well operators.
The EPA spokesperson, while not directly responding to the complaints that transitioning from a Class II permit to a Class VI permit could be problematic, said the guidance document was needed because when finalizing the Underground Injection Control Program Class VI regulations in 2010, it found that there may be some Class II owners or operators conducting enhanced oil recovery that would at some point transition to CO2 injection without EOR or would modify their injection operation in such a way that posed increased risks to underground sources of drinking water beyond those addressed by the Class II requirements. “With this understanding, EPA committed to providing clarity as to when and how transitioning from Class II to Class VI might occur,” the spokesperson said.
The spokesperson went on to state, “Owners or operators of Class II CO2 ER injection operations may be interested in geologic sequestration of carbon dioxide. While the Class VI regulations address increased and unique risks posed by Class VI operations (when compared to Class II ER operations), they do not affect ‘business-as-usual’ Class II wells,” the spokesperson said, adding that the Class VI regulations may be applicable “where Class II owners or operators begin to modify their operation in a manner that changes the risk profile of the operation such that it may adversely impact underground sources of drinking water.” The spokesperson said various factors that come into play in considering whether a well may be re-permitted from Class II to Class VI include in part:
- Increase in reservoir pressure within the injection zone(s);
- Increase in CO2 injection rates;
- Decrease in reservoir production rates;
- Distance between the injection zone and underground drinking sources of water;
- Suitability of the Class II Area of Review (AoR) delineation;
- Quality of abandoned well plugs in the AoR;
- The owner or operator’s plan for recovery of the CO2 at the cessation of injection;
- The source and properties of injected carbon dioxide; and
- Any additional, site-specific factors as determined by the Director.
