1P

Proven reserves are those reserves claimed to have a reasonable certainty (normally at least 90% confidence) of being recoverable under existing economic and political conditions, with existing technology. Industry specialists refer to this as P90 (i.e., having a 90% certainty of being produced). Proven reserves are also known in the industry as 1P. Proven reserves are further subdivided into "proven developed" (PD) and "proven undeveloped" (PUD).[9][10] PD reserves are reserves that can be produced with existing wells and perforations, or from additional reservoirs where minimal additional investment (operating expense) is required.[10] PUD reserves require additional capital investment (e.g., drilling new wells) to bring the oil to the surface.