Pack ice is large block of ice on the surface of the ocean, usually in polar regions. They form when an ice field is broken up by strong waves and wind.

The period extending from 2 million to 10,000 B.P. Literally the Old Stone Age, the period when humans relied on a stone technology to sustain a scavenging/hunting/gathering adaptation (see).

A huge “supercontinent” that encompassed most of the Earth’s crust, 300 to 200 million years ago.

A prooto-ocean that covered two-thirds of the world except for the continent of Pangaea, 300 to 200 millions years ago.

White or colorless pertroleum-derived solid wax. It is often used in making candles and cosmetics.

An antagonistic relationship in which one organism obtains its nutrition from another organism to the harm of the host.

Particulate Matter (PM)
Particles formed by incomplete combustion of fuel. Compression ignition (diesel) engines generate significantly higher PM emissions than spark ignited engines. The particles are composed of elemental carbon, heavy hydrocarbons (SOF), and hydrated sulfuric acid (“sulfate particulates”).

When the costs of drilling, producing and operating have been recouped (to make good a loss) from the sale of products on a well.

Customary abbreviations for polychlorinated dibenzo-p-dioxins and dibenzofurans referring to the dioxins and furans (see).

Peak use period
The period of time when gas use on a particular system is at its maximum. This is the period when gas supply is most likely to be suspended for interruptible service (see) customers. Distributors also employ techniques such as peak shaving (see) to soften the impacts of high demand on the pipelines.

Using sources of energy, such as natural gas from storage, to supplement the normal amounts delivered to customers during peak-use periods. Using these supplemental sources prevents pipelines from having to expand their delivery facilities just to accommodate short periods of extremely high demand (see Peak Use Periods).

Using sources of energy, such as natural gas from storage, to supplement the normal amounts delivered to customers during peak-use periods. Using these supplemental sources prevents pipelines from having to expand their delivery facilities just to accommodate short periods of extremely high demand (see Peak Use Periods).

The study of soils as naturally occurring phenomena taking into account their composition, distribution, and method of formation.

Referring to the open sea at all depths (pelagic animals live in the open sea and are not limited to the ocean bottom).

The downward or lateral movement of water through soil. Percolation is measured in terms of permeability by distance per time.

Frozen soil found in the Arctic and subarctic regions whose age may go back thousands of years.

The ability of an aquifer or water-bearing formation to allow water to pass through it. Permeability is also known as effective porosity because it is a function of interconnected saturated pore spaces.

Peroxyacyl-nitrates (PAN)
Component of photochemical smog, injurious to plants at a concentration of more than 0.05 parts per million (p.p.m.).Represented as R(CO)OO(NO2) where R denotes a hydrocarbon ring or chain.

A chemical (natural or manufactured) used to kill unwanted organisms. Pests can include insects, weeds, fungi, rodents, and other types of organisms. Three of the most common types of pesticides used in production agriculture are herbicides, fungicides, and insecticides.

Petrochemical industry / petrochemistry
Petrochemical industry deals with industrial, chemical, or physiochemical conversions of petroleum as the basic raw material (see). Chemicals derived from petroleum or natural gas – petrochemicals – are an essential part of the chemical industry today. Petrochemistry is a fairly young industry; it only started to grow in the 1940s, more than 80 years after the drilling of the first commercial oil well in 1859. During World War II, the demand for synthetic materials to replace costly and sometimes less efficient products caused the development of petrochemical industry to the levels reached in today’s economy and society.

Field of geologic study dealing with the classification and description of rocks.

Petroleum pipeline
A line of pipe with pumping machinery and other devices (valves, compressors, metering stations, etc.), for conveying a liquid or gas. (see PIPELINE)

A toxic white acidic compound found in the tars of wood and coal, or derived from petroleum, and used primarily as a disinfectant or antiseptic.

The study of the temporal aspects of recurrent natural phenomena. Equivalently, manifestations of a biological phenomenon (particularly of an organism) as a function of time. Example, the phenology of pollimation.

A hormone-like substance that is secreted into the environment. Pheromones secreted by some animals cause specific reactions in other animals. Some animals like moths, use pheronomes to attract mates.


This term is generally used to describe a chemical reaction caused by absorption of ultraviolet, visible, or infrared radiation. See Photochemistry.

Photochemical oxidants
Photochemically produced oxidizing agents capable of causing damage to plants and animals.

Photochemical smog
Natural and artificially emitted hydrocarbons in the presence of oxides of nitrogen undergo photochemical reactions which produce a cloud of toxic chemicals including ozone and a variety of caustic agents. This process is powered by sunlight and some of the products, such as ozone, reach a peak soon after photon flux from the sun reaches a maximum around midday. The thermal inversions often associated with some cities can lead to a dangerous buildup of smog in urban areas. Human deaths have been attributed to photochemical smog since the Industrial Revolution in cities such as London and New York.

Photons are massless particles of light. In physics they are treated equivalently as either discrete particles or as waves. A common picture is to think of them as packets of electromagnetic waves travelling in space.

A physiological response to day light and dark in a 24-hour period length, such as flowering in plants.

Term referring to any animal or plant organism growing in zones of marine environment highly exposed to natural light.

Term referring to any animal or plant organism growing in dark zones of natural environment.

The photochemical and biochemical processes whereby plants and algae transform radiant energy (sunlight) into chemical energy (organic compounds). Photosynthesis involves the consumption of inorganic compounds such as water, carbon dioxide, nitrate and phosphate and the release of oxygen. On land, photosynthesis is dependent upon favourable temperature and moisture conditions as well as the atmospheric carbon dioxide concentration.

Phototropism is the bending of a plant in response to sunlight. This reaction is caused by the growth hormone auxin that is contained in the stem.

Photovoltaic effect
Effect by which light energy is directly transformed into electrical energy in a semiconductor (see).

Physical properties
Any property of matter that can be observed by our senses without alterino the compositions of the matter.

Phytophagous or feeding on plants
(Gr. phyton, plant, + phagein, to eat). Organisms that feed on plants.

Small, usually microscopic, aquatic organims (e.g., bacteria, protists, plants) capable of photosynthesis. The more general term “plankton” is a general designation for various drifting microscopic aquatic organisms in the upper regions of aquatic ecosystems both photosynthetic and non-photosynthetic.

Piezometer well
A non-pumping well, generally of small diameter, that is used to measure the elevation of the water table.

A cylindrical device inserted into a pipeline to inspect the pipe or to sweep the line clean of water, rust or other foreign matter; pipeline inspection and cleaning devices are called pigs because early models squealed as they moved through the pipe. A “smart pig” is also equipped to find corrosion, cracks or weakness in the welding.

Pig trap
A pipeline quick connection for inserting or removing a pig.

Pile dike
A dike (see) constructed of posts or similar piling driven into the soil.

A system of connected lengths of pipe, usually buried in the earth or laid on the seafloor, that is used for transporting petroleum and natural gas.

Pipeline crossings
A point where two or more pipelines cross, but where there is no physical connection between the pipelines. Pipeline segments should not be broken at pipeline crossings.

Pipeline patrol
A general inspection of the pipeline right of way by foot, airplane, or land vehicle to observe surface conditions and activity along or on the right of way and noting changes in vegetation growth for indication of gas leakage.

Pipeline quality gas
A term used to indicate that natural gas has been processed sufficiently to meet the standards of a gathering/transmission/distribution pipeline system.

One of three major ecological groups into which marine organisms are divided, the other two being the nekton and the benthos. Plankton are small aquatic organisms (animals and plants: zooplankton and phytoplankton) that, generally having no locomotive organs, drift with the currents. The animals in this category include protozoans, small crustaceans, and the larval stages of larger organisms, while plant forms are mainly diatoms.

Plastic material
One of many high-polymeric substances, including both natural and synthetic products, but excluding the rubbers. At some stage in its manufacture, every plastic is capable of flowing, under heat and pressure if necessary, into the desired final shape. (2) Made of plastic; capable of flow under pressure or tensile stress.

Capacity of a body for being molded or undergoing a permanent change in shape.

Any of numerous synthetic materials that consist of giant molecules called polymers (see), with extremely long chains of repeating units derived from short molecules. Plastics can be formed into products by moulding or otherwise shaping. The two major divisions of plastics are the thermosetting resins and thermoplastic resins. Raw materials for plastics include coal and cellulose (see), but by far the chief source is petroleum. Because of their easy manipulation, economical manufacture, low specific gravity, and resistance to corrosion, plastics have replaced metal, wood, glass, and other materials in many applications. An immense array of plastic industrial and consumer goods is available.

Rigid parts of the Earth’s crust (see) and part of the Earth’s upper mantle that move and adjoin each other along zones of seismic activity.

An area in which hydrocarbon accumulations or prospects of a given type occur.

Point, pour point
Cloud point: the temperature at which a fuel, when cooled, begins to congeal and take on a cloudy appearance due to bonding of paraffins. Pour point: lowest temperature which oil will readily flow without disturbance when chilled.

Thermoplastic based mainly on styrene monomers used for packaging.

The placement of pollen onto the stigma of a carpel by wind or insects. Pollination is a prerequisite to fertilization.

A substance which emitted into the environment can alter its chemical, physical and biological characteristics with potential risk for human health and the environment itself.

Polluter Pays Principle (PPP)
The principle that countries should in some way recompense the rest of the world for the effects of pollution that they (or their citizens) generate or have generated. Its intent is to force polluters to internalize all the environmental costs of their activities so that these are fully reflected in the costs of the goods and services they provide.

Physical, chemical, or biological change in the characteristics of some component of the atmosphere, hydrosphere, lithosphere, or biosphere (see) that adversely influences the health, survival, or activities of humans or other living organisms.

Polychlorinated Biphenyls (PCBS)
PCBs form a group of compounds which were developed in the 1930s and were mainly used in the electricity supply industry and mining. Due to their accumulation in the food chain, production of PCBs was halted world-wide at the beginning of the 1980s. PCBs are, however, still found in trace concentrations in the sea and in the fatty tissue of marine animals.

Polychlorinated Dibenzofurans
PCDFs, often associated with dioxins (PCDDs), are not industrially produced as such but found as impurities in some heavy chlorinated chemicals and as by-products of combustion (from wastes, coal, petroleum products, wood….). Emissions are regulated in Europe for the incineration processes (94/67/EC).

Polycyclic Aromatic Hydrocarbons (PAH)
Aromatic hydrocarbons with two or more (up to five or six) benzene rings joined in various, more or less clustered forms. PAHs are formed during the incomplete burning of coal, oil and gas, garbage, or other organic substances like tobacco or charbroiled meat. They are usually found as a mixture containing two or more of these compounds, such as soot.

A polymer of ethylene (see), especially any of various lightweight thermoplastics that are resistant to chemicals and moisture, have good insulating properties, and are used especially in packaging and insulation.

When certain individual molecules (monomers) come together and link up in a chain-like fashion, they form a polymer. The chemical reaction that forms a polymer is called polymerisation (see). There are natural polymers (often referred to as biopolymers), such as cellulose, certain rubbers and DNA, and synthetic polymers, such as polystyrene and fibreglass. See also plastics, resins and rubber.

A chemical reaction in which a large number of relatively simple molecules combine to form a large chainlike molecule. A hazardous polymerisation is a reaction which takes place at a rate which releases large amounts of energy.

Polypropylene (PP)
Thermoplastic compound composed of carbon and hydrogen atoms, obtained by the polymerization of propylene (C H3-CH=CH2).

Polyvinil-Chloride (PVC)
A plastic, often abbreviated as PVC. It is not as chemically stable as some other plastics, since it can emit hydrochloric acid (which in turn can damage library materials) as it deteriorates, and therefore has limited application in the preservation of books and paper. Some plastics called vinyl may be polyvinyl chloride.

A subgroup of a species coexisting in the same time and area. Population may also be used in a different sense to refer to the number of individuals in a defined group.

A measure of the amount of voids (pores) in a material. An important property of rocks that determines the quantities of fluids or gases they can store; for example, the amount of water an aquifer can store (see: permeability).

Portland cement
Hydraulic cement consisting of compounds of silica, lime, and alumina.

Possible reserves
Amounts of hydrocarbons that have a lower degree of certainty than probable reserves and are estimated with lower certainty, for which it is not possible to foresee production.

Post Operam
Both terms are used to describe an environmental situation in a given area, before and after a work realization upon a project.

Potential energy
Stored energy in a system which is a function of position or chemical bonds.

In physical geography, the name applied to cavities or holes which appear to have been drilled in the surrounding rocks by eddying currents of water bearing stones, gravel and other detrital matter. The size varies from a few inches to several feet in depth and diameter. The commonest occurrence is in regions where glaciers exist or have existed; a famous locality is the Gletscher Garten of Lucerne, where there are 32 giant’s kettles, the largest being 26 ft. wide and 30 ft. deep; they are also common in Germany, Norway and in the United States. It appears that water, produced by the thawing of the ice and snow, forms streams on the surface of the glacier, which, having gathered into their courses a certain amount of morainic debris, are finally cast down a crevasse as a swirling cascade or moulin.

The rate at which energy is transferred. Electrical energy is usually measured in watts. Also used for a measurement of capacity.

PPM (Parts Per Million)
A measure of concentration; one unit of weight or volume of one material dispersed in one million units of another; e.g., chlorine in water, carbon monoxide in air. Equivalents to indicate small size of this unit: 1 ppm = 1 oz. per 7500 gallons; 1 kernel of corn in 13 bushels; 1/4 sq. in in an acre.

The act of preying upon, a mode of life practised by certain animals in which food is primarily obtained by the killing and consuming of other animals.

Premium gasoline
Gasoline having an antiknock index (R+M/2) greater than 90. Includes both leaded premium gasoline as well as unleaded premium gasoline.

Pressure is a measurement of the force an object pushes against a given area. Air pressure is commonly measured in atmospheres or Newtons per meter squared [N/m2] which is also known as a Pascal [Pa].

Pressure buildup test
It refers to the measurement of bottomhole pressure data acquired after a producing well is shut in. Buildup tests are the best means to determine well flow capacity, permeability thickness, skin effect and other information.

Pressure fall-off test
The measurement of pressure data taken after an injection well is shut in. These data are often the easiest well-test data to obtain at transitory level. Wellhead pressure rises during injection, and if the well remains full of liquid after shut-in of an injector, the pressure can be measured at the surface, and bottomhole pressures can be calculated by adding the pressure from the hydrostatic column to the wellhead pressure.

All the measures taken and arrangements made in all the phases of production to avoid or reduce the risks of damaging the environment and the health of workers or the population at large.

Price-Cap Regulation (RPI-X)
A system in which rates are based directly on an index (such as the consumer price index) without any regard to the utility’s costs. Also a regulation that specifies the highest price that the firm is permitted to set.

Primary distillation
The process of distillation of crude oil from which the principal petroleum fractions are obtained. These fractions are subsequently sent to conversion and treatment units within refinery.

Probable reserves
Amounts of hydrocarbons that are probably, but not certainly, expected to be extracted. They are estimated based on known geological conditions, similar characteristics of rock deposits and the interpretation of geophysical data. Further uncertainty elements may concern: (i) the extension or other features of the field; (ii) economic viability of extraction based on the terms of the development project; (iii) existence and adequacy of transmission infrastructure and/or markets.

A document which defines the manner in which the actions laid down by the management system should be undertaken. It provides management and operational instructions and specifies the responsibilities for their performance.

The phase of the petroleum industry that deals with bringing the well fluids and gas to the surface and separating them and with storing, gauging and otherwise preparing the product for the pipeline. Also, the amount of oil or gas produced in a given period.

Production costs
Costs incurred to operate and maintain wells and related equipment and facilities, including depreciation and applicable operating costs of support equipment and facilities and other costs of operating and maintaining those wells and related equipment and facilities. They become part of the cost of oil and gas produced. The following are examples of production costs (sometimes called lifting costs): … Costs of labor to operate the wells and related equipment and facilities. … Repair and maintenance costs. … The costs of materials, supplies, and fuel consumed and services utilized in operating the wells and related equipment and facilities. … The costs of property taxes and insurance applicable to proved properties and wells and related equipment and facilities. … The costs of severance taxes. … Depreciation, depletion, and amortization (DD&A) of capitalized acquisition, exploration, and development costs are not production costs but also become part of the cost of oil and gas produced along with production (lifting) costs identified above.

Production platform
A fixed structure resting on the seabed or piled into it from which development wells are drilled, using directional drilling, to exploit an oil or gas field. To date, these platforms are of two kinds, although several novel designs are in existence. Gravity structures, either concrete or hybrid with concrete base and steel legs and superstructure, which rest on the seabed by virtue of their own weight, or steel, which are piled into the seabed.

Production sharing agreement
Contract in use in African, Middle Eastern, Far Eastern and Latin American countries, regulating relationships between State and oil companies with regards to the exploration and production of hydrocarbons. The mining concession is assigned to the national oil company jointly with the foreign oil company who has exclusive right to perform exploration, development and production activities and can enter agreements with other local or international entities. In this type of contract the national oil company assigns to the international contractor the task of performing exploration and production with the contractor’s equipment and financial resources. Exploration risks are borne by the contractor and production is divided into two portions: “cost oil” is used to recover costs borne by the contractor, “profit oil” is divided between contractor and national company according to variable schemes and represents the profit deriving from exploration and production. Further terms and conditions may vary from one country to the other.

Production sharing contract
A contract for the sharing of production revenues between the owner of an oil or gas property, either a government or private owner, and the company or companies developing the property. The terms of a PSC can include royalties payable to the owner, the companies’ cost-recovery entitlement, profit split, export duties, petroleum taxes, contract period and procurement terms.

Production test
A test of the well’s producing potential usually done during the initial completion phase (see).

Productivity index
The continuous productive capacity of a well. The Index is measured as volume produced (e.g. barrels per day) divided by the drop in pressure (p.s.i.) to achieve that flow rate starting with a “shut in” pressure.

Products pipelines
Lines that carry finished products from the refinery.

A paraffinic hydrocarbon that is a gas at ordinary atmospheric conditions but is easily liquefied under pressure. It is a constituent of liquefied petroleum gas.

The fuel or oxidizer that, when combined with its counterpart, burns to produce a rocket thrust that propels a spacecraft to a desired destination.

Basic petrochemical derived from the cracking of ethylene, propane and naphtha. Used in the manufacturing of plastics, foams and synthetic fibers.

A potential hydrocarbon trap (see) which has been confirmed by geophysical and geological studies to the degree that it can warrant the drilling of an exploration well.

Protected species
Designates a species which cannot be legally trapped or hunted, usually because it is rare or of special conservation value.

Proteins are one of a group of organic compounds of carbon, hydrogen, oxygen and nitrogen with sulfur and phosphorus possibly present. The protein molecule is a complex structure made up of one or more chains of amino acids, which are linked by peptide bonds. Many of the important molecules in a living thing — for example, all enzymes — are proteins.

Unicellular, colonial or multicellular organisms including protozoa and most algae; a type of eukaryote.

A common subatomic particle found in the nucleus of every atom, often along with neutrons. A proton has a positive charge.

Proved oil and gas reserves
Proved reserves are estimated volumes of crude oil, natural gas and gas condensates, liquids and associated substances which are expected to be retrieved from deposits and used commercially, at the economic and technical conditions applicable at the time and according to current legislation. Proved reserves include: (i) proved developed reserves: amounts of hydrocarbons that are expected to be retrieved through existing wells, facilities and operating methods; (ii) non developed proved reserves: amounts of hydrocarbons that are expected to be retrieved following new drilling, facilities and operating methods. On these amounts the company has already defined a clear development expenditure program which is expression of the company’s determination.

Public health approach
Focuses on effective and feasible risk management actions at the community level to reduce exposures and risks, with priority given to reducing exposures with the biggest impacts in terms of the number of people affected and severity of effect.

Mechanically or chemically produced mass of fibre for production of paper and/or board (thick, stiffish paper widely used for packaging purposes).

Any apparatus intended for slushing pulp or paper.

Process of transforming raw papermaking materials into pulp (see).

Pump and treat
Conventional system of cleaning polluted aquifers by pumping out water, removing the pollutant using non-biological methods such as air stripping or chemical treatment, and returning water to the aquifer.

Pumping stations
The combination of two or more pumps used to boost the discharge from tanker pumps to base-terminal storage, or used along the pipeline for added throughput.

The process of making pure, free from anything that debases, pollutes, or contaminates.

Pyroclastic material
Volcanic rock that has been fragmented by explosions during an eruption or by the collapse and disintegration of the flanks of domes or lava flows.

It’s a pre-treatment of waste at a moderate temperature (450C-750C) in total absence of oxygen. The decomposition of the contained organic matter leads to the production of a gaseous and a solid phase. The pyrolysis technique valorises the heat content within the waste by producing a stable storable solid fuel and an excess of gas to be burned.

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