Monterey Shale

The Miocene Monterey Formation is an organic-rich, siliceous and structurally complex unit present in several California petroleum basins. Much of its historical production is associated with naturally fractured reservoirs rather than the uniform horizontal shale model used in many interior basins. Folding, faulting and varied lithology make formation-wide resource figures difficult to translate into recoverable production.

California production totals span multiple basins and reservoirs and cannot be assigned to the Monterey alone. EIA does not publish a current Monterey-specific production series in STEO. This page avoids repeating broad resource estimates as output and instead preserves the formation, location and operator context needed to interpret California well records.