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Paraffin base-oils	Hydrocarbon liquid with an API gravity greater than 30° API, called light crude oil.

Peak oil	The point in time when the maximum rate of global petroleum production is reached, after which the rate of production enters its terminal decline (see depletion). Peak oil mainly depends on two issues: - Proved reserves of crude oil - Current technology to unlock reserves

Penetration rate	The average or instantaneous distance drilled per unit of time.

Perforating	Perforating a well describes the process of blowing holes via a perforating gun through the production casing into the oil and gas bearing zone. See also hydraulic fracturing.

Perforating gun	A device used to perforate oil and gas wells in preparation for (oil/gas) production. Containing several shaped explosive charges, perforating guns are available in a range of sizes and configurations (see also perforating)

Permeability	Permeability describes the rock property which indicates the presence of flow channels in the rock. The higher the permeability the more flow channels and the greater the potential for recovery of hydrocarbons from the rock. Permeability needs to be differentiated from porosity.

Pipeline	A tube or system of tubes used for transporting crude oil and natural gas from the field or gathering system to the refinery.

Pitting corrosion	A type of corrosion in which there is loss of metal in localized areas. The corrosion rate in the pits is many times greater than the corrosion rate on the entire surface. The resultant pits can be large and shallow or narrow and deep. Pitting is a more dangerous problem than general corrosion because the pitted areas can be easily penetrated.

Pore pressure	The pressure of fluids within a porous formation (see porosity). MWD services are used in certain areas to estimate the formation pore pressure.

Pore space	The open space, or voids, between the individual grains of a rock mass, available for fluid accumulation (see porosity).

Porosity	Effective porosity describes the percentage of the total volume of reservoir rock which is void space connected by flow channels. This effective porosity together with a given permeability permits flow of hydrocarbons through flow channels.

Producing well	A well producing fluids (gas, oil or water)

Production casing	A casing string that is set across the reservoir interval and within which the primary completion components are installed.

Production tubing	A wellbore tubular used to produce reservoir fluids (see oil production). Production tubing is assembled with other completion components to make up the production string.

Proppant	Sized particles mixed with fracturing fluid to hold fractures open after a hydraulic fracturing treatment. In addition to naturally occurring sand grains, man-made or specially engineered proppants, such as resin-coated sand or high-strength ceramic materials like sintered bauxite, may also be used. Proppant materials are carefully sorted for size and sphericity to provide an efficient conduit for production of fluid from the reservoir to the wellbore.