This bill amends the Clean Air Act to exclude marginal oil and natural gas wells from various federal environmental regulations. Specifically, it exempts these wells and their operators from standards of performance and guidelines prescribed by the Environmental Protection Agency (EPA) under Section 111 of the Act. This includes requirements for monitoring, reporting, record-keeping, fugitive emission surveys, and leak detection and repair. A "marginal well" is defined as an oil well producing 15 barrels or less per day, or a natural gas well producing 90,000 cubic feet or less per day, averaged over the preceding year. The bill also prohibits the EPA from requiring state plans to include performance standards applicable to marginal wells. Furthermore, if a state revises its plan to make such standards inapplicable to marginal wells, the EPA must approve or disapprove the revision within 180 days, or it is deemed approved. Upon enactment, the EPA is mandated to revise its regulations and guidance within 180 days to implement these new exclusions. Crucially, any pending enforcement actions related to these specific standards or requirements against marginal wells must be terminated. This aims to reduce the regulatory burden on smaller, lower-producing domestic oil and gas operations.