Petroleum Engineering Notes: Reserves Definitions

proved developed – can be recovered through existing capital. Reserves requiring additional input (ie. secondary recovery) included only after testing has been done.

proved undeveloped (PUD) – input required for recovery. Land has not yet been drilled, or major expenditure required before recovery can begin. If not yet drilled, must be near other wells with proven production.

proved developed producing (PDP) – reserves can be recovered by using present operating methods

proved developed non-producing (PDNP) – reserves that have been completed and tested but are not yet producing due to lack of market, minor completion problems, or wells that require further stimulation based on offsetting wells

proved developed behind-pipe – reserves that are behind the pipe in existing wells that are considered proved by testing or production in offsetting wells